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.