Abstract: This disclosure provides resin formulations which may be used for 3D printing and thermally treating to produce a ceramic material. The disclosure provides direct, free-form 3D printing of a preceramic polymer, followed by converting the preceramic polymer to a 3D-printed ceramic composite with potentially complex 3D shapes. A wide variety of chemical compositions is disclosed, and several experimental examples are included to demonstrate reduction to practice. For example, preceramic resin formulations may contain a carbosilane in which there is at least one functional group selected from vinyl, allyl, ethynyl, unsubstituted or substituted alkyl, ester group, amine, hydroxyl, vinyl ether, vinyl ester, glycidyl, glycidyl ether, vinyl glycidyl ether, vinyl amide, vinyl triazine, vinyl isocyanurate, acrylate, methacrylate, alkacrylate, alkyl alkacrylate, phenyl, halide, thiol, cyano, cyanate, or thiocyanate.

Abstract: This disclosure provides resin formulations which may be used for 3D printing and thermally treating to produce a ceramic material. The disclosure provides direct, free-form 3D printing of a preceramic polymer, followed by converting the preceramic polymer to a 3D-printed ceramic composite with potentially complex 3D shapes. A wide variety of chemical compositions is disclosed, and several experimental examples are included to demonstrate reduction to practice. For example, preceramic resin formulations may contain a carbosilane in which there is at least one functional group selected from vinyl, allyl, ethynyl, unsubstituted or substituted alkyl, ester group, amine, hydroxyl, vinyl ether, vinyl ester, glycidyl, glycidyl ether, vinyl glycidyl ether, vinyl amide, vinyl triazine, vinyl isocyanurate, acrylate, methacrylate, alkacrylate, alkyl alkacrylate, phenyl, halide, thiol, cyano, cyanate, or thiocyanate.

Abstract: A method of repairing a sandwich structure includes: removing a damaged portion of a core and a damaged portion of a first facesheet to form an open volume; filling the open volume with an ultraviolet-curable photomonomer; partially curing the ultraviolet-curable photomonomer to form a plurality of photopolymer waveguides by utilizing ultraviolet light; and arranging a replacement facesheet on the damaged portion of the first facesheet and over the photopolymer waveguides.

Abstract: This invention provides resin formulations which may be used for 3D printing and pyrolyzing to produce a ceramic matrix composite. The resin formulations contain a solid-phase filler, to provide high thermal stability and mechanical strength (e.g., fracture toughness) in the final ceramic material. The invention provides direct, free-form 3D printing of a preceramic polymer loaded with a solid-phase filler, followed by converting the preceramic polymer to a 3D-printed ceramic matrix composite with potentially complex 3D shapes or in the form of large parts. Other variations provide active solid-phase functional additives as solid-phase fillers, to perform or enhance at least one chemical, physical, mechanical, or electrical function within the ceramic structure as it is being formed as well as in the final structure. Solid-phase functional additives actively improve the final ceramic structure through one or more changes actively induced by the additives during pyrolysis or other thermal treatment.

Abstract: Some variations provide a composition for additive manufacturing (3D printing) of metals, comprising: from 10 vol % to 70 vol % of a photocurable liquid resin; from 10 vol % to 70 vol % of metal or metal alloy particles, optionally configured with a photoreflective surface; and from 0.01 vol % to 10 vol % of a photoinitiator. Other variations provide a composition for additive manufacturing of metals, comprising: from 1 vol % to 70 vol % of a photocurable liquid resin; from 0.1 vol % to 98 vol % of an organometallic compound containing a first metal; from 1 vol % to 70 vol % of metal or metal alloy particles containing a second metal (which may be the same as or different than the first metal); and from 0.01 vol % to 10 vol % of a photoinitiator. Many examples of metals, photocurable resins, organometallic compounds, photoinitiators, and optional additives are disclosed, and methods of making and using the composition are described.

Abstract: This invention provides resin formulations which may be used for 3D printing and pyrolyzing to produce a ceramic matrix composite. The resin formulations contain a solid-phase filler, to provide high thermal stability and mechanical strength (e.g., fracture toughness) in the final ceramic material. The invention provides direct, free-form 3D printing of a preceramic polymer loaded with a solid-phase filler, followed by converting the preceramic polymer to a 3D-printed ceramic matrix composite with potentially complex 3D shapes or in the form of large parts. Other variations provide active solid-phase functional additives as solid-phase fillers, to perform or enhance at least one chemical, physical, mechanical, or electrical function within the ceramic structure as it is being formed as well as in the final structure. Solid-phase functional additives actively improve the final ceramic structure through one or more changes actively induced by the additives during pyrolysis or other thermal treatment.

