Additive Manufacturing and Post-Processing of Inorganic Materials

Abstract

Compositions and processes for producing 3D-formed additive manufactured and / or heat-converted composite articles are disclosed. The final product is optionally (i) produced by a closed-loop recycling process, (ii) achieved by an electrical conversion process, (ii) glazed prior to heat conversion, and / or (iv) exposed to energy-efficient conversion techniques such as microwave heating and / or combustion synthesis to promote and / or preserve in the form of nanoparticles or microparticles.

Description

Technical Field

[0001]

[0001] Cross - Reference to Related Applications This application claims the benefit and priority of U.S. Provisional Patent Application No. 63 / 346,475, filed May 27, 2022, the entire content of which is incorporated herein by reference.

[0002]

[0002] Description of Research Funded by the Federal Government None.

Background Art

[0003]

[0003] Additive manufacturing (AM) helps to generate three - dimensionally designed architectures and improve product performance. For example, the strength - to - weight ratio of structural components and the rapid charging ability of battery electrodes can be improved by AM.

[0004]

[0004] State - of - the - art AM methods use a single material of plastic, metal, ceramic, or composite material, and the material does not change rapidly during the AM process. In other words, most materials currently used in AM are usually synthesized as filaments, powders, or resins before the process of generating a 3D structure.

[0005]

[0005] One emerging technology for generating 3D structures of inorganic materials is the combination of AM and thermal conversion used to produce metals and ceramics from organic materials such as UV - curable resins composed of metal ions and pre - ceramic polymers, respectively. Materials produced by the method combining AM and thermal conversion include pure metals, alloys, ceramics, carbon, and carbon - matrix composite materials. At each step, the material is limited to a specific state and / or composition. For example, the material before AM is in a liquid state, the material after AM is an organic material, and the material after thermal conversion is a single material or a particulate composite material. These limited material selections at each step result in a limited range of materials being produced.

Summary of the Invention

[0006]

[0006] Here, to overcome the above limitations, compositions and methods useful for generating 3D forms of composite materials are disclosed. The precursor material before AM is composed of various materials in liquid and / or solid states, the material after AM can be glazed, and the conditions of thermal conversion can generate 3D composite materials or microstructured metal structures.

[0007]

[0007] The method disclosed herein includes: 1) providing a resin containing a monomer or oligomer and one or more microwave susceptor materials or precursors thereof as a liquid, slurry, or solid; 2) additive manufacturing a 3D hydrogel or organogel structure from the resin of step 1); 3) swelling the 3D hydrogel or organogel structure with an aqueous solution containing a metal salt or metal complex to form a metal-containing 3D hydrogel structure; 4) optionally, coating a glazing material on the 3D hydrogel or organogel structure from step 2) or the metal-containing 3D hydrogel structure from step 3); and 5) thermally converting the optionally glazed 3D hydrogel or organogel structure from step 3) or step 4) into a final product. In some embodiments, step 4) is omitted.

[0008]

[0008] Any of the metal-containing species in steps 1) to 5) can be a thermally non-reductive metal-containing species in a liquid state, a thermally reductive metal-containing species in a liquid state, metal particles, metal-containing ceramic particles, metal oxide particles, inorganic particles, and / or a carbon composite material. The glazing material in step 4) is composed of a pre-ceramic polymer and / or a fluid containing metal oxide particles. The glazed 3D structure is thermally converted into different materials depending on the atmosphere applied during the thermal conversion step 5). The combination of the materials and thermal conversion conditions in each step can generate a 3D constructed and microstructured metal, metal composite material, or ceramic composite material with pores, optionally containing additives and / or coatings of metals, ceramics, oxides, inorganic materials, and / or carbon. Such combinations are summarized in FIG. 1.

[0009]

[0009] In one aspect, the resin for additive manufacturing includes a cross-linking agent, a photoinitiator, a UV blocker, and a microwave susceptor or a precursor thereof.

[0010]

[0010] In one embodiment, the cross-linking agent is poly(ethylene glycol) diacrylate, the photoinitiator is lithium phenyl-2,4,6-trimethylbenzoylphosphinate), and the UV blocker is tartrazine.

[0011]

[0011] In one embodiment, the cross-linking agent is selected from the group consisting of acrylate monomers, acrylate oligomers, methacrylate monomers, methacrylate monomers, thiol monomers, thiol oligomers, alkene monomers, alkene oligomers, alkyne monomers, alkyne oligomers, epoxy monomers, epoxy oligomers, epoxy acrylate-based monomers, and epoxy-acrylate-based oligomers.

[0012]

[0012] In one embodiment, the cross-linking agent is selected from the group consisting of acrylic polymers, ether polymers, fluorocarbon polymers, polystyrene polymers, poly(vinyl chloride) polymers, poly(N-vinylpyrrolidone) polymers, and combinations thereof.

[0013]

[0013] In one embodiment, the crosslinking agent is selected from the group consisting of poly(ethylene glycol) diacrylate, 1,3,5-triallyl-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, and combinations thereof. In one embodiment, the crosslinking agent is a metal ion, such as, but not limited to, calcium ion.

[0014]

[0014] In one embodiment, the crosslinking agent includes a carboxylic acid moiety, an amide moiety, an amine moiety, an aldehyde moiety, a ketone moiety, an ester moiety, a thiol moiety, a halogenated alkyl moiety, an alkoxy moiety, a hydroxyl moiety or a phenyl moiety. For example, an acrylamide crosslinking agent can produce poly(acrylamide), and an acrylic acid crosslinking agent can produce poly(acrylic acid) after polymerization.

[0015]

[0015] In one embodiment, the resin further includes a reactive diluent selected from the group consisting of acrylamide, acrylic acid, diurethane dimethacrylate, 2-hydroxypropane-1,3-diyl bis(2-methylacrylate), vinyl acetate, polyethylene glycol monoacrylate and methyl methacrylate.

[0016]

[0016] In one embodiment, the resin includes at least two immiscible solvents (e.g., an aqueous solvent and an organic solvent) formed into an emulsion. For example, two or more crosslinking agents, photoinitiators, UV blockers, microwave susceptors, metal ions or other components incorporated into the 3D structure can each be soluble in different solvents that are immiscible with each other, and the different solvents can be emulsified.

[0017]

[0017] In one embodiment, the photoinitiator is selected from the group consisting of lithium phenyl-2,4,6-trimethylbenzoylphosphinate, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, 2,2-dimethoxy-1,2-diphenyl-ethan-1-one, 1-hydroxy-cyclohexyl-phenyl-ketone, benzophenone, 2-hydroxy-2-methyl-1-phenyl-1-propanone, 2-hydroxy-1-[4-(2-hydroxyethoxy)phenyl]-2-methyl-1-propanone, methyl benzoylformate oxy-phenyl-acetic acid 2-[2-oxo-2-phenyl-acetoxy-ethoxy]-ethyl ester, oxy-phenyl-acetic acid 2-[2-hydroxy-ethoxy]-ethyl ester, alpha,alpha-dimethoxy-alpha-phenylacetophenone, 2-benzyl-2-(dimethylamino)-1-[4-(4-morpholinyl)phenyl]-1-butanone, 2-methyl-1-[4-(methylthio)phenyl]-2-(4-morpholinyl)-1-propanone, diphenyl(2,4,6-trimethylbenzoyl)-phosphine oxide, phosphine oxide, phenylbis(2,4,6-trimethylbenzoyl), bis(eta5-2,4-cyclopentadien-1-yl)bis[2,6-difluoro-3-(1H-pyrrol-1-yl)phenyl]titanium iodonium, (4-methylphenyl)[4-(2-methylpropyl)phenyl]-, hexafluorophosphate(1-), 2,2-dimethoxy-1,2-diphenyl ethane-1-one, isopropylthioxanthone, 2-ethylhexyl-(4-N,N-dimethylamino)benzoate, ethyl-4-(dimethylamino)benzoate, 2-dimethylamino-2-(4-methyl-benzyl)-1-(4-morpholin-4-yl-phenyl)-butan-1-one, azobisisobutyronitrile, benzoyl peroxide and combinations thereof.

