J. Phys. IV France 11 (2001) Pr3-861-Pr3-867
CVD mullite and mullite-alumina corrosion protection coatings for silicon based ceramicsS. M. Zemskova, J. A. Haynes and K. M. Cooley
Oak Ridge National Laboratory, P.O. Box 2008, 1 Bethel Valley Road, Oak Ridge, TN 37831-6063, U.S.A.
Application of silicon-based ceramics (SiC, Si3N4) and SiC/SiC composites as high-temperature structural materials requires the development of environmentally resistant coatings due to rapid degradation of the protective silica scale in high temperature water vapor. The CVD method of fabricating dense, high-purity, crystalline mullite (3Al2O3x2SiO2) and mullite-alumina coatings was utilized in this study. The textured mullite coatings were generally comprised of crystalline grains (0.3-0.5 µm) with a columnar structure. Coatings with thickness of less than 2µm, provided excellent corrosion protection for Si3N4 and SiC/SiC exposed to lowvelocity, high pressure (1 MPa) steam at 1200°C.
© EDP Sciences 2001