A method and system for fusion splicing of modular large components suitable for microgravity environments

Abstract

This invention discloses a method and system for melting and splicing modular large components suitable for microgravity environments, belonging to the field of on-orbit manufacturing technology for space. The method includes: providing prefabricated metal modules; installing a constraint mold around the surfaces to be joined to form a closed cavity; joining the surfaces to be joined; melting the joint area by applying current and using contact resistance heating; applying pressure and acting on the molten metal through the constraint mold; and removing the mold after pressure holding and solidification. Preferably, the surfaces to be joined are mutually matching non-planar geometric joint surfaces, with a micro-bump array and flow-guiding microgrooves on their surfaces; the method also includes being carried out under a low-pressure inert atmosphere of 200-400 Pa. The system includes a module storage unit and a connection operation unit. This invention, through the organic combination of constraint molds and electric heating, combined with a precisely designed non-planar interface and a low-pressure atmosphere, achieves high-quality and high-safety connection of metal modules under microgravity environments, providing core technical support for the on-orbit construction of space stations.

Description

Technical Field

[0001] This invention relates to the field of on-orbit manufacturing and advanced connection technology in space. Specifically, it relates to a melting and splicing method, system, and dedicated interface structure for connecting prefabricated metal module components into ultra-large integral components in microgravity or low gravity environments such as space stations, lunar bases, and spacecraft. Background Technology

[0002] As human space activities shift from short-term exploration to long-term stays and base construction, the development of ultra-large space infrastructure in orbit has become an inevitable trend in aerospace technology. This trend has created an increasingly urgent need for the in-orbit manufacturing of ultra-large metal structural components (such as 100-meter-class trusses, large antenna reflectors, and fuel tank structures). Existing technologies face fundamental limitations: 1. Transportation limitations: Launching large prefabricated components from the ground is extremely costly, and the size of the launch vehicle fairing limits the transport of ultra-large components. For example, the construction of the main truss of the International Space Station requires multiple flights and on-orbit assembly, which is costly and time-consuming. 2. Limitations of on-orbit additive manufacturing: Metal 3D printing equipment typically produces components smaller than 1 meter in size, and has low production efficiency (large components require weeks to months), limited material adaptability (only some alloys can be printed), and anisotropy issues, making it difficult to meet the manufacturing needs of large load-bearing components. 3. Microgravity welding failure: Traditional fusion welding and pressure welding techniques are mature on Earth, but they encounter fundamental difficulties in microgravity environments. -Uncontrolled molten pool behavior: Without gravity constraint, surface tension dominates, and the melt shrinks into a ball that easily detaches from the interface; - Bubbles cannot be expelled: Without buoyancy drive, the porosity is as high as 15-30%, which seriously reduces the joint strength; - Wide heat-affected zone: Local high temperature (>3000°C) leads to microstructure deterioration and high residual stress; - Molten droplet splash: Liquid metal particles scatter, polluting the cabin environment and endangering precision equipment and the safety of astronauts; -Accessibility requirements: The welding torch needs to be close to the joint, which is difficult to implement on complex structures; 4. Existing modular connection solutions are inadequate: - Mechanical connections (bolts, riveting): increase structural weight, cause stress concentration, poor sealing, and are not suitable for large load-bearing structures; - Diffusion welding: requires long time (several hours) of high temperature and high pressure, has low efficiency, and requires extremely high surface flatness; - Brazing: Requires the addition of dissimilar materials (brazing filler metal), resulting in a brittle compound layer at the interface, with the joint strength being only 50-70% of the base material; Friction welding requires rotating or moving the workpiece, making it difficult to use for large, fixed structures. 5. Limitations of Resistance Welding: As a mature terrestrial technology, resistance welding is mainly used for the rapid joining of thin plates and small-section workpieces. Its design goals, process parameters, and application scenarios do not consider the needs of microgravity environments and large components, resulting in the following inherent defects: - No melt constraint design, melt runaway under microgravity; -Due to limitations in thermal conductivity, it is difficult to connect thick-walled workpieces (typically <3mm); - Unidirectional electrode pressure cannot form hydrostatic solidification; - Typically, it is a flat or simple convex surface with no self-positioning function; - No dedicated low-pressure gas protection design; Therefore, there is an urgent need to develop a new modular connection technology that does not rely on gravity, which can achieve efficient, high-quality, and safe connection of prefabricated metal modules in a microgravity environment, providing core technical support for the on-orbit construction of ultra-large space structures. Summary of the Invention

[0003] (a) Technical problems to be solved This invention aims to overcome the shortcomings of existing technologies and provide a modular large-scale component melting and splicing method and system suitable for microgravity environments, in order to solve the following core technical problems: 1. Problems such as melt runaway, inability to expel bubbles, and splashing contamination under microgravity; 2. Difficulty in heat conduction when connecting thick-walled modules; 3. Geometric conflict issues at the intersection of multiple modules; 4. Insufficient heating efficiency when connecting highly conductive materials; 5. Safety requirements for in-cabin operations; 6. Requirements for controllability and quality consistency in the connection process; In a first aspect, the present invention provides a method for fusion splicing modular large components suitable for microgravity environments, comprising the following steps: S1: Provide at least two prefabricated metal module components; S2: Install a removable constraint mold around the surface to be connected of the module element, so that the constraint mold and the module element together form a closed cavity; S3: Connect the surfaces of the module components to be connected together; S4: By applying current to the docked module components, Joule heating is generated at the contact point of the surfaces to be connected, causing the contact area to melt. S5: Apply pressure to the module components and apply the pressure to the molten metal through the constraint mold, causing it to solidify under constraint conditions and form a metallurgically bonded interface; S6: Remove the constrained mold; Preferably, the surfaces to be connected are mutually matching non-planar geometric surfaces. The non-planar geometric surfaces include one or more of the following: V-shaped, W-shaped, sawtooth, wavy, right-angled, T-shaped, or cross-shaped, and their surfaces are provided with an array of micro-bumps and / or flow-guiding microgrooves for initial current focusing and melt guidance; Preferably, prior to the melting step, a step of establishing a low-pressure inert gas protective atmosphere within the enclosed cavity is included. The absolute pressure of the low-pressure inert gas is preferably controlled between 50 Pa and 1000 Pa, more preferably between 200 and 400 Pa. This pressure range is a precisely calculated key process parameter: its lower limit is higher than the saturated vapor pressure of most metals at their melting point (e.g., about 1 Pa for titanium alloys), effectively suppressing the volatilization loss of alloying elements; its upper limit is lower than the critical pressure difference value determined by the Laplace formula ΔP=2γ / r (for titanium alloys with a characteristic molten pool radius of 5 mm and a surface tension of 1.5 N / m, the critical pressure difference is about 600 Pa), avoiding high-pressure gas from damaging the melt stability. This unique pressure range differs from both atmospheric pressure shielded welding on the ground and vacuum electron beam welding, and is a choice specifically optimized for constrained fusion bonding under microgravity environments. Preferably, before installing the constraint mold, a pretreatment step is included for the surfaces to be joined. This pretreatment includes one or more of the following: coating with a high resistivity material, forming a surface microstructure, or pre-applying an intermediate layer. The intermediate layer may be a gradient functional intermediate layer for joining dissimilar materials. Preferably, the inclined structure of the non-planar geometric joint surface is used to convert the applied axial pressure into a normal component force acting on the molten metal, which, together with the lateral reaction force provided by the constraint mold, forms a near-static hydrostatic pressure field. The mechanical principle is as follows: when the axial pressure P_axial acts on the V-shaped or W-shaped joint surface, a normal component force P_n = P_axial·sin(θ / 2) is generated under the action of the inclined angle θ. This component force promotes a tight fit between the molten metal and the module matrix. Simultaneously, the sidewall of the constraint mold applies a radial reaction force to the melt, thereby forming a stress state with essentially equal pressure values ​​in all directions within the melt—that is, a near-static hydrostatic pressure field. This multi-directional stress state effectively suppresses the formation of shrinkage cavities during solidification shrinkage, which is key to achieving high-density joint quality. Preferably, the constraint mold is installed as follows: sealing patches made of non-conductive, high-temperature resistant flexible material are pre-attached to multiple surfaces around the surface to be connected, with only one opening left; then the opening is sealed by a removable end sealing device, which together with the sealing patch forms the closed cavity; Secondly, the present invention provides a modular large-scale component fusion splicing system for implementing the above-described method, comprising: 1. Module storage unit, used to store prefabricated metal module components; 2. Connecting work units, including: - A conductive heating power supply used to provide adjustable current to module components; - A pressurizing mechanism used to apply pressure; - A constraint mold, removably mounted on the periphery of the module component connection surface, is made of non-conductive, high-temperature resistant material and is used to form a closed cavity together with the module component; -A gas protection system for establishing a local protective atmosphere within the enclosed cavity; - Positioning and transfer mechanism, used to realize the picking, docking and moving of module components; Preferably, the constraint mold is made of a non-conductive, high-temperature resistant flexible material, which is non-hydrophilic to liquid metal; Thirdly, the present invention provides a special interface structure for the melting and splicing of modular components in a microgravity environment, located on the connection surface of the metal module element. The interface structure is a non-planar geometric structure that matches each other, and its surface is distributed with an array of micro-bumps for initial current focusing and / or flow-guiding microgrooves for guiding the spread of the melt. Beneficial effects

