Systems and methods of surface-engineered energetic composites for heating and combustion in underwater and liquid environments

Abstract

Provided are systems and method for surface-engineered energetic composites for combustion in underwater or other liquid environments. A method of preparing a surface-engineered energetic composite includes combining a metal fuel and an oxidizer to achieve a metal-oxidizer composite, and coating the metal-oxidizer composite with a surface-engineered layer to generate a surface- engineered metal-oxidizer composite. A energetic composite system includes an energetic composite comprising a fuel component and an oxidizer component, a surface-engineered layer on at least a portion of the energetic composite, and an ignition source; wherein upon heating to a first threshold temperature by the ignition source, the surface-engineered layer decomposes to generate a localized insulating vapor region, and upon heating to a second threshold temperature, the fuel and oxidizer components exothermically react within the insulating vapor region.

Description

Systems and Methods of Surface-Engineered Energetic Composites for Heating and Combustion in Underwater and Liquid EnvironmentsTechnical Field

[0001] The embodiments disclosed herein relate to heating and / or combustion in underwater or liquid environments, and, in particular to systems and methods for surface-engineered energetic composites for heating and / or combustion in underwater or liquid environments.Introduction

[0002] Thermal energy generation underwater is highly desired for certain application such as deep sea mining, construction and manufacturing (e.g., welding), high-thrust systems, propulsion, and medical treatment. However, conventional combustion systems which provide thermal energy are ineffective underwater as they require gaseous oxygen, would lose heat to surrounding liquid, require hydrolysis and oxidation of reactive materials, are hydraulically confined, and would result in quenched reaction fronts.

[0003] During thermal generation underwater cavitation may occur. Cavitation, created either intentionally or unintentionally, causes localized pressure changes and sudden energy releases that can cause damage. Quantification and characterization of underwater energy generation methods and their cavitation effects have been studied extensively to predict performance and prevent unexpected failures. Typically, in research laboratories, pressure driven hydrodynamic techniques, acoustic and electrochemical methods, and mechanical agitation are used to generate bubbles or cavities in water. Research has focused on dynamic characteristics of explosive gases underwater and subsequent bubble and cavitation generation. However, effective materials and approaches for achieving controllable underwater combustion are limited to gas-cavity interactions only. As such, combustion-induced cavitation has not been appropriately studied and is not fully understood.

[0004] Additionally, while combustion has served as the major source of energy for hominids for over a million years, and is still playing a critical role in modern society, there is growing concern for reducing carbon emissions. The combustion of solid energetic materials, especially metal-fuel-based solid energetic nanocomposites, has, therefore, gained attention. Metastable intermolecular composites (MICs), including metal / metal oxide thermites are capable of selfsustained redox reactions independent of gaseous oxygen.

[0005] Compared to traditional combustible materials (e.g., fossil fuels) metal fuels, for example aluminum (Al)-based solid nanocomposites, exhibit versatility of combustion in environments without the presence of gaseous oxygen, rapid heat generation rate, and high energy release. As described above, the utilization of combustion in underwater environments is particularly attractive due to the tremendous potential thermal and mechanical application. However, typical metal fuels used, such as aluminum and magnesium, are highly reductive metals, which can be easily oxidized and deactivated by water, thereby disallowing further exothermic reaction and potential applications. Furthermore, the hydrophilicity of metal and metaloxide, which is the typical oxidizer used in energetic nanomaterial composites, enables enhanced thermal conductivity between the material and surrounding water, preventing the material from reaching the typical combustion temperature above 500°C. Surface engineering such as hydrophobicity modification is required to allow the potential use of energetic nanomaterials in underwater environments. Therefore, there is a need for energetic compositions which are capable of sustained storage underwater, direct ignition while submerged in liquid, rapid and tunable heat release, and controlled vapor cavity generation.

[0006] The generation of underwater cavities by combustion has not been studied. Accordingly, there is a need for systems and methods which allow for underwater combustion to generate cavities for use in underwater applications.Summary

[0007] Provided herein is a method of preparing a surface-engineered energetic composite for combustion in underwater or liquid environments, the method including combining a metal fuel and an oxidizer to achieve a metal-oxidizer composite, and coating the metal-oxidizer composite with a surface-engineered layer to generate a surface-engineered metal-oxidizer composite. The surface-engineered layer may be a hydrophobic substance.

[0008] The method may further comprise pressing the surface-engineered metal-oxidizer composite into a pellet.

[0009] The metal fuel and oxidizer may be nanoparticles and the surface-engineered energetic composite may be a nanocomposite.

[0010] The metal-oxidizer composite may be dispersed within a solution comprising the surface-engineered substance and a solvent, wherein the surface-engineered substance coats the metal-oxidizer when the solvent evaporates.

[0011] The metal-oxidizer composite may have a core-shell structure wherein the metal is the core and the oxidizer is the shell.

[0012] The surface-engineered layer may coat the surface of the shell.

[0013] The metal fuel may be one of aluminum, iron, magnesium, boron, titanium, zirconium, and alloys thereof.

[0014] The metal fuel may be in the form of one of spherical nanoparticles, flakes, nanowires, porous structures, and alloyed composites.

[0015] The oxidizer may be one of CuO, Fe2O3, Co304, MnO2, Mo03, Bi2O3, metal nitrates, metal fluoropolymers, and a composite oxidizer.

[0016] The oxidizer may be in the form of one of layered, nanowire, a porous scaffold, and an embedded matrix.

[0017] The surface-engineered layer may comprise one of a hydrophobic substance, fatty acids, fluoropolymers, silanes, alkyl phosphonates, organophosphonates, PTFE, long-chain hydrocarbons, perfluorinated compounds, amphiphilic polymers, silane-modified polymers, biocompatible hydrophobic coatings, and biodegradable amphiphilic polymers.

[0018] The surface-engineered layer on the metal-oxidizer composite may be in the form of one of a continuous layer, partial coverage, multi-layer coating, and conformal film.

[0019] The metal fuel may be aluminum and the oxidizer may be copper oxide.

[0020] The surface-engineered layer may be stearic acid.

[0021] The metal-oxidizer composite may be a thermite.

[0022] The thermite may be one of a nanothermite and a microthermite.

[0023] The combustion performance of the surface-engineered metal-oxidizer composite may be tunable by altering the weight percentage of the surface-engineered coating.

[0024] Provided herein is a method of combusting the surface-engineered energetic composite, as described above, including placing the surface-engineered metal-oxidizer underwater or in a liquid environment, and igniting the surface-engineered metal-oxidizer by an ignition source.

[0025] The ignition source may be one of a laser radiation, electrical spark, resistive heating, inductive heating, microwave excitation, shock initiation, chemical primer, or electromagnetic radiation.

[0026] The ignition may be performed by one of thin-film resistive heaters, micro-spark electrodes, laser fiber delivery, inductive coils, and capacitive discharge pads.

[0027] When the surface-engineered metal-oxidizer composite is ignited the surface-engineered coating may decompose and form a vapor bubble surrounding the material.

[0028] After the surface-engineered coating decomposes, the metal fuel and the oxidizer may react to release heat and generate a cavity by rapid vapor expansion.

[0029] Growth characteristics of the cavity may be tunable by altering at least one of the surface-engineered coating thickness, the surface-engineered coating percentage, the metal fuel to oxidizer ratio, the geometry of the surface-engineered metal-oxidizer composite, and the structural architecture of the surface-engineered metal-oxidizer composite.

[0030] The ignition of the surface-engineered metal-oxidizer composite may be applied for at least one of controlled cavity generation, energy production, heating, propulsion, and actuation.

[0031] Provided herein is an energetic composite system including an energetic composite comprising a fuel component, an oxidizer component in reactive proximity to the fuel component, a surface-engineered layer disposed on at least a portion of the energetic composite, and an ignition source, wherein upon heating the surface-engineered energetic composite to a first threshold temperature by the ignition source, the surface-engineered layer decomposes to generate a localized insulating vapor region, and upon heating the surface-engineered energetic composite to a second threshold temperature the fuel and oxidizer components exothermically react within the insulating vapor region.

[0032] The energetic composite may have a core-shell structure including a metal particle core, and a metal oxide particle shell, wherein the core-shell structure is coated by a hydrophobic substance.

[0033] The coated core-shell structure composite may be pressed into a pellet to be used for combustion underwater or in liquid environments.

[0034] The fuel component may be aluminum, the oxidizer component may be copper oxide, and the surface-engineered layer may be stearic acid.

[0035] Upon heating to between 180-300C, the stearic acid coating may decompose and release gas to form a vapor bubble around the core-shell structure, and upon decomposition of the stearic acid, at approximately 600C, the aluminum and the copper oxide exothermically may react to release energy and combustion gases to expand the vapor bubble into a vaporous cavity.

[0036] The generation of heat and of the cavity may be used for at least one of propulsion, energy generation, actuation, welding, material processing, mining, medical procedures, drug delivery, microfluidics, and high-thrust applications.

[0037] The energetic composite may be ignitable by at least one of laser radiation, electrical spark, resistive heating, inductive heating, microwave excitation, shock initiation, chemical primer, or electromagnetic radiation.

[0038] Ignition of the hydrophobic metal-oxidizer composite may be applied for at least one of controlled cavity generation, energy production, heating, propulsion, and actuation.

[0039] The combustion characteristics may be tunable by altering at least one of surface-engineered layer thickness, surface-engineered coating percentage, the metal to metal oxide ratio, and the structural architecture of the surface-engineered metal-oxidizer composite.

[0040] The metal may be one of aluminum, iron, magnesium, boron, titanium, zirconium, and alloys thereof.

[0041] The metal oxide may be one of CuO, Fe2O3, Co304, MnO2, Mo03, and Bi2O3.

[0042] The surface-engineered layer may comprise one of a hydrophobic substance, fatty acids, fluoropolymers, silanes, alkyl phosphonates, organophosphonates, PTFE, long-chain hydrocarbons, perfluorinated compounds, amphiphilic polymers, silane-modified polymers, biocompatible hydrophobic coatings, and biodegradable amphiphilic polymers.

[0043] The surface-engineered coating may be in the form of one of a continuous layer, partial coverage, multi-layer coating, and conformal nanoscale film.

[0044] The energetic composite may be at least one of: nano-scale or micro-scale in size.

[0045] The energetic composite may comprise a layered or segmented architecture configured for staged ignition.

[0046] Sequential segments of energetic composite may be independently ignitable to shape a pressure-time or heat-time output profile.

[0047] A controller may be configured to program ignition timing of multiple energetic segments.

[0048] The system may further comprise a gas delivery system configured to direct generated gas to a downstream pneumatic load.

[0049] The system may include a pressure conditioning element configured to shape a gas pressure-time profile.

[0050] The system may generate gas wherein generated gas inflates a buoyancy control bladder or drives a subsea actuator.

[0051] The system may further comprise an electric propulsion subsystem and a controller configured to allocate thrust or power between the electric propulsion subsystem and the energetic system.

[0052] The system may further comprise a cavity-generation port configured to discharge vapor adjacent a vehicle body to reduce hydrodynamic drag.

[0053] The system may further comprise a power conditioning subsystem and a power distribution interface.

[0054] Electrical output may be transmitted via a wired subsea conductor.

[0055] The electrical output may be transmitted wirelessly through inductive or resonant magnetic coupling.

[0056] The system may further comprise a communication transceiver configured to exchange power management data with remote nodes.

[0057] Multiple systems may be configured in a distributed energy network.

[0058] The fuel or oxidizer component may be derived from microbiologically assisted metal extraction.

[0059] Extremophilic microorganisms may be used to concentrate or transform metal-bearing minerals prior to refinement.

[0060] Other aspects and features will become apparent to those ordinarily skilled in the art, upon review of the following description of some exemplary embodiments.Brief Description of the Drawings

[0061] The drawings included herewith are for illustrating various examples of articles, methods, and apparatuses of the present specification. In the drawings:

[0062] Figure 1A is a scanning electron microscopy (SEM) image of AI»CuO, according to an embodiment;

[0063] Figure 1B is a scanning electron microscopy (SEM) image of AI»CuO»SA, according to an embodiment;

[0064] Figure 1C is a scanning transmission electron microscopy (STEM) image of AI»CuO»SA, according to an embodiment;

[0065] Figure 1D is a scanning transmission electron microscopy (STEM) image of AI»CuO»SA, showing, aluminum, copper, oxygen, and carbon layers together, according to an embodiment;

[0066] Figure 1E is a scanning transmission electron microscopy (STEM) image of AI»CuO»SA, showing, aluminum, copper, oxygen, and carbon layers separately, according to an embodiment;

[0067] Figure 1F is a differential scanning calorimetry (DSC) curve of various compositions of AI.CuO.SA and controls, according to an embodiment;

[0068] Figure 1G is a thermogravimetry analysis (TGA) curve of various compositions of AI»CuO»SA and controls, according to an embodiment;

[0069] FIG. 2 are representative images of combustion of an AI»CuO»SA(5%) pellet, according to an embodiment;

[0070] Figure 3A is a graph of cavity volume over time of various compositions of AI»CuO»SA, according to an embodiment;

[0071] Figure 3B is a bar graph of cavity growth rates of various compositions of AI»CuO»SA, according to an embodiment;

[0072] Figure 3C is a graph of AIO emission over time for combustion of AI»CuO»SA, according to an embodiment;

[0073] Figure 3D is a graph of cavity volume versus time of reaction for various compositions of AI.CuO.SA, according to an embodiment;

[0074] Figure 4A is a thermal image of ignition of AI»CuO»SA combustion, according to an embodiment;

[0075] Figure 4B is a thermal image of propagation of AI»CuO»SA combustion, according to an embodiment;

[0076] Figure 4C is a graph of temperature throughout AI»CuO»SA combustion, according to an embodiment;

[0077] Figure 4D is a diagram of the thermal camera setup for AI»CuO»SA combustion, according to an embodiment;

[0078] Figure 5 are images of the stages of AI»CuO»SA combustion underwater and a graph of the stages overtime versus cavity volume overtime, according to an embodiment;

[0079] Figure 6A is a diagram of the process of preparing an AI»CuO»SA core-shell composition, according to an embodiment;

[0080] Figure 6B is a diagram of the thermal camera setup for capturing AI»CuO»SA combustion, according to an embodiment;

[0081] Figure 6C is an image showing the depth of an AI»CuO»SA pellet for combustion, according to an embodiment; and

[0082] Figure 7 is a flow diagram of a method of preparing and combusting a surface-engineered energetic composite, according to an embodiment.Detailed Description

[0083] Various apparatuses or processes will be described below to provide an example of each claimed embodiment. No embodiment described below limits any claimed embodiment andany claimed embodiment may cover processes or apparatuses that differ from those described below. The claimed embodiments are not limited to apparatuses or processes having all of the features of any one apparatus or process described below or to features common to multiple or all of the apparatuses described below.

[0084] Provided herein are systems and methods for underwater heating and combustion. As described above there are various applications of underwater combustion, which will be further discussed herein. Additionally, the systems and methods for underwater heating and combustion described herein are generally realized through the use of nanocomposites or thermites.

[0085] Nanoenerqetic Composites / Thermites

[0086] Thermites traditionally comprise a metal as a fuel and a metal oxide as an oxidizer which together produce highly exothermic reactions which can generate extreme heat without atmospheric oxygen. Therefore, thermites are a prime candidate as a fuel for underwater combustion or even combustion in a vacuum. Thermite heating and / or combustion could be applied to underwater propulsion, energy generation and storage, welding and joining application, etc.

[0087] The thermites described herein are metastable intermolecular composites (MIC) and can be any of nanothermites, microthermites, or any other form of thermite, with the systems and methods described herein not limited to a specific thermite, although specific thermites are discussed by way of example. Nanothermites are on a scale of 100 nanometers or below, while microthermites are on a scale of micrometers. The thermites described herein may also be ordered thermites.

[0088] Suitable metals for a thermite include aluminum, iron, magnesium, boron, titanium, zirconium, and alloys thereof, among other metals. The metal fuel may be in the form of spherical nanoparticles, flakes, nanowires, porous structures, and alloyed composites. Suitable oxidizers may include CuO, Fe2O3, Co304, MnO2, Mo03, Bi2O3, metal nitrates, metal fluoropolymers, and composite oxidizers. The oxidizer may be in the form of core-shell, layered, nanowire, porous scaffold, or embedded matrix.

[0089] Power generation from thermites produces clean energy, does not produce toxic chemicals, and does not produce greenhouse gas emissions. The power generated can be on-demand and continuous. Temperature controlled volumetric heating by thermites reactions results in increased efficiency and complete combustion compared to current methods. Thermite power generation can be integrated into current infrastructures. Thermites can be used for power generation in a thermal power station and to convert heat to electrical power. Electrical power can be converted from heat by combusting or convection of the nano-energetic composites of thermites. Thermites can be combined with an inert liquid or gas carrier. Metallic fuel power generation can be achieved by simple oxidation of metallic powders or by energetic release from existing metallic molecular nano or micro particles operating in a fluid at certain levels of dispersion.

[0090] Energetic composites may be used as primary propulsion sources in liquid environments by harnessing the chemical energy released during controlled exothermic reactions to generate thrust. Such propulsion systems may operate independently of dissolved or atmospheric oxygen, enabling reliable function at depth, beneath ice, or in enclosed liquid systems.

[0091] Propulsion can be achieved by thermite reaction whereby an engine is powered by thermite reaction. Additionally, the byproducts can be captured and recycled using a power generation system with wireless power transmission to produce thrust and power, coupled, mixed or in suspension. Such a system could be used for rockets, in both single stage and multi-stage systems. A propulsion system could also be used for non-rocket launch systems, such as balloon launching, and use of impulse drivers.

[0092] In certain embodiments, an energetic composite comprising a fuel component and an oxidizer component in reactive proximity may be ignited within a pressure-rated reaction chamber. Upon activation, the composite may undergo a two-stage reaction sequence in which a surface-engineered layer first generates a localized insulating vapor region, followed by a primary exothermic reaction that produces high-temperature gases. These gases may be directed through a nozzle assembly to produce thrust in accordance with conservation of momentum principles. The system may be configured for pulsed or sequential operation using multiple independently ignitable chambers to regulate thrust magnitude and duration.

[0093] In certain embodiments, propulsion may be generated by igniting an energetic composite within a sealed or semi-confined reaction chamber that is fluidly coupled to a nozzle. Upon activation, the composite undergoes an exothermic reaction that generates high-temperature gases. These gases expand and are directed through a nozzle, producing thrust according to momentum conservation principles.

[0094] The energetic composite may be configured in pelletized or segmented form to allow discrete impulse events or quasi-continuous thrust through sequential ignition. The chamber may include a surface-engineered layer that enables formation of an insulating vapor region prior to full reaction, permitting stable combustion while submerged. This configuration is analogous to a rocket-type propulsion system, except it operates fully submerged and is oxygen-independent.

[0095] In certain embodiments, propulsion may be achieved through vapor-jet mechanisms in which the energetic composite serves primarily as a high-intensity thermal source. Rather than relying solely on reaction-product gases as reaction mass, the system may be configured to transfer reaction heat to surrounding liquid within a controlled vaporization chamber. The rapid phase change of liquid to vapor may generate high-pressure working fluid, which may then be expelled through an exhaust port to produce thrust. In this configuration, the surrounding liquid effectively serves as reaction mass, while the energetic composite provides the thermal energy required for phase transition. Such systems may be advantageous where minimizing onboard stored propellant mass is desirable, as the ambient liquid may be utilized as the expelled medium.

[0096] In other embodiments, propulsion may be produced in a pulsed mode through rapid pressure generation within confined micro-chambers. Upon ignition, the energetic composite may produce a discrete pressure spike that expels gas or vapor through an exhaust aperture, generating a thrust impulse. By arranging multiple micro-chambers in a controllable sequence, a vehicle may generate repeated pulses that approximate continuous thrust. The frequency and timing of such pulses may be governed by a controller that regulates ignition intervals in response to vehicle dynamics and mission requirements. This pulsed architecture may enable high peak thrust events while limiting structural loading through controlled impulse shaping.

[0097] In certain embodiments, a quasi-continuous propulsion system may be achieved through staged micro-chamber activation. A plurality of energetic composite chambers may be arranged axially or circumferentially within a propulsion module, and ignition may proceed in rapid succession across chambers to create a sustained thrust output. Each chamber may include a vapor-forming surface layer to enable stable reaction in submerged conditions and a confined exhaust pathway for directing reaction products. By staggering activation timing, thrust output may be smoothed, reducing oscillatory loads and improving vehicle stability during operation.

[0098] Energetic composites may also be used to enable cavity-assisted propulsion within liquid environments. In such embodiments, controlled vapor generation may create a low-density region adjacent to the vehicle surface, reducing hydrodynamic drag. Once a vapor cavity is established, reaction gases may expand within the cavity rather than directly against the surrounding liquid, potentially improving expansion efficiency and increasing attainable velocity. The energetic system may be configured to regulate vapor production in response to ambient pressure and vehicle speed, maintaining cavity stability while providing thrust.

[0099] In certain configurations, energetic composites may serve as a pressure amplification mechanism for liquid ejection propulsion. An energetic reaction occurring within a sealed chamber may increase internal pressure and thereby expel a stored liquid through a nozzle. In this embodiment, the expelled liquid rather than the reaction products serves as the primary reaction mass. The energetic composite functions as a compact pressure source, enabling high-thrust liquid jets without requiring large compressed gas storage volumes. Such systems may be particularly advantageous in high-pressure environments where external hydrostatic forces influence nozzle performance.

[0100] In advanced embodiments, reaction products generated by energetic composites may be electrically influenced to improve exhaust shaping. Following ignition, conductive reaction gases or plasma-like regions may be subjected to electromagnetic fields to influence exhaust direction or expansion characteristics. This hybrid approach combines the high energy density of energetic composites with electrical control elements, potentially enabling improved thrust vectoring or modulation in submerged conditions.

[0101] Across all propulsion embodiments, performance may be influenced by energetic composite density, particle size distribution, geometric configuration, chamber confinement ratio,nozzle design, ambient pressure, and liquid temperature. Surface-engineered layers that promote vapor barrier formation may enable stable reaction initiation under full submersion. Pressurerated housings and depth-compensated control strategies may allow operation across a range of hydrostatic pressures.

[0102] Energetic composite propulsion systems offer the advantage of oxygen independence, compact energy storage, high peak power capability, and adaptability to extreme environments. By tailoring composite architecture, ignition sequencing, and exhaust geometry, propulsion performance may be scaled for applications ranging from compact autonomous vehicles to larger liquid-environment platforms.

[0103] In certain embodiments, propulsion within a liquid environment may be achieved or augmented using one or more energetic composite modules configured to operate in submerged conditions. The energetic composite may comprise a fuel component and an oxidizer component in reactive proximity and may be configured to undergo a controlled exothermic reaction upon activation. The reaction may produce high-temperature gases, vaporized liquid, pressure pulses, or thermal gradients that are harnessed to generate thrust either directly or in combination with a primary propulsion system.

[0104] In certain embodiments, propulsion may be generated directly through controlled ignition of an energetic composite within a sealed or partially confined chamber. Upon activation, the composite may undergo a two-stage reaction sequence in which a surface-engineered layer forms a localized insulating vapor region followed by a primary exothermic reaction between fuel and oxidizer components. The resulting high-pressure gases or vapor may be directed through a nozzle or exhaust port to produce thrust. The system may be configured for pulsed or sequential operation through multiple independently ignitable energetic chambers.

[0105] The energetic composite may be formulated to operate under hydrostatic pressure and in direct contact with liquid, enabling oxygen-independent propulsion at depth.

[0106] In certain embodiments, an energetic composite propulsion module may be integrated with an electric propulsor such as a propeller or pump-jet system. The energetic module may provide supplemental impulse thrust during periods of increased acceleration demand. A controller may allocate thrust between the electric motor and the energetic module based on sensed load, battery condition, or mission state.

