A particulate composite ceramic material may include: particles of at least one first ultra-high-temperature ceramic UHTC, the outer surface of the particles being at least partially covered by a porous layer made of at least one second UHTC in amorphous form; and the particles defining a space therebetween; optionally, porous clusters of the at least one second ultra-high-temperature ceramic in amorphous form, distributed in said space; a dense matrix and at least one third UHTC in crystallized form at least partially filling the space; optionally, a dense coating made of at least the third UHTC in crystallized form, covering the outer surface of the matrix, the matrix and the coating representing 5% to 90% by mass with respect to the total mass of the material. A part may include such a particulate ceramic composite material.

Ceramic composite materials that are reinforced with carbide fibers can exhibit ultra-high temperature resistance. For example, such materials may exhibit very low creep at temperatures of up to 2700 F. (1480 C.). The present composites are specifically engineered to exhibit matched thermodynamically stable crystalline phases between the materials included within the composite. In other words, the reinforcing fibers, a debonding interface layer disposed over the reinforcing fibers, and the matrix material of the composite may all be of the same crystalline structural phase (all hexagonal), for increased compatibility and improved properties. Such composite materials may be used in numerous applications.

The present invention relates to a method of producing a SiCSi composite component. The method includes preparing a first molded body containing SiC particles by a 3D printing method, wherein the first molded body has a first average pore diameter M.sub.1; forming a second molded body, in which the first molded body and a dispersion containing carbon particles are brought into contact so that the pores are impregnated with the carbon particles, wherein the carbon particles have a secondary particle having an average particle diameter M.sub.2, and the carbon particles satisfy the following formula:

M.sub.2?M.sub.1/10; and forming a SiCSi composite component by carrying out that the second molded body is impregnated with a metallic si and is reactively sintered; wherein the content of Si is in the range of 5% by mass to 40% by mass in the SiCSi composite component.

The present invention relates to an unsintered composite powder composition comprising silicon carbide and aluminium nitride, a sintering process and a sintered silicon carbide material obtained or obtainable therefrom, as well as a SiCAlN composite ceramic, uses thereof and articles comprising the same. In one aspect, the present invention provides an unsintered composite powder composition comprising from 90.0% to 99.9% by weight silicon carbide and from 0.1% to 10% by weight of aluminium nitride. In another aspect, the present invention provides a SiCAlN composite ceramic material having the formula .sub.x(SiC).sub.1-x (AlN), wherein 0.999?x?0.900; and wherein the composite ceramic material has a fracture toughness of greater than 4.5 MPa.Math.m.sup.1/2; and a thermal conductivity of greater than 120 W/m K.

The present invention relates to a method of producing porous alpha-SiC containing shaped body and porous alpha-SiC containing shaped body produced by that method. The porous alpha-SiC containing shaped body shows a characteristic microstructure providing a high degree of mechanical stability.

The present invention relates to joined silicon carbide (SiC) ceramics and a method for processing the same. And, most particularly, the joined silicon carbide (SiC) ceramics and the method for processing the same provide a method for processing joined silicon carbide (SiC) ceramics including the steps of sintering silicon carbide substrates configuring the joined ceramics, processing a joined silicon carbide ceramics preparation by layering a non-sintered silicon carbide bond having a same composition as the silicon carbide substrate between at least two substrates selected from the sintered silicon carbide substrates, and processing the joined silicon carbide ceramics by performing heat treatment on the joined silicon carbide ceramics preparation. According to the above-described invention, by using a bond having the same composition as the silicon carbide substrate, since residual stress-free joined ceramics can be processed, joined silicon carbide ceramics having a high strength corresponding to 65 to 190% of a strength of the substrate may be processed.

The present invention relates to a method for preparing a fully ceramic capsulated nuclear fuel material containing three-layer-structured isotropic nuclear fuel particles coated with a ceramic having a composition which has a higher shrinkage than a matrix in order to prevent cracking of ceramic nuclear fuel, wherein the three-layer-structured nuclear fuel particles before coating is included in the range of between 5 and 40 fractions by volume based on after sintering. More specifically, the present invention provides a composition for preparing a fully ceramic capsulated nuclear fuel containing three-layer-structured isotropic particles coated with the substance which includes, as a main ingredient, a silicon carbine derived from a precursor of the silicon carbide wherein a condition of L.sub.c>L.sub.m at normal pressure sintering is created, where the sintering shrinkage of the coating layer of the three-layer-structured isotropic nuclear fuel particles is L.sub.c and the sintering shrinkage of the silicon carbide matrix is L.sub.m; material produced therefrom; and a method for manufacturing the material. The residual porosity of the fully ceramic capsulated nuclear fuel material is 4% or less.

The present invention provides a focus ring having favorable plasma resistance. In addition, the present invention provides a method for producing a focus ring which enables the easy production of focus rings having favorable plasma resistance. The focus ring of the present invention is a focus ring made of a sintered body of silicon carbide, in which the sintered body includes a plurality of first crystal grains having an -SiC-type crystal structure and a plurality of second crystal grains having a -SiC-type crystal structure, a content of the first crystal grains is 70% by volume or more of a total of the first crystal grains and the second crystal grains, and a volume-average crystallite diameter of the first crystal grains is 10 m or less.

We provide a method for the in situ development of graphene containing silicon carbide (SiC) matrix ceramic composites, and more particularly to the in situ graphene growth within the bulk ceramic through a single-step approach during SiC ceramics densification using an electric current activated/assisted sintering (ECAS) technique. This approach allows processing dense, robust, highly electrical conducting and well dispersed nanocomposites having a percolated graphene network, eliminating the handling of potentially hazardous nanostructures. Graphene/SiC components could be used in technological applications under strong demanding conditions where good electrical, thermal, mechanical and/or tribological properties are required, such as micro and nanoelectromechanical systems (MEMS and NEMS), sensors, actuators, heat exchangers, breaks, components for engines, armors, cutting tools, microturbines or microrotors.

A silicon nitride substrate including silicon nitride crystal grains and a grain boundary phase and having a thermal conductivity of 50 W/m.Math.K or more, wherein, in a sectional structure of the silicon nitride substrate, a ratio (T2/T1) of a total length T2 of the grain boundary phase in a thickness direction with respect to a thickness T1 of the silicon nitride substrate is 0.01 to 0.30, and a variation from a dielectric strength mean value when measured by a four-terminal method in which electrodes are brought into contact with a front and a rear surfaces of the substrate is 20% or less. The dielectric strength mean value of the silicon nitride substrate can be 15 kV/mm or more. According to above structure, there can be obtained a silicon nitride substrate and a silicon nitride circuit board using the substrate in which variation in the dielectric strength is decreased.