Electrochemical study on the corrosion of molybdenum electrodes in lead glass melts

Abstract

The corrosion of molybdenum in lead glass melts is a two step process. In the cathodic part of the ac heating cycle lead ions of the glass melt are reduced to metallic lead. During the anodic part molybdenum is oxidized. Cyclic voltammetry revealed Mo3+ ions as the intermediate state in the oxidation process. During corrosion experiments a porous layer of Mo(VI) Compounds and MoO2 were detected. A drastic reduction of the corrosion rate was obtained when a small anodic dc potential was superimposed on the ac heating current. Slow voltammetric scans showed passivation of the molybdenum at potentials higher than -300 mV. The protection layer consists most likely of molten K2Pb(MoO4)2.