[0107] The energetic composite may generate high-pressure vapor directed aft of the vehicle to provide parallel thrust to the primary propulsor. Such hybrid architectures may reduce peak electrical load and allow smaller electric motors while maintaining burst-speed capability.

[0108] In certain embodiments, energetic composite exhaust may be injected into the intake or discharge region of a propeller or pump-jet system. The injection of reaction-generated vapor may modify fluid density or velocity profiles within the propulsor duct, increasing effective mass flow rate and transient thrust output. The energetic composite may be activated in short pulsessynchronized with propulsor rotational speed to optimize augmentation while maintaining flow stability.

[0109] In certain embodiments, the energetic composite may generate vapor sufficient to form or stabilize a vapor cavity adjacent to a cavitator or leading surface of the vehicle. By reducing wetted surface area and hydrodynamic drag, the cavity may enable increased velocity using the primary propulsion system. The energetic composite may be activated intermittently to sustain or expand the cavity as ambient pressure changes with depth.

[0110] In certain embodiments, the energetic composite may function as a pressure amplification stage within a reaction-jet propulsion system. A sealed chamber containing the energetic composite may discharge reaction-generated gases into a working fluid reservoir or directly into a nozzle assembly. The energetic reaction may supplement stored compressed gas, enabling higher peak thrust without requiring large pressure vessels.

[0111] In certain embodiments, micro-scale energetic composite chambers may be distributed along an exterior surface of a vehicle. Upon controlled activation, vapor generated by the energetic composite may be injected into the boundary layer adjacent to the vehicle hull, reducing skin friction drag and increasing propulsion efficiency. Activation frequency and magnitude may be regulated by a control system responsive to vehicle speed and ambient pressure.

[0112] In certain embodiments, oscillatory propulsion systems, including fins or hydrofoils, may be augmented by energetic composite pulses synchronized with stroke cycles. Reactiongenerated jets may be emitted during peak stroke angles to reinforce vortex shedding and increase net thrust. The timing of energetic activation may be coordinated with actuator motion to maximize efficiency while limiting mechanical stress.

[0113] In certain embodiments, energetic composite propulsion modules may be housed within self-contained pods attachable to a vehicle. Each pod may include sealed energetic chambers, ignition electronics, exhaust nozzles, and communication interfaces. The pods may operate independently or in coordination with the primary propulsion system. Modular architecture may allow scalable thrust capability or retrofit integration onto existing platforms.

[0114] Methods of synthesis of thermite fuel may include additive manufacturing, physical mixing, chemical, emissive, and missive methods, vapor deposition, pyrolysis, microwave-assisted synthesis, ball milling, exfoliation, sono-chemical, arc-discharge, among others. Thermite fuels may include components or components which arise from: reactive metal compounds; materials with magnetic properties; solids, gases, and liquids; synthetic and nonsynthetic polymers and thermoplastics; mixtures of layers of metals; multi-coated metals with metamaterials; hybrid mixtures of reactive metal compounds in liquid and inert states; in situ space resources; heterogeneous materials including solid propellants, explosive formulations, engineering ceramic precursors, composites, semi-solid metals, conductive pastes, pharmaceuticals, and food slurries, with different particle length scales; two or more componentswith distinct properties (e.g., a soft binder for cohesion and flow, and hard particulates); heterogeneous materials having large contact surface area and internal / external friction high resistance to flow; thermoplastics, natural and synthetic polymers, hydrogels; metal powders, as well as other complex compounds in the form of nanothermites and microthermites.

[0115] Sources of thermite fuel may include:

[0116] Seawater Extraction (Aluminum from Dissolved Minerals)

[0117] In certain embodiments, aluminum used as the fuel component of the energetic composite may be derived from dissolved or sediment-bound aluminum sources present in marine environments. Because dissolved aluminum in seawater exists at extremely low concentrations, typically on the order of approximately 0.001 parts per million, a concentration and pre-processing stage may first be employed to increase aluminum ion density prior to reduction. Such concentration may be achieved using membrane-based filtration systems configured to selectively capture aluminum-bearing complexes, ion-exchange resins tuned for trivalent metal ions, chelating polymer matrices, electrochemical precipitation zones, or adsorption onto functionalized nanomaterials. In some embodiments, suspended marine sediments or aluminosilicate-rich particulates may be collected and processed to liberate aluminum species, thereby increasing available feedstock relative to dissolved concentrations alone. A multi-stage concentration architecture may be implemented to reduce the overall processing volume and improve downstream extraction efficiency.

[0118] Following concentration, aluminum-containing species may be converted into a reducible intermediate suitable for electrochemical refinement. In certain embodiments, dissolved aluminum species may be precipitated as aluminum hydroxide or aluminum oxide intermediates and subsequently transferred into an electrochemical reduction system. Electrolytic refinement may occur within molten salt systems, ionic liquid media, or other electrochemical cells configured for aluminum reduction. Alternative reduction approaches may include plasma-assisted reduction, solid oxide electrochemical systems, or solar-thermal-assisted electrolysis in which external heat sources reduce electrical demand. The electrochemical system may be powered by renewable marine energy sources, including solar arrays, wave-energy harvesters, or hybrid systems integrated into a floating or subsea platform. Reduced aluminum may be collected in particulate, ingot, or powder form depending on the requirements of subsequent energetic composite fabrication.

[0119] Once refined, the aluminum may undergo particle engineering processes to achieve a size distribution and morphology suitable for energetic applications. In certain embodiments, nanoscale aluminum particles may be generated via gas-phase condensation, plasma atomization, laser ablation in inert environments, electro-explosive wire techniques, or vaporphase deposition onto carrier substrates. Alternatively, larger aluminum particles may be mechanically milled or processed under controlled conditions to achieve the desired reactivesurface area. Oxide shell thickness may be controlled through passivation processes to balance stability and reactivity prior to incorporation into the energetic composite.

[0120] In some embodiments, artificial intelligence or machine-learning systems may be integrated into the extraction and refinement platform to optimize aluminum recovery efficiency. Such systems may monitor parameters including aluminum ion concentration, pH, salinity, membrane performance, electrochemical current density, temperature, and energy consumption. A closed-loop optimization algorithm may dynamically adjust filtration rates, ion-exchange cycling, electrolysis parameters, and energy allocation across subsystems to maximize aluminum yield relative to power input. Continuous performance monitoring may enable adaptation to changing marine conditions, thereby improving overall system efficiency despite low feedstock concentration.

[0121] The aluminum recovery system may be integrated into a floating marine platform or autonomous subsea module. A floating platform may include seawater intake systems, multistage filtration and concentration units, electrochemical reduction chambers, aluminum collection modules, and onboard energy harvesting systems. Such a platform may operate autonomously, storing refined aluminum for periodic transfer to energetic composite manufacturing units. In alternative embodiments, subsea modules may extract aluminum from marine sediments using dredging, slurry processing, or in-situ electrochemical techniques, particularly in regions with elevated mineral content.

[0122] The extraction framework may also be extended to extraterrestrial liquid environments. Subsurface ocean probes may extract dissolved or particulate metal species from brine environments, while cryogenic liquid processors may recover metallic species suspended in hydrocarbon lakes. In planetary exploration contexts, locally sourced aluminum or other reactive metals may be refined and incorporated into energetic systems for propulsion, heating, or power generation, thereby reducing the mass of consumables that must be transported from Earth.

[0123] Recovered aluminum may be integrated directly into the energetic composite manufacturing pipeline. This integration may include blending with oxidizer precursors, forming core-shell architectures, applying surface-engineered liquid-repellent layers, and fabricating cartridges or micro-chambers for propulsion or power modules. In certain embodiments, aluminum extraction, refinement, and energetic composite fabrication may be implemented within a closed-loop modular system, enabling sustained production of liquid-operable energetic fuel from environmental resources in terrestrial or extraterrestrial settings. The recovery system and methodologies may be adapted to support recovery of other metals that are suitable for fuel for energetic composites.

[0124] Bauxite & Marine Clay Deposits

[0125] In certain embodiments, aluminum used as the fuel component of the energetic composite may be derived from naturally occurring mineral deposits, including bauxite and aluminum-rich marine clay formations. Bauxite, typically composed of hydrated aluminum oxidesrepresented generally as AI2O3xH2O, is the principal industrial source of aluminum and may be found not only in terrestrial surface deposits but also in coastal, deltaic, and submerged sedimentary environments. Coastal erosion, river discharge, and sediment transport processes can result in accumulation of bauxite-bearing materials in nearshore and shallow subsea regions. In such environments, aluminum-rich sediments may be accessed through subsea extraction systems and subsequently processed to recover aluminum suitable for energetic applications.

[0126] Marine clay deposits and deep-sea sedimentary formations may also contain significant quantities of aluminum in the form of aluminosilicate minerals. In particular, deep-sea hydrothermal vent systems are known to deposit complex mineral assemblages that include aluminum-bearing silicates and oxides. These deposits may form over extended geological timescales and may be concentrated in localized regions of the seabed. In certain embodiments, autonomous underwater vehicles or remotely operated mining drones may be configured to identify, collect, and transport aluminum-rich sediments from such deposits. These systems may employ sonar mapping, spectroscopic sensing, or chemical detection to locate mineral concentrations suitable for recovery.

[0127] Once collected, bauxite-rich or aluminosilicate-bearing sediments may undergo mechanical and chemical processing to isolate aluminum-containing phases. Processing may include crushing, grinding, and separation steps to concentrate aluminum oxides, followed by chemical refinement techniques designed to separate aluminum from silica and other associated minerals. In certain embodiments, hydrometallurgical processes may be used to dissolve aluminum oxides into solution for subsequent precipitation and purification. Alternatively, thermal processing or electrochemical refinement systems may be integrated into a marine or floating platform to convert aluminum-bearing minerals into aluminum oxide intermediates suitable for electrolytic reduction.

[0128] Following refinement to aluminum oxide or similar intermediates, aluminum metal may be produced through electrochemical reduction systems configured for subsea or surface operation. The reduction system may be powered by onboard energy sources such as solar arrays, wave-energy converters, geothermal gradients, or hybrid energy systems integrated into the mining platform. In certain embodiments, the extraction, refinement, and reduction stages may be combined into a modular processing architecture capable of operating in remote marine environments with minimal human intervention.

[0129] Autonomous underwater mining drones may be configured to collect sediment selectively, minimizing disturbance to surrounding environments. These drones may incorporate sediment intake systems, onboard pre-processing modules to remove excess water and unwanted material, and storage compartments for transport to a central processing platform. Artificial intelligence systems may assist in identifying high-yield deposits by analyzing mineral composition data and optimizing collection routes.

[0130] In certain embodiments, aluminum recovered from bauxite or marine clay deposits may be processed into particulate form suitable for energetic composite fabrication. The refined aluminum may be engineered into powders or structured forms, passivated to control oxide shell thickness, and subsequently combined with oxidizer components to produce liquid-operable energetic composites as described elsewhere in the specification. Sourcing aluminum from marine or subsea mineral deposits, the energetic system may reduce reliance on externally supplied fuel and enable localized production of reactive materials for subsea propulsion, heating, power generation, or extraterrestrial exploration systems.

[0131] This mineral-based extraction approach may also be extended conceptually to extraterrestrial ocean or seabed environments, where aluminum-bearing silicates or hydrated oxide deposits may exist beneath ice shells or within hydrothermal systems. In such contexts, robotic mining and in-situ refinement systems may enable the generation of aluminum feedstock for energetic applications without requiring large quantities of material to be transported from Earth, thereby supporting long-duration missions and closed-loop resource utilization strategies.

[0132] Recycling Aluminum from Shipwrecks & Debris

[0133] In certain embodiments, aluminum used as the fuel component of the energetic composite may be obtained through recovery and recycling of aluminum-containing structures present in marine environments. Sunken ships, aircraft, offshore platforms, and industrial debris frequently contain substantial quantities of aluminum alloys used in structural frames, superstructures, panels, fasteners, piping, and equipment housings. Over time, such materials may remain partially intact within subsea environments, providing a concentrated secondary aluminum resource compared to dissolved seawater sources.

[0134] Autonomous or remotely operated robotic systems may be deployed to identify, assess, and recover aluminum-bearing scrap from submerged structures. These systems may incorporate imaging sensors, sonar mapping, magnetic anomaly detection (for mixed-metal discrimination), spectroscopic analysis, or material-recognition algorithms to distinguish aluminum alloys from other structural metals such as steel or copper-based materials. Artificial intelligence-assisted classification systems may analyze structural geometry, corrosion signatures, and spectral data to optimize scrap selection and recovery efficiency.

[0135] Recovered aluminum components may undergo mechanical processing to reduce size and remove contaminants. Processing may include cutting, shredding, abrasive cleaning, or separation of dissimilar metals. In certain embodiments, corrosion layers and marine growth may be removed prior to refining. Alloy compositions may be analyzed and categorized to determine appropriate downstream refining pathways.

[0136] Following collection and preprocessing, aluminum scrap may be subjected to electrolytic or thermal refinement processes to produce purified aluminum suitable for energetic composite fabrication. Refinement may involve remelting in controlled-atmosphere furnaces, molten salt electrolysis, ionic liquid electrochemical systems, or plasma-assisted purification.Impurities such as magnesium, silicon, copper, or iron present in marine-grade aluminum alloys may be reduced or removed depending on desired energetic performance characteristics.

[0137] In some embodiments, a mobile or floating processing platform may integrate scrap intake systems, alloy sorting modules, refining chambers, and aluminum powder production units. Artificial intelligence control systems may optimize refining parameters, including temperature profiles, electrochemical current density, impurity removal cycles, and energy consumption. Such closed-loop systems may continuously convert recovered marine aluminum scrap into refined aluminum feedstock.

[0138] The refined aluminum may then be engineered into particulate or nanostructured forms appropriate for incorporation into energetic composites. Particle formation methods may include atomization, plasma processing, gas-phase condensation, or controlled mechanical milling. The resulting aluminum particles may be passivated to achieve a controlled oxide shell thickness and subsequently blended with oxidizer components and surface-engineered liquidrepellent layers to form liquid-operable energetic materials.

[0139] In certain embodiments, recycling aluminum from submerged debris may provide a sustainable and resource-efficient pathway for producing energetic fuel in marine environments. This approach may be particularly advantageous for autonomous subsea platforms, long-duration marine missions, or remote industrial operations where transport of fresh aluminum feedstock is logistically challenging. The same conceptual framework may also be extended to extraterrestrial environments, where metallic debris from prior missions or structural elements may be repurposed as energetic fuel for propulsion, heating, or power-generation systems.

[0140] Rusted Metal from Underwater Structures

[0141] In certain embodiments, oxidizer components for the energetic composite may be sourced from iron oxide deposits formed on submerged metallic structures. Shipwrecks, abandoned pipelines, offshore platforms, and sunken machinery commonly exhibit extensive corrosion in marine environments, resulting in thick accumulations of iron oxide layers, including hydrated and anhydrous forms commonly referred to as rust. These corrosion products may accumulate over large surface areas and may be periodically shed into surrounding sediments, creating localized concentrations of iron oxide particulates. Alternatively, metallic structures may be submerged for the purpose of sourcing iron oxide deposits.

[0142] Autonomous or remotely operated subsea systems may be configured to collect iron oxide directly from corroded structures or from adjacent sediment deposits enriched in corrosion products. Collection mechanisms may include gentle abrasive harvesting tools, suction-based sediment intake systems, or detachable corrosion-layer removal modules designed to separate oxide scale from underlying metal without destabilizing structural remnants. In certain embodiments, spectroscopic or chemical sensors may be employed to identify oxide-rich regions and distinguish iron oxide from other mineral deposits or marine growth.

[0143] Following collection, the iron oxide material may undergo purification and processing to remove organic matter, salts, marine biofilms, and other contaminants. Processing may include washing, filtration, centrifugation, thermal drying, magnetic separation, and particle-size classification. In some embodiments, heat treatment may be used to convert hydrated iron oxides into more stable oxide phases suitable for energetic reactions. Particle morphology and size distribution may be controlled through milling or classification processes to achieve the desired reactive characteristics when combined with aluminum or alternative fuels.

[0144] The purified iron oxide may then be incorporated as the oxidizer component of a liquid-operable energetic composite. Depending on desired performance characteristics, the oxide may be blended with metal fuel in defined ratios, structured into core-shell or layered architectures, or combined with additional oxidizing agents to tailor reaction kinetics. Surface-engineered layers such as liquid-repellent layers may subsequently be applied to the composite to enable submerged ignition and controlled vapor-envelope formation as described elsewhere in the specification.

[0145] In certain embodiments, a self-sustaining ocean platform may integrate iron oxide harvesting, purification, and energetic composite fabrication within a single modular system. Such a platform may collect aluminum from environmental or recycled sources and oxidizer material from corrosion deposits, thereby producing both fuel and oxidizer components locally. Artificial intelligence control systems may optimize collection routes, monitor oxide purity, regulate processing parameters, and balance material inputs to maintain desired stoichiometry for energetic composite production.

[0146] This approach may enable closed-loop energetic material production in marine environments, reducing reliance on externally supplied oxidizer materials. The concept may also be extended to extraterrestrial or planetary environments in which oxidized metal deposits are present on submerged structures or mineral formations. In such contexts, corrosion-derived or naturally occurring iron oxide deposits may serve as locally sourced oxidizers for propulsion, heating, or power-generation systems operating in non-atmospheric liquid domains.

[0147] Hydrothermal Vents & Deep-Sea Mineral Deposits

[0148] In certain embodiments, the oxidizer component of the energetic composite may be derived from naturally occurring iron-rich mineral deposits associated with deep-sea hydrothermal vent systems. Hydrothermal vents discharge mineral-laden fluids into surrounding seawater, leading to the precipitation and accumulation of iron-bearing sediments and metal oxide deposits in the vicinity of vent fields. Overtime, these deposits may form substantial accumulations of iron oxides and related mineral phases distributed across the seabed near active or inactive vent systems.

[0149] Autonomous underwater mining systems or remotely operated vehicles may be configured to locate and collect iron-rich sediments from such vent-associated deposits. These systems may incorporate sonar mapping, chemical sensing, thermal gradient detection, ormineralogical analysis tools to identify regions with elevated iron oxide concentration. Collection mechanisms may include suction-based sediment intake modules, controlled dredging tools, or mechanical harvesting devices designed to selectively remove oxide-rich material while minimizing disturbance to surrounding geological structures.

[0150] Collected material may undergo onboard or surface-level processing to isolate and purify iron oxide phases suitable for energetic applications. Processing steps may include washing to remove salts and dissolved species, filtration, and centrifugation to separate fine particulates, magnetic separation to concentrate iron-bearing minerals, and thermal treatment to convert hydrated or mixed-phase iron compounds into defined oxide forms. Particle size and morphology may be controlled through milling, classification, or other refinement techniques to produce oxidizer material optimized for reaction with a selected fuel component.

[0151] The purified iron oxide may then be incorporated into the fabrication of liquid-operable energetic composites, either as a primary oxidizer or as part of a blended oxidizer system. The oxidizer may be combined with aluminum or alternative fuel materials in controlled ratios and structured into core-shell, layered, or composite architectures. Surface-engineered layers such as liquid-repellent layers may be applied to the resulting energetic composite to enable submerged ignition and controlled vapor-envelope formation, facilitating reliable energy release in liquid environments.

[0152] In certain embodiments, underwater mining robots and processing modules may operate as part of an integrated subsea platform capable of extracting oxidizer material from hydrothermal vent deposits and combining it with locally sourced or recycled fuel components. Artificial intelligence control systems may monitor mineral composition, optimize collection patterns, regulate processing parameters, and maintain stoichiometric balance during composite fabrication. Such systems may enable localized production of thermite-grade oxidizers for subsea propulsion, heating, power generation, or other energetic applications, reducing reliance on externally supplied materials and supporting long-duration marine or extraterrestrial missions.

[0153] Iron Sand & Seabed Sediments

[0154] In certain embodiments, the oxidizer component of the energetic composite may be derived from naturally occurring iron-bearing mineral deposits found in coastal and deep-sea environments. Certain coastal regions contain iron-rich black sands composed primarily of magnetite (Fe3O4) and other iron-bearing minerals. These deposits are often concentrated by wave and current action, resulting in localized regions of high magnetic mineral content. Such black sand deposits may be harvested using dredging systems, shoreline collection mechanisms, or subsea intake modules integrated into floating or nearshore processing platforms.

[0155] Magnetic separation systems may be employed to concentrate magnetite from collected sand. Because magnetite exhibits strong magnetic properties relative to most surrounding silicate materials, magnetic drums, conveyor-mounted magnets, or electromagnetic separators may be used to isolate iron-rich fractions from bulk sediment. In certain embodiments,multi-stage magnetic separation may be combined with sieving or density-based classification to improve purity. The recovered magnetite may then undergo thermal or chemical processing to convert Fe3O4into other iron oxide phases, including Fe2O3, depending on the desired oxidizer characteristics for the energetic composite. Controlled oxidation or calcination processes may be used to achieve the appropriate phase composition and particle morphology.

[0156] In addition to coastal black sands, deep-sea ferromanganese nodules represent another potential source of iron-bearing material. These nodules, which accumulate on the ocean floor over long geological periods, contain significant concentrations of iron and manganese oxides along with other trace metals. Autonomous underwater vehicles or remotely operated mining systems may be configured to collect ferromanganese nodules from the seabed. Following recovery, mechanical crushing and separation processes may be used to isolate iron-containing fractions. Magnetic separation, chemical leaching, or selective precipitation techniques may further refine iron oxide content for use as an oxidizer component.

[0157] In certain embodiments, a floating or semi-submersible refinery platform may integrate sediment intake systems, magnetic separation modules, particle classification units, and oxide refinement chambers into a single processing architecture. Seabed sand or nodules may be transported to the platform, where magnetic extraction isolates iron-bearing minerals. Subsequent thermal or chemical treatment may produce iron oxide powders with controlled particle size distribution and phase composition suitable for incorporation into liquid-operable energetic composites. Artificial intelligence systems may monitor mineral content, optimize separation efficiency, and regulate processing parameters to maintain consistent oxidizer quality.

[0158] The refined iron oxides obtained from black sands or ferromanganese nodules may be combined with aluminum or alternative fuel components to form energetic composites configured for submerged ignition and controlled energy release. Surface-engineered liquidrepellent layers may be applied to the composite to enable reliable operation in aqueous, saline, or extraterrestrial liquid environments. Sourcing oxidizer material from coastal or deep-sea mineral deposits, enables the system to support localized and potentially self-sustaining production of energetic materials for marine propulsion, heating, power generation, or exploration applications.

[0159] Manganese Oxide (MnO2) from Seabed Nodules

[0160] In certain embodiments, the oxidizer component of the energetic composite may be derived from manganese-bearing mineral deposits, including manganese nodules located on the deep-sea floor. Ferromanganese nodules and related seabed concretions are known to contain significant concentrations of manganese oxides, including MnO2and mixed manganese oxide phases, along with varying quantities of iron, nickel, cobalt, and other trace elements. These nodules accumulate overextended geological periods and may be found distributed across large regions of abyssal plains.

[0161] Autonomous underwater vehicles or remotely operated collection systems may be configured to identify and recover manganese nodules from the seabed. Such systems may employ sonar mapping, optical imaging, and mineralogical sensing to locate nodule-rich regions. Mechanical collection tools, suction systems, or controlled lifting devices may be used to gather nodules while minimizing disruption to surrounding sediments. Following recovery, nodules may undergo crushing, milling, and separation processes to isolate manganese oxide fractions.

[0162] Refinement may include magnetic separation to remove iron-rich components where necessary, followed by chemical or thermal treatment to produce manganese oxide phases with controlled purity and particle size distribution. In certain embodiments, manganese oxide may be processed into fine powders suitable for intimate mixing with a selected fuel component. Particle morphology may be engineered to optimize interfacial contact and reaction kinetics in the resulting energetic composite.

