Pyrolytic boron nitride article

摘要

A pyrolytic boron nitride article has a uniform structure 0.5 or less nodules/cm2 in average all through the overall surface of the article and 2 or less nodules in any portion of a unit square centimeter on the surface of the article. The pyrolytic boron nitride article is produced by depositing boron nitride through a vapor phase, using a boron halide gas and an ammonia gas as the starting materials. In production, the ammonia gas or a gas mixture containing the ammonia gas is not contacted directly with graphite at 300 DEG to 1850 DEG C.