Properties of Low Karat Gold Alloys Part 2. Corrosion Resistance and Tarnish of the Alloys Containing 5 mass% Pd

Abstract

　　From the viewpoint of increasing palladium prices and expression of allergy, the development of low palladium alloys is expected. In this study, 5mass% Pd and 22−47mass% Au with silver and copper eutectic collstituent alloys were experimentally developed. Measurements were carried out on the amount of released element in a mixed solution of 0.1 mol/L lactic acid and 0.1 mol/L NaCl, the potentiodynamic polarization profile in 0.9% NaCl solution and a tarnish test in 0.1 mol/L sodium sulfide. Results were compared with commercial gold−silver−palladium alloy and examined comparatively. As a result, transpassive potential decreased with the reduction of gold content, and was comparable to commercial gold−silver−palladium alloy with above 30 mass% Au alloy. In addition, tarnish resistance was equivalent to commercial gold−silver−palladium alloy by more than 40 mass% Au alloy.