Abstract: This invention provides resin formulations which may be used for 3D printing and pyrolyzing to produce a ceramic matrix composite. The resin formulations contain a solid-phase filler, to provide high thermal stability and mechanical strength (e.g., fracture toughness) in the final ceramic material. The invention provides direct, free-form 3D printing of a preceramic polymer loaded with a solid-phase filler, followed by converting the preceramic polymer to a 3D-printed ceramic matrix composite with potentially complex 3D shapes or in the form of large parts. Other variations provide active solid-phase functional additives as solid-phase fillers, to perform or enhance at least one chemical, physical, mechanical, or electrical function within the ceramic structure as it is being formed as well as in the final structure. Solid-phase functional additives actively improve the final ceramic structure through one or more changes actively induced by the additives during pyrolysis or other thermal treatment.

Abstract: A method of manufacturing a sandwich structure having an open cellular core and a fluid-tight seal surrounding the core includes coupling a mold to a first facesheet to define a reservoir. The method also includes irradiating a volume of photo-monomer in the reservoir with a series of vertical collimated light beams to form a cured, solid polymer border extending around a periphery of the first facesheet. The method also includes irradiating a remaining volume of photo-monomer in the reservoir with a series of collimated light beams to form an ordered three-dimensional polymer microstructure core defined by a plurality of interconnected polymer optical waveguides coupled to the first facesheet and surrounded by the cured, solid polymer border. The method further includes coupling a second facesheet to the ordered three-dimensional microstructure core and the cured, solid polymer border to form the sandwich structure.

Abstract: This invention provides resin formulations which may be used for 3D printing and pyrolyzing to produce a ceramic matrix composite. The resin formulations contain a solid-phase filler, to provide high thermal stability and mechanical strength (e.g., fracture toughness) in the final ceramic material. The invention provides direct, free-form 3D printing of a preceramic polymer loaded with a solid-phase filler, followed by converting the preceramic polymer to a 3D-printed ceramic matrix composite with potentially complex 3D shapes or in the form of large parts. Other variations provide active solid-phase functional additives as solid-phase fillers, to perform or enhance at least one chemical, physical, mechanical, or electrical function within the ceramic structure as it is being formed as well as in the final structure. Solid-phase functional additives actively improve the final ceramic structure through one or more changes actively induced by the additives during pyrolysis or other thermal treatment.

Abstract: A system for fabricating composite parts efficiently. Pre-impregnated (prepreg) composite material is drawn as a sheet from a roll and fed by advancement rollers into a stamping and molding station in which a piece of the prepreg material is cut, on a mold, from the sheet. Pressure is applied to cause the prepreg material to conform to a surface of the mold, and the prepreg is cured with ultraviolet light. Additional layers of prepreg may be cut and cured on any layers that have already been cured on the mold. The complete part may be removed from the mold with ejector pins. Scrap prepreg may be recycled in a recycling station that separates reinforcing fiber from uncured resin.

Abstract: A composition for forming a microlattice structure includes a photopolymerizable compound and a flame retardant material. A microlattice structure includes a plurality of struts interconnected at a plurality of nodes, the struts including: a copolymer including a reaction product of a photopolymerizable compound and a flame retardant material. A microlattice structure includes a plurality of struts interconnected at a plurality of nodes, the struts including: a polymer including a reaction product of a photopolymerizable compound; and a flame retardant material.

Abstract: A method of repairing a sandwich structure includes: removing a damaged portion of a core and a damaged portion of a first facesheet to form an open volume; filling the open volume with an ultraviolet-curable photomonomer; partially curing the ultraviolet-curable photomonomer to form a plurality of photopolymer waveguides by utilizing ultraviolet light; and arranging a replacement facesheet on the damaged portion of the first facesheet and over the photopolymer waveguides.

Abstract: A method and a fugitive mold for producing a cast-metal part are provided. In some embodiments, the fugitive mold may be formed by three-dimensionally (3D) printing a preceramic resin in the shape of a fugitive mold; curing the preceramic resin to form a preceramic polymer, and pyrolyzing the fugitive mold to convert the preceramic polymer to a metastable ceramic material. The metastable ceramic material may include an amorphous silicon oxycarbide ceramic. A cast-metal part may be formed by filling the fugitive mold with a liquid metal or alloy, and allowing the liquid metal or alloy to solidify over a first length of time. The cast-metal part may then be retrieved by heating the fugitive mold at a temperature lower than the melting point of the cast-metal part for a second length of time longer than the first length of time to disintegrate the metastable ceramic material.

