Abstract: Ceramic composite articles having dispersed whiskers or platelets oriented parallel to an outer surface of the articles and in two-dimensionally random directions thereof. The articles may be made by forming and sintering under a pressure of about 1 to 10 atmospheres without using hot press methods or hot isostatic pressing methods.

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: 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.