Mechanisms and mechanical properties of high-temperature high-pressure sintered vanadium carbide ceramics

Vanadium carbide (VC) is extensively employed as a reinforcing agent in coating materials and a grain refiner in hard alloys, owing to its exceptional mechanical properties. A series of bulk VC ceramics were fabricated via high-temperature high-pressure sintering, followed by a comprehensive and systematic investigation of various properties of the sintered samples. The results revealed significant influences of processing temperature on the properties of sintered VC at 5.0 GPa. However, the exact nature of temperature dependence varied depending on the specific property. It was found that VC ceramics sintered at 1100 degrees C and 5.0 GPa exhibited the best overall performance, providing a relatively optimal temperature condition for synthesis. The Vickers hardness of the material reached an astonishing 43.2 GPa under a 9.8 N load, placing it within the category of superhard ma-terials. However, the sintered sample exhibited a gradually lower hardness value of 30.4 GPa under a higher load of 29.4 N. Highly dense with a relative density of 99.8%, exhibiting near full density, the vanadium carbide ceramics possess an impressive Young's modulus of 544 GPa, indentation fracture resistance of 5.4 MPa m1/2, and an oxidation initiation temperature of 758 degrees C. This study offers practical guidance for the design of novel transition metal carbide superhard materials and provides valuable insights for the exploration of visualizing directions in the next generation of superhard materials.