Effects of thermal shock on the microstructure, mechanical and thermophysical properties of ZrC-C composites

To explore the effects of thermal shock cycles on ZrC-C composites, their microstructure, coefficient of thermal expansion (CTE), compressive strength and internal friction behavior after different thermal shock cycles were studied. As the thermal shock cycle between 1500 ℃ and room temperature increased from 0 to 30, the CTE of the ZrC-C composites with the ZrC/PyC (Pyrolytic carbon) weight ratio of 1.7 first increased and then decreased, and its compressive strength increased by 35.8 % (295.4 ± 10.1 MPa) after 10 thermal shock cycles and could still be maintained above 85 % of its original strength after 30 thermal shock cycles. The changed interface bonding strength between ZrC skeleton and PyC resulted in the first decrease and then increase of their internal friction. This work provides an effective strategy for optimizing the thermal shock resistance of ultra-high temperature composites by regulating the component contents.