[0163] Manganese oxide may serve as an alternative oxidizer to iron oxide in aluminum-based energetic systems. An energetic composite comprising aluminum fuel and manganese oxide oxidizer may provide distinct reaction characteristics relative to aluminum-iron oxide systems, including variations in ignition temperature, reaction rate, gas production profile, and thermal output. The aluminum-manganese oxide reaction may be tailored through stoichiometric adjustment, particle size control, and surface engineering to achieve desired performance in submerged environments.

[0164] In certain embodiments, an aluminum and manganese oxide energetic composite may be configured for underwater welding applications, where localized high-temperature generation is required to fuse materials in liquid environments. The composite may be contained within a controlled chamber or directed through a defined interface to deliver concentrated heat at a target surface. In other embodiments, the same reaction system may be coupled to an energy conversion interface to support power generation in subsea or liquid environments. For example, thermal output may be transferred to thermoelectric modules, or pressure pulses generated during reaction may be coupled to mechanical or electrical harvesting systems.

[0165] In other embodiment, manganese dioxide may be combined with aluminum as the fuel component to form an energetic mixture capable of undergoing an exothermic redox reaction. The fuel-to-oxidizer ratio may be selected to achieve desired thermal output, reaction kinetics, and gas generation characteristics. The composite may be structured in particulate, core-shell, layered, or matrix-bound architectures, and a surface-engineered liquid-repellent layer may be applied to enable submerged ignition and controlled vapor-envelope formation.

[0166] Surface-engineered layers such as liquid-repellent layers may be applied to aluminum-manganese oxide composites to enable reliable submerged ignition and controlled vapor-envelope formation. This approach may allow manganese oxide sourced from deep-sea nodules to serve as a locally derived oxidizer in liquid-operable energetic systems. By utilizing manganese nodules as an oxidizer source, the energetic system may expand beyond iron-basedoxidizers and support diversified, potentially self-sustaining production of reactive materials for marine propulsion, heating, welding, or power-generation platforms.

[0167] Sulfur-Based Oxidizers from Hydrothermal Vents

[0168] In certain embodiments, sulfur-bearing mineral deposits present in marine environments may serve as alternative oxidizing or reactive components within energetic composite systems. Deep-sea hydrothermal and sedimentary environments frequently contain sulfide minerals, including iron sulfides such as pyrite (FeS2). These minerals may accumulate around hydrothermal vent systems, in sulfide-rich sediment layers, or within subsea mineral deposits associated with geothermal activity.

[0169] Autonomous underwater collection systems or remotely operated mining platforms may be configured to harvest sulfide-bearing sediments or nodular pyrite deposits from the seabed. Collection systems may utilize mechanical excavation, suction-based intake, or crawlermounted retrieval tools capable of selectively gathering sulfur-rich mineral formations. In certain embodiments, spectroscopic sensing, electrochemical detection, or mineralogical analysis may be used to identify pyrite-rich regions and optimize collection efficiency.

[0170] Following recovery, sulfide minerals may undergo mechanical processing to achieve a controlled particle size distribution. Crushing, milling, and classification steps may be employed to produce particulate feedstock suitable for energetic applications. In some embodiments, additional purification may be performed to remove non-sulfide gangue minerals, excess moisture, or marine contaminants. Thermal or chemical pre-treatment may be used to modify surface chemistry or enhance reactivity.

[0171] Iron sulfide materials, including pyrite, may function as oxidizing or reactive components in thermite-like energetic systems when combined with a suitable fuel component such as aluminum or other reactive metals. The reaction pathway may differ from traditional metal oxide thermite systems, potentially involving sulfur-containing intermediates and distinct reaction energetics. In certain embodiments, aluminum-pyrite mixtures may generate exothermic reactions capable of producing heat and reaction products suitable for localized thermal applications. The fuel-to-reactant ratio may be adjusted to control reaction rate, thermal output, and gas evolution characteristics.

[0172] Surface-engineered layers such as liquid-repellent layers may be applied to sulfide-based energetic composites to enable submerged ignition in aqueous or hydrothermal environments. As described elsewhere, the surface layer may decompose to form an insulating vapor region prior to initiation of the primary reaction, thereby facilitating ignition under liquid immersion and high-pressure conditions.

[0173] In geothermal or hydrothermal vent environments, sulfide-based energetic composites may be particularly advantageous. Naturally elevated temperatures and chemical gradients present near vent fields may reduce ignition energy requirements or assist in sustaining reaction propagation. In certain embodiments, a pyrite-based energetic module may function within asubsea system configured to harvest geothermal heat and augment it with controlled energetic reactions, thereby enabling hybrid thermal generation systems.

[0174] In one illustrative embodiment, a pyrite-based energetic fuel cell architecture may be implemented in which sulfide-derived oxidizing material is combined with aluminum or other fuel sources within a controlled reaction chamber. Thermal and pressure energy generated by the reaction may be coupled to thermoelectric modules or pressure-driven conversion systems to produce usable power. Such systems may be integrated into seabed installations that utilize locally available sulfur-rich mineral deposits, thereby supporting self-sustaining or partially self-sustaining energy production in remote marine environments. The use of sulfide-based minerals as oxidizing or reactive components expands the range of environmentally sourced materials available for energetic composite fabrication and supports closed-loop or in-situ resource utilization strategies for subsea or extraterrestrial liquid environments.

[0175] Magnesium Extraction from Seawater

[0176] In certain embodiments, magnesium may be sourced from seawater and used as a fuel component for liquid-operable energetic composites. Seawater contains abundant dissolved magnesium species, commonly on the order of approximately 1,300 parts per million, primarily present as magnesium salts in ionic form. Because magnesium is substantially more concentrated in seawater than many other metal ions, seawater-derived magnesium represents a practical feedstock for producing reactive metal fuel for energetic applications in marine environments.

[0177] In one embodiment, a seawater processing system may include an intake module configured to draw seawater into a treatment train in which magnesium-containing species are concentrated and converted into a reducible intermediate. Concentration may be performed using membrane separation, selective ion exchange, electrochemical concentration, or precipitation processes that form magnesium-containing solids. In certain embodiments, magnesium hydroxide or other magnesium compounds may be precipitated and collected as an intermediate feedstock for downstream reduction.

[0178] Following concentration and intermediate formation, electrochemical reduction may be performed to produce metallic magnesium. In some embodiments, the reduction system may comprise a high-temperature electrochemical cell, molten-salt electrolysis system, ionic-liquid electrochemical system, or other electrolytic refining approach configured to reduce magnesium-containing intermediates to metallic magnesium. Energy for electrolysis may be supplied by onboard power systems, including renewable sources such as solar arrays, wave-energy converters, or hybrid marine energy harvesting systems, particularly when integrated into a floating or subsea platform. The recovered magnesium may be collected as solid metal, granules, or powder depending on the desired energetic composite form.

[0179] The refined magnesium may then be engineered into particulate form to increase reactive surface area and tailor combustion characteristics. Particle formation may be achievedthrough atomization, controlled milling, plasma processing, or other particulate fabrication methods. Because magnesium is highly reactive, handling and storage may employ protective environments, controlled passivation, or encapsulation within binders or surface-engineered liquid-repellent layers to maintain stability while enabling submerged ignition.

[0180] In certain embodiments, magnesium may be combined with iron oxide (Fe2O3) or other oxidizers to form thermite-like energetic composites. A magnesium-iron oxide system may be configured to generate rapid heat release and vapor expansion in submerged environments. Such energetic composites may be integrated into deep-sea emergency heating modules capable of producing localized thermal output for de-icing, equipment recovery, habitat warming, or subsea maintenance tasks. In propulsion embodiments, the magnesium-based energetic composite may be housed within a confinement chamber having a directional vent or nozzle such that vapor expansion produces impulse thrust for emergency maneuvering, release from entanglement, or controlled displacement of underwater devices.

[0181] In some embodiments, magnesium-based energetic composites may provide advantages in liquid environments due to magnesium’s high reactivity and potential for rapid ignition once thermal insulation is established by the surface-engineered layer. Accordingly, seawater-derived magnesium may support a partially self-sustaining marine energetic platform in which locally sourced magnesium is refined and incorporated into liquid-operable energetic systems for heating, propulsion, power generation, or other underwater applications.

[0182] Magnesium Deposits in Seafloor Sediments

[0183] In certain embodiments, magnesium used as a fuel component for liquid-operable energetic composites may be derived from magnesium-bearing sedimentary rocks and mineral deposits present on the seafloor. Submerged carbonate formations, including dolomite deposits generally represented as calcium magnesium carbonate, may occur in coastal shelves, continental margins, and deep-sea sedimentary basins. These formations may serve as concentrated magnesium sources relative to dissolved seawater.

[0184] Autonomous underwater vehicles or remotely operated mining systems may be configured to identify and collect magnesium-bearing rock fragments or sediment layers from the seabed. Detection systems may include sonar mapping, mineralogical sensing, spectroscopic analysis, or chemical sampling to locate dolomite-rich regions. Collection mechanisms may include mechanical cutting tools, abrasive excavation heads, suction-based sediment intake modules, or crawler-mounted retrieval systems designed to remove mineral material in a controlled manner.

[0185] Following recovery, the magnesium-bearing material may undergo mechanical comminution, including crushing and grinding, to increase surface area and liberate magnesium-containing phases. In certain embodiments, chemical or thermal processing may be employed to separate magnesium from associated calcium and carbonate components. For example, controlled calcination may convert carbonate materials into oxide intermediates, which may thenbe further processed to isolate magnesium compounds. Subsequent reduction processes, including electrochemical or thermal reduction systems, may be used to produce metallic magnesium suitable for energetic applications.

[0186] The refined magnesium may be engineered into particulate form with controlled size distribution to optimize reaction kinetics and thermal output when combined with an oxidizer component. Particle formation methods may include atomization, milling, plasma processing, or other powder-production techniques. Surface treatments or passivation layers may be applied to stabilize the magnesium particles during storage while preserving reactivity upon ignition.

[0187] In certain embodiments, magnesium extracted from seafloor deposits may be combined with iron oxide or alternative oxidizers to form high-energy thermite compositions suitable for deep-sea welding, cutting, or construction activities. The energetic composite may be housed within a controlled welding module capable of directing thermal output toward targeted structural interfaces. Surface-engineered liquid-repellent layers may enable reliable submerged ignition by forming a transient insulating vapor envelope prior to the primary reaction. Such magnesium-based thermite systems may provide localized, high-temperature heat generation for subsea infrastructure assembly, repair, or reinforcement in environments where conventional welding methods are difficult to implement.

[0188] Traditional thermite produces only molten metal and heat. For propulsion, adding gasgenerating compounds is critical to produce thrust. For example: i) boron-potassium nitrate mixtures produce oxygen for more sustained combustion, ii) magnesium-perchlorate additives help generate combustion gases, and iii) silicon-based thermite can generate silicon monoxide (SiO) gas for thrust. Additionally, certain thermites compositions create a faster energy release which would be suitable for high-thrust systems or emergency propulsion units, for example aluminum-copper oxide (Al +CuO) can be used for rapid ignition.

[0189] Another application of thermite underwater would be to use solid thermite as a fuel for a liquid oxidizer injection (e.g., liquid oxygen or hydrogen peroxide), as such a combination would burn controllably allowing for throttle control in deep-sea propulsion systems and underwater drones.

[0190] Another use of thermites underwater is to coat the thermite with a polymer or hydrophobic gel to create a water-resistant thermite pellet to prevent reaction with water enabling long-term underwater storage and controlled ignition.

[0191] Industrial Applications of Underwater Thermite Combustion

[0192] While some applications have been described above, further applications are listed and described briefly below:

[0193] High-speed underwater propulsion systems may be enhanced through the integration of oxygen-independent energetic composite modules capable of generating rapid impulse thrust within liquid environments. Conventional underwater propulsion architectures typically rely on electrically driven propellers, pump-jet systems, compressed gas expansion, or fuel-cell-poweredmotors. While such systems provide sustained cruise efficiency, they are often limited in peak power density and acceleration capability. In contrast, metal-oxidizer energetic systems incorporate both fuel and oxidizer within a single composite material, eliminating the need for external oxygen or oxidizer tanks and enabling high-energy-density operation entirely independent of dissolved oxygen or atmospheric intake.

[0194] In propulsion embodiments, the energetic composite may be housed within a pressure-rated chamber integrated into the vehicle hull or within an external propulsion pod. Upon command from a control system, an ignition subsystem may deliver sufficient energy to initiate the staged reaction sequence described elsewhere in the specification. The surface-engineered layer decomposes to form a transient insulating vapor region, enabling the primary redox reaction to proceed despite full liquid immersion. The exothermic reaction generates rapid heat release and high-pressure vapor expansion within the chamber.

[0195] The resulting vapor expansion may be directed through a controlled exhaust port or nozzle geometry configured to convert internal pressure into directional thrust. Because the surrounding medium is liquid, the expanding vapor displaces water and creates a transient cavity that transfers momentum to the surrounding fluid. The confinement geometry of the chamber and the shape of the exhaust interface may be selected to regulate thrust magnitude, impulse duration, and cavity collapse characteristics. Unlike continuous propeller systems, the energetic propulsion module may operate in discrete pulses, each pulse generating a defined impulse event.

[0196] Autonomous Underwater Vehicles (AUVs)

[0197] High-speed propulsion with no need for external oxygen. For autonomous underwater vehicles, such propulsion modules may be integrated as supplemental high-thrust systems rather than primary cruise propulsion. The AUV may utilize electric propulsion for steady-state operation and deploy energetic impulse modules for rapid acceleration, obstacle avoidance, high-speed maneuvering, or emergency repositioning. Because the energetic composite contains its own oxidizer, performance remains consistent regardless of depth, salinity, or dissolved oxygen concentration. This feature is particularly advantageous for deep-sea or under-ice operations, where oxygen availability and pressure conditions limit traditional combustion systems.

[0198] Multiple energetic chambers may be arranged in an array configuration to provide controlled thrust vectoring. By independently igniting selected chambers, the vehicle may generate translational thrust, rotational torque, or combined motion vectors. Sequential ignition timing may be managed through onboard control electronics to produce stepwise acceleration or modulated impulse profiles. Feedback systems may monitor internal chamber pressure, external hydrostatic pressure, and vehicle acceleration to optimize ignition timing and thrust delivery.

[0199] Because hydrostatic pressure increases with depth, the propulsion module may incorporate pressure-compensated housing structures and controlled venting interfaces. The confinement system may be designed to ensure reliable ignition and predictable cavity formationeven under high external pressures. Vapor expansion characteristics may vary depending on ambient pressure, and chamber design may account for these effects through adjustable vent geometries or rupture membranes that regulate discharge.

[0200] The high energy density of metal-oxidizer composites enable compact packaging of propulsion capability. Compared to lithium-ion battery systems, which are constrained by electrochemical discharge rates, energetic impulse modules can deliver rapid energy release with minimal system mass. This makes them suitable for applications requiring short-duration high-thrust events without substantially increasing vehicle size or weight.

[0201] In certain embodiments, magnesium-based energetic systems may be used for propulsion due to magnesium’s high reactivity and favorable reaction kinetics. Magnesium combined with iron oxide or alternative oxidizers may produce rapid vapor expansion suitable for impulse thrust generation. Aluminum-based systems may provide higher thermal output and potentially longer impulse duration depending on composition and confinement geometry. The selection of fuel and oxidizer may be tailored to achieve desired thrust-to-mass ratios and impulse profiles.

[0202] The propulsion module may be thermally isolated from sensitive vehicle components through insulating barriers and controlled heat transfer interfaces. Post-reaction cooling may occur naturally through the surrounding liquid, which acts as a large heat sink. In multi-chamber systems, spent chambers may remain sealed after discharge, allowing subsequent chambers to be activated as needed.

[0203] Such oxygen-independent energetic propulsion systems are particularly suited for deep-sea exploration vehicles, under-ice research platforms, autonomous inspection drones, and high-speed maneuvering subsea robotics. Because they do not require atmospheric oxygen or continuous oxidizer flow, they are capable of operation in fully enclosed, oxygen-depleted, or high-pressure liquid environments. When integrated with intelligent control systems, these modules provide a hybrid propulsion architecture combining steady electric cruise with rapid impulse acceleration, thereby expanding operational envelopes for autonomous underwater vehicles.

[0204] A hybrid propulsion architecture for submerged vehicles may combine a continuous electric propulsion subsystem with one or more oxygen-independent energetic impulse subsystems to provide both efficient cruise and high-thrust burst capability within liquid environments. In such embodiments, the vehicle includes an electric propulsion unit configured for sustained operation, for example an electric motor coupled to a propeller, pump-jet, ducted propulsor, or other hydrodynamic thruster. The electric propulsion unit is powered by an onboard electrical energy store, such as a battery pack, fuel cell, or hybrid electrical supply, and is controlled by a vehicle controller that manages speed, heading, and energy consumption during normal mission execution.

[0205] The vehicle further includes an energetic impulse propulsion module comprising one or more sealed energetic chambers, each chamber containing a liquid-operable energetic composite that includes a fuel component and an oxidizer component in reactive proximity, together with a surface-engineered liquid-repellent layer configured to enable ignition while submerged. Each chamber is coupled to an ignition subsystem and a thrust interface, such as a nozzle, vent, or directed exhaust path, configured to convert combustion-induced vapor expansion into a directional impulse. The energetic impulse module is preferably configured to operate in a pulsed manner by selectively igniting individual chambers, thereby producing discrete impulse events that supplement or temporarily replace thrust produced by the electric propulsion unit.

[0206] In certain embodiments, the hybrid system is implemented as a multi-mode propulsion controller in which the vehicle operates in an electric cruise mode for low-to-moderate speed transit and transitions to an impulse-augmented mode when rapid acceleration, high-speed dash capability, emergency maneuvering, or obstacle avoidance is required. In electric cruise mode, the energetic chambers remain in a safe state and are isolated from unintended activation by mechanical interlocks and electronic arming logic. In impulse-augmented mode, the controller issues ignition commands to one or more energetic chambers based on a desired impulse profile, and optionally coordinates electric motor output to maintain stability and to shape the combined thrust vector.

[0207] In certain embodiments, the energetic impulse module is arranged as a plurality of chambers distributed along the vehicle in a manner that enables thrust vectoring and torque control. A first subset of chambers may be oriented to provide forward thrust, while additional chambers may be oriented laterally or asymmetrically to provide yaw, pitch, or roll moments. The controller may selectively ignite individual chambers, or sets of chambers, to generate rotational torque for rapid heading changes or to counteract disturbances. In some embodiments, chamber outputs may be sequenced in time such that a series of smaller impulses approximates a continuous thrust augmentation, thereby reducing peak structural loads and improving controllability.

[0208] The hybrid architecture may further include an energy recovery and thermal management subsystem configured to manage heat and pressure produced by energetic events. Thermal shielding and insulation layers may separate energetic chambers from sensitive electronics, buoyancy materials, and structural components. A pressure- rated containment housing may enclose the energetic module and may incorporate controlled venting ports to direct vapor and reaction gases away from the vehicle hull. Because surrounding liquid provides strong convective cooling, the system may rely on external liquid heat sinking for rapid cool-down following an impulse event, while ensuring that localized thermal exposure remains below allowable thresholds for vehicle materials.

[0209] In certain embodiments, the propulsion controller uses sensor feedback to coordinate electric and energetic outputs. Sensors may include inertial measurement units for acceleration and angular rate, depth and ambient pressure sensors, chamber pressure and temperature sensors, and flow or acoustic sensors configured to infer vapor cavity behavior near exhaust ports. The controller may compute a desired thrust and torque command based on mission objectives and stability constraints and may allocate that command between the electric propulsion unit and the energetic impulse module. In a representative allocation strategy, the electric propulsion unit provides baseline thrust for efficiency, while the energetic impulse module provides transient peak thrust where power density requirements exceed the capabilities of the electrical system.

[0210] In certain embodiments, the energetic impulse module supports depth-compensated operation. Because hydrostatic pressure increases with depth and affects cavity formation and exhaust expansion, the controller may adjust ignition timing, chamber selection, and venting strategies as a function of depth. Chambers may be configured with different confinement geometries or nozzle characteristics so that selected chambers are optimized for operation at different pressure regimes. In some embodiments, the system includes a pressure compensation interface, such as a compliant volume, regulated vent, or rupture element, which stabilizes exhaust behavior across varying depths.

[0211] In some embodiments, the hybrid architecture supports mission extensibility by using replaceable energetic cartridges. The energetic chambers may be implemented as removable modules that can be installed during vehicle preparation and replaced between missions. The cartridges may be sealed to prevent water ingress and may incorporate integrated ignition leads or optical ignition windows. A cartridge architecture enables flexible mission planning in which the number of available impulse events, the total impulse budget, and the orientation of impulse ports are selected based on mission requirements.

[0212] In certain embodiments, the hybrid propulsion system supports a supercavitation-assisted mode in which energetic impulse events are used not only to generate thrust but also to create or sustain a vapor cavity near the vehicle body to reduce hydrodynamic drag. In this mode, a portion of the energetic output may be directed through a cavitation port near the nose or leading structure to generate gas and vapor that enlarges a cavity, while a separate portion of the energetic output provides direct thrust. The controller may coordinate cavity generation timing with vehicle speed to stabilize the cavity and maintain drag reduction.

[0213] Safety features may include multi-factor arming logic, redundant ignition inhibit circuits, environmental condition checks, and physical isolation between energetic chambers. In certain embodiments, ignition is permitted only when the vehicle controller confirms a valid command state, verifies that external conditions are within predefined bounds, and confirms that the energetic module is oriented safely with respect to the vehicle hull and mission environment. Thesystem may include fault detection logic that disables energetic activation upon detection of abnormal chamber pressure, unexpected temperature rise, water ingress, or electrical anomalies.

[0214] Accordingly, the hybrid electric and energetic propulsion architecture enables a submerged vehicle to combine efficient continuous propulsion with high-energy-density impulse events, thereby expanding operational envelopes for speed, acceleration, maneuvering authority, depth robustness, and mission resilience. The architecture supports modular scaling from microvehicles to larger autonomous platforms by varying chamber count, chamber mass, nozzle geometry, control logic, and the relative contribution of the electric and energetic subsystems.

[0215] In certain embodiments, a submerged vehicle includes a vehicle controller coupled to an electric propulsion subsystem, an energetic impulse subsystem, a sensor suite, and a safety / interlock subsystem. The vehicle controller may be implemented as a computing module comprising a processor, memory storing propulsion control instructions, and interfaces for power electronics and ignition control. The electric propulsion subsystem includes an electrical energy store, such as a battery pack or fuel cell, a motor controller or inverter, and an electric motor mechanically coupled to a propulsor, pump-jet, or ducted thruster. The energetic impulse subsystem includes one or more sealed energetic chambers containing a liquid-operable energetic composite, one or more ignition elements, and one or more exhaust interfaces configured to convert vapor expansion into thrust, where the exhaust interfaces may include nozzles, controlled vents, or directional discharge ports. The sensor suite includes at least an inertial measurement unit, a depth or ambient pressure sensor, and one or more sensors coupled to the energetic impulse subsystem, such as chamber pressure, chamber temperature, water ingress, or exhaust-side sensing. The safety / interlock subsystem includes arming logic, ignition inhibit elements, and fault detection circuitry configured to prevent activation of the energetic impulse subsystem unless one or more predefined safety conditions are satisfied.

