Effect of an applied electric current on the rate of oxidation of copper at room temperature

Abstract

Investigations have been carried out on the rate of oxidation of Copper at room temperature in dry air under the influence of externally applied currents of both polarities. The rate was found to increase or decrease depending upon the direction of current. The results are discussed with reference to the Cabrera-Mott theory of formation of very thin oxide films at low temperatures. The current is found to alter the concentration of vacant cationic sites in the oxide migrating/sec, due to the electrolysis of the oxide. In. the cathodic case, the change is proportional to the magnitude of current in accordance with Faraday's law. In the anodic case the decrease in rate was not so pronounced, presumably due to the low anodic efficiency of solid electrolytes at low temperatures. The excellent agreement between the theoretical and experimental values of the potential difference between the metal/oxide and oxide/gas interface and the cationic vacancy concentration, seems to support Mott's theory.