[0018]

[0018] In one embodiment, the UV blocker is selected from the group consisting of tartrazine, benzotriazole, benzophenone, triazine, 1-(phenyldiazenyl)naphthalen-2-ol and combinations thereof.

[0019]

[0019] In one embodiment, the microwave susceptor is selected from the group consisting of metals, metal oxides, metal carbides, metal nitrides, carbon, and combinations thereof.

[0020]

[0020] In one embodiment, the resin further comprises a metal complex or a metal salt. In one embodiment, the metal salt is a metal nitrate, metal nitrite, metal hydroxide, metal chloride, metal sulfate, metal carbonate, metal bicarbonate, metal acetate, metal fluoride, metal bromide, metal iodide, metal phosphate, metal chromate, metal cyanide, metal chlorate, metal perchlorate, metal benzoate, metal borohydride, metal acrylate and / or metal sulfide.

[0021]

[0021] In one embodiment, the resin comprises one or more metal acrylates; N,N-dimethylformamide; dimethyl sulfoxide; isopropanol; methanol; glycerol; ethanol; or combinations thereof.

[0022]

[0022] In one aspect, the additive manufacturing and thermal conversion process includes additive manufacturing a 3D structure by photopolymerizing the resin disclosed herein, and thermally converting the 3D structure to a final product by microwave heating. For example, the 3D structure may be exposed to microwave heating for 5 seconds to 15 minutes, or 10 seconds to 10 minutes, or 30 seconds to 5 minutes. In one embodiment, the 3D structure reaches a temperature above 400 °C or above 450 °C or above 500 °C during microwave heating. At these temperatures, the polymer (resin) is decomposed and the metal-containing resin is converted to a resin-free metal-containing material.

[0023]

[0023] In one embodiment, the additive manufacturing and thermal conversion process further includes swelling the 3D structure using an aqueous metal salt solution to form a metal-containing hydrogel. In one embodiment, the process further includes electrochemically introducing a metal into the 3D structure. For example, the step of electrochemically introducing may include plating, converting, reducing, or depositing a metal onto or into the 3D structure.

[0024]

[0024] In one embodiment, the 3D structure is a microwave susceptor-containing organogel, a microwave susceptor precursor-containing organogel, a microwave susceptor-containing hydrogel, or a microwave susceptor precursor-containing hydrogel.

[0025]

[0025] In one embodiment, the additive manufacturing and thermal conversion process further comprises coating a glazing material onto the 3D structure prior to thermal conversion. For example, the glazing material may include a preceramic polymer, a fluid containing metal oxide particles, or a glass precursor. For example, the precursor of the glazing material may include elements selected from the group consisting of magnesium, aluminum, silicon, and combinations thereof.

[0026]

[0026] In one embodiment, the additive manufacturing and thermal conversion process further comprises exposing the 3D structure to a reducing atmosphere, an oxidizing atmosphere, and / or an inert atmosphere during the step of thermal conversion.

[0027]

[0027] In one embodiment, the final product is porous and / or lattice-like. In one embodiment, the final product includes nanoparticles or microstructures, such as microparticles or twins.

[0028]

[0028] In one aspect, the additive manufacturing and thermal conversion process includes preparing a resin; incorporating a metal, a ceramic, a metal oxide, carbon, and / or a precursor thereof into the resin; printing the resin to form an additively manufactured article; and thermally converting the additively manufactured article into a final composite product.

[0029]

[0029] In one embodiment, the step of incorporating a metal, a ceramic, a metal oxide, carbon, and / or a precursor thereof into the resin includes mixing a metal-containing solution with the resin before printing and / or swelling the resin with the metal-containing solution after establishing a predetermined 3D structure.

[0030]

[0030] In one embodiment, the step of incorporating metal, ceramic, metal oxide, carbon, and / or their precursors into the matrix includes electrochemically introducing the metal into the resin after establishing a predetermined 3D structure.

[0031]

[0031] In one embodiment, the step of thermally converting the additive manufactured article includes generating heat from one or more of an external heat source, microwave energy, and combustion synthesis reaction.

[0032]

[0032] Exemplary embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

Brief Description of the Drawings

[0033]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Modes for Carrying Out the Invention

[0034]

[0041] Generally, the terms and phrases used in this specification have meanings recognized in the art and can be found by reference to standard texts, journal references, and contexts known to those of ordinary skill in the art. The following definitions are provided to clarify their specific use in the context of this specification.

[0035]

[0042] As used herein, "moiety" is a part of a molecule.

[0036]

[0043] As used herein, "crosslinking agent" is a molecule that chemically reacts with and covalently bonds oligomers and / or polymers.

[0037]

[0044] The term "hydrogel" refers to a material that contains a network of one or more polymers, typically one or more hydrophilic polymers, and contains water. Hydrogels usually contain a water content selected from the range of 1 wt% to 90 wt% or 10 wt% to 90 wt%.

[0038]

[0045] As used herein, the term "organogel" refers to a material that contains a network of one or more polymers, typically one or more hydrophilic polymers, and contains a water-miscible non-aqueous solvent. Organogels usually contain a water-miscible non-aqueous solvent component selected from the range of 1 wt% to 90 wt% or 10 wt% to 90 wt%.

[0039]

[0046] As used herein, "swelling" (or "swelling-in" or "swell-in") refers to a first material, such as a resin, hydrogel, organogel, or other composition, that incorporates at least one other material and / or chemical species (e.g., an element, molecule, metal ion(s)) such that the at least one other material and / or chemical species becomes part of or is dispersed / interspersed within the first material. Exemplary swelling techniques include, but are not limited to, immersing, injecting, spraying, fumigating, or otherwise contacting the first material with a solution containing at least one other material and / or chemical species that is absorbed or adsorbed by the first material.

[0040]

[0047] As used herein, "microwave susceptor" refers to an atom, molecule, or complex that reflects or absorbs energy in the microwave portion of the electromagnetic spectrum, thereby producing a quantity of heat that is at least partially determined by the microwave penetration depth and loss tangent factor. A neat form of a microwave susceptor is a solid at room temperature characterized by a penetration depth of less than 1 meter and / or a loss tangent factor greater than 0.1. Examples of microwave susceptors include, but are not limited to, metals (e.g., aluminum, copper, silver, gold, zirconium, silicon), metal oxides, metal carbides (e.g., silicon carbide), carbon nanotubes, carbon black, graphite, graphitized carbon powder, and hard carbon powder.

[0041]

[0048] As used herein, "additive manufacturing" refers to a manufacturing process for producing three-dimensional objects by adding raw materials to a partial structure to form a final product made of the raw materials. Exemplary additive manufacturing processes include, but are not limited to, 3D printing, stereolithography, vat polymerization, jet printing, atomic layer deposition, and material extrusion.

