Abstract: This invention is directed to a process for the preparation of boron nitride powder, particularly a fine powder with a low degree of contamination, which demonstrates good caking, heat conductivity and dielectric properties. Specifically, a process for the preparation of amorphous boron nitride (a-BN) is provided wherein the process comprises: mixing powders of boric acid and a carbamide at a temperature in the range of about 250-300° C., thereby forming: ammonium polyborates; boron imide or a mixture thereof and ammonia; and heating of the materials formed in step (a) to a temperature in the range of about 500-600° C., thereby forming a powder of a-BN.

Abstract: A novel process for the preparation of boron carbide, boron nitride and silicon carbide powders comprises carbidization or nitrization step of boron oxide or silicon oxide respectively, using nanoparticles substrates.