Effect of heating rate on the strength of ZrB2-SiC composite subjected to cyclic thermal shock

The effect of heating rate on the mechanical property of a ZrB2-20 vol% SiC composite subjected to cyclic thermal shock was investigated using a homemade coupled thermal-mechanical material testing system. In each cycle, a specimen was heated from room temperature to 2000 degrees C with a prescribed heating rate, and then cooled down naturally back to room temperature. The heating rates involved are 200 degrees C/s, 400 degrees C/s, 700 degrees C/s and 900 degrees C/s, respectively. The residual flexural strength of each specimen after 10 cycles of thermal shock was tested with a three-point bending device. It can be seen that the residual flexural strength decreases monotonically with the increase of heating rate. The fracture morphology of the tested specimens was analyzed with SEM, which shows that the thickness of oxide layer decreases with the increase of heating rate.