[0042]

[0049] In contrast to additive manufacturing, "subtractive manufacturing" refers to a manufacturing process that produces three-dimensional objects by removing a portion of raw material from a workpiece to form a final product made of the raw material. Exemplary subtractive manufacturing processes include, but are not limited to, grinding, milling, turning, engraving, etching, and computer numerical control (CNC) machining.

[0043]

[0050] "Proximal" and "distal" refer to the relative positions of two or more objects, planes, or surfaces. For example, an object that is spatially closer to a reference point relative to the position of another object is considered to be proximal to the reference point, and an object that is spatially farther from the reference point relative to the position of another object is considered to be distal to the reference point.

[0044]

[0051] The terms "direct and indirect" represent the action or physical position of one object with respect to another object. For example, an object that "directly" acts on or contacts another object does so without the intervention of an intermediary. In contrast, an object that "indirectly" acts on or contacts another object does so through an intermediary (e.g., a third component).

[0045]

[0052] The term "metal-containing species" refers to chemical species (e.g., atoms, salts, ions, compounds, molecules, materials) whose chemical formula contains at least one metal element. For example, a material, object, chemical species, compound, molecule, mixture, solution, or dispersion characterized as or referred to as "metal-containing" is, respectively, a material, object, chemical species, compound, molecule, mixture, solution, or dispersion that contains at least one metal and / or metal-containing species. The term "metal-containing material" refers to a material that contains at least one metal and / or metal-containing species. The term "metal-containing hydrogel" refers to a hydrogel that contains at least one metal and / or metal-containing species. The term "metal-containing particles" refers to particles that contain at least one metal and / or metal-containing species (e.g., metal oxides or metal nanoparticles). A metal-containing material may contain one or more metal atoms and / or metal ions involved in ionic, covalent, metallic, and / or coordination bonds of the material.

[0046]

[0053] The term "metal element" refers to the metal elements in the periodic table. Further, as used herein, the term "metal" includes elements that are metalloids. Metalloid elements include B, Si, Ge, As, Sb, and Te, and optionally Po, At, and Se.

[0047]

[0054] The term "metal alloy" refers to an alloy of two or more metals. For example, a metal alloy can be characterized as a solid solution of two or more metal elements (e.g., the metal elements are in the form of atoms or ions in the solid solution), a mixture of metal phases, or an intermetallic compound. A metal alloy can be characterized as including a metallic bond. In certain embodiments, a metal rather than a metal alloy refers to a metallic material having a chemical formula with one metal element (i.e., having a composition with one metal element).

[0048]

[0055] The term "ceramic" refers to a solid material including compounds of ionically and / or covalently bonded metal atoms, nonmetal atoms, and / or metalloid atoms. For example, a ceramic material can be characterized as having cations (e.g., metal ions that can be metalloid ions) and anions (e.g., oxygen ions, nitrogen ions, carbide ions) that are ionically and / or covalently bonded to each other.

[0049]

[0056] As used herein, the term "blank" refers to an additively manufactured 3D structure that does not contain metal-containing species, which can be added in a later step (e.g., via swelling, diffusion, absorption, adsorption, and / or glazing).

[0050]

[0057] As used herein, "resin" refers to a mixture including crosslinking agents such as monomers, polymers, and / or macromolecules. As used herein, a photocurable resin is a resin that includes one or more photoinitiators.

[0051]

[0058] The term "constructed" refers to a system, structure, geometric shape, or feature that has been designed and formed according to a design. In one embodiment, the constructed structure is deterministic or formed according to a deterministic process(es). In one embodiment, the feature and its physical dimensions are designed or predetermined and formed according to the design such that the feature and its physical dimensions are equivalent to the design features and physical dimensions. As used herein, a constructed metal-containing material is a nano-constructed or micro-constructed material (having a nano-constructed or micro-constructed structure).

[0052]

[0059] As used herein, "net shape" refers to an object such as a precursor of a final product that has a size and / or shape similar to the planned size and / or shape of the final product. For example, the net shape precursor of an additive manufactured 3D structure disclosed herein may have the same shape as the final product obtained after heat treatment. In some embodiments, the net shape precursor of an additive manufactured 3D structure may have a size that is 200%, or 100%, or 50%, or 25%, or 10%, or 5% larger than the final product obtained after heat treatment (e.g., after removal of liquids and resins).

[0053]

[0060] Additive manufacturing and thermal conversion for generating three-dimensional constructed composite materials

[0061] As described above, the methods disclosed herein include: 1) incorporating metals, ceramics, carbons, and / or their precursors as liquids or solids into a metal-containing resin; 2) performing additive manufacturing using the metal-containing resin; 3) coating a glazing material on the printed metal-containing resin from step 2); and 4) thermally converting the glazed metal-containing resin from step 3) into the desired final product of those composite materials. In one embodiment, step 3) can be omitted.

[0054]

[0062] The material of step 1) functions as a matrix in the final composite product and is composed of a thermally non-reductive metal-containing resin in a liquid state, a thermally reductive metal-containing resin in a liquid state, and / or a pre-ceramic polymer in a liquid state. The material of step 1) may further contain metal particles, ceramic particles, metal oxide particles, and / or a carbon material. The glazing material is composed of a pre-ceramic polymer or a fluid containing metal oxide particles. The glazed 3D constructed precursor is thermally converted into different materials depending on the atmosphere applied during the thermal conversion step 4). The combination of the material and the thermal conversion conditions in each step can generate a 3D constructed metal matrix composite material or a ceramic-matrix composite material with pores, optionally containing metal, ceramic, oxide, and / or carbon additives and / or coatings. Such combinations are summarized in FIG. 1 and represent a summary of the path from the precursor material to the final material through the additive manufacturing and thermal conversion steps for generating 3D constructed composite materials according to multiple embodiments.

[0055]

[0063] In some embodiments, an aqueous photocurable resin containing a dissolved metal salt, water, a water-soluble crosslinking agent, and a photoactive molecule is used to print a metal salt-containing hydrogel. This is called the "salt-in" process.

[0056]

[0064] In the "swell-in" approach, the metal salt swells to become a hydrophilic polymer. This can be done using an aqueous photocurable resin or an organic photocurable resin containing a water-miscible organic solvent.

[0057]

[0065] The advantages of the processes disclosed herein include, but are not limited to, the following. · Any water-soluble metal salt can be used, and a wide variety of metal oxides can be obtained from heat treatment in air; · Metal oxides generated from metal salts (microwave susceptor precursors) or introduced directly into the resin can function as microwave susceptors that promote microwave heating, which is faster and more energy-efficient than conventional heating methods. · High-speed microwave heating, and in some embodiments combustion synthesis, is beneficial for heterogeneous nucleation and suppresses grain growth that maximizes the possibility of producing 3D materials containing nanoparticles, microparticles, or twins. · By introducing metal or metal oxide particles into the resin, shrinkage during heat treatment can be reduced. · Under appropriate reduction conditions (temperature, heat treatment atmosphere, reagents), metal oxides can be reduced to metals; · Electrochemical reduction may be used to omit the reduction step described above. · When composite oxides (e.g., ternary oxides) are starting materials, alloys can be produced; and / or · Glazing enables multi-materials before or after heat treatment.

[0058]

[0066] Examples of AM and thermal conversion processes for producing 3D constructed materials are shown below. These examples are for illustrative purposes only and are not intended to limit the present invention.

