A simple recoating repair methodology to improve oxidation resistance of C/SiCs

Abstract

Lots of through SiC coating micro-cracks appeared due to the mismatch of thermal expansion coefficient between fibres and matrix, and this could be the diffusion path for oxidising gases to reduce oxidation resistance of as-cracked C/SiCs. In this paper, a simple recoating repair methodology was achieved by grinding off original coating and depositing coating again. The experimental results pointed out that as-repaired specimens had excellent oxidation resistance with the whole temperature range of 500–1500°C, and at sensitive point of 800°C, the weight loss rate of the as-repaired specimens was decreased by 22.1% compared to the as-cracked specimens. From 700 to 1100°C, the flexural strength of the as-repaired specimens has obviously improved compared to the as-cracked specimens. Microstructural analysis showed that the recoating repair methodology can seal and narrow through-coating micro-cracks, leading to oxidation resistance and mechanical properties improvement for the as-repaired specimens.