The Anodic Dissolution of Molybdenum

Abstract The anodic dissolution of Mo was studied in H2SO4-K2SO4 solutions (pH = 0.4–3.4) and K2SO4-K2CO3-KOH solutions (pH = 9.5–13.6) at 25 C (77 F). Faradaic efficiency studies showed the metal to be electrochemically oxidized to the Mo-VI state. Analysis of surface films and polarization measurements indicate the corrosion resistance of Mo to be due to a high coverage of the metal surface with Mo2O5 which is very rapidly formed. An anodic dissolution mechanism is proposed that involves the further oxidation of Mo2O5 to MoO3 which hydrolyzes and dissolves. Additions of Cl− had little or no effect on the dissolution.