The interface mechanical and ablative evolution behaviors under different heat flux of multiphase HfC-SiC matrix composites

Abstract

Multiphase HfC-SiC ceramic matrix composites were prepared by a combination process. The interface mechanics and ablation properties behaviors were investigated. Introducing the PyC-SiC interface, the composites showed a second-order pull-out mechanism. The mechanical failure model showed that fibers and matrix have different failure strain under load depending on the component that fails first. Moreover, the ablative airflow in the center area will spread to the edge area through the thermal shock microcracks generated. Increasing of the heat flux, the crack width gradually increased to be ditches. It accelerated the evolution of surface morphology, which showed HfC-SiC substrate was first transformed into Hf-Si-O solid solution on the process of phase transformation of oxidation products from 1680 ℃ to 2150 ℃, and eventually sintered into HfO₂. The change in the morphology of oxidation product consumed more heat and protected the substrate from oxidation, resulting in improving the ablation resistance of composites.