Multilayer coating for carbon composites - comprises silicon carbide conversion and chemical vapour deposited silicon nitride layers

摘要

Protective coating is formed on C-C composite materials, as used in aerospace applications, to avoid thermal decompsn. in an oxidising atmos.. A layer of pyrolytic graphite, 25.4-127 mm thick, is applied, followed by application of SiC layer, 12.7-762 mm thick, with diffusion of Si into the surface of the material, by embedding treatment. A coating of Si3n4, 76.2-762 mm thick, is then deposited from the gas phase.