[0216] In operation, the vehicle controller receives mission commands and sensor data, determines a desired force and torque vector for the vehicle, and allocates the desired force and torque between the electric propulsion subsystem and the energetic impulse subsystem according to a propulsion allocation policy. The motor controller drives the electric motor to provide baseline continuous thrust, while the ignition control interface selectively activates one or more energetic chambers to provide discrete impulse thrust when transient thrust demand exceeds electric subsystem capability, when rapid maneuvering is required, or when a programmed impulse event is scheduled. The safety / interlock subsystem monitors a set of arming conditions, including controller state, environmental conditions, and chamber health, and blocks ignition commands if a fault condition is detected or if arming requirements are not satisfied.

[0217] In certain embodiments, the energetic impulse subsystem comprises a plurality of independently addressable chambers arranged to provide thrust vectoring by orientation or location. A first subset of chambers may be aligned to provide forward thrust, and a second subset of chambers may be oriented to provide yaw, pitch, or roll control moments. The vehicle controllermay ignite chambers in a sequence to produce a net thrust vector and torque profile, and may coordinate motor output simultaneously to maintain vehicle stability and trajectory. In certain embodiments, a cavity-generation port may be included and coupled to one or more energetic chambers such that selected energetic events generate vapor intended to form or sustain a low-drag cavity near a portion of the vehicle body, and the vehicle controller may modulate cavitygeneration events as a function of speed and depth.

[0218] Depth Charges - Thermite-based charges for underwater breaching and mining. In certain embodiments, a submerged energetic system may be configured as a contained impulse or thermal module used to fracture, cut, or weaken submerged materials such as rock, concrete, steel, or composite structures. The module may include a pressure-rated housing that contains a reactive energetic composite and an ignition subsystem, where the housing further includes a directed energy interface configured to couple the energetic output into a target. The directed energy interface may be implemented as a heat-transfer interface, a pressure-pulse interface, or a combination thereof, and the interface may be positioned in contact with or in close proximity to the target surface.

[0219] In some embodiments, the module operates in a thermal delivery mode in which the energetic reaction primarily provides localized high-temperature output to weaken or melt a portion of the target. In such systems, the housing may include a thermal conductor element, such as a heat shoe or thermal coupling pad, that is pressed against the target to deliver heat into the material. The module may include insulating structures that limit heat transfer into surrounding liquid and into the module body, thereby focusing energy toward the target interface. In underwater cutting or localized weakening applications, the system may be used to create a heat-affected zone that reduces structural strength and enables subsequent mechanical removal or separation using conventional tools.

[0220] In other embodiments, the module operates in a pressure pulse mode in which the reaction is used to generate a rapid pressure transient that induces cracking, spalling, or controlled fracture of the target material. In these embodiments, the housing may include a confinement chamber and a controlled vent path or coupling cavity that directs a portion of the vapor expansion and pressure rise toward the target surface. The module may be configured to produce a shaped pressure pulse, where pulse timing, magnitude, and duration are controlled by chamber geometry, venting features, and staged ignition of multiple energetic sub-chambers. For rock fracturing or mining assistance, repeated pulses may be applied in a controlled sequence to propagate cracks along desired fracture planes, thereby reducing mechanical drilling or cutting requirements.

[0221] In certain embodiments, the system is implemented as a robot-deployable tool head for a remotely operated vehicle (ROV) or AUV, where the vehicle positions the tool head at a target site, establishes contact force or standoff distance, and initiates one or more energetic events under closed-loop control. The robotic platform may monitor local conditions using sensorssuch as contact-force sensors, acoustic emissions sensors, and ambient pressure sensors, and it may adjust pulse scheduling or module placement based on measured response of the target material. In some embodiments, the module is configured as a replaceable cartridge so that a vehicle can perform multiple operations by swapping energetic cartridges rather than carrying a single large energetic unit.

[0222] In underwater mining embodiments, the energetic module may be used as a preconditioning tool that weakens ore-bearing rock prior to mechanical collection, suction dredging, or cutting. For example, an ROV may apply localized pulses to reduce rock cohesion in a defined region, after which conventional collection tools remove loosened material. In subsea trenching or pipeline work, the module may be used to break up hard layers or concretions that impede excavation. In salvage and decommissioning operations, the module may be used to weaken corroded joints, remove encrustations, or separate sections of structure in a controlled manner, with energy delivery tuned to minimize collateral disturbance.

[0223] In all such embodiments, the energetic system may incorporate safety interlocks and operational controls appropriate for industrial use, including multi-factor arming logic, environmental validation checks, fault detection, and post-event verification steps. The housing may be configured to contain reaction products and to direct outputs through engineered interfaces, thereby reducing dispersion into the environment. The system may also be designed to operate under high hydrostatic pressures, with pressure- rated containment and vent regulation to maintain consistent pulse behavior across depth ranges.

[0224] Emergency Escape Systems - For submarines to release energy quickly for buoyancy adjustments. If a submarine is disabled at depth, crew members must escape safely, and a thermite-driven buoyancy system could generate rapid thrust to lift escape pods to the surface; this would be more reliable than traditional compressed gas buoyancy systems.

[0225] Deep-Sea Exploration and Mining Robots - Thermite propulsion for autonomous drills and excavation units; thermite-powered deep-sea mining drones could mine at depths beyond 5,000 meters which are traditionally challenging due to high pressure and energy supply limitations; thermite propulsion could enable fully autonomous underwater mining robots that do not rely on external power sources and can be combined with laser-induced plasma thrusters for high maneuverability.

[0226] Underwater Welding & Cutting - Thermite-based high-energy system for construction and repair; underwater thermite welding has been used for repairing pipelines and offshore structures; next generation thermite-based welding drones could autonomously fix deep-sea structures and eliminate the need for human drivers; can be used for submarine hull repairs, underwater pipelines, offshore structures, etc..

[0227] Exploration in Space, Volcanoes, and Antarctica - Potential for underwater propulsion on moons with thick ice crusts over liquid oceans (e.g., Europa, Enceladus); thermite-powered cryobots could melt and burn through ice, reaching a subsurface ocean for astrobiologicalresearch; deep-sea volcanoes (i.e., hydrothermal vents) which reach extreme temperatures and pressures could also be explored by thermite-powered submarine rovers which could operate where traditional electronics fail; silicon-oxide thermite can generate a high-temperature plasma shield for lava; thermite thrusters could propel robots under Antarctic ice in subglacial lakes.

[0228] Uncontrolled Burn Rate - Use layered fuel-oxidizer structures for staged ignition. In certain embodiments, uncontrolled or overly rapid burn behavior of an energetic composite in liquid may be mitigated by configuring the fuel and oxidizer in a layered or segmented architecture that supports staged ignition. Sequential segments may be independently ignitable to a shape a pressure-time or heat-time output profile. The energetic material may be formed as alternating layers, zones, or packets of fuel-rich and oxidizer-rich regions, optionally separated by inert or low- reactivity interlayers that slow heat transfer and reaction propagation. Such structures may be implemented as laminated foils, printed micro-layers, gradient compositions, or packed pellets with discrete shells. When ignited, a first stage may generate an initial vapor cavity and temperature rise, while subsequent stages ignite sequentially as thermal energy propagates through the structure, thereby extending impulse duration, reducing peak pressure spikes, and improving repeatability across chambers.

[0229] Heat Dissipation in Water - Encapsulate thermite in an insulating barrier (e.g., aerogels) to maintain combustion. In certain embodiments, heat dissipation into surrounding water may be reduced by encapsulating the energetic composite within an insulating barrier that limits conductive and convective heat loss prior to and during combustion. The insulating barrier may comprise a porous insulating medium such as an aerogel, closed-cell foam, ceramic insulation, polymer composites, or multilayer thermal barriers, and may be configured as a shell, capsule, or liner within a reaction chamber. The encapsulation may further include a controlled vent path that allows reaction products to discharge while maintaining a thermal boundary layer around the reaction zone. Such insulation may be particularly beneficial for low-mass energetic charges or micro-thrusters where the surrounding liquid would otherwise quench reaction propagation, and the barrier may be selected to remain stable under hydrostatic pressure and to minimize water infiltration during storage.

[0230] Limited Gas Generation - Add reactive compounds that generate high-pressure gases. In certain embodiments, where an energetic redox reaction produces insufficient gas volume to generate a desired pressure pulse or thrust, the composite may include one or more gasgenerating components that release high-pressure gases upon heating or reaction. Gasgenerating components may include materials that decompose to produce gaseous products, materials that react with available species to form gases, or encapsulated gas-forming agents embedded within the composite or chamber. The gas-generating component may be distributed uniformly or localized in specific regions to shape the pressure-time profile, and may be selected so that gas generation occurs in a controlled sequence relative to the primary energetic reaction.This configuration can increase cavity size, extend impulse duration, and improve thrust efficiency in liquid by increasing the volume of expanding reaction products.

[0231] Underwater Ignition - Use plasma or electric igniters to initiate reaction in wet conditions. In certain embodiments, ignition reliability under wet conditions may be improved by using plasma-based or electrical igniters that deliver localized energy directly into the energetic composite while submerged. The ignition subsystem may include resistive microheaters, capacitive discharge elements, spark-gap igniters, plasma microjets, or electrode pairs configured to produce an arc or plasma region adjacent the composite. The igniter may be integrated into the chamber wall or into a cartridge interface and may be controlled by a driver circuit that delivers a programmed ignition waveform. In some embodiments, the igniter is coordinated with a surface-engineered layer on the composite that decomposes to form a transient insulating vapor region, such that the igniter initiates a first stage that creates thermal isolation and enables the primary reaction to proceed reliably in fully submerged conditions and across a range of salinities and pressures.

[0232] Hybrid Thermite-Electrical Thrusters: Combining thermite with electrically generated plasma for more controllable thrust. In certain embodiments, ignition reliability under wet conditions may be improved by using plasma-based or electrical igniters that deliver localized energy directly into the energetic composite while submerged. The ignition subsystem may include resistive microheaters, capacitive discharge elements, spark-gap igniters, plasma microjets, or electrode pairs configured to produce an arc or plasma region adjacent the composite. The igniter may be integrated into the chamber wall or into a cartridge interface and may be controlled by a driver circuit that delivers a programmed ignition waveform. In some embodiments, the igniter is coordinated with a surface-engineered layer on the composite that decomposes to form a transient insulating vapor region, such that the igniter initiates a first stage that creates thermal isolation and enables the primary reaction to proceed reliably in fully submerged conditions and across a range of salinities and pressures.

[0233] Programmable Burn Rates: Using Al-controlled thermite pellet arrangements for adaptive propulsion systems. In certain embodiments, burn rate and impulse output may be programmed by arranging energetic pellets, segments, or micro-chambers in a defined spatial pattern and controlling the ignition sequence using a controller implementing adaptive logic. The energetic elements may be manufactured as pellets or tiles with different compositions, densities, or coatings such that each element has a distinct ignition threshold and burn profile. A control system may select which elements to ignite and when to ignite them to produce a desired thrusttime curve, such as a rapid initial impulse followed by sustained lower-level thrust. In some embodiments, a data-driven model may adjust ignition schedules based on measured vehicle response, ambient pressure, and mission state, thereby enabling adaptive propulsion outputs that compensate for depth-dependent hydrostatic effects, temperature changes, or vehicle mass changes.

[0234] Self-Sustaining Underwater Propulsion Loops: Integrating thermite with onboard electrolysis systems for long-duration operation. In certain embodiments, long-duration underwater operation may be achieved using a hybrid energy loop that combines energetic impulse modules with onboard electrical systems capable of generating or managing auxiliary working fluids. A vehicle may employ electric propulsion for cruise and reserve energetic modules for high-power maneuvers, while an onboard electrolysis subsystem processes water to generate gases for buoyancy adjustment, auxiliary actuation, or controlled venting functions that support propulsion behavior. The electrolysis subsystem may be powered by onboard electrical energy or by energy harvested from energetic events through thermoelectric or pressure-based conversion interfaces. In this manner, the system may maintain operational endurance by using energetic modules sparingly for peak demands while using the electrical system and waterprocessing subsystem for steady-state functions, and may optionally recycle heat or pressure energy to improve overall energy utilization.

[0235] Silent Propulsion - traditional high-thrust systems rely on gas turbines or electric motors, which generate detectable noise but thermite-based propulsion produces minimal acoustic signature, making it ideal for stealth operations; a nano-thermite hybrid engine could provide a high-thrust burst for rapid acceleration in short distances; AUVs equipped with thermite propulsion can patrol without relying on batteries; thermite fuels provide high-energy density, enabling longer mission durations; can be used for mine clearance, anti-submarine warfare, and reconnaissance; and superheated systems allow for gas production on a high-thrust systems surface so that supercavitation can be achieved along with extremely high speeds.

[0236] Underwater Drilling with Thermite Rockets - Deep-sea drilling requires intense energy to breakthrough rock and ice layers but thermite torches can sustain extreme temperatures and melt through hard seabed materials without needing surface power; this could be employed in undersea construction, oil exploration, and tunnel boring beneath the ocean floor; as noted above, a thermite rocket could be used in space-related underwater applications to propel a submersible in seas or lakes, such as the liquid methane and ethane on Titan, where onboard oxygenproducing thermite could burn fuel efficiently.

[0237] Self-replicating Underwater Factories - Inspired by lunar self-replicating robotic factories, thermite could power autonomous deep-sea construction units; use thermite-fueled robotic arms to build underwater infrastructure from seabed minerals.

[0238] Biomimetic Thermite Swarms - Inspired by fish schools and jellyfish movement, small thermite-powered robotic swarms could explore the ocean in a coordinated way; use thermite micro-explosions for pulsed propulsion, similar to jellyfish locomotion.

[0239] Thermite-Powered Underwater Generators - thermite steam generators can heat water to produce high-pressure steam, which drives turbines to generate electricity; ideal for long-duration underwater habitats, deep-sea mining operations, or military bases; uses encapsulated thermite pellets to ensure controlled reaction and heat distribution; for example, a self-sustainingdeep-sea thermal power station could use controlled thermite reactions to generate electricity for a seafloor base.

[0240] In certain embodiments, a liquid-operable energetic composite may be configured to function as a compact underwater power generation module capable of converting stored chemical energy into usable electrical output while fully submerged. Because the energetic composite contains both a fuel and an oxidizer in reactive proximity, the system operates independently of dissolved oxygen and may function reliably at depth, beneath ice, or in oxygen-depleted or high-pressure liquid environments. The generator may include a sealed reaction chamber containing the energetic composite, an ignition subsystem configured for submerged activation, one or more energy conversion interfaces, and a pressure-rated housing configured to withstand hydrostatic loading.

[0241] In certain embodiments, electrical energy may be generated through thermal conversion. The reaction chamber may be thermally coupled to a thermoelectric module positioned between a hot-side interface adjacent to the energetic chamber and a cold-side interface thermally coupled to surrounding liquid. Upon ignition, the energetic reaction produces substantial heat, creating a temperature differential across the thermoelectric device. Because surrounding water provides a stable and efficient heat sink, a sustained thermal gradient may be established, thereby driving electron flow within the thermoelectric material and producing electrical output. This configuration may be particularly advantageous in deep-sea environments where ambient liquid temperatures are low, enhancing the temperature differential and improving conversion efficiency. Sequential ignition of multiple energetic segments may be employed to extend the duration of the thermal gradient and provide sustained power generation rather than a single transient output.

[0242] In certain embodiments, the generator may utilize pressure-driven conversion mechanisms. The energetic reaction produces rapid vapor expansion and elevated chamber pressure, which may be harnessed to perform mechanical work. The reaction chamber may be fluidly coupled to a micro-turbine, piston, diaphragm, or similar mechanical interface configured to convert pressure rise or directed exhaust flow into rotational or linear motion. That motion may be mechanically coupled to an electrical generator to produce electrical power. In some embodiments, the system may include staged expansion chambers or damping structures that moderate peak pressures and shape the pressure-time profile to protect mechanical components while maximizing recoverable work.

[0243] In other embodiments, both thermal and pressure outputs may be harvested in a hybrid conversion architecture. For example, a thermoelectric module may extract energy from sustained chamber heating while a micro-turbine simultaneously extracts energy from exhaust flow. Additionally, piezoelectric elements may be positioned to convert pressure transients or cavity collapse events into electrical energy. By combining multiple energy harvesting pathwayswithin a single module, total energy extraction efficiency may be increased and power output may be tailored to specific operational requirements.

[0244] To enable controlled and programmable power output, the energetic composite may be structured in layered, segmented, or pelletized form such that ignition may be staged across multiple sub-chambers. A control system may selectively ignite individual segments in a defined sequence to produce controlled ramp-up, sustained plateau, or pulsed power delivery profiles. Sensors monitoring chamber temperature, pressure, and electrical output may provide feedback to a controller that adjusts ignition timing and sequence to maintain a target voltage or power level. Such programmable behavior may be particularly beneficial for powering sensitive subsea instrumentation that requires stable electrical supply.

[0245] Because surrounding liquid rapidly removes heat, insulation strategies may be incorporated to prevent premature quenching of the reaction and to direct thermal energy toward conversion interfaces. The energetic composite may be encapsulated within insulating barriers such as ceramic liners, aerogel layers, composite thermal shells, or multi-layer insulating structures. These barriers may reduce conductive and convective heat loss into surrounding water while preserving controlled exhaust pathways. The housing may be designed to withstand both internal reaction pressures and external hydrostatic forces, ensuring safe and predictable operation across a range of depths.

[0246] Thermite-powered underwater generators may be deployed in a variety of nonweapon applications, including emergency backup power modules for deep-sea vehicles, temporary energy supply for subsea sensors, burst-power systems for autonomous platforms, or remote power sources for long-duration oceanographic installations. In certain embodiments, the generator may be implemented as a cartridge-based unit that is activated only when high energy density is required, thereby conserving primary battery resources during routine operation.

[0247] In cryogenic or extraterrestrial liquid environments, the same architecture may be adapted for operation in non-aqueous liquids such as methane or ethane. The substantial temperature differential between reaction temperatures and ambient cryogenic liquid may enhance thermoelectric conversion efficiency. Pressure-rated housings and surface-engineered layers may be adapted to maintain reliable ignition and structural integrity under those conditions. Such systems may provide compact, oxygen-independent power generation for exploration platforms operating within subsurface oceans or hydrocarbon lakes.

[0248] In certain embodiments, energy generated during the reaction may be partially recycled within a hybrid vehicle architecture. Electrical output may recharge onboard energy storage systems, while excess thermal energy may be routed to preheat subsequent energetic chambers or to support other thermal management functions. By integrating energetic generation with electrical storage and control systems, a closed-loop hybrid energy architecture may be achieved that balances high-energy-density bursts with steady-state electrical operation for extended mission duration.

[0249] Thermite-Driven Thermoelectric Generators (TEGs) - use thermite to create extreme temperature differences, powering thermoelectric generators (Seebeck effect); convert waste heat into usable electrical power without moving parts; reliable for long-duration deep-sea sensor networks and ocean monitoring stations, for example, TEG-powered ocean monitoring buoys, running on thermite heat for years without refueling.

[0250] Thermite-Powered Backup Systems for Submarines - a thermite-based energy system could act as an emergency power source when main power fails, which unlike batteries, does not self-discharge and remains stable until activation; useful for deep-diving submarines, underwater habitats, and escape pods; for example, a submarine emergency power unit, using thermite to generate heat and charge onboard batteries.

[0251] Hybrid Thermite-Fuel Cell Systems - thermite can heat solid oxide fuel cells (SOFCs) to their operational temperatures, enabling rapid startup, and provide instant power while conventional power sources (like hydrogen fuel cells) come online; can be used in underwater drones (AUVs), remote ocean sensors, and military applications, for example, a hybrid thermitehydrogen fuel cell system for long-range underwater drones, extending operational time.

[0252] Thermite-Heated Ocean Thermal Energy Conversion (OTEC) for Deep-Sea Power Generation - OTEC plants use temperature differences between warm surface water and cold deep-sea water to generate electricity, and adding thermite heat sources can increase efficiency in areas where natural temperature gradients are insufficient; useful for seafloor bases or underwater colonies requiring stable power; for example a hybrid OTEC-thermite power station supporting underwater mining operations.

[0253] Thermite-Assisted Geothermal Wells - thermite can be used to drill into geothermal vents on the ocean floor, allowing energy extraction, and help to establish underwater geothermal power plants without requiring complex mechanical drills; for example, a seafloor geothermal station that taps into volcanic vents, using thermite as an initial drill.

[0254] Thermite-Powered Plasma Drills for Seabed Oil Extraction - traditional oil rigs struggle with high-pressure deep-sea environments, and a thermite-plasma drilling system could vaporize rock to open oil and gas reservoirs efficiently, for example, a self-contained drilling robot using thermite plasma torches to extract deep-sea fossil fuels.

[0255] Self-Regenerating Energy Loops - thermite provides initial heat - drives turbines -excess heat recovers materials for new thermite fuel; use recycled aluminum from seawater electrolysis to manufacture new thermite charges; for example, a deep-sea energy harvester, continuously regenerating its own fuel using ocean minerals.

[0256] Thermite Fusion Ignition Systems - high-temperature thermite could ignite controlled fusion reactions in advanced underwater reactors and could be combined with metallic hydrogen research for future compact fusion power sources; for example, a thermite-assisted cold fusion reactor for unlimited clean energy under the sea.

[0257] Underwater Thermal Reactors for Habitats - a thermite-based heat generator could provide a reliable heat source for underwater stations and submarines; can be used for climate control, water desalination, and food preparation; workswell in deep-sea research stations, where solar or wind power is unavailable; for example, a self-contained thermal pod heating an underwater habitat using slow-burning thermite pellets.

[0258] Thermite-Heated Thermal Batteries - a compact thermal storage unit that uses a thermite reaction to store and release heat on demand; ideal for emergency warmth in deep-sea survival pods or diving suits for extreme depths; for example, a heat pack for deep-sea divers, activated by water exposure to generate warmth.

[0259] Thermite-Heated Fluid Circulation for Submarines - instead of traditional nuclear reactors, thermite could act as a backup heating system for submarines; provides silent, high-energy heating without emissions, improving stealth for military applications; for example, a thermite heat exchanger keeping a submarine warm during stealth operations.

[0260] Thermite-Heated Hydraulic Systems - hydraulic fluids in deep-sea drilling rigs, mining robots, and autonomous underwater vehicles (AUVs) can freeze in extreme cold; thermite prevents freezing and maintains fluid viscosity in extreme depths, for example, a thermite-powered hydraulic heater for deep-sea drilling robots.

[0261] Thermite Survival Heaters for Divers & Submarine Crews - small portable heat packs activated in cold water to prevent hypothermia; useful for submarine escape pods, survival suits, and emergency shelters; for example, a self-heating wetsuit using slow-burning thermite to keep divers warm in deep-sea conditions. Heat-Generating Buoys for Icebreaker Support - floating thermite buoys can be deployed to melt sea ice, keeping shipping lanes clear; can be used for rescue missions in polar waters, preventing vessels from being trapped; for example, a heatemitting buoy deployed in Arctic waters to keep sea lanes open.

[0262] In yet other applications, thermite fuel systems may be combined with thermophotovoltaic (TPV) systems for underwater applications. The systems and methods for thermite fuel and TPV system that comprises of emitter and receivers which use thermites for heat generation and are deployable, additively manufacturable, and inflatable and can have multidimensional geometric shapes which hare symmetric or asymmetric. The TPV systems could employ smart networking for power management using artificial intelligence and / or machine learning for continuous operations.

