Creep behavior of CVD-SiC Coating at HIgh Temperatures using BSR Method

Abstract

SiC is an excellent material for high temperature applications and therefore used intensively for high temperature applications and as a coating material. Therefore it is very important to know the creep behavior of SiC at high operating temperatures. In this work, we intended to measure the creep properties of CVD-SiC coating around 30 um in thickness. There were significant difficulties in performing tensile creep for CVD-Sic coating due to thin thickness, difficulty in handling thin and brittle nature of SiC. Therefore, bend stress relaxation (BSR) technique was used to study the creep behavior of CVD-SiC coating layer and predict tensile creep strain (ε_c) from BSR data. At high temperature (>1400℃) and stress (200MPa) we observed increase in tensile creep strain (ε_c) whereas at 1300℃ the material was quite stable. This can be attributed to high mobility of atoms and dislocations at high temperature and more than one creep mechanisms can be operative at high temperatures as shown by many people.