[0004] Compared with the prior art, the present invention has the following beneficial effects: 1. Beneficial effects of the basic scheme (applicable to both planar and non-planar surfaces): -Breaking through size limitations: Through modular splicing, it is possible to manufacture ultra-large components of any size in orbit; - Adaptable to microgravity environment: The mold physically seals the melt, preventing molten droplet splashing and ensuring safety inside the chamber; multi-directional pressurization compensates for the difficulty of feeding under zero gravity conditions, achieving near-static water pressure solidification; no electric arc, no strong light, no electromagnetic interference, and does not interfere with electronic equipment inside the chamber. - Strong connection capability of thick-walled modules: Heat is generated directly at the interface contact point, regardless of the module wall thickness, and can easily connect thick-walled modules of 200mm or more with a very small heat-affected zone; - High efficiency and energy saving: The heating time of a single interface is only 1-10 seconds, the constrained mold can be reused, and it is suitable for automated continuous operation; - Wide material adaptability: Applicable to all castable or machinable metal materials such as titanium alloys, aluminum alloys, steel, copper, and high-temperature alloys; - Compatible with existing manufacturing systems: Modules can be prefabricated using mature ground technologies, forming a complete industrial chain of "ground prefabrication - launch - on-orbit assembly"; 2. Additional beneficial effects of the preferred solution (non-planar geometric interface): - Self-positioning function: The male and female mating structure with non-planar joints automatically aligns during docking, reducing the accuracy requirements of the transfer mechanism and making it particularly suitable for remote operation outside the cabin; - Current focusing effect: Non-planar structure enables initial contact from point to surface, significantly increasing local current density and lowering the connection threshold of highly conductive materials (such as copper and aluminum); - Mechanical enhancement and stress optimization: After solidification, the non-planar joint forms a three-dimensional interlocking structure, which improves the joint's shear and torsional resistance; at the same time, its inclined angle can convert axial pressure into normal component force, and it is easier to form a near-static hydraulic pressure field when combined with the constraint mold. - Connecting highly conductive materials is feasible: By using high-resistivity coatings or surface microstructure treatments, contact resistance can be significantly improved, making it possible to connect highly conductive materials such as copper and aluminum. - Dissimilar material connection: Through the pre-processing design of the pre-set gradient functional intermediate layer, a highly reliable connection of dissimilar materials (such as titanium-steel, copper-aluminum) can be achieved, and the joint strength can reach more than 85% of the weaker side of the base material. Attached Figure Description

[0005] Figure 1 This is a process flow diagram of the fusion splicing method of the present invention.

[0006] Figure 2 The diagram shows the non-planar geometric interface structure of the module connection surface, where (a) is V-shaped, (b) is right-angled, and (c) is W-shaped.

[0007] Figure 3 A schematic diagram for constraining mold installation.

[0008] Figure 4 This is a schematic diagram of the current distribution and self-regulating melting mechanism during the electric heating process.

[0009] Figure 5 This is a schematic diagram of the multi-directional pressurization principle.

[0010] Figure 6 A flowchart for customizing constraint molds and electrodes based on splicing conditions.

[0011] Figure 7 Examples of constraint mold and electrode design for several typical splicing scenarios are provided.

[0012] Figure 8 This diagram illustrates the high resistivity coating, intermediate layer, and surface treatment of the connection surface.

[0013] Figure 9 This is a schematic diagram illustrating a solution using node modules in the grid splicing process.

[0014] Figure 10 This is a schematic diagram of the cross node module structure in Embodiment 5 of the present invention.

[0015] Figure 11This is a schematic diagram of the h-BN rigid-flexible composite constraint mold in Embodiment 10 of the present invention.

[0016] Figure 12 for Figure 11 An enlarged view of region A in the middle, showing the microchannel structure.

[0017] Figure 13 This is a schematic diagram of the modular constraint tool structure based on a rigid frame in Embodiment 11 of the present invention.

[0018] Figure 14 This is a schematic diagram of the real-time bonding and sealing scheme based on h-BN flexible material in Embodiment 12 of the present invention.

[0019] Figure 15 This is a schematic diagram of the full patch sealing scheme in Embodiment 12 of the present invention. Detailed Implementation

