An article may include a substrate including a ceramic matrix composite (CMC); a composite coating layer including a first coating material that includes a rare-earth disilicate and a second coating material that includes at least one of a rare-earth monosilicate, a CMAS-resistant material, or a high-temperature dislocating material, where the second coating material forms a substantially continuous phase in the composite coating layer.

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.

A composite composition comprising tungsten carbide particles having a barrier coating and a binder is described, which is used as hardfacing materials. The tungsten carbide particles comprise at least one kind of cast tungsten carbide, carburized tungsten carbide, macro-crystalline tungsten carbide and sintered tungsten carbide. The barrier coating comprises at least one of metal carbides, borides, nitrides, carbonitrides, carboborides, nitroborides and carbonitroborides. The binder alloys take one of the forms selected from a welding/brazing tube, rod, rope, powder, paste, slurry and cloth, which are suitable for being applied by various welding or brazing methods. The barrier coating would prevent or mitigate the degradation of the tungsten carbide particles due to attack of a molten binder alloy during a welding or brazing process.

Nanopowders containing nanoparticles having a core particle with a thin film coating. The core particles and thin film coatings are, independently, formed from at least one of a rare earth metal-containing oxide, a rare earth metal-containing fluoride, a rare earth metal-containing oxyfluoride or combinations thereof. The thin film coating may be formed using a non-line of sight technique such as atomic layer deposition (ALD). Also disclosed herein are nanoceramic materials formed from the nanopowders and methods of making and using the nanopowders.

The invention concerns a method for surface treatment of a ceramic material in powder form, wherein said method comprising the step of providing a powder formed of a plurality of particles of the ceramic material to be treated, and wherein said ceramic powder particles are subjected to an ion implantation process by directing towards an external surface of said particles a beam of singly or multiply charged ions produced by a charge of singly or multiply charged ions, for example of the electron cyclotron resonance ECR type, wherein said particles have a generally polyhedral shape.

The invention also concerns a material in powder form, formed of a plurality of particles having a ceramic external layer and a ceramic core, wherein said particles have a generally polyhedral shape.

An article may include a substrate including a ceramic matrix composite (CMC); a composite coating layer including a first coating material that includes a rare-earth disilicate and a second coating material that includes at least one of a rare-earth monosilicate, a CMAS-resistant material, or a high-temperature dislocating material, where the second coating material forms a substantially continuous phase in the composite coating layer.

Coated components are provided that include a substrate having a surface; a bondcoat over the surface of the substrate; a thermally grown oxide layer over the bondcoat; and an environmental barrier coating over the thermally grown oxide layer. The bondcoat includes a plurality of core-shell particulates and a plurality of oxide-sintering aid globular phases dispersed within a metalloid-based material matrix. The plurality of core-shell particulates have a shell comprising a metalloid oxide around a core comprising a metalloid-based material. The plurality of oxide-sintering aid globular phases includes a mixture of the metalloid oxide and a sintering aid.

A method of manufacturing a ceramic matrix composite component may include introducing a gaseous precursor into an inlet portion of a chamber that houses a porous preform and introducing a gaseous mitigation agent into an outlet portion of the chamber that is downstream of the inlet portion of the chamber. The gaseous precursor may include methyltrichlorosilane (MTS) and the gaseous mitigation agent may include hydrogen gas. The introduction of the gaseous precursor may result in densification of the porous preform(s) and the introduction of the gaseous mitigation agent may shift the reaction equilibrium to disfavor the formation of harmful and/or pyrophoric byproduct deposits, which can accumulate in an exhaust conduit 340 of the system.

Disclosed are methods of forming a chamber component for a process chamber. The methods may include filling a mold with nanoparticles or plasma spraying nanoparticles, where at least a portion of the nanoparticles include a core particle and a thin film coating over the core particle. The core particle and thin film are formed of, independently, a rare earth metal-containing oxide, a rare earth metal-containing fluoride, a rare earth metal-containing oxyfluoride, or combinations thereof. The nanoparticles may have a donut-shape having a spherical form with indentations on opposite sides. The methods also may include sintering the nanoparticles to form the chamber component and materials. Further described are chamber components and coatings formed from the described nanoparticles.

A method for producing a ceramic body includes: a forming step of forming a forming material containing SiC powders having an average particle size D50 of 15 to 50 ?m and SiC powders having an average particle size D50 of 2 to 8 ?m in a mass ratio of 3:7 to 7:3 to obtain a formed body; and a firing and impregnating step of firing the formed body and impregnating it with metal Si.