A mullite/SiC oxidation protective coating for carbon/carbon composites

• Published in: Journal of the European Ceramic Society Vol. 33; no. 1; pp. 191 - 198
• Main Authors: Wang, Kai-Tong, Cao, Li-Yun, Huang, Jian-Feng, Fei, Jie
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.01.2013
• Subjects: Carbon; Carbon-carbon composites; Coating; Hydrothermal electrophoretic deposition; Mullite; Mullite coating; Oxidation; Oxidation resistance; Protective coatings; Silicon carbide; Hydrothermal electrophoretic deposition; Oxidation; Mullite coating; Carbon/carbon composites
• ISSN: 0955-2219; 1873-619X
• DOI: 10.1016/j.jeurceramsoc.2012.08.009

To protect carbon/carbon (C/C) composites against oxidation, a mullite coating was prepared on SiC precoated C/C composites by a hydrothermal electrophoretic deposition process. The phase composition, microstructure and oxidation resistance of the prepared mullite/SiC coatings were investigated. Results show that hydrothermal electrophoretic deposition is an effective route to achieve crack-free mullite coatings. The mullite/SiC coating displays excellent oxidation resistance and can protect C/C composites from oxidation at 1773K for 322h with a weight loss rate of only 4.89×10−4g/cm2h. The failure of the multi-layer coatings is considered to be caused by the volatilization of silicate glass layer, the formation of microholes and microcracks on the coating surface and the formation of penetrative holes between the SiC bonding layer and the C/C matrix at 1773K. The corresponding high temperature oxidation activation energy of the coated C/C composites at 1573–1773K is calculated to be 111.11kJ/mol.