[0263] In yet other applications, thermite fuel systems may be combined with thermal conversion systems:• Thermal Power Plant - use thermite composites for power generation which allows for the heating and / or ignition of therm ite / energetic composites through induction, specifically via heating using eddy currents or heating via hysteresis, or heating using a combination of both eddy currents and hysteresis, wherein the heating is used as part of a boiler for power generation in a power plant.o The thermal power plant could be used for cogeneration to generate electricity and useful heat simultaneously. Wasted thermal energy is put to some productive use. o The thermal power plant could be used for multi-generation to simultaneously generate electricity, useful heat, cooling, propulsion, energy storage, and industrial products.o The thermal power plant can be combined with renewal and non-renewal power generation systems for generation and / or multi-generation of generate electricity, useful heat, cooling, propulsion, energy storage, and industrial products. Nonrenewal power generation systems include but are not limited to oil, gas, coal, natural gas, and nuclear power or the like. Renewal power generation systems include but are not limited to solar thermal, biomass, compressor, fuel cell, and geothermal or the like.o In other implementations, multi-generation is achieved through spin-mediated interconversion phenomena between dissimilar physical entities to create electricity, light, sound, vibration and heat - on Earth and in Space. These phenomena include but not limited to the Seeback effect, Peltier effect, Spin Seebeck effect, Spin Peltier effect, Spin Hall effect and Inverse spin Hall effect. Spin conversionstake place in regions near the interface between physical entities that are mediated by spins, which transfer angular momentum allowing for interconversion of electricity, light, sound, vibration and heat.o Excess energy is stored in Energy Storage Systems for on-demand applications and distribution. These systems include but are not limited to electrochemical, electromagnetic, thermodynamic, and mechanical. Stored energy is used either directly or indirectly through energy conversion processes as needed to provide a balance between energy supply and demand.• Driving steam engine - by means of combustion and / or sintering, for heating the working fluid where nano- / micro-thermites and energetic materials are used to heat the working fluid by way of complete combustion or convection to enable a phase change.• Double Combustion - drive multiple processes using systems above, where byproducts on reaction become the products of another.• Chemical Looping and / or Metal Looping - drive process to create electricity; by means of combustion or sintering for byproduct production and processing of materials and / or byproducts; includes thermal storage systems and recycling radiant heat.• In Situ Resource Utilization - Using different nanothermite fuels along with in space resources utilization as a fuel source - composite plus materials from the moon, mars, asteroids, & other celestial bodies, or a combination.

[0264] Power Distribution Networks

[0265] In certain embodiments, energy generated by a liquid-operable energetic composite may be conditioned, stored, and distributed through wired or wireless transmission architectures suitable for submerged, high-pressure, or non-atmospheric liquid environments. The system may include an energetic power module configured to generate electrical output through thermal-to-electric, pressure-to-electric, or hybrid conversion mechanisms, coupled to a power management and distribution subsystem that regulates voltage, current, frequency, and energy routing to downstream loads.

[0266] Electrical output from an energetic generator may be inherently transient or pulseshaped depending on the ignition sequence and burn profile. Accordingly, a power conditioning subsystem may include rectifiers, DC-DC converters, voltage regulators, current limiters, and capacitive or inductive smoothing elements configured to transform raw output into stable, loadcompatible electrical supply. In certain embodiments, energy storage components such as supercapacitors, batteries, or high-pressure electrochemical cells may buffer energetic pulses and provide continuous regulated output to connected systems.

[0267] The conditioning subsystem may dynamically adjust conversion ratios in response to load demand, depth-related pressure variations, or generator output fluctuations. In hybrid electric-energetic architectures, the conditioning module may coordinate between energetic generation events and onboard electrical storage systems to optimize efficiency and prolong operational endurance.

[0268] Electrical output from an energetic generator may be inherently transient or pulseshaped depending on the ignition sequence and burn profile. Accordingly, a power conditioning subsystem may include rectifiers, DC-DC converters, voltage regulators, current limiters, and capacitive or inductive smoothing elements configured to transform raw output into stable, loadcompatible electrical supply. In certain embodiments, energy storage components such as supercapacitors, batteries, or high-pressure electrochemical cells may buffer energetic pulses and provide continuous regulated output to connected systems.

[0269] The conditioning subsystem may dynamically adjust conversion ratios in response to load demand, depth-related pressure variations, or generator output fluctuations. In hybrid electric-energetic architectures, the conditioning module may coordinate between energetic generation events and onboard electrical storage systems to optimize efficiency and prolong operational endurance.

[0270] In certain embodiments, conditioned electrical energy may be transmitted through wired conductors integrated into subsea platforms, autonomous vehicles, or distributed sensor networks. Subsea power cabling may include pressure-rated insulation, corrosion-resistant conductors, and dielectric materials selected for compatibility with saline or non-aqueous liquids. The distribution network may be arranged in radial, bus, or mesh topologies depending on mission architecture.

[0271] Connectors and junction interfaces may include sealed, pressure-balanced housings that prevent water ingress while maintaining electrical continuity. In certain embodiments, power distribution nodes may incorporate local regulators and protective devices to isolate faults and prevent cascading failures. Wired distribution may be particularly advantageous for stationary subsea installations, seabed sensor arrays, mining platforms, or under-ice exploration systems requiring sustained power delivery over defined distances.

[0272] In certain embodiments, wireless power transmission may be achieved through inductive coupling between a primary coil integrated into a power generation module and a secondary coil integrated into a remote load or vehicle. Because water attenuates electromagnetic radiation at high frequencies, inductive systems may operate at optimized frequencies that balance transmission efficiency and attenuation characteristics. Encapsulated coil assemblies may be embedded within pressure-rated housings and separated by minimal standoff distances to maintain strong magnetic coupling.

[0273] Such systems may enable contactless charging of autonomous underwater vehicles, remotely operated tools, or sensor nodes without requiring exposed electrical connectors. Inductive charging pads integrated into subsea docking stations may receive energy from thermite-powered generators and wirelessly transfer power to visiting vehicles.

[0274] In certain embodiments, resonant magnetic coupling techniques may be used to increase transmission distance beyond direct-contact inductive systems. Transmitter and receiver coils may be tuned to matched resonant frequencies, enabling efficient power transfer across moderate distances in liquid environments. Shielding and field-shaping structures may be used to confine magnetic flux and reduce losses.

[0275] Such systems may support modular subsea platforms in which power modules are physically separated from load modules but remain electrically coupled through resonant magnetic fields. This may be particularly advantageous where sealed separation between modules improves safety or reliability.

[0276] In certain embodiments, wireless power transfer may be implemented using capacitive coupling between submerged electrodes separated by dielectric layers. Such systems may transmit power through displacement currents across insulating barriers. Capacitive transmission may be used for short-range power transfer across sealed enclosures or between modules where direct conductive coupling is undesirable.

[0277] In certain embodiments, mechanical or acoustic energy generated by energetic events may be converted into electrical energy at a remote location through acoustic transmission. Pressure pulses generated by the energetic module may propagate through water and be captured by piezoelectric receivers tuned to specific frequencies. The captured mechanical energy may then be converted to electrical energy. Although lower in efficiency than wired transmission, acoustic systems may enable distributed power delivery to remote sensors without physical wiring.

[0278] In certain embodiments, the system may incorporate both wired and wireless power distribution. For example, a central energetic power module may deliver bulk energy via wired connections to a docking hub, which in turn wirelessly distributes energy to mobile platforms. Alternatively, wired distribution may serve primary loads while wireless transmission provides redundancy or temporary power during maintenance operations.

[0279] A controller may dynamically select transmission mode based on environmental conditions, load demand, cable integrity, or mission state. Intelligent switching networks may isolate faults and maintain power continuity.

[0280] Because hydrostatic pressure increases with depth, transmission systems may incorporate pressure-balanced enclosures, oil-filled dielectric cavities, or compliant housings to maintain structural integrity. Insulation materials may be selected to prevent dielectric breakdown under high pressure and to resist long-term exposure to saline environments.

[0281] For cryogenic liquid environments, transmission components may be adapted for low-temperature operation, with materials selected to maintain conductivity and mechanical stability.

[0282] In certain embodiments, energetic gas generation modules may power pneumatic actuators while simultaneously generating electrical energy that is routed through the distribution system. Hybrid architectures may integrate propulsion modules, gas generators, and electrical generation modules into a unified energy network. Energy harvested from pressure pulses or thermal gradients may be conditioned and distributed to onboard systems or to external loads.

[0283] In certain embodiments, a subsea energy ecosystem may include: 1) Bio-assisted feedstock harvesting modules 2) Energetic composite fabrication modules 3) Thermite-based energy generation modules 4) Power conditioning and storage systems4) Wired and wireless distribution networks 5) Autonomous control systems. Such an integrated system may enable localized energy production and distribution in remote marine or extraterrestrial liquid environments without reliance on surface infrastructure.

[0284] In certain embodiments, a liquid-operable energetic power system may be integrated into a distributed subsea energy network comprising multiple generation nodes, transmission pathways, transceivers, and intelligent control systems. The energetic power module may generate electrical energy through thermal-to-electric, pressure-to-electric, or hybrid conversion mechanisms, and the generated electrical output may be conditioned, stored, transmitted, and dynamically routed across a network of interconnected submerged systems. The network may support autonomous underwater vehicles, stationary subsea installations, distributed sensor arrays, mining platforms, or extraterrestrial liquid exploration infrastructure.

[0285] The energetic generation module may include a sealed reaction chamber containing an energetic composite, an ignition subsystem, and one or more energy conversion interfaces such as thermoelectric modules, micro-turbines, or pressure-driven generators. Electrical output from the generator may be directed into a power conditioning subsystem comprising voltage regulators, DC-DC converters, rectification circuits, filtering components, and energy storageelements such as batteries or supercapacitors. Because energetic generation may be pulsebased or staged, the conditioning subsystem may buffer transient outputs and provide stable, regulated electrical supply suitable for sensitive loads and transmission lines.

[0286] In certain embodiments, conditioned electrical energy may be distributed through wired subsea transmission lines. These lines may include corrosion-resistant conductors, pressure-rated dielectric insulation, and sealed connectors designed to withstand hydrostatic compression and long-term immersion. The wired distribution network may be configured in radial, ring, bus, or mesh topologies depending on mission architecture. Each node within the wired network may include local power regulation, protection circuitry, and fault isolation features to prevent cascading failures. Wired distribution may provide high-efficiency bulk energy transfer for stationary platforms or high-demand loads.

[0287] In addition to wired transmission, wireless power transmission systems may be incorporated into the network. Inductive coupling systems may include primary coils integrated into generation nodes and secondary coils integrated into receiving modules. These coils may operate at optimized frequencies selected to balance electromagnetic attenuation in liquid with coupling efficiency. Encapsulated coil assemblies may be housed in pressure-balanced enclosures, enabling contactless power transfer between docking stations and mobile vehicles. In certain embodiments, resonant magnetic coupling techniques may be used to extend transmission range and improve efficiency across moderate standoff distances. Capacitive coupling or electrostatic transfer methods may also be employed for short-range transmission across dielectric barriers. In some embodiments, acoustic energy transmission may be used to convey mechanical energy through water to remote receivers, where piezoelectric transducers convert pressure oscillations into electrical power.

[0288] The system may further incorporate communication transceivers configured to exchange power management data at remote energy nodes. Each generation module, distribution hub, vehicle, or sensor station may include a transceiver configured for data exchange using acoustic, optical, electromagnetic, or hybrid signaling modalities compatible with submerged environments. Multiple systems may be configured in a distributed energy network. These transceivers may support bidirectional communication for power management coordination, fault detection, demand signaling, and synchronization of energetic events. In certain embodiments, the same physical structures used for wireless power coupling may also serve dual purposes as communication antennas or coils, enabling integrated power-and-data transmission.

[0289] In a networked embodiment, multiple energetic generation modules may be distributed across a subsea field and interconnected through wired and / or wireless links to form a resilient energy grid. Each node may function as a generation, storage, relay, or load module. Intelligent control systems may dynamically route energy based on load demand, generator status, environmental conditions, or mission priorities. For example, if one node experiences a reductionin generation capacity, adjacent nodes may increase output or redistribute stored energy. Energy flow may be managed through programmable switching networks and monitored through distributed sensing.

[0290] In certain embodiments, the energy network may operate as a self-organizing mesh system. Each node may periodically broadcast status information, including available generation capacity, storage level, and load demand. A distributed control algorithm may allocate energy resources across the network to maintain system stability and optimize efficiency. Hybrid architectures may combine wired backbone connections with wireless redundancy to enhance fault tolerance and simplify modular deployment.

[0291] The network may further integrate gas-generation modules and propulsion subsystems. For example, an autonomous underwater vehicle may dock with a stationary energetic generation node and receive wireless charging through inductive coupling. Alternatively, a mobile vehicle equipped with its own energetic module may supply supplemental power to a stationary node through wired or resonant magnetic transfer. In certain embodiments, energy generated from thermite-based modules may be shared among multiple robotic agents operating collaboratively within a mining or exploration zone.

[0292] Pressure-rated housings, oil-filled dielectric enclosures, or compliant structures may be used to protect transmission components and transceiver electronics from hydrostatic compression. Materials may be selected for long-term resistance to corrosion, biofouling, and cryogenic exposure. In extraterrestrial liquid environments, transmission and communication subsystems may be adapted to operate within non-aqueous fluids such as methane or ammonia-rich brines, with frequency selection and insulation tailored to fluid dielectric properties.

[0293] In certain embodiments, the network may form part of a closed-loop subsea energy ecosystem that includes bio-assisted feedstock harvesting modules, electrochemical refinement systems, energetic composite fabrication units, power generation modules, distribution infrastructure, and communication-enabled transceivers. Such a system may enable autonomous or semi-autonomous energy production and distribution in remote marine or planetary liquid environments without reliance on surface-based infrastructure.

[0294] Thermite-Based Gas Generation Modules

[0295] In certain embodiments, energetic composites commonly referred to as thermites or thermite-like metal-oxidizer systems may be configured primarily as gas generation sources rather than as heat sources. In these embodiments, the energetic system is engineered so that ignition produces a controlled quantity of gas and / or vapor that can be routed into a defined gas volume, accumulator, actuator, or pressure network, thereby providing an oxygenindependent, compact gas supply in submerged, sealed, or remote environments. The system may be particularly useful where conventional compressed gas cylinders are impractical due to size, leakage, long-duration storage requirements, or logistic constraints.

[0296] A thermite-based gas generator may comprise a sealed reaction chamber containing an energetic composite, an ignition subsystem configured for reliable initiation in liquid or humid environments, and a gas handling interface that directs generated gases into a downstream volume. The gas handling interface may include a flow path, checkvalves, filters, and a pressure regulation element, such as a burst diaphragm, a calibrated restrictor, or a spring-biased relief valve. The generator may further include a heat management structure and particulate capture features so that hot particulates and condensed reaction products are contained within the generator housing while gas flow is delivered downstream in a controlled manner.

[0297] In certain embodiments, gas generation may be achieved through one or more complementary mechanisms. A first mechanism includes vapor generation from surrounding or contained liquid, where reaction heat rapidly vaporizes water or another working fluid within a designated vaporization zone, producing a high-pressure gas phase that can be used as a pneumatic source. A second mechanism includes incorporation of gas-generating components that decompose or react upon heating to release gaseous species, thereby increasing total gas yield relative to the primary condensed-phase redox reaction alone. A third mechanism includes staged gas production, where an initial ignition stage produces a localized insulating vapor region and a subsequent stage sustains gas generation over a longer interval through sequential activation of multiple energetic segments.

[0298] Because energetic reactions can produce rapid pressure rise, the system may include pressure conditioning features that shape the pressure-time curve to match the requirements of the driven load. In certain embodiments, a staged expansion cavity, baffle structures, or a multichamber plenum may be used to reduce peak pressure while extending gas delivery duration. In other embodiments, a regulator may meter gas into a reservoir to achieve stable output pressure. Filters, cyclonic separators, sintered metal screens, or condensation traps may be used to prevent particulate migration into downstream pneumatic components and to improve reliability of valves and actuators.

[0299] In certain embodiments, the gas generator is implemented as an array of discrete cartridges or micro-chambers that are independently ignitable, enabling programmable gas delivery. A controller may select which cartridge to initiate and when to initiate it, thereby generating a sequence of pressure pulses or a quasi-continuous gas supply. This architecture allows the system to support repeated actuation events, controlled inflation, or periodic pressure replenishment over extended deployments. Sensor feedback, including pressure and temperature sensing, may be used to adjust ignition scheduling and to maintain a target reservoir pressure within a specified range.

[0300] Thermite-based gas generators may be used to supply gas for buoyancy control systems, including controlled inflation of buoyancy bladders or lift bags for salvage, subsea installation, or emergency ascent of scientific payloads. The generator may also supply pressurized gas for pneumatic loads for pneumatic actuators, such as valves, latches, clamps,sampling mechanisms, or emergency release couplings, particularly for subsea robotics where compact, long-shelf-life actuation sources are advantageous. In certain embodiments, generated gas may be used for purging and drying operations within sealed housings, for example to clear moisture from optical ports or to displace liquid from a sampling chamber. In other embodiments, the gas output may be routed through a micro-turbine or diaphragm generator to produce electrical power from the pressure differential, thereby enabling a combined gas-and-power module for remote subsea instruments.

[0301] In certain embodiments, gas generation is configured for reliable operation under high hydrostatic pressure. The reaction chamber may be pressure-rated, and the gas delivery system may incorporate a pressure compensation strategy so that gas discharge remains effective at depth. For example, the system may fill an internal accumulator above ambient pressure, or may use staged generation to overcome external compression. The control system may adjust ignition timing and cartridge selection as a function of ambient pressure to achieve consistent gas yield and pressure rise across depth ranges.

[0302] In certain embodiments, the gas generation concept is adapted to non-aqueous liquids, including cryogenic hydrocarbon environments. The gas generation module may be configured to vaporize a selected working fluid or to produce gases from integrated gasgenerating components while maintaining stable operation at low ambient temperatures. Surface-engineered layers and insulated housings may be used to preserve ignition reliability and to manage thermal gradients in cryogenic liquids, thereby enabling oxygen-independent gas supply for exploration platforms operating in non-terrestrial liquid environments.

[0303] Benefits of Thermites as Fuel

[0304] Some benefits of using thermites as fuel include waste heat recycling for thermal efficiency, fuel regeneration for continuous operation, and autonomous recycling robots for sustainability:

[0305] Thermoelectric & Heat Exchange Systems - the extreme heat from thermite reactions can be reused for power generation via thermoelectric generators (TEGs); heat exchangers could capture and transfer heat to power desalination units, hydrothermal systems, or deep-sea habitats; for example, a closed-loop heat exchanger that repurposes thermite heat for oceanic research stations.

[0306] Reusing Waste Heat for Water Purification & Desalination - thermite-powered heat could boil seawater, producing fresh water for drinking or industrial use; useful for underwater bases, submarines, or deep-sea mining operations; for example, a self-sustaining desalination unit, powered by thermite waste heat.

[0307] Regenerating Thermite Fuel from Oceanic Resources - aluminum & iron are abundant in the ocean and can be extracted using: electrolytic metal recovery (extracting Al from seawater), deep-sea mining (extracting Fe2O3from seabed minerals); a floating or submerged recycling platform could continuously reprocess waste aluminum oxide into new thermite fuel; for example,a thermite-powered underwater factory that extracts aluminum from ocean minerals to refuel itself.

[0308] Hydrogen Production for Hybrid Systems - thermite reactions release extreme heat, which can power hydrogen production via water electrolysis; A hybrid thermite-hydrogen system could store excess energy in fuel cells, creating a backup power supply; for example, a deep-sea energy station that uses thermite heat to generate hydrogen, extending mission duration.

[0309] Self-Collecting Thermite Residue Bots - small autonomous robots could recover and separate molten iron and aluminum oxide waste for recycling; bots could operate around underwater habitats, oil rigs, and deep-sea mining sites; for example, Al-powered recycling drones, collecting and reprocessing waste from thermite-based welding and heating systems.

[0310] Al-Optimized Resource Harvesting for Closed-Loop Systems - Al-powered systems can monitor thermite byproducts and optimize material recovery; integrated into deep-sea mining rigs, underwater research stations, and submarine recycling facilities; for example, an Al-controlled deep-sea refinery, automatically extracting metals for thermite-based power generation.

[0311] Thermite Harvesting

[0312] Thermite materials may be harvested through bioleaching, which is the microbial extraction of metals, such as iron and aluminum, from seawater and rocks. Examples includes:• Iron-Oxidizing Bacteria for Rust Production - certain bacteria, such as Leptothrix ochracea and Gallionella ferruginea, oxidize dissolved iron (Fe2+) into iron oxide (Fe2O3), forming rust-like deposits; these natural iron oxide deposits could be harvested and refined as a thermite oxidizer; for example, a bioreactor filled with iron-oxidizing bacteria that continuously produces iron oxide for thermite fuel.• Aluminum Extraction by Acid-Producing Microbes - acidophilic bacteria, such as Acidithiobacillus ferrooxidans, can dissolve minerals and release aluminum from bauxiterich sediments; these microbes are already used in biomining and could be adapted for deep-sea aluminum extraction, for example, a bio-mining system that extracts aluminum from marine clay using acid-producing microbes.• Manganese-Oxidizing Bacteria for Alternative Oxidizers - some bacteria, like Bacillus spp.and Pseudomonas putida, convert dissolved manganese into manganese oxides (MnO2), which can serve as an oxidizer in thermite-like reactions; deep-sea manganese nodules, formed by these microbes, could be harvested for alternative thermite fuels; for example, deep-sea bacterial farm growing manganese oxide deposits for thermite fuel.

[0313] Extremophile-Assisted Harvesting of Thermite Feedstocks

[0314] In certain embodiments, extremophilic microorganisms may be used to assist in the extraction, concentration, transformation, or purification of metal-bearing materials suitable for use as components of energetic composites. Extremophiles, including thermophiles, acidophiles, halophiles, piezophiles, and chemolithotrophs, are capable of surviving and metabolizing inenvironments characterized by high temperature, high salinity, high pressure, or extreme pH, such as deep-sea hydrothermal vents, saline basins, and subsea sedimentary systems. These organisms may be leveraged as biological agents for bioleaching, biomineralization, or selective metal recovery in submerged or harsh environments where conventional industrial processing is difficult.

[0315] In certain embodiments, acidophilic or chemolithotrophic microorganisms may be used to liberate metal ions from marine sediments, hydrothermal vent deposits, black sands, manganese nodules, or sulfide-rich formations. Such microorganisms may oxidize or reduce mineral phases, generating chemical conditions that increase solubility of iron, manganese, aluminum-bearing minerals, magnesium compounds, or other metal-containing substrates. For example, microorganisms capable of oxidizing sulfide minerals may accelerate breakdown of pyrite or related compounds, thereby releasing iron species that may subsequently be processed into iron oxides suitable for energetic oxidizer components. Similarly, microbial activity may enhance dissolution of aluminosilicates or magnesium-bearing carbonates in controlled bioreactors deployed subsea or on floating platforms. Bioleaching systems may operate in closed or semi-closed bioreactor modules integrated into subsea mining platforms. The bioreactors may include circulation systems, pH control, temperature regulation, and separation units that collect dissolved metal species for downstream refinement.

[0316] In certain embodiments, extremophiles may be used not only to dissolve minerals but also to selectively precipitate desired metal species into defined mineral forms. Certain microbial metabolic pathways alter local redox conditions or pH in a manner that promotes formation of iron oxides, manganese oxides, or other metal oxide precipitates. For example, iron-oxidizing bacteria may facilitate conversion of dissolved iron into iron oxide particulates with defined morphology. These biologically produced oxides may exhibit distinct particle size distributions or surface chemistries advantageous for energetic composite fabrication. Controlled biomineralization may provide a low-energy pathway to produce finely divided oxidizer particles without extensive mechanical milling. Such systems may be particularly valuable in deep-sea environments where energy availability is constrained, and mechanical refinement is energy intensive.

[0317] Although aluminum and magnesium are typically bound in stable mineral phases, certain extremophiles may enhance breakdown of aluminosilicates or carbonate minerals through acid generation or chelation mechanisms. In certain embodiments, microorganisms may be engineered or selected to secrete organic acids or ligands that preferentially bind aluminum or magnesium ions, increasing their mobility in aqueous solution. Following biological mobilization, the metal-containing solution may be directed to an electrochemical refinement stage where metal ions are recovered as purified feedstock. The integration of biological pre-processing may reduce chemical reagent requirements and lower overall energy input compared to purely chemical extraction methods.