[0020] To enable those skilled in the art to better understand the present invention, a detailed description is provided below in conjunction with the accompanying drawings and specific embodiments; It should be noted that this invention relates to the field of on-orbit manufacturing technology. The process parameters (such as current, pressure, and gas pressure), material selection, and predicted joint properties (such as strength and density) given in the following embodiments are derived based on mature materials science theories, heat transfer, fluid mechanics, and finite element numerical simulation techniques. Specifically, the thermal process analysis is based on the ANSYS finite element heat transfer model, the melt flow behavior is based on Fluent fluid dynamics simulation, the stress field analysis is based on Abaqus thermo-mechanical coupling calculation, and the solidification structure prediction is based on phase field method simulation. All simulation models are established based on the microgravity environment assumption (gravitational acceleration g=0) and a vacuum / low-pressure gas environment. The inventors have conducted a rigorous theoretical derivation of the feasibility of this invention based on the following generally accepted scientific principles: Joule's law of heating (Q=I²Rt): determines the controllability of interfacial resistance heating; Laplace's formula (ΔP=2γ / r): is used to calculate the critical pressure that the surface tension of a melt can withstand under microgravity, thereby determining the safe upper limit of the protective gas. Solidification theory: used to demonstrate the inevitability of shrinkage porosity being suppressed under multi-directional pressure (near hydrostatic pressure); Vacuum physics: used to calculate the degree to which the volatilization of alloying elements is suppressed under low-pressure inert gas conditions; Terminology Explanation: - Near-static pressure field: This refers to the pressure exerted on molten metal from all directions during solidification, with the pressure values ​​being essentially equal or nearly equal in all directions, thereby effectively suppressing the formation of shrinkage porosity and cavities. This invention achieves this through the combined action of the lateral reaction force constraining the mold and the normal component force of the non-planar interface. - Voltage steady-state criterion: When the interface is completely melted, the voltage drop in the circuit will tend to stabilize due to the stable resistivity of the liquid metal and the fixed geometry, forming a characteristic steady state. By monitoring the voltage signal in real time, the melting is determined to be complete when the steady state is detected, and the current is cut off, achieving precise process termination. This method requires no additional sensors and has outstanding advantages such as fast response, strong anti-interference, and suitability for space applications. - Self-regulating melting: refers to the use of the characteristic that the resistivity of metal increases significantly after melting, so that the current path automatically shifts from the melted area to the unmelted area, realizing the sequential melting of the interface from point to surface, without the need for complex external feedback control. The self-regulating melting mechanism of this invention not only achieves sequential melting of the interface, but also provides a natural signal for process termination through a voltage plateau criterion: - Fluctuation and rise period: The melting zone gradually expands, but the current will dynamically choose the low resistance path that has not yet melted to pass through. Therefore, the overall resistance shows fluctuation or step-like rise, reflecting the process of each micro-bump melting in sequence. -Stability period: When the entire interface is completely melted, there is no low-resistivity solid path to choose from, and the current is forced to pass entirely through the liquid region with higher resistivity. At this time, the loop resistance reaches its maximum value and stabilizes, forming the characteristic voltage steady state. This electrical characteristic makes heating control extremely simple and reliable—simply monitoring the appearance of a steady voltage state is enough to accurately determine complete melting and automatically cut off the power, without the need for complex time presets or external sensors. The physical essence of a steady voltage state is that current is "forced" to flow entirely through the high-resistivity liquid region only when the interface is 100% melted; at this point, the stability of the resistance signifies the completion of melting. It should be further noted that the material selections involved in the various embodiments of the present invention (including constraint mold materials, flexible sealing materials, pretreatment coating materials, etc.) are intended to exemplify the feasibility of the present invention and are not intended to limit the scope of protection. After reading this specification, those skilled in the art can, based on specific engineering requirements such as the melting point of the target connection material, on-orbit environmental conditions, cost control, and number of reuses, make reasonable selections and equivalent substitutions based on the material categories disclosed in this invention (such as high-melting-point ceramics, flexible fiber composite materials, high-resistivity metal coatings, etc.). These are all conventional choices under the concept of this invention and should be considered to fall within the scope of protection of this invention. After reading this specification, those skilled in the art, in conjunction with the aforementioned well-known theories and the parameter ranges provided in this application, can reproduce the method under microgravity conditions and obtain the aforementioned beneficial effects.

[0021] Example 1: Fused splicing of planar interface modules (reference) Figure 1 , Figure 3 , Figure 4 , Figure 5 ) This embodiment aims to illustrate the applicability of the basic solution of the present invention to planar interfaces. 1. Module Preparation: Two Ti-6Al-4V titanium alloy modules, each measuring 200 mm × 200 mm × 200 mm, are provided. The connection surfaces of the modules are flat. 2. Constraint mold installation: Install a removable constraint mold (e.g., ...) around the planar interface between the two modules. Figure 3 (As shown). The constraint mold consists of an upper cover plate, a lower support plate, and two end sealing plates, which together with the module plane form a six-sided closed cavity. The constraint mold is made of boron nitride (BN), which is heat resistant to 1800°C, non-conductive, and does not wet titanium alloy; 3. Docking and positioning: The two modules are precisely aligned and brought into contact using an external positioning mechanism; 4. Establish a protective atmosphere: Set up a local protective cover around the constraint mold and module connection area. For in-chamber operation scenarios, first evacuate the protective cover to <10 Pa to remove air, then fill it with argon gas to 300 Pa absolute pressure and maintain it dynamically; for external vacuum scenarios, the environment itself is a vacuum, so simply fill it with argon gas to 300 Pa absolute pressure. The selection of 300 Pa is based on the following: the vapor pressure of the alloying elements at the melting point of titanium alloy is about 1 Pa, which is sufficient to effectively suppress volatilization; at the same time, according to the Laplace formula, the surface tension of liquid titanium is about 1.5 N / m, and when the characteristic radius of the molten pool is 5 mm, the theoretical critical pressure difference is about 600 Pa. 300 Pa is far below this critical value and will not destroy the stability of the melt. 5. Electrical Heating: A pulsed current (peak value 10,000 A, pulse width 100 ms, duty cycle 50%) is applied to the module via a conductive heating power supply. Due to the presence of micro-protrusions caused by surface roughness in planar-planar contact, the initial contact area is much smaller than the apparent area, thus contact resistance still exists. After the current is applied, Joule heating first occurs at the micro-protrusion contact points. As these points melt, the contact area gradually increases, and the melting zone gradually expands until a uniform molten layer is formed across the entire interface. The total heating time is approximately 3-4 seconds. 6. Multi-directional pressurization: Immediately after energization, an axial pressure of 30 MPa is applied. The upper cover plate, lower support plate, and end sealing plate of the constrained mold provide lateral reaction forces, creating a multi-directional pressure field of 15-20 MPa in the melt region; 7. Pressure holding and solidification: Hold pressure for 20 seconds, during which the melt solidifies under multi-directional pressure; 8. Remove the constraint mold: Release the pressure and remove the constraint mold after the module has cooled down. Due to the non-hydrophilic properties of BN material, the joint does not adhere to the mold; 9. Effect Analysis: Based on finite element thermo-mechanical coupling simulation analysis, this scheme can also achieve splash-free connection, with an interface density >99% and tensile strength exceeding 95% of the parent material. However, due to the lack of self-positioning and current focusing effects of non-planar structures, higher positioning accuracy is required, and a larger initiation current may be needed when connecting highly conductive materials.