[0059]

[0067] As a general overview, in one embodiment, microwave heating releases water to the temperature of a hydrogel containing metal ion(s) to form metal oxides at about 150 - 250 °C. The completely or partially dried hydrogel containing metal oxides is further microwave heated above about 500 °C to decompose the hydrogel resin into a gas (e.g., CO2, NO X ) leaving only the metal oxides. The entire conversion occurs in about 3 minutes (e.g., more than 1 minute and less than 10 minutes) with very uniform heating. In contrast, conventional heating methods such as heating by a tube furnace require more than 48 hours at a slow heating rate to achieve uniform heating.

[0060]

[0068] Example 1 This example demonstrates the additive manufacturing of a metal ion-containing aqueous resin and a plurality of metal-containing organic resins formed in an emulsion, and the production of a metal-matrix glass-particle composite material by thermal conversion in a reducing atmosphere.

[0061]

[0069] The metal ion-containing aqueous resin is prepared by mixing a cross-linking agent (e.g., poly(ethylene glycol) diacrylate), a photoinitiator (e.g., lithium phenyl-2,4,6-trimethylbenzoylphosphinate), a UV blocker (e.g., tartrazine), water, and a metal salt (e.g., metal nitrate). The metal ion-containing aqueous resin is then formed into an emulsion with an organic resin containing a plurality of metal acrylates, a photoinitiator, a UV blocker, a cross-linking agent, and a surfactant. The metal ions in the emulsion include metal ions that are not reduced by heat treatment in a hydrogen-containing atmosphere such as magnesium, aluminum, silicon, etc.

[0062]

[0070] The emulsion is 3D printed by a lithography-based 3D printer (e.g., an LCD 3D printer). The printed resin is thermally converted into a metal-matrix glass-particle composite material at a high temperature (600 °C to 1000 °C) in an inert atmosphere or a reducing gas (e.g., ammonia and hydrogen) to accelerate the reduction process to metal / alloy. The resulting 3D-structured composite material contains a metal matrix containing a glass additive.

[0063]

[0071] Example 2 This example demonstrates the production of a ceramic / metal composite material by AM of a mixed resin of a pre-ceramic polymer and a metal acrylate-containing resin, and thermal conversion in a reducing atmosphere.

[0064]

[0072] A metal ion-containing organic resin is prepared by mixing a cross-linking agent (e.g., poly(ethylene glycol) diacrylate), a photoinitiator (e.g., lithium phenyl-2,4,6-trimethylbenzoylphosphinate), a UV blocker (e.g., tartrazine), and a metal acrylate, and then blending with a pre-ceramic polymer resin.

[0065]

[0073] The metal ion-containing organic resin having a preceramic polymer resin is 3D printed by a lithography-based 3D printer (e.g., an LCD 3D printer). The printed resin is thermally converted into a ceramic-metal composite material at a high temperature (600 °C to 2000 °C) in an inert atmosphere or a reducing gas (e.g., ammonia and hydrogen) to accelerate the reduction process to metal / alloy. The resulting 3D-structured composite material contains metal and ceramic.

[0066]

[0074] Example 3 In this example, the production of a composite material of different metals by AM of a metal ion-containing resin and different metal / metal oxide particles, and thermal conversion in a reducing atmosphere are shown.

[0067]

[0075] The metal ion-containing aqueous resin is prepared by mixing a cross-linking agent (e.g., poly(ethylene glycol) diacrylate), a photoinitiator (e.g., lithium phenyl-2,4,6-trimethylbenzoylphosphinate), a UV blocker (e.g., tartrazine), water, and a metal salt (e.g., metal nitrate). Then, reducible metal particles or metal oxide particles such as oxides of iron, copper, cobalt, nickel, and silver are mixed into the metal ion-containing resin under a reducing atmosphere.

[0068]

[0076] The metal ion-containing aqueous resin having metal or metal oxide particles is 3D printed by a lithography-based 3D printer (e.g., an LCD 3D printer). The printed resin is thermally converted into a composite material of different metals at a high temperature (600 °C to 1000 °C) in an inert atmosphere or a reducing gas (e.g., ammonia and hydrogen) to accelerate the reduction process to metal / alloy. The resulting 3D-structured composite material contains different metals. Such a composite material shows high structural integrity and is particularly useful for tall objects and avoidance of shrinkage.

[0069]

[0077] Example 4 This example demonstrates the additive manufacturing of silver ion-containing resins and coating with a glazing material, as well as the production of a composite material of silver with a glass coating by thermal conversion in air.

[0070]

[0078] The silver ion-containing aqueous resin is prepared by mixing a cross-linking agent (e.g., poly(ethylene glycol) diacrylate), a photoinitiator (e.g., lithium phenyl-2,4,6-trimethylbenzoylphosphinate), a UV blocker (e.g., tartrazine), water, and a silver salt (e.g., silver nitrate). The silver ion-containing aqueous resin is then 3D printed by a lithography-based 3D printer (e.g., an LCD 3D printer).

[0071]

[0079] The printed resin is then coated with a glazing material containing oxides, silica, water, and / or metals. The glazed 3D resin is thermally converted to silver using a glass coating at high temperature (600 °C to 1000 °C) in air.

[0072]

[0080] Additive manufacturing by microwave assistance and solution combustion synthesis

[0081] Conventional thermal conversion processes affect gas formation, nucleation, and growth of inorganic materials, and sintering requires a slow heating rate of 0.5 °C to 2 °C / min to enable uniform shrinkage of the 3D constructed structure. In addition, the thermal conversion process is carried out by an electric furnace using an external heating element that is an energy-intensive process.

[0073]

[0082] Here, to overcome the drawbacks of the conventional slow and energy-intensive thermal conversion process, methods are disclosed to make the thermal conversion process faster and more efficient using microwave-assisted heating and solution combustion synthesis. These methods improve the rate-limiting and most expensive steps in metal-based AM. Also, the rapid heating process suppresses grain growth, which is beneficial for heterogeneous nucleation in the resin and maximizes the potential to produce 3D constructed materials containing nanoparticles and / or microstructures.

[0074]

[0083] The disclosed thermal conversion method includes: 1) providing an organic resin containing a strong oxidizing agent such as nitrate to cause an autocatalytic combustion reaction; 2) microwave heating the liquid and organic materials before conversion; and 3) microwave heating the oxide and metal materials after conversion. The resin(s) in step 1) that function(s) as a precursor(s) for the microwave-assisted thermal conversion process is / are composed of a metal / ceramic precursor, nano / micro particles of a microwave susceptor material, a precursor of a microwave susceptor material (e.g., a metal-containing organic resin), an oxidizing agent that causes combustion synthesis, and / or a UV-curable resin material for lithography-based additive manufacturing and an extrudable material for extrusion-based additive manufacturing. During steps 2) and 3), the microwave energy heats the resin and the microwave susceptor material. When the combustion synthesis by the oxidizing agent is initiated, the autocatalytic combustion synthesis raises the temperature, forms an inorganic material, and accelerates the microwave heating. The combination of microwave combustion synthesis and an increase in the microwave absorption material enables rapid sintering, shortens the thermal conversion time, and thereby saves energy. An external heat source can be used to accelerate the heating process. The atmosphere can be controlled according to the target final material. Utilizing the rapid heating process and heterogeneous nucleation of a self-supporting 3D-constructed precursor, the process can generate unconventional microstructures of materials such as nano grains or amorphous microstructures.

[0075]

[0084] Examples of AM by microwave assistance and solution combustion synthesis are shown below. These examples are for illustrative purposes only and are not intended to limit the present invention.

