Synthesis of WC and dense WC-5 vol. percent Co hard materials by high-frequency induction heated combustion

摘要

Tungsten carbide (WC) and dense WC-5 vol. percent Co materials, with grain size of approx 1 mum, were synthesized by high-frequency induction heated combustion synthesis (HFIHCS) method in one step from elemental powders of W, C, and cobalt (Co) within several minutes. Simultaneous combustion synthesis and densification were accomplished under the combined effects of an induced current and mechanical pressure. In the absence of cobalt additive, WC can be formed, but its relative density was low (about 70 percent) under simultaneous application of a 60 MPa pressure and the induced current. However, in the presence of 5 vol. percent cobalt, the density increased to 98.5 percent under the same experimental conditions. The percentages of the total volume shrinkage occurring before and during the synthesis reaction of WC-5 vol. percent Co were 7 and 57 percent, respectively. The fracture toughness and hardness values obtained of WC-5 vol. percent Co were 7 MPa m~(1/2) and 2100 kg/mm~2, respectively.