[0318] In certain embodiments, extremophilic biofilms may be used as selective metal accumulation platforms. Microbial biofilms may bind dissolved metal ions from seawater or hydrothermal fluids onto extracellular polymeric matrices. Overtime, metal-enriched biofilms may be harvested mechanically and processed to recover concentrated metal content. Artificial substrates deployed in metal-rich marine environments may promote biofilm growth and selective metal capture. These substrates may be periodically retrieved and processed within a refining module. This approach may allow gradual accumulation of feedstock in low-concentration environments without continuous high-energy filtration.

[0319] Because many extremophiles are naturally adapted to high hydrostatic pressure and high temperature environments, bio-assisted extraction systems may operate directly at depth without requiring large pressure vessels. Bioreactors may be pressure-balanced with ambient seawater and may leverage natural geothermal gradients near hydrothermal vents. The ability to operate at depth may reduce logistical complexity and eliminate the need to transport bulk sediment to the surface for processing. Metal-rich solutions or concentrates may instead be transported in smaller volumes to a central refinement module.

[0320] In certain embodiments, a closed-loop subsea platform may integrate: 1) Bioleaching modules 2) Biomineralization modules 3) Electrochemical refinement systems 4) Energetic composite fabrication modules, The biological stage concentrates or transforms raw mineral inputs. The electrochemical stage produces refined metal feedstock. The fabrication stage produces energetic composite elements for propulsion, gas generation, or power modules. Artificial intelligence systems may monitor microbial activity, metal concentration, pH, temperature, and output yield to dynamically regulate flow rates and nutrient supply. This integration may enable semi-autonomous feedstock production in remote marine environments.

[0321] In certain embodiments, extremophile-assisted harvesting may be extended to extraterrestrial ocean environments where microbial ecosystems may exist or may be introduced in controlled bioreactors. If metallic ions are present in subsurface brines or hydrothermal systems, bio-assisted concentration and transformation may provide a low-energy mechanism for in-situ resource utilization. Such systems may operate within enclosed bioreactor modules to avoid environmental contamination while leveraging biological mechanisms for metal mobilization and precipitation.

[0322] Thermite Regeneration

[0323] Microbial Metal Recycling for Continuous Fuel Regeneration - after a thermite reaction, byproducts like molten iron and aluminum oxide (AI2O3) remain; metal-reducing bacteria, such as Shewanella oneidensis, can help break down these waste materials, recovering metals for reuse; for example, a self-healing thermite generator, where extremophiles recover aluminum and iron for new thermite fuel cycles.

[0324] Bacterial Rust Regeneration for Infinite Iron Supply - iron-oxidizing bacteria can replenish iron oxide deposits on submerged structures, creating a renewable iron oxide supply;thermite oxidizers could be grown rather than mined; for example, a bioreactor that continuously “grows” rust for thermite fuel production.

[0325] Autonomous Thermite Production

[0326] By combining extremophiles, Al-driven monitoring, and automated fuel processing, a closed-loop thermite production system can be created. An example implementation may include: i) iron-oxidizing bacteria continuously generate iron oxide from seawater, ii) acidophilic microbes extract aluminum from marine sediment, iii) metal-reducing bacteria recycle thermite byproducts for reuse, and iv) Al-driven monitoring optimizes bacterial growth for sustained fuel production. This system could be use, for example, in a deep-sea Al-powered bioreactor that autonomously produces and recycles thermite fuel.

[0327] The systems and methods herein provide surface-engineered energetic composite compounds and configurations which allow for combustion underwater, particularly to generate heat and cavities underwater. Below, as an example, an aluminum copper oxide energetic composite with a hydrophobic stearic acid coating is discussed. In other embodiments the energetic composite may include other fuels and oxidizer and a surface engineered coating or layer of the energetic composite may have other repellent characteristics. That is, while a hydrophobic layer will repel or protect from water, energetic composites may also be used in nonwater liquid environments and require other repellants, such as oleophobic, lyophobic, solvophobic, or omniphobic coatings.

[0328] Cavitation

[0329] There are established methods for cavitation characterization with potential energy often used to evaluate the effects. Given that the pressure outside of a cavity is significantly larger than the pressure within the cavity and the static pressure of the water column is two orders of magnitude smaller than atmospheric pressure, the maximum potential energy of a cavity can be approximated by:EP max—P “V max

[0330] For a mechanically induced cylindrical cavitation resulting from high velocity and acceleration of a water flow, the growth and decay can be described by:where * is the fraction of cavity volume over the maximum cavity volume and t* is time over the characteristic time for the cavity to reach its maximum volume.

[0331] It has been previously demonstrated that the explosion generated gaseous bubbles exhibit similar growth and collapse trends to mechanically induced cavitation. While these explosive tests were not constrained to a cylindrical environment, both methods utilized a nearly instantaneous initial energy input following the same trend. It can be expected that, considering the source of the gases generated via thermite combustion, as described herein, the theoretical models for growth and collapse of mechanically induced cylindrical cavities can be used as a reference point to describe the formation and dynamics of the combustion induced cavities.

[0332] As noted herein, an unconventional fuel that has potential for rapid reaction underwater and cavity generation is thermite, or metastable intermolecular composites (MICs). The exothermic reactions between a metal fuel, typically aluminum, and solid oxidizers of thermite mixtures, have demonstrated unique characteristics such as self-sustaining combustion without requiring environmental oxygen, tunable reactivity using nano-sized constituents, and geometrical functionality through surface modification. In addition, different MIC systems exhibit distinct gas generation behaviors from their thermite reaction. For example, combustion of AI / CuO and AI / Fe2O3 MICs can produce different peak pressures (reflecting varying amounts of combustion gases) and pressurization rates of 0.191MPa, 12.34 MPa / s and 0.121 MPa, 1.11 MPa / s, respectively. Nevertheless, despite extensive research efforts in investigating the structuredependent reactivity and energetic properties of MICs, investigations on MIC combustion behaviors underwater have been rare.

[0333] Significant challenges are associated with combustion of MICs in water, e.g., oxidation of the reactive aluminum by water, hydrolysis of metal oxide particles, excessive heat loss from the burning sample to water, water vaporization at the interface, and effects of hydraulic pressure. Some previous work has been attempted to address these problems. Meir et al. developed a technique to encapsulate and ignite thermite powder underwater by utilizing the bubble-marble effect. However, this method faced practical difficulties with underwater fuel storage and use. Advanced physical and chemical deposition methods have been used to produce superhydrophobic nanoenergetic composites. Some of these materials were implemented for underwater combustion, including an AI / Fe203 / fluorocarbon produced using ALD-CVD by Nixon et al. and an AI / Co304 / fluoroalkylsilane produced using magnetron sputtering. A 50% performance loss was observed in the AI / Co304 / fluoroalkylsilane sample after storing underwater for two days. These sophisticated deposition methods have a very limited production rate. Recently, Yang et al. prepared an AI»FAS-17 / PTFE nanocomposite using chemical methods to obtain a hydrophobic Al-polymer thermite. However, the thermite presented a slow burning rate of 0.6 m / s and had to be ignited in air, before propagating into water. Physical macrostructure control of core-shell nano-rod structures has also been demonstrated to provide hydrophobic properties, however, lack underwater testing limits the applications of the material. Naturally occurring substances have also been shown to demonstrate promising water resistant properties that may enable hydrophobic nanoenergetic reactions.

[0334] Thermite Combustion Induced Cavitation

[0335] Generation of underwater cavities requires rapid expansion of a gaseous volume which may be achieved via the exothermic reactions of nanoenergetics such as thermites. Herein is described the formation of combustion induced vaporous cavitation and its dynamics using a novel super-hydrophobic AI»CuO»SA MIC developed with a simple SA (stearic acid) coating on core-shell AI»CuO particles for underwater combustion. Different material characterization methods were used including high resolution imaging, Differential Scanning Calorimetry andThermogravimetry Analysis (DSC-TGA), Fourier-Transform Infrared Spectroscopy (FTIR), zeta potential and water contact angle measurement were carried out to determine the microstructure and thermal properties of the material and to evaluate possible reaction pathways. The MIC pellet was directly ignited in water using a laser. The underwater combustion led to generation of gaseous bubbles vaporous cavities, which were evaluated using high-speed imagery and photodiodes. The growth and collapse of the cavity were analyzed alongside that of cavities generated by mechanical means, to demonstrate key characteristics of staged cavitation formation and dynamics. Finally, temperature measurement and discussion provide insights into the reaction mechanism for the underwater combustion of AI»CuO»SA MICs.

[0336] The superhydrophobic, stearic acid (SA) coated, core-shell nanocomposite addresses the challenges associated with the high hydrophilicity of metallic nanoparticles and subsequent deactivation of aluminum by water which hinders ignition and flame propagation. A compound of aluminum and copper oxide coated with stearic acid is herein referred to as AI»CuO»SA. With 1% SA, AI»CuO»SA combusts violently, achieving a maximum cavity volume above 25 mL and a cavity growth rate up to 13 L / s using only 20 mg of material. At 5% SA, AI»CuO»SA stayed submerged for two weeks and retain excellent reactivity. The combustion performance was tuned by adjusting the sample composition to control the reactivity and material properties of the nanoenergetics. The rates of the cavity growth and decay were investigated using high-speed imaging and analyzed in a non-dimensional analysis to demonstrate the key characteristics of combustion induced cavitation. It was observed that the cavity generation process occurs across several stages including SA decomposition around 300°C, creating a small bubble surrounding the sample which reduces heat loss to water and promotes the thermite reaction, and the exothermic reaction at 600°C resulting in the formation and rapid growth of the major cavity. Thermal analyses in controlled heating and during combustion provided insights into the reaction mechanisms. The results of the AI»CuO»SA analyses are described below.

[0337] Microstructures of Al» CuO»SA

[0338] Revealing the microstructure of AI»CuO»SA allows an understanding of how the SA coating interacts with the reactive AI»CuO powder. Multiple tests were carried out with key results including high resolution imaging and DSC-TGA. Additional tests demonstrated the level of SA coating on the core-shell particles as well as the superhydrophobic quality of the final samples.

[0339] Morphology characterizations

[0340] Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images were taken to characterize the coating structure of AI»CuO and AI»CuO»SA(5%). Figures 1A-B show the SEM images of AI»CuO and AI»CuO»SA. Figure 1A illustrates a dense cluster of AI»CuO nanoparticles. The uneven surface of the nanoparticles shown in the image indicates the deposition of small CuO nanoparticles on larger Al nanoparticles. The formed core-shell structure of AI.CuO significantly increases the interfacial contact area between Al and CuO nanoparticles, shortening the mass transfer distance required for the exothermic reactions and promoting thecombustion of the material. Some uncoated Al nanoparticles also appear in the image, which is consistent with previous publications. Figure 1B exhibits the surface morphology of AI»CuO»SA(5%) nanocomposites. The overall size and morphology do not change significantly after the addition of SA, indicating no significant alteration has been made to the AI»CuO structure after the addition of the SA layer. However, the surface of the particles presents some minor changes, showing reduced smoothness with SA coating, which was further investigated by using higher resolution imaging techniques.

[0341] Scanning transmission electron microscopy- electron energy loss spectroscopy / energy dispersive x-ray spectroscopy (STEM-EELS / EDS) was utilized to investigate the coating structure of AI»CuO»SA (5%), which is shown in Figures 1C-E. A partially coated AI»CuO particle was selected to better illustrate the elemental distribution. The STEM image of the particle, shown in Figure 1C, clearly presents the core particle of aluminum (100 nm) partially coated by the much smaller CuO particles. The coating of SA, however, is unable to be observed solely from the STEM images. Different layers are used to present the location of different elements in EELS overlay (Figure 1 D, and single layer in Figure 1 E of aluminum, copper, oxygen, and carbon). The circle indicates that the Al core, which can also be seen in STEM image, remains untouched after CuO and SA coating. The Al core is covered by a thin but continuous circle containing oxygen, indicating the spontaneously formed amorphous AI2O3 shell on the surface of Al nanoparticles, which has a thickness around 3 nm. The copper on the left and bottom-right of the Al particle indicates the formation of CuO nanoparticles covering the surface of Al, forming a core-shell AI»CuO structure. The carbon circle, which is clearly seen in both separate and overlay images, proves the existence of carbon in the core-shell structure of AI»CuO»SA. Carbon can only originate from SA, thus the carbon mapping is a strong indicator of the location of SA in the nanocomposite.

[0342] Two different patterns of carbon distribution are observed in AI»CuO»SA. First, similar to the AI2O3 shell, a near continuous circle of carbon is seen on the top of bare Al nanoparticles, indicating the direct coating of SA on the surface of Al nanoparticles. However, unlike the AI2O3 shell indicated by oxygen mapping, the SA coating is not even on Al nanoparticles. On the area where Al is bare, such as the top-right corner of the particle, the coating is thicker and more solid. On the area that is covered by CuO, the coating is thinner, as part of the Al surface is already covered by CuO. Meanwhile, SA also appears in locations other than the surface of Al nanoparticle, including the surface of CuO nanoparticles, seen in the bottom left and bottom right of the image. This demonstrates that SA not only covers the surface of Al nanoparticles, but also forms a layer on the CuO nanoparticles, providing a complete coverage and protection against water when the AI»CuO»SA composite is submerged. Overall, the thickness of the SA coating on the particle ranges from about 2 to 6 nm depending on location for the AI»CuO»SA(5%) sample. It is known that the length of one SA chain is approximately 2.47 nm. Therefore, assuming that the stearic acid chains are not perfectly perpendicular to the surface, it can be reasonablyassumed that there is a layer of a few SA molecules coating the outer edges of the surface. As long as the particles are coated and prevent the deactivation of the energetic aluminum it is expected that they will be reactive underwater.

[0343] Differential scanning calorimetry and thermogravimetry analysis (DSC-TGA)

[0344] DSC-TGA measurements were carried out to distinguish the possible chemical reactions with different coating amounts. The DSC curves for raw SA, AI»CuO and AI»CuO»SA(5%) are presented in Figure 1F, and the corresponding TGA curves are shown in Figure 1G. For both Figure 1E and Figure 1G the top line represents AI»CuO»SA(5%), the next line down AI»CuO»SA(3%) , the next line down AI»CuO»SA(1%) , the next line down AI»CuO, and the bottom line is SA alone. The first major thermal process of SA is its melting at 67°C, shown as a sharp endothermic peak in the DSC curve without any mass change in TGA. Stearic acid begins to break down at 160°C and continues up to around 350°C as the material fully decomposes with almost no mass remaining. The thermal decomposition process of SA under an inert atmosphere has been discussed thoroughly in publications. The two broad exothermic peaks in the range of 196-362°C and 452-630°C during decomposition process demonstrate molecular chain breakdown, decomposition, and pyrolytic vaporization of SA, respectively.

[0345] For the core-shell AI»CuO, there is not any significant weight loss during the measurement upto 1000°C, which is well below the boiling temperature of Al, AI2O3 and Cu. The major chemical reaction that occurred during the TGA-DSC process of AI»CuO is the chemical redox reaction between fuel (Al) and oxidizer (CuO). The onset temperature of the main exothermic reaction is around 560°C and the peak temperature is around 600°C. Most of the process occurs before the system reaches the melting point of Al at 660°C, indicating the occurrence of the reaction of AI-CuO in the condensed phase and corresponding well with previous publications about core-shell structured AI»CuO nanocomposite. Only a minor peak exist around 750 °C due to leftover Al and CuO from the main reaction. The absence of the decomposition process of CuO around 950°C in TGA-DSC results indicates that the CuO had been fully consumed during the reaction due to the fuel rich nature of the nanocomposite at ER 2.5.

[0346] The TGA curve of AI»CuO»SA is a simple combination of the TGA measurements of SA and AI»CuO. Only one minor mass loss is seen during the entire heating process. The 4.7% mass loss after between 250 to 370°C is attributed to the decomposition of SA and escape of the gaseous products. The percentage of weight loss (1, 2.8, and 4.7%) at this stage in all three samples corresponds very well with the SA percentage (1, 3, and 5%) in AI»CuO»SA, further confirming that the weight loss originated from the decomposition of SA.

[0347] Multiple exothermic peaks exist in the DSC curves of AI»CuO»SA. The first one occurs at 300 °C, which has not been seen in AI»CuO thermite, but very close to the first exothermic peak observed in the DSC of SA. However, the energy release of this peak is around 100 - 200 J / g, much higher than the reasonable energy to be generated solely from the decomposition ofSA considering its content of only 1 % to 5% in the nano-composite, Stearic acid exhibited intense exothermal reaction behavior with aluminum during its pyrolysis. As reported in literature, the pyrolysis of stearic acid commenced at approximately 215 °C, corresponding well with the DSC-TGA results in Figure 1. The primary products resulting from the pyrolysis of stearic acid include H2O, CO2, C2H4, CO, and CH2O. As the temperature reaches the pyrolysis temperature of stearic acid, it decomposed into C2H4, C2H3, C2H5, and other free radicals (such as HO2 and OH). The generated hydrocarbon radicals and water can then react with aluminum nanoparticles. The primary mechanism involves rapidly transferring electrons from the aluminum surface to the radical. This results in the formation of a hydrocarbon anion and an aluminum cation, which can subsequently participate in further reactions within the system. Therefore, it is reasonable to believe that the decomposed products of SA react with Al, providing the extra heat in the first peak around 300°C.

[0348] Meanwhile, the exothermic reaction between Al and CuO around 600°C and 750°C undergo a significant reduction of 12% (1% SA) to 65% (5% SA) in terms of total energy release. Therefore, it is reasonable to believe that the decomposed products of SA react with the aluminum nanoparticles, providing the extra heat in the first peak around 300°C, but this deactivates part of the Al and reduces the major reaction between Al and CuO. Due to the large number of decomposed species of SA it is difficult to determine the exact reactions occurring at each phase of the DSC-TGA measurement as several may be taking place. However, this deactivation of Al at low-temperature may not be considered during the combustion process of AI»CuO»SA due to the much faster heating rate, allowing AI»CuO to reach the combustion threshold temperature within a few milliseconds, leaving much shorter time for the deactivation of Al from SA decomposition products. It should also be noted the thermal analysis for AI»CuO»SA(10%) has not been moved forward after 250 °C due to an explosion inside the instrument resulted by the reaction between Al and decomposition product of SA.

[0349] Underwater combustion ofAI» CuO» SA

[0350] The energetic behavior of AI»CuO»SA combustion underwater was optically recorded and analyzed using a high speed camera from the side of the combustion container, as shown in Figure 6B. It was immediately found that the SA was able to act as a hydrophobic barrier, allowing the AI»CuO»SA particles to be ignited and propagate underwater, something that has not been seen in nanothermites coated in other hydrophobic materials as done in previous literature. A series of samples with equivalence ratios between 1.5 and 4.0 were first tested to determine the optimal ER. All samples with ERs between 1.5 to 3.0 were successfully ignited, while the sample of ER 4.0 (very Al rich) was not. Representative images from the combustion of AI»CuO»SA with different equivalence ratios are provided in Figure S1 in the supporting information. Among the samples that were ignited, it was found that an equivalence ratio of 2.5 gave the highest combustion reactivity and best consistency, and was selected for the study. The optimal equivalence ratio of 2.5 is also consistent with our previous research.

[0351] The effect of SA loading in AI»CuO»SA was then analyzed once the optimal equivalence ratio of 2.5 had been established. At all SA percentages of 1, 3, 5, and 10%, the AI»CuO»SA samples easily ignited and combusted, as shown in the representative images in Figure S2 in supporting information. However, the violence of the reaction decreases with the increasing SA loading. With AI»CuO»SA(1%) combusting rapidly and most violently, AI»CuO»SA(10%) reacts slower and produces a weaker reaction. Figure 2 demonstrates the representative combustion stages of an AI»CuO»SA(5%) pellet, including the ignition, nucleation, growth, and collapse of a gaseous bubble and cavity underwater. A video of the combustion is provided in the supporting material. Upon laser excitation, the incident face of the sample pellet undergoes rapid heating. After a short ignition delay on the order of a few milliseconds, the hot spot reaches a critical temperature such that a small bubble is formed on the sample surface. This small initial bubble is gaseous SA evaporating due to laser exposure. As the laser continues to heat the sample inside this small bubble, the temperature rises such that the nanocomposite particles in the sample begin to react rapidly, causing an explosive reaction.

[0352] Due to the rapid reaction and large energy production of the nanocomposite, the combustion propagates through the sample, and the cavity grows at an extremely rapid rate, and products of the thermite combustion can be seen escaping the initial bubble forming the cavity above the sample. The combination of these two gaseous entities will be referred to as the cavity during the majority of this work as the gaseous SA will have minor contributions to this gaseous volume. The cavity grows in a cylindrical fashion which may be caused by the directionality of the combustion reaction, and by the confinement of the container used for holding the pellet and water. After the cavity has reached its maximum volume when the reaction terminates, the cavity rapidly collapses in an oscillatory fashion as the pressure and heat generated inside of the cavity due to combustion are equalized with that of the surroundings. The general shape of the cavity collapse, with a large implosion from above the cavity, has been demonstrated for cavities near a solid boundary in the past similar to the acrylic substrate here. It is noticeable that a few smaller bubbles remain after collapse and are very likely the remaining gaseous SA. The remaining gas may also reduce, but not eliminate, the pulsation typical of explosive cavity generation as demonstrated in the past. It can also be found that the energy produced during this reaction is large enough to cause the combustion tank and base to jump over several centimeters into the air, similar to a water hammer effect, observed in Figure 2 at 15 ms, during cavity collapse.

[0353] Quantitative results on combustion induced cavitation

[0354] Three different measurements were taken to quantify the volume change of the cavity over time, the ignition delay of the samples, and 488±10 nm light wavelength emittance from the combustion intermediate AIO, as shown in Figures 3A-D. At least three parallel combustion tests were carried out for each composition to obtain the average values and errors of each measured quantity. The volume of the cavity over time was calculated for each video frame, assuming that the 2D view of the cavity is axisymmetric in 3D. Figure 3A demonstrates the cavity volume overtime of typical AI»CuO»SA samples of varying SA composition during the cavity growth stage during combustion. The volume was not able to be measured during decay due to a lack of light on the sample after combustion. Figure 3A also demonstrates the calculated potential energy of each cavity during growth. It can be calculated that -12-18% of the energy generated during combustion is transferred to potential energy of the cavity, based on the measured energy release from DSC-TGA. AI»CuO»SA compositions at 1 , 3, 5, and 10% are represented by the lines from left to right. The combustion violence decreases with increased percentage of SA, as indicated by the change of maximum rate of cavity growth and cavity volume with corresponding potential energy. The sample with 1% SA generates a cavity that reaches a maximum volume of 25 mL after 3.5 ms, while the cavity generated from the sample with 10% SA only reaches a maximum volume of 15 mL after nearly 20 ms. The long combustion times on the order of milliseconds are significantly longer than typical detonations that are caused by nuclear and chemical explosions.6 It is notable that there are no detonation waves generated during the cavity generation via slower combustion.

