Defects formation mechanism and control of SiC coatings by chemical vapor deposition

The surface and cross section micro-morphologies of silicon carbide anti-oxidation coatings deposited by chemical vapor deposition (CVD) were observed by scanning electron microscope. The formation mechanism of coating cracks, net-defects, and plane-defects were investigated. The defects control of the coatings was discussed based on the CVD process. Slow deposition is favorable to the coating defects control, especially to the plane-defects. Multilayer coatings without the plane-defects can be obtained by the slow deposition. Oxidation tests indicate that the three dimensional C/SiC with the slow deposition coatings shows the increase of mass of slow oxidation in air at 1300°C.