Influence of alternating current frequency on the corrosion behaviour of molybdenum electrodes in glass melts

Abstract

Literature data that show the complicated course of the frequency dependence of the corrosion rate with a maximum and a minimum were confirmed for several glass types. The results obtained for lead glasses demonstrate that in the region of corrosion retardation the depolarization and the corrosion rates are a function of the ratio of current density to the square root of frequency. At the frequency of minimum corrosion rate, local maxima of mean electrode potential and of voltage are found, which are related to the course of the potential in the anodic half-period. The proposed explanation of this behaviour is based on the effect of protective layers that would be destructed by oxygen evolution at lower frequencies.