Influence of silicon content on microstructure and antioxidation property of SiC coating for carbon-carbon composites

A SiC coating for carbon-carbon composites was prepared by the pack cementation method in an argon atmosphere. The influence of the silicon content in the pack cementation powder on the microstructure and antioxidation property of SiC coatings were studied. As the silicon content is <82.4 wt-%, the as obtained coating possesses a porous structure with β-SiC phase. While the silicon content is up to 85.7 wt-%, the as prepared coating is of a dense structure consisting of β-SiC, α-SiC and Si. The thickness of the coating increases with the increase in silicon content. Oxidation test shows that the antioxidation property of the coating improves greatly as the silicon content is >82-4 wt-%.