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 ΔL.sub.c>ΔL.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 ΔL.sub.c and the sintering shrinkage of the silicon carbide matrix is ΔL.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.

A ceramic composite sintered body, including: a metal oxide as a main phase, and silicon carbide as a sub-phase, in which crystal grains of the silicon carbide are dispersed in crystal grains of the metal oxide and at crystal grain boundaries of the metal oxide, and an average crystal grain size of the silicon carbide dispersed at the crystal grain boundaries of the metal oxide is 0.30 μm or less.

A ceramic substrate made of a dielectric material including silicon carbide particles, which is used as a forming material, in which the number of the silicon carbide particles per unit area on the surface of the substrate is smaller than the number of the silicon carbide particles per unit area in a cross section of the substrate.

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.2M.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.

This electrostatic chuck device (1) includes a base (11) having one main surface serving as a mounting surface (19) on which a plate-shaped sample is mounted, and an electrode for electrostatic attraction (13) provided on the side opposite to the mounting surface (19) in the base (11), in which the base (11) consists of a ceramic material as a forming material, and the ceramic material contains aluminum oxide and silicon carbide as main components thereof, and has a layered graphene present at a grain boundary of the aluminum oxide.

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

Part comprising said particulate ceramic composite material.

Method for manufacturing said part.

A SiC powder containing 70% by mass or more of a -SiC, wherein in a volume-based cumulative particle size distribution measured by a laser diffraction method, a D50 is 8 to 35 m and a D10 is 5 m or more.

A method of manufacturing a composite sintered body includes a step (Step S11) of molding mixed powder in which Al.sub.2O.sub.3, SiC, and MgO are mixed, into a green body having a predetermined shape and a step (Step S12) of generating a composite sintered body by sintering the green body. Then, in Step S11, the ratio of SiC to the mixed powder is not lower than 4.0 weight percentage and not higher than 13.0 weight percentage. Further, the purity of Al.sub.2O.sub.3 in Step S11 is not lower than 99.9%. It is thereby possible to suppress the abnormal grain growth of Al.sub.2O.sub.3 and suitably manufacture a composite sintered body having high relative dielectric constant and withstand voltage, and low tan .

Provided is a SiC sintered body which contains nitrogen atoms, wherein a ratio R.sub.max/R.sub.ave of a maximum volume resistivity R.sub.max of the sintered body to an average volume resistivity R.sub.ave of the sintered body is 1.5 or lower; a ratio R.sub.min/R.sub.ave of a minimum volume resistivity R.sub.min of the sintered body to the average volume resistivity R.sub.ave is 0.7 or higher; and a relative density of the sintered body is 98% or higher.

A composite sintered body, wherein the composite sintered body consists of ceramic composite sintered body, the ceramic composite sintered body comprises aluminum oxide as a main phase, and silicon carbide as a sub-phase, in which the composite sintered body has mullite in crystal grains of the aluminum oxide.