Evaluation of heat resistance of SiC-based ceramic fibers via in situ elastic modulus and electrical conductivity measurement at elevated temperatures

Abstract

SiC-based ceramic fibers have numerous applications as reinforcement materials. Herein, the in situ thermal stability of four types of SiC-based ceramic fibers from three generations was investigated in terms of elastic modulus and electrical conductivity at temperatures up to 1800 °C in a vacuum under low pressure (<10–4 Pa). A specific tensile test device (MacaSiC) for single fibers was used. Mechanical and physical properties were monitored during heating and cooling at 1200, 1500, and 1800 °C for 10 min. Fibers exposed at 1200, 1500, and 1800 °C for 10 min were evaluated by measuring tensile strength retention, and correlating them with fiber crystallinity and microstructural evolution. Third-generation fibers exhibited excellent thermal stability at temperatures up to 1800 °C. The strength degradation of the third-generation SiC fibers was associated with the enlargement of apparent β-SiC crystallites and carbonization caused by the release of Si in the annular region of the fibers.