Abstract: A catalyst assembly comprising a substrate, nanofilaments which have a nanometer-size diameter and are formed on the substrate, and particles which have a nanometer-size diameter, at least one of the nanofilaments and the particles having a catalytic function, is provided to use a catalyst more efficiently and to provide a catalytic function more efficiently. Interstices between the nanofilaments serve as distribution channels of a reactive gas, and the reactive gas spreads sufficiently not only around the ends of nanofilaments but also inside a catalyst assembly. A combination of nanofilaments and particles enables dispersion of a catalyst at a distance of not more than about 100 nanometers.

Abstract: A zirconia based ceramic material having improved and well-balanced mechanical strength and toughness consists essentially of 0.5 to 50 vol % of Al.sub.2 O.sub.3 having an average grain size of 2 .mu.m or less and the balance of a partially stabilized zirconia having an average grain size of 5 .mu.m or less. The partially stabilized zirconia consists essentially of 8 to 12 mol % of CeO.sub.2, 0.05 to 4 mol % of TiO.sub.2 and the balance of ZrO.sub.2. Fine Al.sub.2 O.sub.3 grains having an average grain size of 1 .mu.m or less are dispersed within the grains of the partially stabilized zirconia at a dispersion ratio. The dispersion ratio is defined as a ratio of the number of Al.sub.2 O.sub.3 grains dispersed within the grains of the partially stabilized zirconia relative to the number of the entire Al.sub.2 O.sub.3 grains dispersed in the ceramic material, and at least 2% in the present invention. The ceramic material can be made by the following process.

Abstract: A process for the production of a sintered composite boron carbide body, the process comprising:(a) mixing 40.0 to 99.5 volume % of B.sub.4 C with 0.5 to 60.0 volume % of fine grain powdered SiC, TiC, or both in an organic solvent;(b) drying to form a powder mix; and(c) hot pressing the mix at 1,800.degree. to 2,300.degree. C. for 5 to 600 minutes,whereby the body comprises SiC, TiB.sub.2 or both dispersed in the B.sub.4 C and whereby the body further comprises(i) B.sub.4 C matrix crystal grains having an average grain size of not more than 3.0 .mu.m and(ii) dispersed uniform fine grains of SiC, TiB.sub.2, or both having an average grain size of 1 to 500 nm free of coarse grains and whiskers, the dispersed fine grains being distributed within the matrix crystal grains.

Abstract: The strength of a composite sintered body including yttrium oxide is improved. A composite ceramics sintered body includes a matrix of yttrium oxide and silicon carbide particles dispersed within the matrix. A compound oxide phase including yttrium and silicon is present at the surface of the sintered body. A sintered body is obtained by compression-molding mixed powder including yttrium oxide powder and silicon carbide powder in an inert gas atmosphere of at least 1550.degree. C. The sintered body is subjected to a heat treatment for at least 0.5 hour and not more than 12 hours in an atmosphere including oxygen gas in the range of at least 900.degree. C. and less than 1200.degree. C.

Abstract: A sintered composite boron carbide body with SiC and/or TiB.sub.2 having a grain size of the order of nanometers and distributed among B.sub.4 C crystal grains and/or within the B.sub.4 C crystal grains is produced by hot-pressing a powder mix, which is composed of 44-99.5 vol. % B.sub.4 C, 0.5-60 vol. % SiC and/or 0.5-60 vol. % TiC, at 1,800-2,300.degree. C. for 5-600 minutes.

Abstract: A sintered ceramic-metal composite product has a ceramic matrix of polycrystalline ceramic in which a metal phase is dispersed for adding improved toughness. The metal phase has a higher melting point than the sintering temperature of the ceramic matrix and comprises at least one metal selected from the groups IVa, Va and VIa of the periodic table. The metal phase is dispersed intragranular within the grains of the ceramic matrix to realize nano-order dispersion of the metal phase which is responsible for remarkably improved toughness as well as strength. The ceramic-metal composite product is successfully fabricated by several unique methods utilizing the mixture of the ceramic and metal or metal oxide, hydride or alkoxide.

