A method of forming a water resistant boundary on a fissile material for use in a water cooled nuclear reactor is described. The method comprises mixing a powdered fissile material selected from the group consisting of UN and U.sub.3Si.sub.2 with an additive selected from oxidation resistant materials having a melting or softening point lower than the sintering temperature of the fissile material, pressing the mixed fissile and additive materials into a pellet, sintering the pellet to a temperature greater than the melting point of the additive. Alternatively, if the melting point of the oxidation resistant particles is greater than the sintering temperature of UN or U.sub.3Si.sub.2, then the oxidation resistant particles can have a particle size distribution less than that of the UN or U.sub.3Si.sub.2.

Ultra-high temperature carbide (UHTC) foams and methods of fabricating and using the same are provided. The UHTC foams are produced in a three-step process, including UHTC slurry preparation, freeze-drying, and spark plasma sintering (SPS). The fabrication methods allow for the production of any kind of single- or multi-component UHTC foam, while also providing flexibility in the shape and size of the UHTC foams to produce near-net-shape components.

There is provided a raw material for a zirconia sintered body formed by pressureless sintering and having a high fracture toughness value measured by an SEPB method, a sintered body formed from the raw material, and a method for producing at least one of the raw material and the sintered body.

Also provided is a sintered body that includes zirconia that contains a stabilizer and having a monoclinic fraction of 0.5% or more. Such a sintered body is produced by a method including using a powder that contains a stabilizer and zirconia with a monoclinic fraction of more than 70%, wherein monoclinic zirconia has a crystallite size of more than 23 nm and 80 nm or less.

The disclosure relates to methods of fabricating of ceramic structures, and more particularly to methods of fabricating ceramic structures having profiled surfaces and more particularly to methods of fabrication of ceramic mirror blanks. In one embodiment, a method of forming a shaped ceramic article, includes: forming, via one of a cold-pressing process or pressure casting process, a green ceramic article comprising a first surface, an opposing second surface and at least one high aspect ratio feature shaped into at least one surface; heating the green featured ceramic part to form a debound featured ceramic part; and densifying the debound featured ceramic part via one of a pressureless sintering process or a hot-pressing process.

Provided herein is a control method for volume fraction of multistructural isotropic fuel particles in a fully ceramic microencapsulated nuclear fuel including: preparing a mixture of silicon carbide, sintering additives, and organic binders, producing a coating body by coating multistructural isotropic fuel particles by using the prepared mixture, forming the coating body, and performing pressureless sintering on the formed coating body, wherein volume fraction of multistructural isotropic nuclear fuel particles may be controlled by controlling the coating layer thickness on multistructural isotropic nuclear fuel particles, wherein the coating layer was configured with a mixture of silicon carbide, sintering additives, and organic binders. As described above, stability and tolerance against nuclear fuel related accidents may be significantly enhanced, and advantageous effects of enabling a pressureless sintering procedure to be performed while maximizing volume fraction of the multistructural isotropic fuel particles may be expected.

A method of forming a water resistant boundary on a fissile material for use in a water cooled nuclear reactor is described. The method comprises mixing a powdered fissile material selected from the group consisting of UN and U.sub.3Si.sub.2 with an additive selected from oxidation resistant materials having a melting or softening point lower than the sintering temperature of the fissile material, pressing the mixed fissile and additive materials into a pellet, sintering the pellet to a temperature greater than the melting point of the additive. Alternatively, if the melting point of the oxidation resistant particles is greater than the sintering temperature of UN or U.sub.3Si.sub.2, then the oxidation resistant particles can have a particle size distribution less than that of the UN or U.sub.3Si.sub.2

The present invention relates to the field of MAX-phase ceramic-based composites, specifically to a short-fiber-reinforced oriented MAX-phase ceramic-based composite and a preparation method therefor. By using a new process with a fiber, a nano lamellar MAX-phase ceramic powder, other additives, etc., for preparing a fiber-reinforced MAX-phase ceramic-based composite, a novel ternary composite is prepared, wherein a matrix is composed of a highly oriented lamellar MAX-phase ceramic, the fiber is distributed parallel to the lamellar MAX-phase ceramic in an axial direction, and a granulate ceramic phase enhancement phase is dispersed in the matrix. Thus, the problems of a MAX-phase ceramic-based composite matrix material prepared by an existing method, such as coarse grains, multiple internal defects and a low strength, and a poor fracture toughness; and a reaction sintering temperature being too high such that fibers are chemically and physically damaged in a substrate, resulting in performance degradation, are solved. Fibers prepared by the method are suitable for large-scale industrial preparation and have properties that are far superior to those of any existing known fiber MAX-phase composite.

A highly oriented nanometer MAX phase ceramic and a preparation method for a MAX phase in-situ autogenous oxide nanocomposite ceramic. The raw materials comprise a MAX phase ceramic nano-lamellar powder body or a blank body formed by the nano-lamellar powder body, wherein MAX phase ceramic nano-lamellar particles in the powder body or the blank meet the particle size being between 20-400 nm, and the oxygen content is between 0.0001%-20% by mass; MAX phase grains in the ceramic obtained after the raw materials are sintered are lamellar or spindle-shaped, the lamellar structure having a high degree of orientation. Utilizing special properties of the nano-lamellar MAX powder body, orientation occurs during compression and deformation to obtain a lamellar structure similar to that in a natural pearl shell, and such a structure has a high bearing capacity and resistance to external loads and crack propagation, just like a brick used in a building.

Methods of forming composite materials, composite materials, and articles. The composite materials may include electromagnetic shielding materials. The methods may include providing a mixture of ultra-high temperature ceramic particles and a liquid preceramic precursor, curing the mixture to form a solid mixture, forming particles of the solid mixture, and pressing the particles into a mold.

A method of forming a water resistant boundary on a fissile material for use in a water cooled nuclear reactor is described. The method comprises mixing a powdered fissile material selected from the group consisting of UN and U.sub.3Si.sub.2 with an additive selected from oxidation resistant materials having a melting or softening point lower than the sintering temperature of the fissile material, pressing the mixed fissile and additive materials into a pellet, sintering the pellet to a temperature greater than the melting point of the additive. Alternatively, if the melting point of the oxidation resistant particles is greater than the sintering temperature of UN or U.sub.3Si.sub.2, then the oxidation resistant particles can have a particle size distribution less than that of the UN or U.sub.3Si.sub.2.