In-situ synthesis of WC-x%Co composite in WO3 - Co3O4 - C system by mechanical activation carbothermic reduction method: physical and mechanical properties

The aim of this research is in-situ production of WC-Co composite with different combination of 13% to 33% of cobalt from metal oxides WO3 and Co3O4 by use of carbothermic reduction method and then testing its physical and mechanical properties. In this study, cobalt and tungsten metal oxides powder with- different ratios with 17% carbon (30% more than stoichiometric value) after homogenization and mechanical activation in a planet ball mill with argon shielding gas for 20 hours, pass pressing, reduction heat treatment and sintering (temperature of 1500 oC for 2 hours and under shielding layer of alumina and carbon powder). Hardness (Vickers), toughness (Vickers indentation and crack length measurement) and density (Archimedes) of sintered sample were evaluated and relation of properties and microstructure was discussed using electron microscope observations. The results showed that in the milling stage no reduction reaction occurred even up to 20 hours and only powder activation took place. Between investigated composites, the composites with 23% cobalt showed highest density and strength while the composite with 33% and 13% cobalt showed highest toughness and hardness, respectively.