[0355] Figure 3B demonstrates the cavity growth rates during the thermite combustion stage of the reaction. Ignition delay bars are on the left and growth rate bars are on the right in each pair of bars. The growth rates were calculated between 10% and 90% of the maximum cavity volume, where a linear growth rate is seen during thermite combustion. The continuous energy input via combustion alters the growth rate properties compared to that of mechanically induced cavities. Depending on SA loading, the rate of cavity growth during combustion ranges from up to 13 L / s in the samples containing 1% SA to less than 1 L / s in 10% SA samples. It can be seen in Figure 3B that as the SA composition increases, the rate at which the cavity forms decreases along with the reduction of the maximum obtained cavity volume. It is also seen that the inconsistency of the combustion, as indicated by the standard deviation of cavity growth rate, also decreases with increasing SA percentage. This trend is caused by the increased homogeneity with increased SA percentage, allowing the combustion to propagate more smoothly throughout the sample. The changes of cavity growth rate with varying SA contents indicates that the SA, while enabling the reaction due to its hydrophobic nature, is also limiting the reaction rate of the thermite. The addition of excess SA creates a physical barrier that prevents the reaction from propagating at more rapid rates. The control of the SA coating amount allows fine tuning of combustion and cavity generation for the AI»CuO»SA samples.

[0356] The ignition delay was measured using the optical high-speed combustion tests to evaluate how SA changes the initiation of the reaction within the samples. Figure 3B demonstrates that both small and large amounts of SA cause an increase in the ignition delay of the samples. It is hypothesized that when the SA loading is at 1 %, only a thin layer of SA insulates the core-shell particles from the water, which is sufficient for ignition, but allows some heat transfer from the pellet to the water during heating. This heat transfer increases the required laser heating time to achieve ignition. For a high SA loading of 10%, the thicker boundary between core-shellparticles is increasing the ignition delay as more energy is required for the reaction to melt / evaporate and decompose the SA surrounding the particles. Considering all different factors of reaction violence, ignition delay and consistency, the sample containing 5% SA is selected for further experiments.

[0357] The 488 nm wavelength measurement was taken to determine the times at which the thermite reaction is taking place. The reaction between Al and oxygen emits a characteristic light at 483 nm, which is highly indicative of the reaction period between the core-shell material. The light was filtered and captured using a 488±10 nm band-pass filter and a photodiode in this research. Figure 3C demonstrates the measurement of the AIO emission over time as a non-dimensional percent of the maximum light seen throughout the experiment. This is plotted with the non-dimensional percent of the maximum cavity growth over time. It can be seen that the rate of cavity growth as a percentage of maximum growth is similar to that of the rate of 488 nm wavelength light intensity as a percentage of maximum light reception. It is also seen that the reaction terminates before the maximum cavity volume is reached, indicating that there are slower energy transfer mechanisms taking place after combustion. The heat transfer is tied closely to the cavity growth, which continues to occur after combustion, creating more water vapor due to the increased temperature within the cavity.

[0358] Figure 3D demonstrates the dimensionless thermite induced cavity volume vs time of the reaction. The plotted data uses a modified definition of V* compared to mechanically induced cavitation, demonstrated by:

[0359] wherein is the total bubble and cavity volume at a given time, V10 is the total volume at 10% of the maximum volume, approximating the starting point of the thermite dominated cavity growth, and Vmax is the maximum total cavity volume. The plotted data also uses a modified definition of t*, calculated by t* = t / Tc, compared to mechanically induced cavitation. In this case t is the time of combustion beginning after the cavity reaches a total volume of 10% of its maximum and Tc is the time between 10% and maximum growth, representing the time of thermite cavity growth. Utilizing the new definitions the dimensionless volume and time, the growth and decay of the combustion induced cavity are plotted.

[0360] While the general appearance of the cavity growth and decay are similar during combustion to those in mechanical and explosion induced cavities, there are significant differences between the cavitation rates. In plotting the data, it can be seen that there is a clear trend for each of the dimensionless cavity growth and decay respectively that do not follow the trends for mechanically induced cylindrical cavitation, and explosive bubble generation as previously described in Equation 2. In the growth stage it can be seen that there is approximately a linear relation between the growth rate over time. It can be calculated that V* = t* during cavitygrowth. This is consistent during the combustion of the sample, which is hypothesized to have a constant burn rate, and energy release over time during combustion. The balance between the energy input due to combustion and the energy output due to ejected particles and heat transfer lead to the linear cavity growth. In the decay stage, it can be seen that the volume decreases at a rate similar to that of mechanically induced cavities to 60-75% of the maximum volume. Fluctuations in the rate of volume decrease are then seen as the cavity and the gases within approach an equilibrium state. In the 5% SA case the volume increases slightly before decreasing again due to these fluctuations. The influence of heat and mass transfer of the combusting material is seen to have a significant effect on the cavitation properties, altering its characteristics compared to mechanically and explosion generated cavities, leading to a milder cavity collapse. It is of note that the shallow container and minimal water overhead may also cause some fluctuations in the decay rate of the cavities.

[0361] While a dimensionless analysis is beneficial for analyzing the behaviors and general characteristics of cavity growth via combustion, explosion, or mechanical means, it is worth noting that the scales of these cavities may vary drastically. For example, explosives such as TNT or RDX have a higher energy density, and shorter reaction durations than the nanothermite presented, leading to larger cavities and more rapid growth rates.

[0362] Temperature measurement

[0363] Thermal imaging, which was completed to evaluate the temperature of the combusting material and surrounds, may offer insights into the mechanisms of the reacting materials and allow for a deeper understanding of the combustion processes for these underwater combustion samples. For these measurements, an IR camera was used which required an alternative setup to that of high speed imaging. Since neither water or acrylic is considered transparent for the IR camera, a CaF2 plate, which is considered IR transparent, was used as a viewing window at the base of the sealed water bath with the thermal camera taking measurements from underneath as shown in Figure 4D. Additionally, as it was desired to view the cavity propagation in the thermal images, the laser ignition occurred at the side of the sample, rather than the top, such that outward cavity propagation would be observable. Due to the rapid nature of combustion and limited frame rate (400 Hz) of the thermal camera, only a few frames were recorded to illustrate different stages of combustion of AI»CuO»SA underwater. The calibration range of the camera was set at 0°C to 337°C. Therefore, all temperatures under 0°C and above 337°C were not accurately recorded, specifically showing the temperature of the vapor around the pellet during the ignition instead of the combustion of nanoenergetic materials themselves.

[0364] Figures 4A and 4B demonstrate two consecutive thermal images taken during combustion, representing the stages of ignition and propagation of AI»CuO»SA combustion. The point of laser ignition can be seen in Figure 4A as the point within the initial SA bubble on the edge of the sample. The hot spot generated by the laser heating is around 1 mm in size. Within one frame (2.5 ms), the sample is ignited and the combustion starts to propagate, as shown inFigure 4B. It is noted that the pellet shifts downwards during combustion due to the violence of the reaction and the force induced by ignition at the side of the sample.

[0365] In the thermal images the cavity propagation can be clearly seen, as well as the gasliquid boundary surrounding the sample. It can be seen that the gas within the cavity reaches very high temperatures that are above 337°C, above the boiling point of water and the decomposition temperature of SA found in TGA. As the colder liquid-gas boundary is the experimental focus, the exact temperature of the hot gas within the cavity was measured.

[0366] Analyzing the liquid-gas boundary in Figure 4A, it can be measured that a steep thermal gradient of up to approximately 9*102 °C / mm occurs between the hot combustion gases and the surrounding water. This boundary is wider and less apparent in the propagation image due to the water vapor produced in this boundary region at the edge of the cavity during combustion. Due to the calibration of the camera between 0-337°C for analysis of the cavity formation, accurate temperature profiles of the combusting pellet cannot be measured, indicated by the saturated region in Figure 4B. The images clearly present the formation of an initial bubble surrounding the ignition point with a temperature of 160-180°C, indicating the SA decomposition and evaporation followed by some cooling due to the surrounding water. This is followed by the more reactive thermite reaction.

[0367] The temperature through the water and produced gases is seen in Figure 4C at a y-position of 3.25 mm within the viewing window. It is of note that this temperature plot does not demonstrate the maximum gradient between the hot gases and surrounding water, but is representative of the boundary. At 7.5 ms (the bottom line) it can be seen that there is a steep gradient between the hot gases and the cold water, even though the maximum temperature of the gases has not yet reached 200 °C. It is also seen that the temperature curve smooths out above 100 °C indicating that this is where the liquid vapor boundary exists, as water will boil at 100 °C. Above this transition point a smooth temperature increase exists between the combustion area and the liquid boundary. At 10 ms (the top line) it can be seen that there is a shallower average gradient, but still a distinct change in temperature between 100 and 120°C where the boundary between water and vapor exists. The increased temperature of the transition region can be explained by the increased pressure, and therefore increased water vapor pressure, within the cavity during the thermite combustion. There exists a smoother temperature curve above 120 °C where the liquid-vapor boundary is not influencing the measured temperature as heavily. The first temperature plateau of around 250 °C is caused by sporadic hot, solid, ejected particles during the sample combustion. The second temperature plateau demonstrates the maximum measurable temperature of the thermal camera under the selected settings. The thermal imaging can be used to support the optical images of the combustion as well as the thermal DSC-TGA analysis to better describe the reaction and mechanisms of the underwater combustion of AI*CuO*SA.

[0368] Discussion

[0369] Combining the observations from high-speed, thermal imaging, and material characterization results, it can be concluded that underwater combustion induced cavitation may be described by the seven stages as shown in Figure 5. At the first stage (I), laser heating successfully increases the temperature of the reactive nanoenergetic powder due to the insulating SA coating. This stage lasts for 2-3 ms. Then at the second stage (II), SA starts to decompose and produces a gaseous bubble. Recalling the DSC curve shown in Figure 1E, this process is exothermic and leads to further temperature increase. During Stage II, the bubble nucleation can be attributed to both decomposition and evaporation of the SA coating between 200 to 300°C, which reasonably agrees with the temperature of 180°C in thermal imaging if considering the cooling effect of water. The generated SA gas bubble initially forms a smooth liquid-gas boundary with the surrounding water, as more clearly shown in the 5 ms image. This boundary is further demonstrated in the thermal plots as a steep temperature gradient across the boundary. Worthwhile to note, this SA gas bubble provides a hydrophobic layer between water and the reactive powder undergoing laser heating, reducing the heat loss to water as well as preventing the direct interactions between water and Al. These effects allow the sample to reach the ignition temperature of the thermite combustion between Al and CuO. It is possible that there is a small amount of Al reacting with SA during this stage. However, this is a relatively slow, thermally driven reaction that will not have time to propagate before ignition of the thermite particles within the sample as outlined in the following stage.

[0370] Ignition of the sample occurs between 3 ms and 5 ms, leading to rapid a rise in the gas temperature surrounding the sample. At this stage (III), an immense amount of energy is released from the thermite reaction of the core-shell particles, resulting in the expansion of the SA bubble present during the second stage and the cavity growth caused by water vaporization at the interface between the hot gases and water. Interestingly, the smooth SA bubble is able to stay near the surface of the substrate, as shown in these images of 5 ms, 7.35 ms and 7.85 ms. A rapid linear growth of the cavity volume is visible in Stage III, demonstrated by the growth rate calculations from the optical images. It is also shown in the increasing measurement of 488 nm light during the cavity growth stage. The thermite induced vaporous cavity possesses an uneven gas-liquid boundary due to the explosive and uneven nature of the nanocomposite combustion inside the cavity causing density variations near the cavity surface. Combustion of separate particles ejected from the sample is also possible within the vapors cavity, until the reactions are complete at around 7.35 ms. Due to the rapid nature of the kinetically driven thermite reaction, it is not expected that SA will react strongly with aluminum during this stage. The amount of SA simply dictates the rate of reaction and cavity growth as seen in the results by being a physical barrier between reacting thermite particles.

[0371] The cavity volume reaches its maximum value of around 21 mL at 7.85 ms (Stage V), followed by a brief period of rapid cavity growth (shown by a steep slope approaching V). The cause of this behavior may be explained by the mechanical effects of the upward moving flowdriven by the fast expansion of the cavity and by the final particles or debris being combusted near the cavity boundary. The rapid collapse (Stage VI) follows a similar behavior to the mechanically induced cavity, as previously illustrated. However, oscillation in volume of the cavity (VII) is very different than the collapse of mechanically induced cavities, likely due to the material and heat transfer properties of the vaporous cavity.

[0372] Herein is provided rapid underwater combustion of a novel core-shell AI»CuO»SA nanocomposite and subsequent bubble formation and cavitation growth and collapse. SA coating was found to play two roles. First, the SA coating enabled extremely violent underwater reactions by providing a hydrophobic layer that prevented the deactivation of Al submerged in water. Second, the SA coating provided an insulating layer between the thermite particles and the surrounding water during ignition, which reduced water permeability and reduced heat loss, allowing the thermite reaction to propagate and cause rapid cavity growth underwater. Electron microscopic images, supported by FTIR and zeta potential measurements confirmed the SA coating on the surface of Al and CuO nanoparticles. With only 1% of SA addition, AI»CuO»SA was found to be superhydrophobic by water contact angle tests. The growth rate of cavitation reached up to 13 L / s with a maximum volume of up to 25 ml_, caused by the rapid energy release from a 3 mm diameter x 3 mm tall (20 mg) pellet. With the increasing amount of SA, the reactivity decreased while the consistency improved, allowing fine tuning of reactivity and cavity generation rate as desired.

[0373] AI»CuO»SA(5%) was found to provide consistent samples with the shortest ignition delay, demonstrating that the SA can also hinder the reaction by adding a physical barrier between reaction particles at higher SA loading. An aging study revealed the SA coated coreshell particles were very reactive after stored in water for up to 2 weeks. This work is also the first to analyze combustion induced cavities underwater. A dimensionless analysis was completed to demonstrate the growth and collapse characteristics of combustion induced cavitation, showing a linear cavity growth rate and fluctuating collapse rate. This analysis demonstrated a significant difference between combustion and mechanically, or explosion induced cavitation. The longer timescale for cavity generation via combustion also contributed to very different reaction properties, such as the lack of detonation waves that are seen in explosive cavities. Finally, the combustion mechanism of AI»CuO»SAwas concluded on the basis of DSC-TGA, thermal camera analysis and combustion footage analysis. A unique multi-stage reaction of the AI»CuO»SA was demonstrated, showing the initial SA bubble formation, followed by the rapidly growing cavity from violent thermite combustion, and its subsequent decay. The use of a nanoenergetic compound or thermite, such as AI»CuO, coated with a hydrophobic coating, such as stearic acid, has the potential to be researched further, scaled, and implemented in several engineering applications including underwater mining, propulsion, manufacturing, and high-thrust systems where high energy is desired without explosion induced shockwaves.

[0374] Methods

[0375] Aluminum copper oxide nanoenergetic composite / thermite, was prepared according to previous research wherein the aluminum copper oxide exists as a core-shell nanocomposite. Figure 6 shows the process of preparing the core-shell nanocomposite and coating the core-shell with a hydrophobic coating. The preparation is described in detail below.

[0376] Hydrophobic Nanocomposite Pellet Preparation

[0377] AI»CuO core-shell nanocomposite was prepared according to our previous research and was the selected material used in the experiments of this work. In a typical synthesis of AI»CuO at an equivalence ratio (ER) of 2.5, 50 mg of Al nanoparticles were dispersed in 15 mL ethanol in a sonication bath for 2 hours, while 215 mg of Cu(NO3)2 2.5H2O was added in 35 mL of ethanol with 325 pL of ammonia solution. After sonication, the Al dispersion was added to the copper-ammonia suspension and stirred for 1 hour. The final AI»CuO product was obtained by collecting the solid material using filtration and annealing it for 3 h at 230°C. The ER value of the sample was calculated using ER = (nAI / nCuO)actuai / (nAI / nCuO)stoichiometric.

[0378] Hydrophobic surface treatment of AI»CuO using SA was carried out with the calculated 1, 3, 5, and 10 wt.% SA. The predetermined amount of SA was dissolved in 10 mL n-hexane in a sonication bath until the solution was transparent. 100 mg of AI»CuO was then dispersed in the SA solution and left at ambient temperature for solvent evaporation. The remaining powder was placed in the oven at 40°C for 4 h to remove any remaining n-hexane and obtain the final AI»CuO»SA product. Figure 6A demonstrates the core / shell / coating structure and synthesis process. Figure 6A also demonstrates the mechanisms that allow SA to repel water from the core-shell nanoparticles. The hydrophilic end of the SA molecules stick to the core-shell structure due to its polar nature while the hydrophobic end of the SA molecule is left closer to the water. The excess SA present in the synthesis of the core-shell particles will agglomerate to the outside of these particles during evaporation. This will affect the hydrophobic nature of the coating as demonstrated in the water contact angle tests in the supporting information where it is shown that the sample with 1% SA has the greatest hydrophobic coating. Without the excess SA on the outside of the particles there is a stronger polar effect that easily repels the water molecules, keeping the thermite particles active.

[0379] Underwater Combustion of Hydrophobic Nanocomposite Pellet

[0380] The experimental setup for high speed imaging of underwater combustion tests is demonstrated in Figure 6B. Pellets made with 20 ± 0.3 mg of dried AI»CuO»SA powder were prepared using a 3 mm diameter cylindrical mold and hydraulic press held at 250 psi for 1 minute which led to approximately 50% theoretical maximum density for each pellet. A container for underwater combustion was constructed using epoxy, a square acrylic tube, and a PLA base plate. The thermal camera was not capable of measuring the temperature through water or acrylic. Therefore, the base plate used for thermal imaging included a 1- inch diameter CaF2 window in the center as CaF2 is IR transparent, allowing temperature to be measured from the bottom side of the sample. Each combustion trial, for both high speed video and thermalmeasurement, was performed with 150 mL of tap water in the container, which resulted in the pellets being submerged in approximately 4 cm of water as shown in Figure 6C. The pellets were ignited using a 5W 532 nm continuous laser at 90% power. The high-speed footage of the combustion was captured with a phantom v2012 camera at 20000 frames per second and an exposure time of 50 microseconds. High-speed footage allowed for automating the volume calculations for cavity growth due to the light emitted during combustion. Cavity volume during decay was manually calculated at discrete intervals for select experiments presented. A Telops M350 thermal camera equipped with a 1X macro lens was used to record the temperature during the combustion of the pellet at 400 fps, with the calibrated temperature range set at 0°C to 337°C. Note that high speed and thermal videos were not taken using the same setup and were not taken in sync due to the base plate adjustments required for thermal measurements, which would have interfered with the high speed video. A 488±10 nm light bandpass filter connected to oscilloscope was used to measure the light emittance from the combustion, with 483 nm being the characteristic emission wavelength from the AI-0 reaction. For all combustion tests, the sample pellets were ignited within 3 minutes after they had been submerged in water. For combustion tests of sample aging underwater, pellets were submerged underwater for various time duration up to 14 days before attempting combustion. For the feasibility study of samples with different ER values, three combustion tests were carried out per sample. For all tests used for the quantitative study (samples of ER 2.5, SA weight percentage of 1, 3, 5, and 10%), at least three combustion tests were carried out to ensure repeatability and error evaluation.

[0381] The example of aluminum copper oxide and stearic acid, described above, can be extrapolated to other metals, oxidizers, and hydrophobic coatings.

[0382] Suitable metals for a nanoenergetic compounds, nanocomposites, or thermites include aluminum, iron, magnesium, boron, titanium, zirconium, and alloys thereof, among other metals. The metal fuel may be in the form of spherical nanoparticles, flakes, nanowires, porous structures, and alloyed composites. Suitable oxidizers may include CuO, Fe2O3, Co304, MnO2, MO03, Bi2O3, metal nitrates, metal fluoropolymers, and composite oxidizers. The oxidizer may be in the form of core-shell, layered, nanowire, porous scaffold, or embedded matrix. Suitable coatings include fatty acids (e.g., stearic acid), fluoropolymers, silanes, alkyl phosphonates, organophosphonates, PTFE, long-chain hydrocarbons, perfluorinated compounds, amphiphilic polymers, silane-modified polymers, biocompatible hydrophobic coatings, biodegradable amphiphilic polymers, and may be in the form of a continuous layer, partial coverage, multi-layer coating, conformal nanoscale film, coating the fuel and / or oxidizer, penetrating interparticle interfaces, or modifying surface energy.

[0383] Ignition methods may include laser radiation (visible, IR, UV), electrical spark, resistive heating, inductive heating, microwave excitation, shock initiation, chemical primer, or other electromagnetic radiation. Ignition methods may include micro-ignition through thin-film resistiveheaters, micro-spark electrodes, laser fiber delivery, inductive coils, or capacitive discharge pads. Ignition may be tuned by coating thickness, electric pulse duration, and a preheating cycle.

[0384] In some embodiments, the hydrophobic layer may be multi-layered, include phasechange materials, include energetic polymer binders, and be patterned non-uniformly.

[0385] In some embodiments, the oxidizer may be partially replaced with fluoropolymers, include nano-laminate structures, or be embedded in porous metal scaffolds.

[0386] In some embodiments, the composite may be integrated with microelectronics, trigger circuits, pressure sensors, and feedback control systems.

[0387] Figure 7 is a flow diagram of a method 700 of preparing and combusting a surface engineered nanocomposite pellet to generate at least one of heat and a cavity underwater.

[0388] At 702, a metal is combined with an oxidizer, e.g., a metal oxide to form a thermite composition, nanocomposite, or nanoenergetic particles. The metal-oxidizer composition may have a core-shell composition wherein the core is the metal and the shell is the oxidizer. For example, the core-shell composition may be an AI»MOx»SA (metal oxide & stearic acid) coreshell nanomaterial as described herein.

[0389] At 704, the core-shell composition is treated with a surface treatment, for example stearic acid. The surface treatment coats or otherwise provides a full or partial layer of a surfaceengineering substance to the core-shell composition, or other metal-oxidizer composition such that the composition repels water.

[0390] As shown in the above example, the fabrication of the superhydrophobic energetic nanocomposite pellet may use a simple solution-based chemical method rather than complex physical deposition. The metal-oxidizer core-shell structure may be formed via electrostatic selfassembly, where metal nanoparticles are mixed with a solution containing the oxidizer to ensure adequate surface contact between the fuel (metal) and the oxidizer. This composite is then dispersed in a hydrophobic solution and as the solvent evaporates, a protective and superhydrophobic layer coats the surface of the metal-oxidizer nanoparticles.

[0391] At 706, the coated core-shell composition (or other coated metal-oxidizer composition) is pressed into a pellet to form a surface-engineered pellet of nanoenergetic material. The surface-engineered coating may prevent water infiltration (or other liquid or solvent infiltration), reduce heat loss during ignition, thermally decomposes at a temperature below the primary thermite / nanoenergetic particle reaction, and form an initial gaseous envelope which thermally insulates the reactive core.

[0392] At 708, the surface engineered pellet is placed underwater or within another type of liquid environment.

[0393] At 710, the surface-engineered pellet is ignited by an ignition source. The ignition source may be a laser. The ignition source may be electrical, spark, resistive, inductive, microwave, etc. When the pellet is ignited heat is generated and a cavity is formed. The surface-engineered pellet is composed for rapid explosion and generation of heat and cavities inunderwater or liquid environments. Both the heat and the cavity can be used for any number of applications as described above as well as below.

[0394] When the surface-engineered pellet is ignited and heated to a first threshold temperature, the surface-engineered layer decomposes to generate a localized insulating vapor region, and upon further heating to a second threshold temperature the fuel and oxidizer components exothermically react within the insulating vapor region. This reaction may generate heat, a cavity, and / or other energy. The reaction is tunable by altering the composition and configuration of the fuel, oxidizer, and surface-engineering components.

[0395] As an example, when ignition is initiated underwater (e.g., using a continuous wave laser), the composite undergoes a unique two-step reaction mechanism, i) hydrophobic layer decomposition wherein the coating decomposes and forms an initial vapor bubble surrounding the pellet, and upon heating to approximately 150-400°C, the hydrophobic layer decomposes and releases gaseous products which form an insulating vapor envelope that reduces convective heat loss, prevents water contact, and allows internal temperature rise; and ii) core redox reaction wherein the metal fuel reacts with the oxidizer, releasing heat and generating rapid vapor expansion, producing a transient cavity in the surrounding liquid, and at approximately 450-800°C, the metal fuel reacts with the oxidizer in a condensed-phase reaction, generating rapid heat release, gaseous byproducts, vaporized water, and rapid cavity expansion.

