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.

Disclosed is a carbon fiber preform, a preparation method therefor and a preparation method for carbon/carbon composites, falling within the technical field of composites. The carbon fiber preform provided by the present disclosure includes a plurality of stacked carbon fiber cloths and prestressed layers arranged between every two of adjacent carbon fiber cloths, the prestressed layer including a boron-containing phenol-formaldehyde resin coating and carbon fiber bundles distributed within the boron-containing phenol-formaldehyde resin coating. In the present disclosure, the prestressed layers are formed by adding the carbon fiber bundles and a boron-containing phenol-formaldehyde resin precursor to a two dimensional (2D) stacked preform, thereby counteracting internal stresses during carbonization and obtaining a carbon/carbon composite having higher strength and being less prone to cracking.

A method is provided for forming a carbon/carbon (C/C) disk with boron nitride (BN) doping. Borazine is generated using a set of borazine precursors. Starting carbon fibers are coated or impregnated with the borazine in an inert atmosphere. The starting carbon fibers are needled into layered fabric and the layered fabric is needled into boards from which a preform is cut, the needling and cutting performed in the inert atmosphere. The borazine in the preform is stabilized to convert the borazine to polyborazylene. The polyborazylene in the preform is cured. The polyborazylene in the preform is then crystalized to form BN particulates. The preform with the BN particulates is carbonized and then densified with pyrolytic carbon.

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.

A method is provided for forming a carbon/carbon (C/C) disk with boron nitride (BN) doping. Borazine is generated using a set of borazine precursors. Starting carbon fibers are coated or impregnated with the borazine in an inert atmosphere. The starting carbon fibers are needled into layered fabric and the layered fabric is needled into boards from which a preform is cut, the needling and cutting performed in the inert atmosphere. The borazine in the preform is stabilized to convert the borazine to polyborazylene. The polyborazylene in the preform is cured. The polyborazylene in the preform is then crystalized to form BN particulates. The preform with the BN particulates is carbonized and then densified with pyrolytic carbon.

The present invention stands directed at polymer derived ceramic material. More specifically, boric acid and 2,4,6-trimethyl-2,4-6-trivinylsilazane are reacted to form a polymeric resin followed by the addition of a crosslinking agent and then subsequent crosslinking and pyrolysis to provide an improved ceramic yield.

Provided is a method for charging, with ceramic, open pores formed in a matrix of a ceramic matrix composite that includes the matrix and reinforcing fibers provided in the matrix. The ceramic comes to constitute the matrix. The method includes repeating the following steps (A) and (B) in a state where the ceramic matrix composite is arranged in a liquid material serving as a matrix material. At the step (A), the ceramic matrix composite is heated such that the liquid material is brought into a film-boiling state, and the ceramic derived from the liquid material is thereby generated in the open pores. At the step (B), the ceramic matrix composite is cooled until a temperature of the ceramic matrix composite becomes lower than a boiling point of the liquid material.