Pre-ceramic particle solutions can prepared by a Coordinated-PDC process, a Direct-PDC process or a Coordinated-Direct-PDC process. The pre-ceramic particle solution includes a polymer selected from the group consisting of (i) an organic polymer including a metal or metalloid cation, (ii) a first organometallic polymer and (iii) a second organometallic polymer including a metal or metalloid cation different from a metal in the second organometallic polymer, a plurality of particles selected from the group consisting of (a) a ceramic fuel particle and (b) a moderator particle, a dispersant, and a polymerization initiator. The pre-ceramic particle solution can be supplied to an additive manufacturing process, such as digital light projection, and made into a structure (which is pre-ceramic particle green body) that can then be debinded to form a polymer-derived ceramic sintered body. In some embodiments, the polymer-derived ceramic sintered body is a component or structure for fission reactors.

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. The resin formulations may contain a solid-phase filler, to provide high thermal stability and mechanical strength (e.g., fracture toughness) in the final ceramic material.

Solid or liquid NH free, C-free, and Si-rich perhydropolysilazane compositions comprising units having the following formula [N(SiH.sub.3).sub.x(SiH.sub.2).sub.y], wherein x=0, 1, or 2 and y=0, 1, or 2 when x+y=2; and x=0, 1 or 2 and y=1, 2, or 3 when x+y=3 are disclosed. Also disclosed are synthesis methods and applications for the same.

Solid or liquid NH free, C-free, and Si-rich perhydropolysilazane compositions comprising units having the following formula [N(SiH.sub.3).sub.x(SiH.sub.2).sub.y], wherein x=0, 1, or 2 and y=0, 1, or 2 when x+y=2; and x=0, 1 or 2 and y=1, 2, or 3 when x+y=3 are disclosed. Also disclosed are synthesis methods and applications for the same.

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 CX double bonds or CX 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.

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 CX double bonds or CX 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.

Hybrid composite materials including carbon nanotube sheets and flexible ceramic materials, and methods of making the same are provided herein. In one embodiment, a method of forming a hybrid composite material is provided, the method including: placing a layer of a first flexible ceramic composite on a lay-up tooling surface; applying a sheet of a pre-preg carbon fiber reinforced polymer on the flexible ceramic composite; curing the flexible ceramic composite and the pre-preg carbon fiber reinforced polymer sheet together to form a hybrid composite material; and removing the hybrid composite material from the lay-up tooling surface, wherein the first flexible ceramic composite comprises an exterior surface of the hybrid composite material.

Hybrid composite materials including carbon nanotube sheets and flexible ceramic materials, and methods of making the same are provided herein. In one embodiment, a method of forming a hybrid composite material is provided, the method including: placing a layer of a first flexible ceramic composite on a lay-up tooling surface; applying a sheet of a pre-preg carbon fiber reinforced polymer on the flexible ceramic composite; curing the flexible ceramic composite and the pre-preg carbon fiber reinforced polymer sheet together to form a hybrid composite material; and removing the hybrid composite material from the lay-up tooling surface, wherein the first flexible ceramic composite comprises an exterior surface of the hybrid composite material.

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.

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.