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 SiO 2 particles, and a smooth SiO 2 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.

Preparation of hollow SiC ceramic fibre from polycarbosilane fibre by diffusion-controlled cross-linking method

“…Since Yajima et al reported their pioneering work about preparing silicon carbide (SiC) fibre from polycarbosilane (PCS) via a sequence of spinning, curing and pyrolysis in the 1970s, the precursor-derived method has been a primary way to prepare continuous and dense SiC fibre [1]. Up to date, the preparation method has been mature and the third generation of SiC fibre with high tensile strength (2.6-3.2 GPa), high elastic modulus (380-420 GPa) and excellent heat resistance (over 1800°C) has been achieved [2,3]. Due to its excellent properties, SiC fibre as a ceramic reinforcement for ceramic matrix composites has been widely applied in harsh environment, such as aerospace, nuclear, industrial and automotive [4][5][6].…”