Ablation resistance of ZrC coating modified by polymer-derived SiHfOC ceramic microspheres at ultrahigh temperature

Abstract

Polymer-derived ceramics (PDCs) method opens up new possibilities for the preparation of novel multiphase ceramic nanocomposites owing to the molecular design of the precursors at the nanoscale level. In the current work, ZrC coatings incorporated with polymer-derived ceramic microspheres (CMS), SiHfOC_CMS, were deposited to enhance the ablation resistance by supersonic atmosphere plasma spraying. Upon 10.0 MW·m–2 plasma ablation at above 3000 °C, the linear ablation rate of ZrC-SiHfOC_CMS coating was reduced to 0.20 µm·s–1, 62% lower than that of the pristine ZrC coating. The improvement was ascribed to the presentence of viscous SiO2/HfO2 molten mixed phase, rather than HfSiO4, which can effectively seal pinholes and cracks. Moreover, the in-situ generated crystalline SiO2 had a lower oxygen diffusion rate than amorphous SiO2, meanwhile, m-HfO2 could improve the stability of SiO2 glassy film, thus further enhancing the ablation resistance.