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

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. (C) 2004 Elsevier Ltd. All rights reserved.