Electrochemical Corrosion and Protection of Molybdenum and Molybdenum Disilicide in a Molten Soda-Lime Silicate Glass Environment

Electrochemical corrosion of Mo and MoSi₂ in a molten soda-lime silicate glass environment was studied using a two-electrode cell with Pt as the counterelectrode. XRD, SEM, and EDS were used to characterize the corroded specimens. When Mo was cathodically polarized (-1 V), no corrosion and a Mo surface were observed after 12 h of electrochemical corrosion. Under anodic polarization (+1 V), higher corrosion (0.42 mm) was observed due to formation of MoO₂, which did not form a coherent passive layer. Cathodic protection occurred by electrostatic repulsion of oxygen ions, thus discouraging oxidation of Mo. Anodically polarized (+1 V) MoSi₂ showed a significant decrease in recession at the glass line due to formation of SiO₂ product which attenuated convective flow currents. Accelerated corrosion was observed under cathodic polarization (-1 V), where streams of Mo particles were observed flowing downward in the melt. MoSi₂ was interpreted to decompose into neutral molybdenum and silicon anions, which were rejected into the melt.