[0076]

[0085] Example 5 This example shows the microwave-assisted heating of a 3D-constructed resin containing a UV-curable hydrogel, nickel nitrate salt, and SiC nano particles.

[0077]

[0086] Resins or UV-curable hydrogels for microwave-assisted heating are prepared by mixing a crosslinking agent (e.g., polyethylene glycol diacrylate), a photoinitiator (e.g., lithium phenyl-2,4,6-trimethylbenzoylphosphinate), a UV blocker (e.g., tartrazine), water, and nickel nitrate. The UV-curable hydrogel is then mixed with SiC nanoparticles that function as microwave susceptor particles.

[0078]

[0087] The nickel nitrate-containing hydrogel resin with SiC nanoparticles is 3D printed by a lithography-based 3D printer (e.g., an LCD 3D printer). The thermal conversion process is achieved by microwave heating, where the microwaves are absorbed by water and SiC nanoparticles to dry the self-standing hydrogel. When the temperature reaches the combustion synthesis temperature, combustion synthesis occurs, forming nickel oxide with non-uniform nucleation. Then, the nickel oxide functions as a microwave susceptor, enabling microwave sintering. The final material is a 3D constructed nickel oxide-matrix composite material with SiC nanoparticle additives.

[0079]

[0088] Example 6 This example shows microwave-assisted heating by an external heat source in a reducing atmosphere of a 3D constructed resin containing a UV-curable hydrogel, copper nitrate salt, and a pre-ceramic polymer.

[0080]

[0089] Resins for microwave-assisted heating are prepared by mixing a crosslinking agent (e.g., poly(ethylene glycol) diacrylate), a photoinitiator (e.g., lithium phenyl-2,4,6-trimethylbenzoylphosphinate), a UV blocker (e.g., tartrazine), water, and copper nitrate. The UV-curable hydrogel is then mixed with a pre-ceramic polymer that functions as a microwave susceptor precursor.

[0081]

[0090] The prepared resin is 3D printed by a lithography-based 3D printer (e.g., an LCD 3D printer). The thermal conversion process is carried out using external heat sources such as microwave heating and an electric furnace. Microwave heating and external heating dry the 3D-constructed self-supporting resin, cause combustion synthesis, and result in the formation of silicon carbide and copper oxide that function as microwave susceptors. Under a reducing atmosphere such as forming gas (90% N2 and 10% H2), the accelerated heating by these microwave susceptors can reduce copper oxide to copper and achieve microwave-assisted sintering. The shortening of the sintering time by SiC that can function to suppress grain growth can achieve the microstructure of nano-particles of the copper matrix. The final material is a 3D-constructed copper matrix composite material with silicon carbide-based additives.

[0082]

[0091] Recycling of Metal-Containing Materials for Additive Manufacturing

[0092] Additive manufacturing is a process that produces three-dimensional constructed products with minimal waste, in contrast to conventional subtractive manufacturing such as machining and cutting. Additively manufactured products are adopted in our society, from household products to industrial products such as automotive engines.

[0083]

[0093] After the end-of-life of these products, an ideal solution to achieve closed-loop inter-product manufacturing with minimal waste is to recycle these products for materials that can be reused by AM to generate controlled form factors and material compositions. State-of-the-art recycling processes, including AM, mainly focus on extrusion-based AM. For example, the recycling of powder residues produced by a selective laser sintering process has been investigated to produce composite filaments for extrusion-based AM. Furthermore, although recycling is established in conventional manufacturing processes, an economically and energetically expensive process is required to remove impurities and improve formability to control the form factor of products with the desired material composition of recycled materials.

[0084]

[0094] Disclosed herein is a recycling process that can overcome the above problems and be employed in gellable metal / ceramic AM. Gellable metal / ceramic AM is a process of 3D printing metal ion-containing gels by lithography-based 3D printing (e.g., LCD 3D printing, SLA 3D printing, and DLP 3D printing) and thermally converting these gels into metals / alloys or ceramics at micron-scale resolution.

[0085]

[0095] Figures 2-4 illustrate a method for recycling and forming end products having a desired composition and architecture via different routes. Metal-containing objects, including but not limited to metal scraps, metal ores, oxides, 3D printed metal-containing objects, etc., can be recycled by chemically dissolving them in a solution (Figure 2 - Step 1). The dissolution solution includes, but is not limited to, hydrochloric acid, nitric acid, sulfuric acid, alkoxides, acetic acid, and combinations thereof. Then, if desired, the metal-containing solutions are mixed to achieve the target final metal / ceramic composition (Figure 2 - Step 2). Once a solution with the desired composition is obtained, this solution is blended with a crosslinking agent, photoinitiator, UV blocker, and other compounds to obtain a UV curable gel for 3D printing or other AM processes (Figure 2 - Step 3). The process of mixing the metal-containing solutions can be carried out after producing a "blank" resin composed of the above-mentioned chemicals (i.e., crosslinking agent, photoinitiator, and UV blocker) excluding the metal-containing solution (Figure 3 - Step 8). Then, the "blank" resin can be additively manufactured and the metal-containing solution can be swollen into the "blank" resin (Figure 3 - Step 9). Then, the metal-containing 3D resin is thermally converted into a 3D constructed metal / alloy / ceramic (Figure 2 - Step 5 or Figure 3 - Step 10). In this approach, the mixing process to achieve the desired composition is carried out at an energetically beneficial low temperature (e.g., room temperature) in contrast to the dry metallurgical route. Further, this approach does not undergo metal processing (e.g., bending, machining, welding), but is AM in gel form, which allows for the arbitrary shaping of recycled materials with nano / micron scale resolution that is impossible with conventional recycling processes. Figure 4 shows the disclosed method in which a recycling process is used to produce a 3D constructed metal-containing object. Iron ore-derived material 11, metal scrap 12, and / or 3D printed metal-containing object 13 are dissolved in solution 14. A metal-containing solution 15 having a UV curable resin within resin tray 16 is 3D printed onto build head 17 to produce a 3D printed object 18. Then, the fully printed object 19 is thermally converted into a metal / alloy / ceramic having a 3D architecture 20.

[0086]

[0096] Examples of recycling metal-containing materials for additive manufacturing are shown below. These examples are for illustrative purposes only and are not intended to limit the present invention.

[0087]

[0097] Example 7 This example shows the recycling of iron or copper scrap to form an iron or copper-containing 3D architecture.

[0088]

[0098] Iron or copper scrap is dissolved in a nitric acid solution to produce an iron or copper-containing solution at room temperature. Solutions containing other metals such as alloying elements such as cobalt, manganese, and chromium can be prepared by dissolving the metal or oxide in nitric acid. After mixing these metal-containing solutions with each other to obtain the desired composition, they are used to produce a UV-curable resin by blending with a cross-linking agent (e.g., poly(ethylene glycol) diacrylate), a photoinitiator (e.g., lithium phenyl-2,4,6-trimethylbenzoylphosphinate), and a UV blocker (e.g., tartrazine). Then, the metal-containing UV-curable resin is 3D printed with an LCD 3D printer. The printed resin is thermally converted to a metal / alloy at a high temperature (600 °C to 1000 °C) in an inert atmosphere or a reducing atmosphere (e.g., ammonia and hydrogen) to accelerate the reduction process to the metal / alloy. The resulting 3D structured object consists of iron, copper, an iron alloy, a copper alloy, an iron-based oxide, a copper-based oxide, or a combination thereof.

