HIGH TEMPERATURE MECHANICAL PROPERTIES OF CVD-SiC THIN FILMS

Abstract

Silicon carbide ( SiC ) coatings were fabricated using a chemical vapor deposition (CVD) process onto a graphite substrate at different deposition temperatures. The mechanical properties such as hardness, modulus, and creep properties from room temperature to 500°C were investigated using nanoindentation techniques. The SiC coatings deposited at 1300°C exhibited a small grain size (0.2 ~ 0.4 µ m ) and [111] preferred orientation, while the coatings obtained at 1350°C had a large grain size (0.5 ~ 1.0 µ m ) and [220] preferred orientation. The hardness was decreased with testing temperature, but no significant change in the modulus was measured with testing temperature from high temperature nanoindentation test, and the apparent creep behavior was observed in the high temperature. The high temperature mechanical properties of CVD- SiC coatings were relate to their microstructure and crystal orientation, and CVD- SiC coatings deposited at 1300°C exhibited high stability and reliability at high temperature.