A hybrid PACVD B4C/CVD Si3N4 coating for oxidation protection of composites Original Research Article

Plasma-assisted Chemical Vapor Deposition (PACVD) B4C coating and a hybrid PACVD B4C/CVD Si3N4 coating were deposited on a two-dimensional CC substrate. Oxidation behavior of coated and uncoated CC composites was studied using a thermogravimetric analyzer (TGA) in both the isothermal and kinetic mode. The PACVD coating provided an excellent oxidation protection of the CC substrate at temperatures up to 900 °C, whereas the PACVD B4C/CVD Si3N4 coating provided good oxidation protection at temperatures up to 1300 °C. Microstructural and chemical characterizations of coated composites were performed using EDS, FTIR, XPS, and XRD. A correlation between coating microstructure, composition and oxidation behavior is discussed.