Abstract: A crystalline sialon comprising crystals containing aluminum, silicon, nitrogen and oxygen, in which the crystal structure has a hexagonal system wurtzite structure identical with that of AlN crystals, and the volume of the unit cell thereof has a value smaller than that of the AlN crystals. The crystalline sialon can be synthesized by mixing a silicon-containing gas, an aluminum halide, a nitrogen atom-containing gas and an oxygen atom-containing gas, converting the gas mixture into plasmas by microwave discharging and depositing a film on the surface of a substrate, in which the temperature of the substrate, while controlling a flow rate of the silicon-containing gas and a flow rate of the oxygen-containing gas. The crystalline sialon of the present invention has high hardness, is excellent in oxidation resistance, as well as excellent in heat conductivity and adhesion with a superhard substrate.

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: A carbon/carbon composite having oxidation resistance is produced by filling the voids of a carbon/carbon composite comprising 10-70% by volume of carbon fibers and 5-90% by volume of a carbonaceous matrix and having a void percentage of 10-55%, with at least one of carbon and a ceramic by chemical vapor infiltration and then coating the deposit surface with a ceramic or both ceramic and carbon by chemical vapor deposition.

Abstract: A membrane for use in an X-ray mask composed of a compound comprising at least three kinds of elements of boron (B), silicon (Si) and nitrogen (N) in which the content of silicon in the compound is at least 15 atomic percent, but less than 100 atomic percent, and the atomic ratio of Si/(B+Si) in the compound is at least 0.2, but less than one. The membrane is synthesized from source gases including at least the foregoing three kinds of elements by chemical reaction under such conditions that the ratio of nitrogen to boron plus silicon is at least one in the source gases and thereby depositing a film of the compound onto a substrate. Since the membrane thus prepared has a high transmittance in the visible region and X-ray and their residual stress can be readily controlled by adjusting the conditions for the formation of the membrane, it is suitable for the preparation of X-ray masks.

Abstract: The specification discloses a polycrystalline boron nitride of high purity and high density consisting essentially of rhombohedral crystals in which the three-fold rotation axes, parallel to the c-axis in the notation of hexagonal crystal system, of the crystals have a preferred orientation. The polycrystalline rhombohedral boron nitride can be obtained as bulk or thin film articles with desired shapes by chemical vapor deposition including the steps of introducing a source gas of boron and a source gas into a reactor containing a heated substrate and depositing boron nitride onto the heated substrate, wherein a diffusion layer of the source gas of nitrogen and/or the carrier gas is formed around the substrate. The polycrystalline rhombohedral boron nitride such obtained is very useful in applications such as crucibles for melting semiconductors, various jigs for high temperature services, high-frequency insulator, microwave transmission window and source material of boron for semiconductor.

Abstract: A transparent BN-type ceramic material comprising 10 to 40 wt. % of boron (B), 35 to 55 wt. % of nitrogen (N) and 3 to 40 wt. % of silicon (Si) as the main component elements, and 1 to 10 wt. % of sub-component elements, with the property of not being crystallized by heat treatment at 1600.degree. C. for one hour, and a method of producing the above ceramic material by reacting a boron-containing compound, a nitrogen-containing compound and a silicon-containing compound at deposition temperatures in a range of more than 1300.degree. C. to less than 1700.degree. C. with the total gas pressure within a reaction furnace maintained in the range from 10 Torr to 100 Torr by use of a chemical vapor deposition method are disclosed.

Abstract: The present invention relates to a method of producing a functionally grant material whose components and structure are continuously adjusted by the coating, plating and powder metallurgy techniques to change its function in turn and provide a method of producing a functionally gradient material superior in heat-resistance, corrosion-resistance and resistance to thermal fatigue by distributing a third component having a lower Young's modulus or formed of high-strength material sufficiently durable to the fracture strength among ceramics as a first component and metals or other ceramics as a second component to change the function.

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.

Abstract: Boron nitride containing titanium nitride in an amount of 0.05 to 10 wt. % which is produced at a relatively low temperature, utilizing a chemical vapor deposition technique. In the deposition process, boron, titanium and nitrogen source gases are introduced into an evacuated reactor together with a carrier and/or diluent gas and contacted with a heated substrate previously mounted in the reactor, whereby boron nitride with titanium nitride is deposited onto the substrate. The deposit thus obtained has a high density, a significantly improved heat-shielding ability, a high degree of anisotropy with respect to thermal diffusivity and a high chemical stability. By using such anisotropic boron nitride with BN ceramics, very useful BN type composite ceramics can be produced.

Abstract: Titanium-containing silicon nitride film bodies include a film body having an essentially amorphous structure and containing particle-like titanium nitride, a film body consisting mainly of .alpha.-type crystal and containing particle-like TiN deposited in the crystal and having a crystal orientation of crystal face (OOl), and a film body consisting mainly of .beta.-type crystal and containing column-like TiN deposited in the crystal along the c-axis direction thereof and having a crystal orientation of crystal face (OOl), which are produced by blowing a nitrogen depositing source, a silicon depositing source and a titanium depositing source on a substrate heated at 500.degree.-1,900.degree. C. by means of a blowpipe composed of a pipe assembly to perform chemical vapordeposition reaction.