Abstract: Carbon fiber reinforced silicon nitride based nanocomposite material is produced by mixing a powder mixture of silicon nitride powders (with or without alumina powders), and fine silicon carbide powders, with a solution of a preceramic polymer containing silicon and nitrogen, to form a solution for impregnation, by passing carbon fibers through the solution to produce a mass of impregnated carbon fibers, forming the mass to a desired shape and by sintering in an inert atmosphere. Ultra-high strength and toughness are produced due to reinforcement by nanocompositization of the matrix phase, that by dispersion of fine particles and that by long carbon fibers, part of matrix phase is generated by thermal cracking of preceramic polymer.

Abstract: A ceramics composites prepared by dispersing any one of the following materials (i) to (viii) in Al.sub.2 O.sub.3 which as a matrix-containing crystalline grains having a grain size of 0.5 to 100 .mu.m. (i) 3 to 40% by volume of fine TiN particles having a particle size of not more than 2 .mu.m and 3 to 40% by volume of fine SiC particles having a particle size of not more than 2 .mu.m. (ii) 3 to 40% by volume of fine TiN particles having a particle size of not more than 2 .mu.m and 3 to 40% by volume of fine Si.sub.3 N.sub.4 particles having a particle size of not more than 2 .mu.m. (iii) 2 to 35% by volume of fine TiC particles having a particle size of not more than 2 .mu.m and 5 to 40% by volume of SiC whiskers having a diameter of 0.05 to 2 .mu.m. (iv) 2 to 35% by volume of fine TiC particles having a particle size of not more than 2 .mu.m and 5 to 40% by volume of Si.sub.3 N.sub.4 whiskers having a diameter of 0.1 to 2 .mu.m.

Abstract: A sintered ceramic-metal composite product has a ceramic matrix of polycrystalline ceramic in which a metal phase is dispersed for adding improved toughness. The metal phase has a higher melting point than the sintering temperature of the ceramic matrix and comprises at least one metal selected from the groups IVa, Va and VIa of the periodic table. The metal phase is dispersed intragranular within the grains of the ceramic matrix to realize nano-order dispersion of the metal phase which is responsible for remarkably improved toughness as well as strength. The ceramic-metal composite product is successfully fabricated by several unique methods utilizing the mixture of the ceramic and metal or metal oxide, hydride or alkoxide.

Abstract: An Si.sub.3 N.sub.4 -Al.sub.2 O.sub.3 composite sintered body suitable for use in high-temperature structural materials consists of .alpha.-Al.sub.2 O.sub.3 and at least one crystal phase of Si.sub.3 N.sub.4 and sialon and is produced by sintering a shaped body of a particular Si.sub.3 N.sub.4 -Al.sub.2 O.sub.3 mixed powder at 1,500.degree.-1,900.degree. C.

Abstract: An alumina-zirconia-silicon carbide sintered ceramic composite having high strength and high hardness is composed of 5 to 50 volume percent of partially stabilized zirconia powder of mean particle size between 0.1 and 1.0 .mu.m, 3 to 40 volume percent of silicon carbide powder of mean particle size smaller than 1 .mu.m or silicon carbide whiskers of 1 .mu.m or less in diameter with an aspect ratio between 3 and 200 or combination of said silicon carbide powder and said silicon carbide whiskers, the balance being substantially alumina powder, wherein zirconia plus silicon carbide accounts for 55 volume percent at most of the total.The sintered ceramic composite is manufactured by making a mixed powder composed of 5 to 50 volume percent of partially stabilized zirconia powder of mean particle size between 0.1 and 1.0 .mu.m, 3 to 40 volume percent of silicon carbide powder of mean particle size smaller than 1 .mu.m or silicon carbide whiskers of 1 .mu.