[0022] Example 2: Fused splicing of V-type interface modules (reference) Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 ) This embodiment uses a titanium alloy module as an example to illustrate the preferred scheme for using a non-planar interface. 1. Module Preparation: Two Ti-6Al-4V titanium alloy modules with dimensions of 200 mm × 200 mm × 200 mm are provided. The connection surfaces of the modules are designed with convex V-shaped and concave V-shaped structures respectively (e.g., Figure 2 (As shown in Figure a). A micro-bump array is distributed on the V-shaped inclined surface, with its height gradually decreasing from the V-shaped tip to the two edges: the height of the micro-bump array at the tip is 0.15 mm, in the middle area it is 0.10 mm, and at the edges it is 0.05 mm, with a spacing of 0.5 mm. This gradient height design ensures that the tip micro-bump array contacts first during docking, concentrating the current there; as the tip melts and axial pressure continues, the modules gradually approach, and subsequent rows of micro-bump arrays contact and melt in sequence, thus achieving layer-by-layer controllable melting of the interface. The inclined surface also has guiding microgrooves (0.05 mm deep, radially distributed) to guide the uniform spread of the melt. The theoretical basis for this gradient height design is as follows: According to Hertzian contact theory, the height difference of the micro-bump array determines the initial contact sequence during docking. The micro-bump array with the highest tip contacts first, generating the greatest contact pressure, thus forming the highest contact resistance and Joule heat; as this point melts, the modules move closer under axial pressure, and the next highest micro-bump array contacts in sequence, achieving controlled sequential melting of the mating surfaces. This design avoids current dispersion caused by simultaneous contact of large flat surfaces, ensuring the stability and uniformity of the heating process. 2. Mold installation: Same as in Example 1; 3. Docking and positioning: The two modules are docked, and the V-shaped structure automatically centers using the inclined plane, eliminating the need for a high-precision external positioning mechanism; 4. Establish a protective atmosphere: Same as in Example 1; 5. Electrical Heating: A pulsed current (peak value 10,000 A, pulse width 100 ms, duty cycle 50%) is applied to the module via a conductive heating power supply. The heating process has self-regulating characteristics. -Initial stage: Current only passes through the micro-bump array, resulting in high contact resistance (approximately 500 μΩ) and high heat generation power, concentrated at the V-shaped tip; - Tip melting: The V-shaped tip reaches the melting point of titanium alloy (1,660°C) within 0.5 seconds, resulting in localized melting; - Self-regulating transfer: After melting, the resistivity of liquid titanium is about 4 times higher than that of solid titanium. As the resistance of this region increases, the current is automatically transferred to the adjacent unmelted region. - Layer-by-layer progress: The melting zone gradually expands until the entire V-shaped interface is uniformly melted, with a total heating time of approximately 3 seconds; - Process monitoring and termination: During the heating process, the circuit voltage drop is monitored in real time. When the steady-state voltage is detected to last for more than 2 sampling cycles (20ms), the control system automatically cuts off the current to ensure that heating is terminated immediately after complete melting to avoid overheating; 6. Multi-directional pressurization: Immediately after energization, an axial pressure of 30 MPa is applied. At a V-angle of 45°, the normal component force P_n = P_axial·sin(θ / 2)≈11.5MPa; the upper cover plate, lower support plate, and end sealing plate of the constrained mold provide lateral reaction forces, creating a near-static hydrostatic pressure field of 20-25 MPa in the melt region; 7. Pressure Holding and Solidification: Hold pressure for 20 seconds, during which the melt solidifies under hydrostatic pressure. Solidification microstructure characteristics: Grains grow epitaxially from both sides of the module surface, continuously penetrating the original interface; no shrinkage porosity; heat-affected zone width <1 mm; 8. Remove the constraint mold: Same as in Example 1; 9. Theoretical Analysis of Effect: Based on solidification theory and finite element mechanical simulation, the tensile strength of the interface can reach more than 96% of that of the parent material, the elongation can reach more than 93% of that of the parent material, and the fatigue strength is comparable to that of the parent material.

[0023] Example 3: Fused splicing of W-type interface modules (reference) Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 ) This embodiment is designed for scenarios requiring higher connection strength and employs a W-type multi-peak interface (such as...). Figure 2 (As shown in c). The module dimensions are the same as in Example 2, but the connection surface is designed as a W-shaped structure (continuous double V), with a cycle number of n=3. Each V-shaped unit has an angle of 45° and a height of 8mm, increasing the total connection length to 2.5 times that of the V-shape. Heating characteristics: The W-type junction forms multiple current focusing points, and the three V-shaped tips melt preferentially and simultaneously. Multiple small molten pools expand independently and then merge. Based on real-time voltage drop monitoring, the curve shows a step-like descent, corresponding to the stages of melting in sequence from peak to valley. Mechanical enhancement: After solidification, a three-dimensional interlocking structure is formed. Finite element analysis shows that the shear strength is about twice that of the V-type, the tensile strength is about 50% higher, and the torsional resistance is significantly improved.

[0024] Example 4: Pretreatment scheme for high-resistivity coating of high-conductivity materials (reference) Figure 2 , Figure 8 ) This embodiment addresses the challenge of heating highly conductive materials, specifically targeting a pure copper module (resistivity 1.7 μΩ·cm). 1. Module preparation: Two pure copper modules are provided, with a 45° V-shaped connection surface (same as in Example 2); 2. Surface Pretreatment: The V-shaped connection surface is treated with a high resistivity coating using plasma spraying. A 0.1 mm thick tungsten coating (resistivity 5.6 μΩ·cm, approximately 3.3 times that of copper, melting point 3422°C, much higher than copper's 1085°C) is applied. Coating Function: Significantly improves interfacial contact resistance. Upon heating, the tungsten coating preferentially generates Joule heat, which is conducted to the copper substrate, causing it to melt. Some of the tungsten dissolves in the copper, forming a dispersed reinforcing layer. Besides tungsten coatings, those skilled in the art, based on the principle of resistance heating, know that any material that does not melt at the connection temperature and has a resistivity significantly higher than the base material, such as high-melting-point metal coatings or composite foils like molybdenum and tantalum, can be used as a pretreatment material to improve interfacial contact resistance. The required thickness can be theoretically calculated based on Joule heating formulas and the material's thermophysical properties. 3. Connection parameter adjustment: current 8,000 A (lower than in Example 2, due to the increased resistance from the coating), heating time 1 second (70% shorter than the untreated version), other steps are the same as in Example 2; 4. Effect Analysis: Based on diffusion kinetics and mechanical property simulation, the interface strength can reach more than 98% of the parent material. The interface hardness is slightly higher than that of the parent material due to tungsten dispersion strengthening. The tungsten content is extremely low and its impact on the overall conductivity is negligible. 5. Alternative solutions: Surface microstructure treatment (laser texturing to form a dense array of microbumps) or pre-placed intermediate layer (placement of 0.05 mm nickel foil) can also achieve similar results.

[0025] Example 5: Node module scheme for multi-module intersection nodes (reference) Figure 9 , Figure 10 ) This embodiment addresses the scenario where four modules intersect within a grid pattern, employing a cross-shaped node module (such as...). Figure 10 (As shown), to avoid geometric conflicts caused by direct splicing of multiple seams; It adopts a cross-node module, characterized by: a central integral casting structure, V-shaped interfaces on the end faces of the four arms (matching the standard module), and arm lengths that are coordinated with the dimensions of the standard module (e.g., 200 mm). Connection sequence: Fix the cross-shaped node module at the connection station, and sequentially fuse the four standard modules to the four arms of the cross-shaped node one-to-one (according to the method in Example 2). Each connection is completed independently and without interference. A six-arm node module (corresponding to the positive and negative directions of X, Y, and Z) can be used in three-dimensional space, with the same principle. Effect analysis: It completely avoids geometric conflicts caused by multiple seams, ensures consistent quality at all connection interfaces, and ensures that the overall structural strength is not affected by the nodes.

[0026] Example 6: Customized solutions for different splicing situations (reference) Figure 6 , Figure 7 ) Customization process such as Figure 6 As shown in the typical splicing solution library: straight splicing uses a T-shaped constraint mold; right-angle splicing uses an L-shaped constraint mold to achieve synchronous heating; Customization process: 1. Geometric Analysis: Obtain the geometric topology information of each connection in the target component through the design and simulation module; 2. Type identification: Classify the splicing situation (straight line, right angle, T-shape, cross, etc.); 3. Selection of standard parts: If it is a standard type, select the corresponding standard constraint mold and electrode from the library; 4. On-site customization: For special cases not included in the standard library, on-site manufacturing can be initiated, such as quickly printing constraint molds using a small ceramic 3D printer.

