Effect of grain growth inhibitors on the zinc-induced disintegration of cemented carbides: A study on Cr3C2, Mo2C, and VC additions

Recycling of WC-Co cemented carbides is essential for securing the supply of the critical raw materials tungsten and cobalt. Among established routes, the zinc process enables efficient recovery of WC-Co powders while preserving the original phase constitution. Although grain growth inhibitors are widely used to tailor microstructure and mechanical properties during cemented carbide production, their influence on zinc-induced disintegration during recycling has not yet been systematically investigated. In this study, the effects of Cr3C2, Mo2C, and VC additions in WC-9Co cemented carbides were examined over a broad concentration range from 0 to 1.5 wt% using a statistically designed experimental approach. Disintegration behavior during exposure to zinc vapor was quantified as a function of inhibitor type and content, Zn to cemented carbide ratio, and holding time. A dedicated reference series without grain growth inhibitors enabled direct comparison and assessment of inhibitor-induced effects. The results reveal clear and systematic trends. Cr3C2 significantly suppresses zinc-induced disintegration, Mo2C markedly accelerates the process, and VC exhibits an intermediate inhibitory effect. These differences are correlated with changes in binder reactivity, interfacial characteristics, and microstructural stability, which together govern zinc infiltration and Co-Zn phase formation. The findings demonstrate that zinc-induced disintegration kinetics are strongly influenced by minor alloying additions and are not governed by chemical interactions alone. Understanding how grain growth inhibitors affect both microstructural integrity and reaction kinetics provides a basis for designing cemented carbide compositions optimized for recyclability without compromising service performance.