Oxidation of a gold-palladium PFM alloy

In this study, the influence of oxygen pressure, as well as oxidation time and temperature, on the oxide formation of a gold-palladium-indium-gallium alloy was investigated. After oxidation (vacuum/air, 1-10 min, 940-1020 degrees C) the oxides were removed selectively by means of leaching in 37% hydrochloric acid. Concentrations of the metallic parts of the oxide layers were determined by means of an emission spectrometer. The composition of the oxide layer was computed on the basis of these measurements. Palladium oxide was not found. The formation of In2O3 and Ga2O3 was detected. The oxidation time did not influence the composition of the oxide layer. A higher oxidation temperature gave a slightly greater In2O3 concentration. Oxidation in vacuum resulted in a much higher Ga2O3 content. Under all conditions gallium oxidized preferentially.