[0027] Example 7: Theoretical Analysis of In-cabin Operation Safety This embodiment verifies the safety of fusion splicing technology operating inside a manned cabin through theoretical analysis. The analysis is based on the following theoretical models and simulation tools: electromagnetic field analysis uses ANSYS Maxwell finite element simulation software, fluid dynamics analysis uses Fluent software, and thermal analysis uses Abaqus software. All simulation models are established based on the microgravity environment assumption (gravitational acceleration g=0) and a vacuum / low-pressure gas environment. 1. Analysis of molten droplet splashing: The confined mold closes the six sides of the melt. Based on fluid dynamics simulation, the melt remains in a contracted state under the action of surface tension and is stable in the V-groove without external disturbance, thus achieving zero splashing. 2. Smoke concentration analysis: The vapor pressure of titanium alloy at its melting point is about 1 Pa. Under 300 Pa argon atmosphere, the evaporation rate decreases by two orders of magnitude. The total amount of vapor evaporation at a single interface is <0.1 mg, and the concentration inside the chamber is negligible. 3. Optical radiation analysis: No electric arc is generated, the heating mechanism is Joule heating, the melt temperature is only slightly higher than the melting point (about 1700°C), the radiation spectrum is mainly infrared, and the module body blocks the leakage of visible light. 4. Temperature field simulation: Finite element thermal analysis shows that the highest temperature at the interface center is 1700°C, the temperature at 10 mm from the interface is about 800°C, the temperature at the module surface (50 mm away) is <200°C, and the temperature at the outer surface of the constraint mold is <100°C. 5. Electromagnetic interference analysis: The current frequency is <100 Hz (low frequency), the current loop is closed within the module and electrodes, the metal module itself is a good shield, the electric field at 1 meter away is <1 V / m, and the magnetic field is <0.1 μT, which meets aerospace standards; 6. Gas Consumption Calculation: Assuming a local protective shield volume of approximately 0.1 m³ and an absolute pressure of 300 Pa, the mass of argon gas required for a single connection is approximately 0.0005 kg. A standard 40L gas cylinder (15 MPa, containing approximately 6 m³ of atmospheric pressure gas) can support approximately 30,000 connections. Theoretical analysis shows that the fusion splicing technology meets all safety requirements for operations inside manned spacecraft cabins.

[0028] Example 8: Extended Analysis of Adaptability Theory for Different Materials This embodiment uses theoretical analysis to illustrate the applicability of the present invention to different materials; Material Resistivity (μΩ·cm) Melting point (°C) resistivity multiple after melting Vapor pressure melting point (Pa) Titanium alloy (Ti-6Al-4V) 42 1,660 Approximately 4 times ~1 Aluminum alloy (6061) 2.7 660 Approximately 3 times Precautions should be taken regarding Mg volatilization. pure copper 1.7 1,085 Approximately 6 times <0.1 Stainless steel (304) 10 1,400 Approximately 5 times <1 High-temperature alloy (Inconel) 15 1,400 Approximately 4 times <1 Connection strategies for each material: -Titanium alloy: The basic scheme (Example 2) is directly applicable; - Aluminum alloy: Low-pressure protective gas (300 Pa) can suppress most of the Mg volatilization, and heating time <2 seconds reduces the amount of volatilization; -Pure copper: High-resistance coating or surface treatment (Example 3); - Stainless steel / high-temperature alloy: moderate resistivity, directly applicable to basic solutions; - Dissimilar material bonding: A gradient intermediate layer scheme is adopted (see Example 9); Differences from existing connection technologies To clearly demonstrate the innovativeness of this invention, a systematic comparison with existing connection technologies is conducted below: Technology type heat source pressure Material condition Microgravity adaptability Wall thickness adaptability Interface strength Security efficiency Fusion welding external heat source none Local melting Difference Difference 70-90% Difference middle Pressure welding Resistance heating / friction heating have Solid or localized melting middle middle 80-95% middle Medium and high brazing external heat source none solder melting middle good 50-70% middle high diffusion welding external heat source have Solid diffusion middle Difference 90-95% good Extremely low Mechanical connection none have solid state good good 30-80% good high This invention Interface contact resistance There is (multi-directional pressure). Surface melting excellent Excellent (regardless of wall thickness) 95-98% excellent excellent This invention, for the first time, combines the following technical features to form a novel technical approach: self-generating heating through interfacial contact resistance (no external heat source required, heat is generated directly at the melting point), non-planar geometric interfaces (achieving current focusing, self-positioning, and melt guidance), constrained molds (physically sealing the melt, preventing splashing, and transmitting multi-directional pressure), low-pressure inert gas protection (200-400 Pa, suppressing volatilization and preserving melt stability), multi-directional pressurization (achieving near-static water pressure solidification, eliminating shrinkage cavities), and self-regulating melting (automatically controlling the heating process by utilizing the increased resistance after metal melting). This combination is not disclosed in existing technologies and solves the fundamental problem of connection technology in microgravity environments.

[0029] Example 9: Melt splicing of titanium and steel dissimilar materials (for dissimilar material joining schemes, refer to...) Figure 2 , Figure 8 ) This embodiment addresses the connection requirements between titanium alloy (Ti-6Al-4V) and stainless steel (304); 1. Module preparation: One Ti-6Al-4V titanium alloy module and one 304 stainless steel module are provided, with the connection surfaces all having a 45° V-shaped structure; 2. Surface pretreatment – ​​Pre-set gradient function intermediate layer: - Titanium alloy side: A layer of pure vanadium (V) is deposited, approximately 0.1 mm thick. Vanadium is infinitely soluble in titanium and has good compatibility with iron; - Stainless steel side: A layer of pure copper (Cu) is deposited, approximately 0.1 mm thick. Copper does not form brittle intermetallic compounds with iron; - Intermediate matching layer: An extremely thin vanadium / copper composite foil (0.05 mm thick) is sandwiched between the two V-shaped surfaces. 3. Mold installation, docking, and protective atmosphere: Same as in Example 2; 4. Electrical Heating and Process Control: Apply pulsed current (peak value 12,000 A, pulse width 80 ms, duty cycle 40%). Monitor the circuit voltage drop in real time; when the voltage drop curve shows a second plateau (corresponding to the complete melting of the intermediate layer and wetting of both base materials), immediately cut off the current. The total heating time should be controlled within 1.5 seconds. 5. Multi-directional pressurization and pressure holding solidification: After the power is turned on, apply an axial pressure of 25 MPa and hold the pressure for 15 seconds; 6. Effect Analysis: Based on phase diagram analysis and diffusion kinetics theory, the thickness of the brittle Ti-Fe compound layer can be controlled to less than 1 μm, and the tensile strength can reach more than 85% of that of the titanium alloy base material.

