Microstructure and mechanical properties of SiC fibres after exposure at elevated temperature

Abstract

To understand the service behaviour of SiC fibres, the effects of ambient environment and temperature on the microstructure, mechanical property and oxidation behaviour of these fibres were investigated. The result shows that, the surface of SiC fibres becomes rough after exposure in air from 973 to 1573 K due to the formation of small SiO₂ particles, and a smooth SiO₂ film will be formed on the SiC fibre at 1773 K. In Ar atmosphere, SiC fibres will change into clusters of large SiC crystals after heat treatment for 2 h at 2373 K. The tensile strength of SiC fibres decreased by 66 and 95% when the fibres were exposed at 1773 K for 5 min in air and 2373 K for 2 h in Ar, respectively. This degradation is associated with the evaporation of CO and SiO from the fibres as well as with SiC grain growth in the fibres.

Keywords:

• Microstructure
• Oxidation
• SiC fibres
• Heat treatment

Acknowledgements

The authors of this work acknowledge funding supported from the National Natural Science Foundation of China (Grant Nos. 51521061 and 51272212), and the Research Fund of State Key Laboratory of Solidification Processing (NWPU), China (Grant No. 85-TZ-2013).