The molybdenum corrosion and lead precipitation ratestogether with the overall electrode current were investigated in terms of thepotential of the molybdenum electrode in three glass melts. Two of themcontained 24 wt.% lead oxide, one of them containing also a small addition ofarsenic oxide, and the third glass melt was free from lead oxide. The comparisonof the rate of precipitating lead, of the corrosion rate and of the totalelectrode current in the melt free from arsenic oxide showed that molybdenum isfor the most part transferred into the glass melt in the form of Mo(VI) even atpotentials substantially more negative than the rest corrosion potential. Thestationary polarization curves obtained for all the three glass melts exhibitedcourses typical of passivation. In the case of melts containing lead oxide thepassivation already set in at the rest corrosion potential, or in the presenceof arsenic oxide even at a more negative potential. Alternating current canaffect the corrosion and lead precipitation rate in various glass melts in bothdirections. The accelerating effect always occurs in parallel with reduction ofthe mean electrode potential and vice versa. The effect of the electrodepotential, of the alternating current and of the content of alkalies on thecorrosion rate in the glass melts, can be explained by affecting the presence orlayer thickness of molybdenum dioxide on the electrode.