[0030] Example 10: h-BN rigid-flexible composite constraint mold (e.g.) Figure 11 , Figure 12 (As shown) This embodiment provides a constraint mold solution consisting of a rigid hexagonal boron nitride (h-BN) microporous module and a flexible h-BN material, combined with an external rigid concave frame; 1. Mold structure The constraint mold consists of an external rigid concave frame and four independent rigid-flexible composite modules: (1) External rigid concave frame The concave frame structure, made of high-strength, lightweight materials (such as carbon fiber composites and titanium alloys), is matched to the external dimensions of the metal modules to be connected. - The inner side of the frame is equipped with a groove or guide structure for installing and constraining the four rigid-flexible composite modules; - The overall stiffness design of the frame meets the requirement that the deformation is less than 0.1 mm when subjected to the maximum radial thrust. (2) Rigid-flexible composite module - The structure of each composite module is as follows: a rigid hexagonal boron nitride (h-BN) microporous module serves as the substrate, with its inner side (the surface in contact with the metal module) wrapped with flexible hexagonal boron nitride (h-BN) material, and its outer side in contact with the rigid concave frame; - Rigid h-BN microporous module: Made of dense h-BN material, with an internally machined microporous flow channel structure for gas delivery. The rigid structure provides stable support and precise gas passage; - Flexible h-BN material: Wrapped around the inner surface of the rigid module (the surface in contact with the metal module), with a thickness of approximately 1-2 mm. This material has the following intrinsic properties: non-conductive (volume resistivity > 10¹). 4 Ω·cm), high temperature resistance (≥2000°C), flexible and compressible (compression rebound rate >30%), non-hydrophilic to liquid metal (contact angle >120°); (3) Three-level constraint relationship Outer layer: Rigid concave frame – provides overall structural support and radial reaction force Middle layer: Flexible h-BN material – achieving high-temperature dynamic sealing and filling gaps. Inner layer: Rigid h-BN microporous module – providing precise gas channels and pressure transmission 2. Gas Channel Design The rigid h-BN microporous module integrates a microchannel network, which collects gas through guide holes and connects to a quick-connect interface on the outer surface of the module, thus communicating with the gas protection system. During operation, the protective gas is delivered to the interior of the chamber through the microporous channels within the rigid module. 3. Assembly and Operation Procedures Step 1: Mold Arrangement - Install the four rigid-flexible composite modules into the grooves of the external rigid concave frame, with the flexible h-BN material surface of each module facing inward (i.e., the direction of the metal module to be connected). -Move the rigid frame of the assembled composite module as a whole to the outer perimeter of the metal module to be connected, so that the center of the frame is aligned with the joint area of ​​the module. Step 2: Radial advancement and formation of sealing cavity - Radial pressure is applied to the four composite modules via a propulsion mechanism (such as a screw or hydraulic device) on a rigid frame. -The composite module moves toward the surface of the metal module under the action of thrust, and the flexible h-BN material first contacts the surface of the metal module. - Continue pushing to the preset pressure (e.g., 5-10 MPa), where the flexible material undergoes elastic deformation, completely filling the tiny gap between the rigid and metal modules. - The flexible layers of the four composite modules are pressed against each other under pressure, forming a continuous flexible sealing band around the module joints. - The external rigid concave frame provides reaction force support for all radial pressures during this process, preventing the composite module from shifting outward. Step 3: Gas replacement The gas protection system is connected via a quick-connect interface on the rigid module to evacuate the sealed cavity and fill it with low-pressure protective gas. Step 4: Connect the job - Connect the metal modules according to the standard procedure (electric heating, pressurized solidification). During energization, the external rigid frame continuously provides radial reaction force to maintain sealing stability. Step 5: Mold Removal - After connection is complete, release the radial pressure. - Reverse drive propulsion mechanism to make the composite module move backward -Due to the non-hydrophilic properties of flexible materials, the composite module can be easily separated from the metal module. - The rigid frame and composite module can be removed as a whole and reused. 4. Advantages - Three-layer constraint, reliable sealing: The external rigid frame provides overall reaction force, the rigid microporous module transmits pressure, and the flexible layer achieves dynamic sealing. The three layers work together to ensure the reliability of the seal under high temperature and high pressure. - Rigid-flexible composite with synergistic functions: The rigid module provides precise gas flow channels and stable support; the flexible outer layer fills micro gaps to compensate for thermal deformation and processing errors; - Modular design for easy maintenance: The four independent composite modules can be replaced individually, and damage to a single point will not affect the whole; only the module needs to be replaced after the flexible layer wears down. -Integrated gas delivery: The rigid module's internal microchannels directly deliver protective gas to the sealed cavity, eliminating the need for external piping and resulting in a compact structure; - High reusability: The elastic properties of the flexible material ensure a reliable seal even after multiple uses, with an expected reuse rate of >100 times; - Uniform pressure distribution: The external frame provides reaction force, and the rigid module transmits pressure, ensuring uniform contact between the flexible layer and the surface of the metal module and avoiding local overload; 5. Extended Material Specifications This embodiment uses h-BN material as the preferred material, but other combinations of non-conductive, high-temperature resistant materials can also achieve similar functions. - External rigid frame: carbon fiber composite material, titanium alloy, aluminum alloy, high-strength steel - Rigid matrix materials: dense h-BN, silicon nitride ceramics, alumina ceramics, machinable glass ceramics - Flexible sealing materials: h-BN flexible material, alumina fiber composite paper (≤1600°C), yttrium oxide fiber material (≤2200°C), mica-based flexible board (≤1000°C) Those skilled in the art can make reasonable selections based on the melting point of the target bonding material, on-orbit environmental requirements, and cost factors.

[0031] Example 11: Design of a Modular Constraint Tool Based on a Rigid Frame (Reference) Figure 13 ) This embodiment provides a special constraint tool for melting and splicing square metal components. The tool adopts a rigid frame that matches the size of the square metal components to be connected, and is equipped with a radially advancing constraint module to achieve high-precision and high-reliability on-orbit connection operations. 1. Tool Structure a. Customized rigid frame A rigid frame specifically designed for square metal modules of a certain size (such as a 200 mm × 200 mm cross section) has an internal contour that precisely matches the shape of the module. The single-sided gap between the frame and the module is controlled within the range of 5-20 mm, providing space for the installation and advancement of the constrained module. The frame is made of high-strength lightweight materials (such as carbon fiber composites, titanium alloys or aluminum alloys), and the overall stiffness design meets the requirement that the deformation is less than 0.1 mm when subjected to the maximum radial thrust (such as 50-100 kN / side) to ensure the uniformity of pressure transmission and positioning accuracy. The frame has multiple precision threaded through holes or guide holes evenly distributed on its four sides. The number and location of these holes are predetermined based on the module size and required pressure distribution (e.g., 2-3 propulsion points evenly distributed on each side for a 200 mm module). The inner side of the frame is equipped with grooves or guide structures for mounting and restraining radially propellable constraint module components. b. Constraint module components Each side is equipped with an independent constraint module that corresponds to a frame point. The number, size, and layout of the modules are all optimized designs for modules of that specific size. Each constraint module adopts a rigid-flexible composite structure (same as in Example 10): - Rigid substrate: Made of dense h-BN ceramic or other high-temperature resistant non-conductive materials, with integrated gas microchannels inside and threaded holes or ball joints on the outer surface for connection with the propulsion screw; - Flexible sealing layer: The surface of the rigid substrate in contact with the metal module is covered or wrapped with h-BN flexible material (1-3 mm thick) for high-temperature dynamic sealing. This material has the following intrinsic properties: non-conductive (volume resistivity > 10¹). 4 Ω·cm), high temperature resistance (≥2000°C), flexible and compressible (compression rebound rate >30%), non-hydrophilic to liquid metal (contact angle >120°); The module size design ensures that when all constraint modules are advanced to the preset position, the flexible layer of adjacent modules is slightly compressed (compression amount 0.5-1 mm), forming a continuous sealing strip; c. Promotion and Guidance Mechanism - Propulsion screws: Each constraint module is connected to the rigid frame via 2-4 high-precision screws. One end of the screw is fixedly connected to the rigid base of the constraint module (a ball joint can be used to accommodate small angular deflections), and the other end passes through a precision threaded hole in the side wall of the frame; - Drive method: The outer end of the screw can be designed as a manual screwing head (for ground debugging or emergency operation), or configured with a micro motor drive unit (for automated operation) to achieve precise radial feed control; -Guide column: Optional guide column and linear bearing to ensure that the constraint module moves in a parallel plane during the advancement process and avoids deflection; - Pressure sensor: A thin-film pressure sensor is integrated on each screw or constraint module to monitor the contact pressure in real time and realize closed-loop control; - Position encoder: An encoder is integrated into the motor end to achieve closed-loop position control with an accuracy of ±0.02 mm; d. Gas interface integration Each constraint module has a rigid base with a quick-connect gas interface, which connects to the central gas distribution system via a flexible hose. Internal microchannels within the module deliver gas to the sealing surface area in contact with the metal module, ensuring thorough gas replacement within the sealed cavity. e. Three-level constraint relationship The tool described in this embodiment forms a three-layer constraint structure similar to that in Embodiment 10: -Outer layer: Customized rigid frame – providing overall structural support and radial reaction force -Middle layer: Flexible sealing layer of the constraint module—achieving dynamic sealing at high temperatures and filling gaps. -Inner layer: Rigid base of the constraint module—transmits pressure and integrates gas channels. 2. Operating Procedures Step 1: Equipment Preparation and Positioning Two square metal modules, matching the dimensions of the tools, are transported to the connection station via a transfer mechanism and initially connected using a V-shaped interface. A custom rigid frame is then moved to the periphery of the modules; due to the precise match between the frame's internal contour and the module's shape, the frame can be quickly and accurately fitted into the module's connection area. Step 2: Containment module advancement and sealing cavity formation Start the drive motor of each constraint module (or manually turn the screw) to advance the module radially toward the surface of the metal module. After the flexible sealing layer of the constraint module contacts the surface of the metal module, continue to advance to the preset pressure (e.g., a contact pressure of 5-10 MPa). The flexible material undergoes elastic deformation and completely fills the tiny gap between the constraint module and the metal module. The flexible layers of adjacent constraint modules are squeezed against each other under pressure, with the compression controlled at 0.5-1 mm, forming a continuous flexible sealing strip around the module joint. At this point, the outer surfaces of the custom rigid frame, multiple constraint modules, and metal modules together form a closed cavity, which is connected to the outside only through the gas interface on the constraint module; Step 3: Gas replacement and establishment of protective atmosphere The sealed cavity is evacuated through the gas interface on the constraint module, and then filled with a low-pressure inert protective gas (such as argon, absolute pressure 200-400 Pa) and maintained dynamically. Step 4: Electrical heating and fusion bonding A current is applied to the two metal modules by a conductive heating power source, generating Joule heating through the contact resistance at the interface, causing the interface region to melt. During the energizing process, the rigid frame bears the radial reaction forces of all constrained modules, maintaining structural stability. Step 5: Multi-directional pressure solidification Immediately after power-on, axial pressure (e.g., 20-30 MPa) is applied to both modules via an external pressurization mechanism. Simultaneously, additional radial pressure (e.g., 10-20 MPa) is applied to the constraint module via a drive mechanism, subjecting the molten zone to pressure from multiple directions and creating a near-hydrostatic pressure field. The rigid frame provides reaction force support for all radial pressures during this process. Step 6: Pressure Holding and Removal Hold pressure until the melt is completely solidified (usually 10-30 seconds). Release the axial and radial pressures, and rotate the screw in the opposite direction to retract the restraint module, separating it from the metal module. Remove the rigid frame to complete one connection operation.

