High-Pressure Synthesis Of Tan Compacts With High Hardness And Thermal Stability

High-hardness TaN compacts with a diameter and height of 6 mm were synthesized through the phase transformation of CoSn-type into WC-type TaN under experimental conditions of high temperature and high pressure. The Vickers hardness of WC-type TaN compacts obtained at the pressure of 5 GPa and the temperature of 1873 K is found to be similar to 21.5 +/- 1.5 GPa with a load of 3 Kg, which is comparable to that of the pure tungsten carbide compact (similar to 20 GPa) and higher than those of ultrahigh temperature ceramics ZrB2 and HfB2 under the same load. The high hardness of WC-type TaN compacts presented in this work is attributed to the deviatoric strain and well bonded nanograins. The synthesized WC-type TaN compacts also possess a high oxidation temperature (1072 K). These results suggest that the WC-type TaN with high hardness and high thermal stability holds great promise for industrial applications.