STUDY ON CORROSION OF MAGNESIUM ALLOY IN SIMULATED COOLING WATER BY MEANS OF IN SITU SPECTROSCOPIC ELLIPSOMETRY

In situ spectroscopic ellipsometry was employed to investigate the corrosion behavior of AZ40 magnesium alloy in a simulated cooling water without and with molybdate inhibitor.By deconvoluting the ellipsometric data with a one-layer model,the evolution of the refractive indices and the thickness of the interface layer of electrode-medium were obtained.Based on the deconvolution results,three regimes,which were dissolution of native oxide film,formation of adsorption film and precipitation of corrosion products,were proposed for the corrosion process of magnesium alloys in the simulated cooling water.The addition of molybdate weakened the dissolution of the native oxide film and made the adsorption film and the precipitated film much compact,which was responsible for the effective inhibition of molybdate on corrosion of magnesium alloys in the simulated cooling water.