Abstract: An aperture system for a bottom-up stereolithography device including a reservoir having a lower opening, an aperture including a flexible membrane positioned within the reservoir and covering the lower opening, and a boundary seal positioned around a periphery of the flexible membrane, the boundary seal including one or more boundary seal components and immobilizing the periphery of the flexible membrane against the reservoir. The flexible membrane is formed of a material having a low affinity for a liquid resin used in the stereolithography device as well as cured photopolymer resin parts produced by the device. In addition, the flexible membrane is able to deform as the cured resin part is pulled away from the aperture, thus enabling lower energy mixed mode adhesive failure to occur at the interface between the cured resin and the aperture and reducing the chance of cohesive damage to the cured photopolymer part.

Abstract: A cellular material includes a continuous solid phase including an ordered ceramic material, the solid phase having a solid core including the ordered ceramic material. A composition for forming a cellular material includes: a first UV curable pre-ceramic monomer; a second UV curable pre-ceramic monomer; and a photoinitiator. A method of forming at least one ceramic waveguide includes: securing a volume of a composition including a UV curable pre-ceramic monomer; exposing the composition to a light source to form at least one polymer waveguide including a pre-ceramic material; and converting the pre-ceramic material of the polymer waveguide to a ceramic material to form a ceramic waveguide.

Abstract: Some variations provide a preceramic resin precursor formulation comprising: first molecules comprising at least one Si—C bond and/or at least one Si—N bond, wherein the first molecules include at least one silyl hydride group (Si—H) available for hydrosilylation; and second molecules with at least one unsaturated carbon-carbon bond attached to a UV-active functional group. The first molecules and second molecules may be reacted, via hydrosilylation with a homogeneous or heterogeneous metal-containing catalyst, to produce third molecules comprising a hydrosilylation-modified polysilazane that contains the UV-active functional group. Many possible starting formulations are described, and methods are disclosed for carrying out the chemical reactions to generate the hydrosilylation-modified polysilazanes. The hydrosilylation-modified polysilazanes may then be 3D-printed and thermally treating to fabricate a ceramic material.

Abstract: A method for repairing a composite structure. A damaged portion of a first facesheet of the structure is removed, forming a hole in the first facesheet. A damaged portion of the underlying core is removed to form a cavity in the sandwich. If the second facesheet is damaged, the damaged section is removed, and covered and sealed with a facesheet repair section. If the core material is an open-cell material, a dam is formed around the perimeter of the cavity, to act as a barrier between the cavity and the core material. The cavity is at least partially filled with a photomonomer resin, which then is illuminated through a mask with collimated light to form a truss structure in the cavity. Residual photomonomer resin is removed, and a facesheet repair section is bonded over the hole in the first facesheet.

Abstract: This disclosure enables direct 3D printing of preceramic polymers, which can be converted to fully dense ceramics. Some variations provide a preceramic resin formulation comprising a molecule with two or more C?X double bonds or C?X triple bonds, wherein X is selected from C, S, N, or O, and wherein the molecule further comprises at least one non-carbon atom selected from Si, B, Al, Ti, Zn, P, Ge, S, N, or O; a photoinitiator; a free-radical inhibitor; and a 3D-printing resolution agent. The disclosed preceramic resin formulations can be 3D-printed using stereolithography into objects with complex shape. The polymeric objects may be directly converted to fully dense ceramics with properties that approach the theoretical maximum strength of the base materials. Low-cost structures are obtained that are lightweight, strong, and stiff, but stable in the presence of a high-temperature oxidizing environment.

Abstract: A method of manufacturing an ordered cellular structure including a series of interconnected unit cells. Each unit cell includes at least one straight wall segment. The method includes irradiating a volume of photo-monomer in a reservoir with at least one light beam from at least one light source to form the ordered cellular structure. Irradiating the volume of photo-monomer includes directing the at least one light beam though a series of interconnected apertures defined in a photo-mask covering the reservoir.

Abstract: A sacrificial substrate for use in stereolithography, having a first surface configured to be attached to a build platform, and a second surface of the sacrificial substrate configured to be attached to a photopolymer part. The sacrificial substrate physically separates the build platform and the photopolymer part, and serves as the deposition surface for the photopolymer part in place of the build platform. The sacrificial substrate may be separated from the build platform and then separated from the photopolymer part via pyrolysis, oxidation, or etching to thereby yield the free photopolymer part without subjecting the part to excess physical force or damage.