Preparation of dispersed phase ceramic boron nitride and aluminum composite coatings by chemical vapor deposition

BN+AlN coatings were deposited on Al#72O#73 from the BCl#73-AlCl#73-NH#73 reagent system at 700#8#.1200#+C. The composite coatings consisted of very small BN and AlN regions which were either crystalline or amorphous, depending on deposition temp. and reagent concentrations. For example, a composite containing AlN whiskers of A100 nm diam. in a matrix of turbostratic BN of 2 nm grain size was deposited at 1100#+ and 20 kPa.