Effect of temperature-dependent nano SiC on the ablation resistance of ZrC coating

Temperature-dependent nano SiC obtained from the polymer-derived ceramics method was used to modify ZrC coating by supersonic atmosphere plasma spraying. The crystallinity and grain size of SiC increased with increasing annealing temperatures. SiC annealed at 1400 °C exhibited the lowest crystallinity of 48.4 %, which led to massive re-pyrolyzing gas spillage from the modified ZrC coating during ablation, causing penetrating cracks. SiC annealed at 2100 °C exhibited the largest grain size of 190.4 nm, which could produce locally massive amounts of SiO₂, accelerating the sintering of ZrO₂ in the coating and leaving maximum residual stress. SiC annealed at 1800 °C possessed a medium crystallinity of 81.5 % and a grain size of 12.2 nm, which was favorable to improve the ablation resistance of ZrC coating for forming fine-grained ZrO₂ scale with minimum residual stress. Our work provides a novel perception of the microstructure-property relationship for ablation-resistant coating under extreme conditions.