Effect of pH and Potential on the Corrosion Behavior of WC-Ni-Cr-Mo Cemented Carbide in NaCl Solution

Abstract

The corrosion resistance of WC-Ni-Cr-Mo cemented carbides in aqueous NaCl solutions at various pH values has been investigated by electrochemical measurements, surface observation and solution analysis. In acidic environments, WC passivates and binder metals selectively dissolve. In neutral environments, Cr and Ni passivate at corrosion potential and lower potentials than 0.5 V and WC either passivate or dissolve at a slower rate, while transpassive dissolution of Cr in the binder and dissolution of W occurs at potentials higher than 0.5 V. In a basic environment, the dissolution behaviour of the WC-Ni-Cr-Mo alloy is similar to that in a neutral environment, however, the dissolution of WC occurs significantly with increasing anodic potential from corrosion potential.