Synthesis of WC and dense WC– xvol.%Co hard materials by high-frequency induction heated combustion method

Abstract

WC and dense WC– xvol.%Co materials, with grain size of <1 μm, were synthesized by high-frequency induction heated combustion synthesis (HFIHCS) method in one step from elemental powders of W, C and Co within several minutes. In the absence of cobalt additive, WC can be formed, but its relative density was low (about 70%) under simultaneous application of a 60 MPa pressure and the induced current. However, in the presence of just 5 vol.% cobalt, the density increased to 98.5% under the same experimental conditions. The effects of Co content on the hardness, fracture toughness, and the relative density of the dense WC– xvol.%Co composites were investigated. Also, the effect of the carbon ratio to the tungsten on the mechanical properties was researched. The hardness of the WC–Co composites decreased with increasing Co content, while the fracture toughness increased. The maximum fracture toughness and hardness were 15.1 MPa m 1/2 at WC–20vol.%Co and 1928 kg/mm 2 at WC–5vol.%Co.