Mechanical and Electrical Characteristics of WB Synthesized at High Pressure and High Temperature.

Single-phase tungsten diboride (WB) was synthesized at high pressure and high temperature. The different grain sizes ranging from 300 nm to 3 µm were successfully obtained in WB by controlling the experimental conditions. The effects of grain size on hardness and resistivity properties were investigated. The Vickers hardness of WB was modulated with grain size. The maximum asymptotic Vickers hardness is 25.5 GPa for WB with a grain size of 300 nm which is a 10% increase compared to WB with a grain size of 3 µm. The optimal electrical resistivity of WB was 10 Ωm with the biggest grain size of 3 µm, which is ascribed to low grain boundary density. The superior properties of hardness and electrical resistivity demonstrate that WB should be a new functional hard material replacing WC which is widely used in industrial production.