An in-situ FT-IR investigation of the anodic behaviour of WC-Co hardmetal

An in-situ FT-IR spectroelectrochemical and voltammetric study of the corrosion of a WC-Co hardmetal grade is reported in this communication. A slightly acidic sulphate solution is considered. The potential- and time-dependent anodic formation of CO, and Co(OH)(2) can be followed with the variation of the vibrational spectra. The formation of CO2 occurs at the same potential at which tungsten oxidation starts to be detected and the breakdown of passivity can be observed by electrochemical methods. Our results suggest that a threshold potential exists for the oxidation of WC in WC-Co, giving rise to the concomitant oxidation of tungsten and carbon at more noble potentials than those typical for the oxidation of the individual elements.