Evolution of the structure and mechanical performance of Cansas-II SiC fibres after thermal treatment
XH Chen and ZG Sun and XM Niu and J Bian and YD Song and JC Liu, CERAMICS INTERNATIONAL, 47, 27217-27229 (2021).
Herein, an in-depth analysis of the effect of heat treatment at temperatures between 900 and 1500.C under an Ar atmosphere on the structure as well as strength of Cansas-II SiC fibres was presented. The untreated fibres are composed of beta-SiC grains, free carbon layers, as well as a small amount of an amorphous SiCxOy phase. As the heat- treatment temperature was increased to 1400 degrees C, a significant growth of the beta-SiC grains and free carbon layers occurred along with the decomposition of the SiCxOy phase. Moreover, owing to the decomposition of the SiCxOy phase, some nanopores formed on the fibre surface upon heating at 1500 degrees C. The mean strength of the Cansas- II fibres decreased progressively from 2.78 to 1.20 GPa with an increase in the heat-treatment temperature. The degradation of the fibre strength can be attributed to the growth of critical defects, beta-SiC grains, as well as the residual tensile stress.
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