[0032] Example 12: Real-time bonding and sealing scheme based on h-BN flexible material (reference) Figure 11 , Figure 14 ) This embodiment provides a module connection sealing solution as simple as applying transparent tape. After the modules are connected, the operator or robotic arm holds the h-BN flexible patch and applies it to three sides along the gap in real time. The last side is sealed with a composite module and connected to the gas protection system. 1. Module integration First, align the two metal modules face to face according to standard procedure, using the self-positioning function of the non-planar interface to achieve initial alignment. At this point, gaps exist between the modules and need to be sealed. 2. Apply sealing patches in real time (on all three sides) Operators or robotic arms hold sealing patches made of flexible hexagonal boron nitride (h-BN) material and apply them in real time along the module seams, much like applying transparent tape. - Attach to three sides: Select the top, bottom, and left directions of the module, align the patch with the gap, and gently press it to adhere to the metal surface; - Patch characteristics: non-conductive, high temperature resistant (≥2000°C), flexible and compressible, non-hydrophilic to liquid metal; -Attachment method: The back of the patch has a heat-dissipating, high-temperature resistant adhesive layer. It can be pressed and adhered at room temperature, and the adhesion is sufficient to withstand subsequent operations. - Reserve one side: The right side will not be attached for the time being, as an opening for the subsequent installation of composite modules; 3. End seal and cavity formation (one surface) After the patches on all three sides are attached, Figure 11 The rigid-flexible composite constraint module shown moves to the reserved opening. This composite module includes: - Rigid h-BN microporous matrix (internal integrated microchannels). - Flexible h-BN sealing layer; -Gas interface; Optional integrated heating element (for assisting disassembly); The composite module is pressed against the module surface by a propulsion mechanism, ensuring full contact and adhesion between the flexible layer and the module surface. The flexible layer adheres firmly to the metal surface through its own adhesive force, forming a reliable seal and sealing the final gap. The propulsion mechanism can then be released or removed, and the seal is maintained by the adhesive force between the composite module and the metal surface. At this point, the sealing patches on the three sides, which are attached in real time, together with the composite module, form a complete closed cavity; 4. Gas protection and connection operations Connect to the gas protection system via the gas interface on the composite module: a. Evacuate the sealed cavity to <10 Pa to remove air; b. Fill with a low-pressure inert protective gas (such as argon, absolute pressure 200-400 Pa). c. Dynamically maintain gas pressure; Then, connection operations such as electric heating and multi-directional pressure solidification are carried out according to standard procedures. 5. Mechanical analysis of the sealing patch under small displacement conditions In this embodiment, the relative displacement of the modules generated by axial pressure is approximately 0.1–0.3 mm, which is comparable to the original gap size between the modules (0.1–0.5 mm). Part of the displacement is used to eliminate the macroscopic gap between the modules, while the other part is converted into compression of the h-BN sealing patch. According to elasticity analysis, the relationship between the compression Δh of the patch and the displacement δ is as follows: Δh = k·δ, where k is a coefficient related to the patch position (0.3~0.7). Taking typical values ​​δ = 0.2 mm and k = 0.5, then Δh = 0.1 mm. For an h-BN patch with an initial thickness of 1 mm, the strain is ε = 0.1. The elastic modulus of the h-BN flexible material E ≈ 0.2 GPa, therefore the internal stress of the patch σ = E·ε = 20 MPa, which is much lower than the yield strength of h-BN at 800°C (>100 MPa). At the same time, this strain value (10%) is much smaller than the elastic limit of the h-BN material (compression resilience >30%), indicating that the patch is in a state of fully elastic deformation. Furthermore, according to Hertzian contact theory, the contact pressure distribution at the interface between the patch and the module is uniform, with no stress concentration. Therefore, although the axial movement distance is very small, it is this small displacement that keeps the patch compression within the elastic range, achieving both reliable sealing and avoiding plastic deformation, thus laying the foundation for the reuse of the patch. 6. Patch removal after assembly After the connection is completed, the sealing patch needs to be removed for reuse. -Heat debonding: Slightly heat the patch to 150-200°C (using a hot air gun, flexible heating pad, or heating element integrated on the composite module), which can thermally debond the adhesive and significantly reduce its tackiness; --Easy to peel off: Use a robotic arm or astronaut hand tools to easily peel off the patch, just like tearing off transparent tape; - Residue-free design: h-BN material itself is non-hydrophilic to metals, and there is no residue after the adhesive is pyrolyzed, leaving the module surface clean as new; -Restore to standby: After the patch cools down, the adhesive regains its stickiness and can be used again; 7. Advantages - Simple and intuitive operation: Apply in real time like applying transparent tape, no pre-treatment required; - Highly adaptable: The attachment position and angle can be adjusted according to the site conditions; -Low cost: The cost of 2D patch is much lower than that of 3D mold; -Full functionality: Retains all functions of the gas protection system (vacuuming, gas filling, pressure maintenance); -Reusable: The patch uses a thermolytic adhesive, which can be removed without damage by slight heating and reused repeatedly; - No residue design: The module surface is clean after disassembly and does not affect subsequent connections; - Modular compatibility: Composite modules can be directly reused. Figure 11 The design is consistent with the rest of the system; - Adaptable to the space environment: Simple and reliable operation, suitable for in-vehicle / out-of-vehicle operations; 8. Alternative solution: Rigid object pressing against non-adhesive patch seal. The above solution uses a pyrolytic adhesive layer to achieve temporary fixation and repeated removal of the patch. Alternatively, the patch can be completely adhesive-free, relying solely on the continuous pressure of a rigid object for sealing. a. Implementation method - Adhesive-free patch: The patch is made of h-BN flexible material with no adhesive layer on the back, relying solely on the flexibility and elasticity of the material itself; - Rigid clamping components: ordinary rigid clamping blocks, plates or clamps are used to apply continuous pressure to the patch; - Sealing mechanism: The rigid clamping component presses the patch tightly against the surface of the metal module. The patch undergoes elastic deformation, filling the micro gaps and forming a pressure-maintaining seal. b. Operating Procedures - Patch Placement: After the module docking is completed, the operator or robotic arm places the adhesive-free patch on the surface of the gap to be sealed (three sides). - Rigid clamping: Install the rigid clamping component in place, and apply continuous pressure through the pushing mechanism to make the patch fit tightly against the metal surface; -Seal maintenance: During subsequent operations, the clamping force continues to apply, and the patch remains compressed to maintain the sealing effect; - Disassembly method: After the connection is completed, release the clamping force. The patch will return to its original shape due to its own elasticity and can be removed directly without heating; c. Hardware simplification: Ordinary rigid clamping components are sufficient. This alternative does not require the use of Figure 11 The rigid-flexible composite module shown is designed to achieve this. Since the adhesive-free patch itself possesses the flexibility required for sealing, and maintaining the seal only requires continuous pressure, a standard rigid clamping element is sufficient. - Clamping material: can be metal (such as titanium alloy, stainless steel), ceramic or composite material, as long as it has sufficient rigidity and high temperature resistance; -Structure: It can be a simple pressure block, pressure plate, clamp, or end effector of a robotic arm; - Pressure source: Continuous pressure can be maintained by threaded screws, springs, pneumatic or hydraulic mechanisms; - No gas path required: Since three of the surfaces in this solution do not involve gas protection (or gas protection is achieved by other means), the clamping component does not need to integrate gas flow channels and interfaces; Significantly simplified hardware: From Figure 11 The multi-functional composite module is simplified into a purely mechanical clamping component, further reducing cost and complexity; 9. Further simplification: A full patch sealing solution under conditions with no risk of vaporization (refer to...) Figure 15 ) For certain metallic materials (such as high-melting-point metals like tungsten and molybdenum, or alloys with extremely low vapor pressure at the connection temperature), there is no risk of trace metal vaporization during melting, eliminating the need for suppressing volatilization with a low-pressure inert atmosphere. In such conditions, the sealing solution can be further simplified: - Sealing method: Sealing can be achieved by using sealing patches on all four sides. The patches can be pyrolytic patches with adhesive layers, or a combination of adhesive-free patches and ordinary rigid clamping components to apply continuous pressure; - Gas environment: No inert protective gas is required; the sealed cavity only needs to be maintained in a vacuum state. For external operations, the natural vacuum environment of space can be utilized; for internal operations, only the vacuum needs to be evacuated to the required pressure (e.g., <10 Pa), without the need for a gas filling step. - Hardware simplification: Since no gas protection is required, the composite module and its integrated gas channels and interfaces can be omitted. The entire sealing structure is completed independently by a composite of patch and ordinary rigid clamping component or self-adhesive patch, further reducing system complexity and cost; This simplified solution is applicable to metal materials with no risk of volatilization, and achieves maximum simplification of hardware and operating procedures while ensuring sealing reliability. Best practice

