The corrosion of coated and uncoated Mo and of uncoated Mo-ZrO2 in glass melts under a. c. loading

Sintered and deformed molybdenum, molten and deformed molybdenum and Mo-5ZrO2 (Mo with 5 volume % ZrO2) were exposed to molten C-, white- and green-glass under an alternating current loading of 1 A/cm2. Via mass loss measurement and chemical analysis of the glass melts corrosion rates of the various materials were determined. The most significant deviation to lower corrosion could be found for Mo-5ZrO2 in green-glass. Retardation of intercrystalline corrosion by the dopant itself or - more likely - the formation of a viscous layer promoted by the presence of the dopant are responsible for this behavior. Sibor (Si-B) coated molybdenum was also tested in C-glass melt under the same conditions. After an initial period of strong dissolution and bubbling the corrosion rate decreased and became lower than that of the 3 uncoated materials. Presumably the preferential dissolution of Si (B) over the period observed is responsible for this effect. (author)