Microstructural characterization and corrosion resistance of WC-Ni-Cr-Mo composite – the effect of Mo

Abstract

WC-Ni-Cr-Mo are good candidates for replacing WC-Co for its better corrosion performance. This work investigated the effect of different Mo content on the mechanical properties and corrosion susceptibility of WC-Ni-Cr-Mo composites in chloride and sulphate acidic media. Chemical, microstructural, and electrochemical analysis were performed. Results show chlorides are frankly more aggressive than sulphates, but additions of up to 0.6 wt% in Mo can enhance the active-passive transition, particularly in the presence of chlorides, and guarantee the passive state in sulphates. Also, Mo was effective in hindering WC grain growth and in increasing hardness in 5%, simultaneously reducing toughness in 4%.