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 degrees 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)B-2, (Hf,W)C and WB precipitates. This combinative effect is responsible for its excellent H.T. mechanical property of WC doped HfB2-SiC ceramic. (C) 2015 Elsevier Ltd. All rights reserved.