[0033] In the above embodiments, the fusion splicing scheme of the V-type interface titanium alloy module described in Embodiment 2 is the best way to implement the present invention because of its simple interface structure, typical process parameters, and strong material adaptability. The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art can make various improvements and modifications without departing from the spirit and principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for melting and splicing modular large components suitable for microgravity environments, characterized in that, Includes the following steps: Provide at least two prefabricated metal module components; A removable constraint mold is installed around the surface to be connected of the module element, so that the constraint mold and the module element together form a closed cavity; Connect the surfaces of the module components to be connected together; By applying current to the docked module components, Joule heating is generated at the contact point of the surfaces to be connected, causing the contact area to melt. Pressure is applied to the module components, and the pressure is applied to the molten metal through the constrained mold, causing it to solidify under constrained conditions and form a metallurgically bonded interface; Remove the constraint mold.

2. The method according to claim 1, characterized in that, The surfaces to be connected are non-planar geometric surfaces that match each other.

3. The method according to claim 1, characterized in that, Prior to the melting step, a step of establishing a low-pressure inert gas protective atmosphere within the enclosed cavity is also included.

4. The method according to claim 1, characterized in that, Before installing the constraint mold, the process also includes a pretreatment step for the surfaces to be connected. The pretreatment includes one or more of coating with a high resistivity material, forming a surface microstructure, or pre-setting an intermediate layer. The intermediate layer is a gradient functional intermediate layer for connecting dissimilar materials.

5. The method according to claim 2, characterized in that, The inclined structure of the non-planar geometric interface is used to convert the applied axial pressure into a normal component force acting on the molten metal, and together with the lateral reaction force provided by the constraint mold, it forms a near-static hydrostatic pressure field; the non-planar geometric interface is one or more of the following: V-shaped, W-shaped, sawtooth, wave-shaped, right-angled, T-shaped, or cross-shaped, and its surface is provided with an array of micro-bumps and / or flow-guiding micro-grooves for initial current focusing and melt guidance.

6. The method according to claim 1, characterized in that, By monitoring the voltage drop in the energized circuit, complete melting is determined when the voltage drop reaches a characteristic steady state, and heating is terminated.

7. A modular large-scale component fusion splicing system for implementing the method according to any one of claims 1-6, characterized in that, include: Module storage unit, used to store prefabricated metal module components; Connecting work units, including: A conductive heating power supply is used to provide adjustable current to module components; A pressurizing mechanism used to apply pressure; The constraint mold is removably mounted on the periphery of the module component connection surface. It is made of non-conductive, high-temperature resistant material and is used to form a closed cavity together with the module component. A gas protection system is used to establish a local protective atmosphere within the enclosed cavity; The positioning and transfer mechanism is used to enable the picking, docking, and movement of modular components.

8. The system according to claim 7, characterized in that, The constraint mold is made of a non-conductive, high-temperature resistant flexible material that is non-hydrophilic to liquid metal.

9. A dedicated interface structure for fusion splicing of modular components under microgravity conditions, characterized in that, Located on the connection surface of the metal module element, the interface structure is a non-planar geometric structure that matches each other, and its surface is distributed with an array of micro-bumps for initial current focusing and / or flow-guiding micro-grooves for guiding melt spreading.

10. The dedicated interface structure according to claim 9, characterized in that, The micro-bump array has a gradient height distribution to achieve a self-regulating heating effect of layer-by-layer contact and sequential melting during docking.

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