Abstracts Chemistry

The anodic dissolution of molybdenum in acid sulfate solutions

by Ching-Kuo Chen

"The world's resources of metals are decreasing. Due to this and the cost of replacing corroded materials, it has come to be realized that prevention is better than cure. The increasing demand for molybdenum and molybdenum alloys has stimulated a great amount of research into the corrosion characteristics of these materials. The result of such research has assisted in the development of suitable molybdenum alloys and protective coatings to retard corrosion. When a molybdenum anode and a suitable cathode are immersed in an oxygen-free electrolyte and are connected to a direct current power source, molybdenum is dissolved. This process is called anodic dissolution and a study of it is useful for many reasons: (1) The apparent valence of the metal undergoing dissolution can be determined. (2) An empirical expression for the dissolution rate can be established. (3) A dissolution reaction mechanism can be hypothesized that may aid in retarding corrosion and predicting behavior in other environments. The mechanism of the anodic dissolution of molybdenum has been formulated only in very vague terms. The purpose of this investigation was to study the dissolution in sulfuric acid solutions of various pH and if possible to establish a mechanism consistent with the data. Toward this end, experiments were performed to determine the relationships between the current density, potential, pH, and faradaic efficiency during dissolution. The effect of chloride ion on the process was also determined" – Introduction, p. 1.