[0396] Described below is the process for the AI»CuO»SA composition:

[0397] 1. Bubble Nucleation: As the material is heated to approximately 180°C to 300°C, the stearic acid coating decomposes and evaporates, releasing initial gas and forming a smooth vaporous bubble around the sample. This bubble acts as a crucial thermal insulating layer between the highly energetic material and the surrounding water, preventing heat loss and allowing the internal temperature to rapidly rise.

[0398] 2. Main Thermite Reaction: Once the insulated material reaches the threshold reaction temperature of approximately 600°C, a violent exothermic redox reaction occurs between the Al core and the CuO shell. This releases an immense amount of energy and combustion gases, rapidly expanding the initial bubble into a massive vaporous cavity.

[0399] The cavity may exhibit linear growth phase, accelerated expansion, nonlinear collapse, and oscillatory pressure equalization.

[0400] The combustion and cavity growth characteristics may be tunable by coating thickness, hydrophobic loading percentage, metal-to-oxidizer ratio, pellet geometry, nanostructure, or microstructure architecture.

[0401] Benefits and novelty of a hydrophobic energetic nanocomposite include:

[0402] Overcoming Water Deactivation & Heat Loss: T raditional energetic nanomaterials (like bare Al and typical thermites) are highly hydrophilic, causing them to rapidly lose heat to the surrounding water and fail to reach combustion temperatures (above 500°C). The SA coating completely protects the reactive aluminum core from being oxidized and deactivated by water.

[0403] Extreme Super-Hydrophobicity with Minimal Coating: super-hydrophobicity is achieved (water contact angles over 150°) with the addition of only 1% to 5% stearic acid by weight.

[0404] Direct Underwater Ignition: The composite can be directly and easily ignited while completely submerged in water within milliseconds.

[0405] Long-Term Underwater Stability: The material possesses excellent anti-aging properties. Composites modified with 5% SA retain their combustibility and violent reactivity even after being continuously submerged in water for up to two weeks.

[0406] Simple and Scalable Fabrication: Fabrication bypasses sophisticated but low-yield manufacturing techniques (like ALD-CVD or magnetron sputtering) in favor of an easily scalable, solution-based chemical coating process.

[0407] The applications described above were described in general for thermite or nanoenergetic particle combustion underwater, but not in particular for hydrophobic pellets of thermites or other nanoenergetic particles. For each of the applications described above a hydrophobic pellet could be used as the fuel source for systems and methods of underwater combustion.

[0408] Provided herein is a system and method for underwater micro-propulsion and high-thrust systems actuation. A system may include a submersible propulsion unit or high-thrust systems containing a combustion chamber loaded with an array of energetic composites. The composites are formulated with a low stearic acid (SA) concentration (e.g., 1% by weight) to maximize reaction violence and cavity growth rates. The system includes an integrated ignition source, such as a localized fiber-optic continuous wave laser (similar to the 532 nm laser used in testing) directed at the target fuel. A method of operation may include when thrust is required, the laser initiates the pellet. Within milliseconds, the SA coating decomposes to form an initial vaporous insulating bubble. The main thermite reaction then rapidly raises the temperature past 600°C, explosively generating a vaporous cavity. A tiny 20 mg pellet can generate a maximum cavity growth rate of up to 13 Liters / second and a peak volume of 25 mL in just 3.5 milliseconds, the directional channeling of this rapidly expanding cavity and the ejected mass out of an exhaust nozzle provides immense, instantaneous thrust without the need for environmental gaseous oxygen.

[0409] Provided herein is a system and method for submarine welding and manufacturing. A system may include an underwater joining system comprising a pre-formed pellet or direct-writing paste of the aluminum copper oxide composite applied directly to the seam of two metallic parts submerged in water. Forthis application, a higher SA concentration (e.g., 5% to 10%) is preferred to slow down the reaction rate, increase combustion consistency, and prolong the underwater shelf-life of the material (up to two weeks) before use. A method of operation may include wherein a localized heat source is applied to the composite paste. The composite undergoes its first reaction phase, evaporating the SA coating at around 180°C to 300°C to form a smooth, protectivegaseous bubble around the joint. This bubble acts as a critical thermal barrier, preventing the surrounding water from quenching the reaction. Once thermally insulated, the main Al and CuO redox reaction takes place at high temperatures in the condensed phase, safely melting and fusing the adjoining metals inside the bubble before the cavity collapses.

[0410] Provided herein is a system and method for underwater mining and high-thrust systems. A system may include an explosive charge or energetic composites packed with bulk AI»CuO»SA pellets, designed to be inserted into drill holes for hard rock dredging or utilized in anti-ship / submarine high-thrust systems. A method of operation may include wherein the utility of this system relies on the tremendous mechanical force generated during the collapse of the combustion-induced cavity. Upon detonation, the material rapidly combusts to form a massive vaporous cavity. Once the thermite reaction terminates and the heat supply is discontinued, the intense pressure and heat equalize with the surroundings, causing the massive cavity to rapidly collapse in an oscillatory fashion. This violent collapse generates a profound "water hammer effect" and a high potential energy release, which can impart massive mechanical shockwaves capable of fracturing surrounding hard rock or rupturing the hull of a target vessel.

[0411] Provided herein is a system and method for microfluidic pumping, soft actuation, and targeted drug delivery. A system may include a micro-mechanical device, such as a lab-on-a-chip or a cephalopod-inspired soft hydro-jet engine, containing micro-chambers loaded with precisely measured quantities of AI»CuO»SA. A method of operation may leverage the finely tunable nature of the composite's cavity generation. By adjusting the SA content and the mass of the pellet, engineers can precisely calculate the resulting cavity volume and expansion rate. When a micro-laser selectively targets a chamber, the expanding cavity acts as a rapid, physical "vapor piston." In a microfluidic chip, this piston instantly displaces water to drive fluid flow or deliver a targeted payload of medicine. In a soft robot, the rapid expansion and subsequent parabolic decay (collapse) of the cavity can drive the mechanical actuation of synthetic muscles, mimicking the jet-propulsion swimming of squids or octopuses

[0412] Provided herein is a system and method for dispatchable thermal and mechanical energy generation. A system may include a sealed, on-demand energy generation unit (such as a closed-loop boiler or piston-driven generator) containing a submerged combustion chamber, an automated pellet-feeding mechanism, and a continuous wave laser ignition array. The system utilizes a magazine of AI»CuO»SA solid energetic nanocomposites, which act as highly stable "chemical batteries" capable of rapid heat generation and high energy release. Because the composites can be modified with 5% stearic acid (SA), they can be stored continuously in the water-filled chamber for up to two weeks without losing their reactivity.

[0413] A method of operation may include leveraging the ability of the composite to undergo self-sustaining combustion without the need for environmental gaseous oxygen, making it ideal for dispatchable power in isolated, aquatic, or oxygen-deprived environments, by:

[0414] 1. Tunable Fuel Selection: Depending on the immediate grid or system demand, the feeding mechanism selects a pellet with a specific stearic acid concentration to control the energy release profile. For an instantaneous, explosive burst of mechanical energy, a 1% SA pellet is used, which achieves maximum cavity growth rates of up to 13 Liters / second and peak volumes of 25 ml_. For a slower, more sustained thermal release, a 10% SA pellet is selected, which reduces the cavity growth rate to less than 1 Liter / second.

[0415] 2. Rapid Initiation: Upon power demand, the 532 nm continuous wave laser targets the submerged pellet. Within milliseconds, the SA coating decomposes at approximately 300°C to form an insulating vapor bubble.

[0416] 3. Energy Extraction: This insulation allows the internal core-shell particles to rapidly reach their 600°C condensed-phase combustion threshold. The resulting violent redox reaction releases immense thermal energy and massive vaporous cavitation.

[0417] 4. Power Conversion: The immense thermal gradient (up to 9x10A2 °C / mm at the gas-liquid boundary) rapidly heats the surrounding working fluid, while the extreme volumetric expansion of the cavity (acting as a high-pressure gas piston) provides direct mechanical kinetic energy. Both the heat and the expansion pressure can be captured by conventional turbines or pistons to generate dispatchable electrical or mechanical power on demand.

[0418] Other applications include pulsed micro-thruster arrays where multiple energetic micro-dots may be arranged in linear arrays, radial arrays, programmable matrix grids, and wherein sequential ignition enables: directional steering, rotational torque, controlled step-wise locomotion, or micro-swimmer propulsion.

[0419] Another application includes a self-contained micro-robot wherein a fully integrated device may include a microcontroller, thin-film ignition elements, energetic micro-chambers, sealed hydrophobic compartments, and pressure venting membranes.

[0420] These micro-applications may operate in seawater, freshwater, blood, saline, or cerebrospinal fluid.

[0421] Energy generation modes which employ hydrophobic pellets may include mechanical energy, electrical energy, thermal energy, acoustic energy, and pulsed energy output.

[0422] Hydrophobic pellets may be used in reactor and device architectures including microscale reactors with <50mm device size, energetic mass between 0.01 and 10 mg, and pulsed ignition; macro subsea reactors with gram-scale energetic chambers, pressure rated housings, sequential multi-chamber ignition, and sustained output modes; and hybrid power modules with integrated thermoelectric arrays, encapsulated energetic cartridges, and replaceable reactive modules.

[0423] Hydrophobic pellets may also be applied in biomedical applications, such as:

[0424] Localized Cavitation Therapy - controlled vapor cavity generation may: disrupt clot structures, fragment calcifications, enhance drug penetration, induce localized mechanical stress; cavity diameters may range: 0.1 mm to 20 mm.

[0425] Targeted Thermal Ablation - controlled combustion may produce: rapid localized heat pulse, thermal necrosis zone, limited heat diffusion due to short pulse duration; heat deposition may be confined spatially using: micro-chambers, directional barriers, insulating outer shells.

[0426] Drug Delivery Enhancement - the transient cavity may: increase local permeability, disrupt cellular membranes; improve transport of therapeutic agents, act as micro-pump within catheter systems.

[0427] Biodegradable Variant - Energetic particles may be: Encapsulated in biodegradable polymer matrices, Designed to degrade post-combustion, Produced using bioresorbable oxidizers, Configured for transient implants.

[0428] Safety & Containment can be achieved via - Pressure-limiting membranes, Frangible rupture discs, Directional venting ports, Biocompatible encapsulation shells, Microfluidic confinement chambers.

[0429] Examples of biomedical embodiments include:

[0430] Injectable Micro-Actuator - 1 mg energetic micro-pellet; biodegradable hydrophobic coating; encased in polymer shell; activated via thin-wire ignition; produces 1-5 mm cavitation pulse

[0431] Micro-Swimmer Propulsion - array of 10 micro-thrusters; sequential pulsed ignition; generates directional impulse; operates submerged in saline.

[0432] Catheter-Based Clot Disruption -energetic micro-dot at catheter tip; laser fiber ignition; controlled cavity expansion; localized mechanical disruption.

[0433] For biomedical embodiments the energetic material (i.e., the metal-oxidizer) may be patterned via inkjet printing, embedded in flexible structures, integrated into soft robotics, used in microfluidic valves, and applied in transient electronics. The hydrophobic coating may include stimuli-responsive polymers, temperature sensitive polymers, pH-sensitive coatings, and degradable coatings.

[0434] The hydrophobic pellet system described herein is also particularly well suited within the space domain, as the system can be compact, is oxygen-independent, is operable in liquid, has high energy density, provides instant impulse, has no atmospheric requirements, is scalable from micro to macro, and is storable until ignition occurs. Liquid environments in space may include subsurface oceans beneath ice, cryogenic hydrocarbon lakes, high-pressure saline oceans, ammonia-water mixtures, supercooled brines, and subglacial extraterrestrial reservoirs. Such environments may have characteristics such as an absence of atmospheric oxygen, high hydrostatic pressure, extreme cold temperatures, high thermal conductivity of liquid, limited solar energy availability, power density constraints, and restricted communication abilities. Conventional energy systems are unsuitable for these environments, but a hydrophobic pellet system is operable without atmospheric oxygen, under high pressure, in near-zero gravity, and in cryogenic conditions.

[0435] Hydrophobic nanoenergetic pellets could be used in sub-ice penetration systems to provide thermal energy, pressure pulse assistance, fracture assistance, controlled cavitation, autonomous energy release, and localised high temperature regions, and in subsurface propulsion systems to provide thrust in liquid, enable micro-swimmer motion, provide burst impulse, and enable maneuverability in subsurface oceans. These systems can have a small footprint.

[0436] The hydrophobic pellet system could be used as a subsurface energy source for supplemental burst power, an emergency impulse system, an acoustic signalling generator (e.g. acoustic communication through pressure waves, acoustic signals, and subsurface communication pulses), an ice fracture generator, and a sample acquisition impulse generator.

[0437] In some embodiments, coatings can be adapted to the environment, for example, coatings could be designed for hydrocarbon liquids instead of water or could be designed to repel methane and ethane.

[0438] In energy generation embodiments, the energy many be harvested by thermoelectric modules, piezoelectric conversion, turbine-driven generators, or pressure-driven mechanical systems. The energy may be used as an emergency power source for an emergency burst heater, a de-icing element, a stuck-probe release system, or a backup propulsion unit.

[0439] In some embodiments, the nanoenergetic composite pellets may be encased in pressure rated housings for use in pressure adaptation, wherein the pellets are configured to ignite above a threshold pressure and could be designed to operate at great depths.

[0440] Examples of applications of hydrophobic nanoenergetic pellets as an energy source include a sub-ice cryobot assistance module with an encapsulated energetic cartridge using sequential ignition to produce heat pulses to penetrate ice layers; an ocean-world micropropulsion unit with a micro-energetic composite chamber employing laser of resistive ignition for a directional vent which operates in high-pressure saline environments; and a cryogenic hydrocarbon variant using liquid-repellant fluoropolymer coating to be operable in methane / ethane lakes to provide acoustic signalling pulses.

[0441] While the above description provides examples of one or more apparatus, methods, or systems, it will be appreciated that other apparatus, methods, or systems may be within the scope of the claims as interpreted by one of skill in the art.Claims:1. A method of preparing a surface-engineered energetic composite for combustion in underwater or liquid environments, the method comprising:combining a metal fuel and an oxidizer to achieve a metal-oxidizer composite; andcoating the metal-oxidizer composite with a surface-engineered layer to generate a surface-engineered metal-oxidizer composite.2. The method of claim 1 wherein the surface-engineered layer is a hydrophobic substance.3. The method of claim 1 further comprising pressing the surface-engineered metal-oxidizer composite into a pellet.4. The method of claim 1 wherein the metal fuel and oxidizer are nanoparticles and the surface-engineered energetic composite is a nanocomposite.5. The method of claim 1 wherein the metal-oxidizer composite is dispersed within a solution comprising the surface-engineered substance and a solvent, and wherein the surface- engineered substance coats the metal-oxidizer when the solvent evaporates.6. The method of claim 1 wherein the metal-oxidizer composite has a core-shell structure wherein the metal is the core and the oxidizer is the shell.7. The method of claim 6 wherein the surface-engineered layer coats the surface of the shell.8. The method of claim 1 wherein the metal fuel is one of aluminum, iron, magnesium, boron, titanium, zirconium, and alloys thereof.9. The method of claim 1 wherein the metal fuel is in the form of one of spherical nanoparticles, flakes, nanowires, porous structures, and alloyed composites.10. The method of claim 1 wherein the oxidizer is one of CuO, Fe2O3, Co304, MnO2, Mo03, Bi2O3, metal nitrates, metal fluoropolymers, and a composite oxidizer.11. The method of claim 1 wherein the oxidizer is in the form of one of layered, nanowire, a porous scaffold, and an embedded matrix.

Claims

12. The method of claim 1 wherein the surface-engineered layer comprises one of a hydrophobic substance, fatty acids, fluoropolymers, silanes, alkyl phosphonates, organophosphonates, PTFE, long-chain hydrocarbons, perfluorinated compounds, amphiphilic polymers, silane-modified polymers, biocompatible hydrophobic coatings, and biodegradable amphiphilic polymers.

13. The method of claim 1 wherein the surface-engineered layer on the metal-oxidizer composite is in the form of one of a continuous layer, partial coverage, multi-layer coating, and conformal film.

14. The method of claim 1 wherein the metal fuel is aluminum and the oxidizer is copper oxide.

15. The method of claim 1 wherein the surface-engineered layer is stearic acid.

16. The method of claim 1 wherein the metal-oxidizer composite is a thermite.

17. The method of claim 16 wherein the thermite is one of a nanothermite and a microthermite.

18. The method of claim 1 wherein the combustion performance of the surface-engineered metal-oxidizer composite is tunable by altering the weight percentage of the surface- engineered coating.

19. A method of combusting the surface-engineered energetic composite of claim 1, comprising:placing the surface-engineered metal-oxidizer underwater or in a liquid environment;igniting the surface-engineered metal-oxidizer by an ignition source.

20. The method of claim 19 wherein the ignition source is one of a laser radiation, electrical spark, resistive heating, inductive heating, microwave excitation, shock initiation, chemical primer, or electromagnetic radiation.

21. The method of claim 19 wherein the ignition is performed by one of thin-film resistive heaters, micro-spark electrodes, laser fiber delivery, inductive coils, and capacitive discharge pads.

22. The method of claim 19 wherein when the surface-engineered metal-oxidizer composite is ignited the surface-engineered coating decomposes and forms a vapor bubble surrounding the material.

23. The method of claim 22 wherein, after the surface-engineered coating decomposes, the metal fuel and the oxidizer react to release heat and generate a cavity by rapid vapor expansion.

24. The method of claim 23 wherein growth characteristics of the cavity are tunable by altering at least one of the surface-engineered coating thickness, the surface-engineered coating percentage, the metal fuel to oxidizer ratio, the geometry of the surface-engineered metaloxidizer composite, and the structural architecture of the surface-engineered metaloxidizer composite.

25. The method of claim 19 wherein ignition of the surface-engineered metal-oxidizer composite is applied for at least one of controlled cavity generation, energy production, heating, propulsion, and actuation.

26. An energetic composite system comprising:an energetic composite including:a fuel component;an oxidizer component in reactive proximity to the fuel component; anda surface-engineered layer disposed on at least a portion of the energetic composite to generate a surface-engineered energetic composite; andan ignition source;wherein upon heating the surface-engineered energetic composite to a first threshold temperature by the ignition source, the surface-engineered layer decomposes to generate a localized insulating vapor region; andupon heating the surface-engineered energetic composite to a second threshold temperature, the fuel and oxidizer components exothermically react within the insulating vapor region.

27. The energetic composite system of claim 26, wherein the energetic structure has a coreshell structure including:a metal particle core; anda metal oxide particle shell;wherein the core-shell structure is coated by a hydrophobic substance.

28. The energetic composite system of claim 27 wherein the coated core-shell structure composite is pressed into a pellet to be used for combustion underwater or in liquid environments.

29. The energetic composite system of claim 26 wherein the fuel component is aluminum, the oxidizer component is copper oxide, and the surface-engineered layer is stearic acid.

30. The energetic composite system of claim 29 wherein:upon heating to between 180-300C, the stearic acid coating decomposes and release gas to form a vapor bubble around the core-shell structure; andupon decomposition of the stearic acid, at approximately 600C, the aluminum and the copper oxide exothermically react to release energy and combustion gases to expand the vapor bubble into a vaporous cavity.

31. The energetic composite system of claim 26 wherein the generation of heat and of the cavity is used for at least one of propulsion, energy generation, actuation, welding, material processing, mining, medical procedures, drug delivery, microfluidics, and high- thrust applications.

32. The energetic composite system of claim 26 wherein the composite is ignitable by at least one of laser radiation, electrical spark, resistive heating, inductive heating, microwave excitation, shock initiation, chemical primer, or electromagnetic radiation.

33. The energetic composite system of claim 32 wherein ignition of the hydrophobic metaloxidizer composite is applied for at least one of controlled cavity generation, energy production, heating, propulsion, and actuation.

34. The energetic composite system of claim 26 wherein combustion characteristics are tunable by altering at least one of surface-engineered layer thickness, surface-engineered coating percentage, the metal to metal oxide ratio, and the structural architecture of the surface-engineered metal-oxidizer composite.

35. The energetic composite system of claim 26 wherein the metal is one of aluminum, iron, magnesium, boron, titanium, zirconium, and alloys thereof.

36. The energetic composite system of claim 26 wherein the metal oxide is one of CuO, Fe2O3, Co304, MnO2, Mo03, and Bi2O3.

37. The energetic composite system of claim 26 wherein the surface-engineered layer comprises one of a hydrophobic substance, fatty acids, fluoropolymers, silanes, alkyl phosphonates, organophosphonates, PTFE, long-chain hydrocarbons, perfluorinated compounds, amphiphilic polymers, silane-modified polymers, biocompatible hydrophobic coatings, and biodegradable amphiphilic polymers.

38. The energetic composite system of claim 26 wherein the surface-engineered coating is in the form of one of a continuous layer, partial coverage, multi-layer coating, and conformal nanoscale film.

39. The energetic composite system of claim 26 is at least one of: nano-scale or micro-scale in size.

40. The energetic composite system of claim 26, wherein the energetic composite comprises a layered or segmented architecture configured for staged ignition.

41. The energetic composite system of claim 26, wherein sequential segments are independently ignitable to shape a pressure-time or heat-time output profile.

42. The energetic composite system of claim 26, further comprising a controller configured to program ignition timing of multiple energetic segments.

43. The energetic composite system of claim 26, further comprising a gas delivery system configured to direct generated gas to a downstream pneumatic load.

44. The energetic composite system of claim 42, wherein the system includes a pressure conditioning element configured to shape a gas pressure-time profile.

45. The energetic composite system of claim 42, wherein the generated gas inflates a buoyancy control bladder or drives a subsea actuator.

46. The energetic composite system of claim 26, further comprising an electric propulsion subsystem and a controller configured to allocate thrust or power between the electric propulsion subsystem and the energetic system.

47. The energetic composite system of claim 26, further comprising a cavity-generation port configured to discharge vapor adjacent a vehicle body to reduce hydrodynamic drag.

48. The energetic composite system of claim 26, further comprising a power conditioning subsystem and a power distribution interface.

49. The energetic composite system of claim 46, wherein electrical output is transmitted via a wired subsea conductor.

50. The energetic composite system of claim 46, wherein electrical output is transmitted wirelessly through inductive or resonant magnetic coupling.

51. The energetic composite system of claim 46, further comprising a communication transceiver configured to exchange power management data with remote nodes.

52. The energetic composite system of claim 46, wherein multiple systems are configured in a distributed energy network.

53. The energetic composite system of claim 26, wherein the fuel or oxidizer component is derived from microbiologically assisted metal extraction.

54. The energetic composite system of claim 53, wherein extremophilic microorganisms are used to concentrate or transform metal-bearing minerals prior to refinement.

55. The energetic composite system of claim 26, wherein the composite is configured for placement within a reaction chamber fluidly coupled to an exhaust interface to generate thrust within a liquid environment.

56. The energetic composite of claim 26, wherein activation of the composite produces gas expansion directed through a nozzle to propel a vehicle submerged in liquid.

57. The energetic composite system of claim 26, wherein the composite is configured to generate a vapor cavity adjacent to a vehicle body to reduce hydrodynamic drag during propulsion.

58. The energetic composite system of claim 26, wherein ignition timing is controlled to shape a thrust-time profile.

59. The energetic composite system of claim 26, wherein the composite is configured to provide supplemental thrust in addition to thrust generated by a primary propulsion system.

60. The energetic composite of system claim 57, wherein reaction-generated gas is directed aft of a propeller or pump-jet to augment baseline thrust.

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