In situ synthesis, mechanical properties, and reaction mechanism of the WB2–SiC composites

Abstract

In the present work, WB₂–SiC composite powders containing 20 vol.% of SiC were in situ synthesized by the boro/carbothermal reduction with WO₃, SiO₂, B₄C, and carbon black as raw materials at 1400°C, 1500°C, and 1600°C, respectively. The as-synthesized composite powders were then consolidated by spark plasma sintering (SPS) technique to obtain WB₂–SiC composite bulk samples. The experimental results showed that the relative density of the WB₂–SiC composite ceramic samples achieved in this study was higher than 97.5%. Also, electronic microscopy observations showed that SiO₂ had reacted completely during the preparation process, and the SiC grains were homogenously embedded among the WB₂ grains with the formation of a three-dimensional structure. The Vickers hardness and fracture toughness values of the composite ceramic fabricated by powder heat treated at 1400°C were 24.6 ± 0.7 GPa and 5.4 ± 0.7 MPa·m^1/2, respectively, which were the highest among three samples prepared in this study.