Sintered product having a relative density of greater than 90%, with, to more than 80% of the volume thereof, a stack of flat ceramic platelets, the assembly of the platelets having a mean thickness of less than 3 μm, having a width of greater than 50 mm, and including more than 20% of alumina, as a percentage on the basis of the weight of the product. The width of the product is the largest dimension measured in the plane in which the length of the product is measured, along a direction perpendicular to the direction of the length. The length of the product is the largest dimension thereof in a plane parallel to the general plane in which the platelets extend.

Polymer-derived, graphene reinforced ceramic matrix composites and processes for producing graphene-ceramic ceramic matrix composites are provided. An example process mechanically delaminates graphite mixed in a thermosettable, liquid preceramic polymer through a mechanical, high shear process to generate a composition of a preceramic polymer in which graphene is homogeneously dispersed. This example process does not require high temperatures and pressures to produce the graphene. The resulting composition can be pyrolytically converted to a graphene-reinforced ceramic matrix composite. A polysilazane can be used as the preceramic polymer, in some cases providing ammonia or an amine in the process to facilitate delamination of the graphite to graphene. Ceramic, metal, mineral or carbon particulates, platelets, or fibers may be added to the composition to impart enhanced mechanical and/or electrical properties to the finished graphene-reinforced ceramic matrix composites.

A method of making a ceramic composite component includes providing a fibrous preform or a plurality of fibers, providing a first plurality of particles, coating the first plurality of particles with a coating to produce a first plurality of coated particles, delivering the first plurality of coated particles to the fibrous preform or to an outer surface of the plurality of fibers, and converting the first plurality of coated particles into refractory compounds. The first plurality of particles or the coating comprises a refractory metal.

A method of separating a mixture of used refractory components of different chemistry types obtained from a demolished refractory includes hydrating the mixture of refractory components to destructively hydrate at least some components of the mixture of refractory components, and separating, based on size, the at least some components from other components of the mixture of refractory components.

An example method includes forming an interlayer on a carbon fiber fabric to form a composite fiber fabric. The interlayer comprises a binder. The method further includes winding the composite fiber fabric around a core to form a composite fiber preform comprising a plurality of layers defining an annulus extending along a central axis. The method further includes densifying the composite fiber preform.

A glassy carbon compact according to the present invention has a maximum inscribed sphere diameter of 5 mm or greater, comprises pores having diameters of 500 nm or less dispersed throughout the glassy carbon compact, and has a density of 1.1 g/cm.sup.3 or greater.

Ultra-lightweight aerogels and methods for fabricating such aerogels from ammonia borane and a support structure, where the support structure is either two-dimensional nanostructures, or hydrocarbon polymer colloids. The components are mixed, then annealed. The properties of the disclosed aerogels can be tuned by controlling the ratio between the support structure and the ammonia borane, or by infiltrating the aerogels with additives.

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.

Provided are alumina particles containing molybdenum and with their shape controlled. The alumina particles contain phosphorus and molybdenum. The alumina particles are preferably plate-like or card house-like. The phosphorus is preferably unevenly distributed in surface layers of the alumina particles. Also provided are a resin composition containing the alumina particles and a resin, a molded body made by molding the resin composition, and a method for producing the alumina particle including a step of firing the aluminum compound in the presence of a molybdenum compound and a phosphorous compound.

A method for forming a ceramic-based material comprises depositing a ceramic-precursor composition comprising nanoparticles having at least one dimension less than 100 nm and an aspect ratio of 1.5 or greater, and a carrier fluid on a surface of a substrate to form an as-deposited layer of the ceramic precursor composition; and sintering the as-deposited layer of the ceramic precursor composition at a sintering temperature to form a ceramic-based material.