Densification, microstructure evolution and mechanical properties of WC doped HfB2–SiC ceramics

Despite of good oxidation resistance and ablation resistance, challenge to densify and tendency to loss high temperature (H.T.) strength have limited its potential applications in aerospace for HfB2–SiC ceramic. In this work, dense HfB2–SiC ceramic with improved H.T. flexural strength was prepared using WC as sintering aid. Pure HfB2–SiC ceramic exhibited creep deformation at 1600 °C with measured strength value of 389 ± 82 MPa, whereas WC doped sample showed much higher flexural strength of 658 ± 69 MPa with linear elastic behavior prior to fracture. In addition to clean grain boundary, the addition of 5 vol.%WC into HfB2–SiC ceramic promoted the formation of fine (Hf,W)B2, (Hf,W)C and WB precipitates. This combinative effect is responsible for its excellent H.T. mechanical property of WC doped HfB2–SiC ceramic.