[0089]

[0099] Example 8 This example shows the formation of a copper / copper alloy having a 3D form factor from copper oxide.

[0090]

[0100] Copper scrap or copper oxide extracted from copper ore is dissolved by a nitric acid solution to produce a copper-containing solution at room temperature. Solutions containing other metals used for alloying can be prepared by dissolving the metal or oxide in nitric acid. After mixing these metal-containing solutions to obtain the desired composition, it is used to produce a UV-curable resin by blending with a cross-linking agent (e.g., poly(ethylene glycol) diacrylate), a photoinitiator (e.g., lithium phenyl-2,4,6-trimethylbenzoylphosphinate), and a UV blocker (e.g., tartrazine). Then, the metal-containing UV-curable resin is 3D printed with an LCD 3D printer. The printed resin is thermally converted into a metal / alloy at 600 °C to 900 °C in an inert atmosphere or a reducing atmosphere (e.g., ammonia and hydrogen) to accelerate the reduction process to the metal / alloy. The resulting 3D structured object is composed of copper, copper alloy, copper-based oxide, or a combination thereof.

[0091]

[0101] Composite material metal-containing precursor, net shape manufacturing, and conversion

[0102] Net shape manufacturing is an important technology for generating a desired shape with a controlled microstructure and material. One of the emerging technologies in net shape manufacturing is AM, which additionally generates a three-dimensional design architecture. Additive manufacturing of metal and ceramic-based materials can produce an optimized structure with desired properties, which can be of interest because it may not be achievable with conventional processes where material selection is limited to materials that can undergo machining or metalworking processes.

[0092]

[0103] The state-of-the-art AM techniques for hard materials can be mainly divided into two methods. That is, directly solidifying hard material powders by locally applying energy (e.g., heat from a laser), and 3D-structuring hard material particles or precursors in the form of oxides or ions etc. in a soft material matrix by continuous extrusion or 2D patterning. The second method is relatively low-cost compared to the first method. However, the process of removing the non-metal matrix and consequently shrinking it may distort the designed 3D structure. Furthermore, current conversion or removal processes generally rely on uncontrollable thermal processes, making it difficult to produce exotic materials that are non-equilibrium materials such as amorphous materials.

[0093]

[0104] To overcome these limitations, a method is disclosed herein that can produce net-shaped metals, ceramics, or composites thereof. Starting from a slurry composed of metal or oxide powders in a metal-ion-containing liquid solution, which becomes a 3D-constructed precursor in solid form and then converting the solid form by a controllable low-energy method offers significant advantages over conventional approaches.

[0094]

[0105] This method includes (1) incorporating metals, ceramics, carbon, and / or their precursors as liquids or solids into a metal-containing resin or a blank organic resin, (2) net-shape manufacturing these materials by additive manufacturing, injection molding, or casting, (3) swelling metal ions into the resin, and (4) converting the materials produced in steps (2) and (3) into the desired final product. In one embodiment, step (3) may be omitted or performed simultaneously with step (4).

[0095]

[0106] The precursor material produced through steps (1) to (3) is composed of a metal ion-containing resin as a matrix and a powder additive. When hard material powder is present in the net-shaped precursor material, the thermal shrinkage is reduced compared to the conversion process from a resin not containing a hard material additive. Further, by using a metal ion-containing resin having a material that causes a combustion synthesis (for example, metal nitrate), an electrochemical reduction, or a photoreduction process, low-temperature conversion (or local rapid heating and cooling) becomes possible, and the fine structure of the used powder such as an amorphous material is maintained. Metal ions can be supplied to the net-shaped precursor through a metal salt dissolved in a liquid solution during the conversion process. The conversion process is selected from the group consisting of thermal conversion by an external heat source (for example, a furnace), thermal conversion derived from microwaves, combustion synthesis-induced thermal conversion, electrochemical reduction, photochemical synthesis, and combinations thereof.

[0096]

[0107] Thermal conversion derived from microwaves is advantageous because it achieves rapid heating with limited energy input, accelerates production compared to a process using a conventional heating method, and promotes nucleation resulting in a final product with a nano-structure or micro-structure.

[0097]

[0108] Electrochemical conversion is also advantageous because metal-containing products can be obtained in various forms. For example, one product may contain metal particles dispersed throughout the resin matrix, and the metal is produced through the electrochemical reduction of a metal oxide. The resin containing metal particles may itself be the final product, or it may be heat-treated to remove the resin, leaving only metal or metal carbide as the final product.

[0098]

[0109] The processes starting from a slurry containing a metal ion-containing resin and a slurry containing an organic resin are summarized in FIGS. 5 and 6, respectively.

[0099]

[0110] Examples of composite material metal-containing precursors, net-shaped manufacturing, and conversion are shown below. These examples are for illustrative purposes only and are not intended to limit the present invention.

[0100]

[0111] Example 9 This example shows the production of a net-shaped silver or silver alloy from a slurry of a metal nitrate-dissolving resin and silver particles by net-shaped production of the slurry and rapid thermal conversion derived from combustion synthesis.

[0101]

[0112] The silver ion-containing aqueous resin is prepared by mixing a cross-linking agent (e.g., polyethylene glycol diacrylate), a photoinitiator (e.g., lithium phenyl-2,4,6-trimethylbenzoylphosphinate), a UV blocker (e.g., tartrazine), water, and silver nitrate. The silver ions can be incorporated by dissolving silver scrap in a nitric acid solution. Then, silver particles are mixed into the silver ion-containing resin. The prepared slurry undergoes net-shaped production including lithography-based 3D printing (e.g., LCD 3D printing), extrusion-based 3D printing, or injection molding. The shaped slurry is solidified by UV light. The combination of the slurry composition and the solidification induction process may be applied to other types of resins (e.g., thermosetting or thermoplastic) and heat. Next, the net-shaped silver precursor is heated to a temperature that induces the combustion synthesis of the metal nitrate, and the resulting rapid heating and cooling process can complete the conversion process to the metal at a temperature significantly lower than the conventional sintering temperature. The type and concentration of the metal nitrate can be selected according to the desired silver alloy composition. The metal formation from the metal nitrate resin and the presence of the metal powder enable a lower thermal shrinkage than either the thermal conversion process from the metal ion-based resin or the sintering of the metal powder. Annealing may be performed to homogenize the alloy composition or reduce the porosity.

[0102]

[0113] Example 10 This example shows the production of a net-shaped alloy or metal matrix composite material from a slurry of a metal nitrate-dissolving resin and metal particles by net-shaped production of the slurry and electrochemical reduction by a simultaneous ion swelling process.

