Enhanced mechanical and ablation properties of lamellar porous ZrB2-SiC ceramics by highly textured pyrolytic carbon

Abstract

Porous ZrB₂-SiC ceramics are promising lightweight materials applied in harsh environments. However, excessive pores can degrade their mechanical properties and ablation resistance. This work aims to enhance the strength and ablation properties of porous ZrB₂-SiC ceramic by depositing highly textured pyrolytic carbon (HTPyC) through the chemical vapor infiltration (CVI) method. The obtained ZrB₂-SiC/HTPyC composite exhibited a low density of 2.97 ± 0.04 g/cm³ and superior mechanical properties. The Vickers hardness, longitudinal compressive stress, and radial compressive stress were 6.78 ± 1.0 GPa, 82.84 ± 6.48 MPa, and 91.96 ± 4.89 MPa, respectively, which were 129 %, 135 %, and 182 % higher than those of the original ZrB₂-SiC porous ceramic. The ablation results revealed that the incorporation of HTPyC can significantly improve the ablation resistance of the ZrB₂-SiC/HTPyC composite. After plasma flame ablation at 2300 °C for 120 s, the mass and linear ablation rates were 0.143 ± 0.013 mg/s and 0.583 ± 0.046 μm/s, respectively, contrasting with the rates of −4.888 ± 0.397 mg/s and 1.950 ± 0.214 μm/s for the ZrB₂-SiC ceramic.