Influence of μ-size WC on the Corrosion Behavior of Ultrafine WC/WC-Co Cemented Carbides

Resumo

The electrochemical behavior of ultrafine WC/μ-WC-Co alloy with different grain sizes of WC particles was investigated in 1M HCl and 1M NaOH solutions using potentiodynamic polarization and surface analytical techniques. Good linear grain size dependence existed for the corrosion current density (I_corr). Alloys with smaller WC exhibited better corrosion resistance. Addition of μ-size WC particles can weaken the corrosion resistance of ultrafine WC/μ-WC-Co cemented carbide. The corrosion mechanism is discussed based on the SEM and EDS analysis. The predominant dissolution of the Co particles as the binder phase in HCl solution as well as WC matrix remained at the tangent surface. The benefits of Co(OH)₂ protective film can only be utilized in alkaline solution.