[0103]

[0114] The aqueous resin is prepared by mixing a crosslinking agent (e.g., poly(ethylene glycol) diacrylate), a photoinitiator (e.g., lithium phenyl-2,4,6-trimethylbenzoylphosphinate), a UV blocker (e.g., tartrazine) and water. A metal salt (e.g., silver nitrate) can be dissolved during this process. Then, metal or alloy particles are mixed into the metal ion-containing resin. The prepared slurry undergoes net shape manufacturing including lithography-based 3D printing (e.g., LCD 3D printing), extrusion-based 3D printing, or injection molding. The shaped slurry is solidified by UV light. The combination of the slurry composition and the solidification induction process may be applied to other types of resins (e.g., thermosetting or thermoplastic) and heat. If the metal salt does not dissolve, the net shape resin may be immersed for an ion swelling process. Next, the net shape metal ion-containing precursor is partially immersed in a metal ion-containing solution to supply metal ions to the net shape resin while undergoing electrochemical reduction from the contacted cathode (i.e., the simultaneous swelling process). Alternatively, the net-shaped metal ion-containing precursor contains a sacrificial portion that is removed after the electrochemical reduction step to enable electrochemical reduction of the entire structure of the final product. The contact position of the anode with the resin and the contact position of the resin with the solution can be adjusted to achieve uniform electrochemical reduction. The anode is inserted into the metal ion-containing solution. This enables low-temperature synthesis and substantially zero shrinkage during conversion. FIGS. 6, 7, and 8 show the electrochemical reduction process with simultaneous ion swelling. As shown in FIG. 7, the container 11 of the metal ion-containing solution 10 is in contact with the cathode 9 and holds the net-shaped precursor 8. The corresponding anode 12 is immersed in the solution 10. As shown in FIG. 8, the container 17 of the metal ion-containing solution 16 contacts the sacrificial precursor 14 with the cathode 15 and holds the net-shaped precursor 13. The corresponding anode 18 is immersed in the solution 10. The contact of the cathode 15 with the precursor 13 or 14 and the contact position of the precursor 13 with the solution 16 may be adjusted. When the incorporated metal or alloy particles are in a non-equilibrium state, this process effectively maintains the state during the conversion process, which is impossible to achieve in a thermal conversion process. If desired, a post-annealing process may be performed to homogenize the alloy composition.

[0104]

[0115] Furthermore, an electric gradient can be established during the process of electrochemical reduction, which can be used to establish a metal concentration gradient along at least one dimension of the net-shaped resin and the associated final product, in combination with controlling the level of immersion of the net-shaped resin into the metal ion-containing solution.

[0105]

[0116] The examples disclosed above relate to net-shaped precursors, but those skilled in the art will understand that precursors of other shapes can be advantageously formed and subjected to the disclosed methods.

[0106]

[0117] References

[0118] Narita, K., Citrin, M. A., Yang, H., Xia, X. & Greer, J. R. 3D architected carbon electrodes for energy storage. Adv. Energy Mater. 11, 2002637 (2021).

[0107]

[0119] Haghdadi, N., Laleh, M., Moyle, M. & Primig, S. Additive manufacturing of steels: a review of achievements and challenges. J. Mater. Sci. 56, 64 - 107 (2021).

[0108]

[0120] Pelz, J. S., Ku, N., Meyers, M. A. & Vargas - Gonzalez, L. R. Additive manufacturing of structural ceramics: a historical perspective. Journal of Materials Research and Technology 15, 670 - 695 (2021).

[0109]

[0121] Gross, A. F., Jacobsen, A. J. & Cumberland, R. Ceramic microtruss. US Pat. No. 8,435,438 (2013).

[0110]

[0122] Chapiro, M. R., Delay, M. J., Dunn, R. C. & Zilar, D. M. Additive manufacturing of composite materials. US Pat. No. 10,875,288 (2020).

[0111]

[0123] Yee, D.W., Lifson, M.L., Edwards, B.W. & Greer, J.R. Additive Manufacturing of 3D-Architected Multifunctional Metal Oxides. Adv. Mater. 31, 61901345 (2019).

[0112]

[0124] Vyatskikh, A., Kudo, A., Delalande, S. & Greer, J.R. Additive manufacturing of polymer-derived titania for one-step solar water purification. Materials Today Communications 15, 288 - 293 (2018).

[0113]

[0125] L. Wang, A. Kiziltas, D.F. Mielewski, E.C. Lee, D.J. Gardner, Closed-loop recycling of polyamide12 powder from selective laser sintering into sustainable composites, J.Clean. Prod. 195 (2018) 765 - 772.

[0114]

[0126] M. Snyder, J. Dunn, A. Kemmer, E. Gonzalez, Recycling materials in various environments including reduced gravity environments, US Pat. No. 10,759,089 (2020).

[0115]

[0127] Scrap metal recycling process, CN Pat. No. 102151685 (2011)

[0116]

[0128] B.K. Reck, T.E. Graedel, Challenges in metal recycling, Science. 337(2012)690 - 695.

[0117]

[0129] C.G. Lee, S.-J. Kim, T.-H. Lee, C.-S. Oh, Effects of Tramp Elements on Formability of Low-Carbon TRIP-aided Multiphase Cold-Rolled Steel Sheets, ISIJ Int. 4(2004)737 - 743.

[0118]

[0130] K. Suzuki, S. Kumai, Y. Saito, T. Haga, High-speed twin-roll strip casting of Almg-Si alloys with high iron content, Mater. Trans. 46(2005)2602 - 2608.

[0119]

[0131] Worsley, M.A., Campbell, P.G., Huoss, E.B., Oakdale, J.S., Spadaccini, C.M. & Hensleigh, R US Pat. No. 10,379,439(2019)

[0120]

[0132] Vyatskikh, A., Delalande, S.J. & Greer, J.R. US Pat. Pub. No. 20200073236(March 5, 2020)

[0121]

[0133] Yee, D.W.L, Greer, J.R. Lifson, M.L. & Citrin, M.A US Pat. Pub. No. 20200156035(May 21, 2020), now US Pat. No. 11,318,435(May 3, 2022)

[0122]

[0134] Saccone, M.A., Gallivan, R.A., Narita, K., Yee, D.W., Greer, J.R., “Additive Manufacturing of Micro-Architected Metals via Hydrogel Infusion,” Nature, 612, (Oct 20, 2022), 685 - 692.

[0123]

[0135] Bhattacharya, M. and Basak, T., “A review on the susceptor assisted microwave processing of materials,” Energy, 97, (Feb. 15, 2016), 306 - 338.

[0124]

[0136] Description of Incorporation by Reference and Variations All references cited through this application, including, for example, patent documents including issued or granted patents or equivalents; published patent application publications; and non - patent document writings or other source materials; are hereby incorporated by reference in their entirety as if each reference were individually incorporated by reference, to the extent that each reference does not at least partially conflict with the disclosure of this application (e.g., a partially conflicting reference is incorporated by reference except for its partially conflicting part).

[0125]

[0137] The terms and expressions used in this specification are used as terms for explanation and not as terms for limitation. In the use of such terms and expressions, there is no intention to exclude equivalents of the features shown and described or parts thereof, but it is recognized that various modifications are possible within the scope of the claimed invention. Accordingly, although the present invention has been specifically disclosed by preferred embodiments, exemplary embodiments and optional features, modifications and variations of the concepts disclosed herein may be used by those skilled in the art, and it should be understood that such modifications and variations are considered to be within the scope of the present invention as defined by the appended claims. The specific embodiments provided herein are examples of useful embodiments of the present invention, and it will be apparent to those skilled in the art that the present invention can be implemented using numerous variations of the devices, device components, and method steps described herein. As will be apparent to those skilled in the art, the methods and devices useful for the present methods and devices can include any number of arbitrary compositions and processing elements and steps. All functional equivalents known in the art of materials and methods are intended to be included in this disclosure. Nothing in this specification should be construed as an admission that the present invention has no right to antedate such disclosure by virtue of prior invention.

[0126]

[0138] When a group of substituents is disclosed herein, it is understood that all individual members and all subgroups of that group are separately disclosed. When Markush groups or other groupings are used herein, all individual members of the group and all possible combinations and subcombinations of the group are intended to be individually included in this disclosure.

