LAUSR

The main aim of this study is to show the fabrication of WC–Co composite with different content of cobalt (13–33% wt) from WO3 and Co3O4 by in-situ carbothermic reduction method while using activated carbon as a reducing agent. Cobalt and tungsten oxide powders with different ratio and 17% carbon (30% more than stoichiometric value) were mixed by ball milling under atmosphere of argon for 20 h. The homogenized powder mixture followed the process of pressing and heat treatment (carbothermic reduction + sintering) under different protective layer or atmosphere at 1500 °C for 2 h. To evaluate the appropriate temperature for carbothermic reduction, the differential thermal analyses (DTA) were conducted on mixture sample of WO3, Co3O4, and C. Hardness (Vickers), toughness (Vickers indentation and crack length measurement), density (Archimedes), phase composition (XRD), and micro structure (scanning electron and optical microscopic) of sintered sample were evaluated. DTA results show the complete reduction of oxides at 1050 °C and the formation of tungsten carbide and the metallic phase of cobalt. The XRD results showed that in the milling stage even up to 20 h no reduction reaction occurred and only powder activation took place; therefore, the reduced compacted samples show the presence of unreduced oxides and extra phases protective foil of steel in comparison with alumina and carbon mixture as a layer protective. From investigated composites, the composites with 25% cobalt showed the highest density and strength while the composite with 36 and 14% cobalt showed the highest toughness and hardness, respectively.