Effects of HfN content on microstructure and mechanical properties of ZrB₂-HfN ceramic materials

ZrB₂ -HfN ceramic materials were fabricated by the vacuum hot-pressing sintering, and the influence of HfN content by mass on the microstructure and mechanical properties of the ZrB₂ -HfN ceramic materials was studied. The results show that, with the HfN content by mass increasing from 5% to 15%, the Vickers hardness and flexural strength of the ZrB₂ -HfN ceramic materials first increase and then decrease, while the fracture toughness increase gradually. When the content of HfN is 15%, the fracture mode ofZrB₂ -HfN ceramic material is the coexistence of transgranular fracture and intergranular fracture. When the content of HfN is 10%, the ZrB₂ -HfN ceramic material obtains the better mechanical properties, and the hardness, flexural strength, and fracture toughness are(16.47±0.24) GPa, (734.48±25) MPa, and (5.37±0.20) MPa·m ^1/2, respectively.