Sintering pure polycrystalline zirconium carbide ceramics with enhanced mechanical properties under high-pressure and high-temperature

Abstract

Pure polycrystalline zirconium carbide (ZrC) ceramics were fabricated using high-pressure and high-temperature (HPHT) methods, and a systematic and comprehensive study of their properties was conducted. ZrC ceramics sintered at 5.0 GPa pressure and 1300 °C displayed optimal properties, with a Vickers hardness of 27.4 GPa and an indentation fracture toughness of 4.3 MPa·m^1/2, which are 29 % and 39 % higher than the reported experimental data, respectively. Additionally, they had an average grain size of approximately 425 ± 153 nm, a relative density near 98.5 %, a Young's modulus of 412 GPa and an oxidation onset temperature of 713 ℃. This study offers critical insights into the sintering of pure, polycrystalline and fine-grained ceramics and provides a preparation method for improving the mechanical properties of other new ultra-high temperature ceramics (UHTCs).