[0127]

[0139] As used in this specification and the appended claims, it should be noted that the singular forms "a", "an", and "the" include plural references unless the context clearly indicates otherwise. Thus, for example, reference to "a molecule" includes a plurality of such molecules and their equivalents known to those skilled in the art. Similarly, the terms "a" (or "an"), "one or more", and "at least one" can be used interchangeably herein. It should also be noted that the terms "comprising", "including", and "having" can be used interchangeably. The expression "as recited in any of claims XX to YY" (where XX and YY refer to claim numbers) is intended to provide alternative forms of multiple dependent claims and, in some embodiments, is interchangeable with the expression "as recited in any one of claims XX to YY".

[0128]

[0140] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, the preferred methods and materials are described.

[0129]

[0141] Whenever a range is given in this specification, for example a range of integers, a temperature range, a time range, a composition range, or a concentration range, all intermediate ranges and sub-ranges, as well as all individual values included in the given range, are intended to be included in this disclosure. As used herein, a range specifically includes the values provided as the end-point values of the range. As used herein, a range specifically includes all integer values of the range. For example, the range of 1 to 100 specifically includes the end-point values of 1 and 100. It will be understood that any sub-range or individual value within a range or sub-range included in the description herein can be excluded from the claims of this specification.

[0130]

[0142] As used herein, "comprising" is synonymous and can be used interchangeably with "including", "containing", or "characterized by", is inclusive or open-ended and does not exclude additional, unrecited elements or method steps. As used herein, "consisting of" excludes any element, step, or ingredient not specified in the claims. As used herein, "consisting essentially of" does not exclude materials or steps that do not substantially affect the basic and novel characteristics of the claims. In each instance herein, any of the terms "comprising", "consisting essentially of", and "consisting of" may be replaced by either of the other two terms. The invention exemplified herein can be practiced appropriately without any element(s) or limitation(s) not specifically disclosed herein.

Claims

1. Crosslinking agent; Photoinitiator; UV blocking agents; and Microwave susceptors selected from the group consisting of metals, metal oxides, metal carbides, metal nitrides, metal complexes, metal salts, carbon, and combinations thereof. A resin for additive manufacturing, which includes inorganic materials and whose final product consists of inorganic materials.

2. The resin according to claim 1, wherein the crosslinking agent is selected from the group consisting of acrylate monomers, acrylate oligomers, methacrylate monomers, methacrylate monomers, thiol monomers, thiol oligomers, alkene monomers, alkene oligomers, alkyne monomers, alkyne oligomers, epoxy monomers, epoxy oligomers, epoxy acrylate monomers, and epoxy-acrylate oligomers.

3. The resin according to claim 1, wherein the crosslinking agent is selected from the group consisting of acrylic polymer, ether polymer, fluorocarbon polymer, polystyrene polymer, poly(vinyl chloride) polymer, poly(N-vinylpyrrolidone) polymer, and combinations thereof.

4. The resin according to claim 1, wherein the crosslinking agent is selected from the group consisting of poly(ethylene glycol) diacrylate, 1,3,5-trialyl-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, and combinations thereof.

5. The resin according to claim 1, further comprising a reactive diluent selected from the group consisting of acrylamide, acrylic acid, diurethane dimethacrylate, 2-hydroxypropane-1,3-diirbis(2-methylacrylate), vinyl acetate, polyethylene glycol monoacrylate, and methyl methacrylate.

6. The resin according to claim 1, further comprising at least two immiscible solvents formed in an emulsion.

7. The resin according to claim 1, wherein the crosslinking agent comprises a carboxylate portion, an amide portion, an amine portion, an aldehyde portion, a ketone portion, an ester portion, a thiol portion, an alkyl halogen portion, an alkoxy portion, a hydroxyl portion, or a phenyl portion.

8. The photoinitiator is lithium phenyl-2,4,6-trimethylbenzoyl phosphinate, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, 2,2-dimethoxy-1,2-diphenyl-ethane-1-one, 1-hydroxycyclohexyl-phenyl-ketone, benzophenone, 2-hydroxy-2-methyl-1-phenyl-1-propanone, 2-hydroxy-1-[4-(2-hydroxyethoxy)phenyl]-2-methyl-1-propanone Panone, methylbenzoylformate oxyphenyl acetate 2-[2oxo-2phenylacetoxyethoxy]ethyl ester, oxyphenyl acetate 2-[2-hydroxyethoxy]ethyl ester, alpha,alpha-dimethoxy-alpha-phenylacetophenone, 2-benzyl-2-(dimethylamino)-1-[4-(4-morpholinyl)phenyl]-1-butanone, 2-methyl-1-[4-(methylthio)phenyl]-2-(4-mol (Folinyl)-1-propanone, diphenyl(2,4,6-trimethylbenzoyl)-phosphine oxide, phosphine oxide, phenylbis(2,4,6-trimethylbenzoyl), bis(ethanol-5-2,4-cyclopentadien-1-yl)bis[2,6-difluoro-3-(1H-pyrrole-1-yl)phenyl]titaniumiodonium, (4-methylphenyl)[4-(2-methylpropyl),phenyl]-,hexafluorophosphate(1-),2,2 The resin according to claim 1, selected from the group consisting of -dimethoxy-1,2-diphenylethane-1-one, isopropylthioxanthone, 2-ethylhexyl-(4-N,N-dimethylamino)benzoate, ethyl-4-(dimethylamino)benzoate, 2-dimethylamino-2-(4-methylbenzyl)-1-(4-morpholine-4-ylphenyl)-butan-1-one, azobisisobutyronitrile, benzoyl peroxide, and combinations thereof.

9. The resin according to claim 1, wherein the UV blocking agent is selected from the group consisting of tartrazine, benzotriazole, benzophenone, triazine, 1-(phenyldiazenyl)naphthalene-2-ol, and combinations thereof.

10. The resin according to claim 1, wherein the inorganic material is selected from the group consisting of metals, alloys, oxides, nitrides, carbides, ceramics, and composite materials thereof.

11. The resin according to claim 1, further comprising a metal complex or a metal salt.

12. The resin according to claim 11, wherein the metal salt or metal complex is a metal nitrate, metal nitrite, metal hydroxide, metal chloride, metal sulfate, metal carbonate, metal bicarbonate, metal acetate, metal fluoride, metal bromide, metal iodide, metal phosphate, metal chromate, metal cyanide, metal chlorate, metal perchlorate, metal benzoate, metal boron hydride, metal acrylate, and / or metal sulfide.

13. Additively producing a 3D structure by photopolymerizing the resin described in claim 1; and The 3D structure is converted into a final product by microwave heating. Additive manufacturing and thermal conversion processes, wherein the final product consists of inorganic materials.

14. The process according to claim 13, further comprising swelling the 3D structure with an aqueous solution of a metal salt to form a metal-containing hydrogel.

15. The process according to claim 13, wherein the 3D structure is a microwave susceptor-containing organogel or a microwave susceptor-containing hydrogel.

16. The process according to claim 13, further comprising electrochemically introducing a metal into the 3D structure.

17. The process according to claim 13, further comprising coating the 3D structure with a glazing material before thermal conversion.

18. The process according to claim 17, wherein the glazing material comprises a preceramic polymer, a fluid containing metal oxide particles, or a glass precursor.

19. The process according to claim 13, further comprising exposing the 3D structure to a reducing or oxidizing atmosphere during the heat conversion step.

20. The process according to claim 13, wherein the final product comprises nanoparticles, microparticles, or twins.

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