Influence of contact materials on the formation of palladium-oxides by mechanochemical reaction

Influence of contact materials on the formation of palladium oxides by mechanochemical reaction in air are examined. Mechanical break-make actions of palladium contacts in air cause formation of powdery products of palladium oxides on the electrode surfaces, and consequently significant increase of contact resistance. The same products are also produced on Ag-Pd 50% and Ag-Pd 70% contacts, but such an increase of contact resistance is not observed. It is confirmed that contact resistance of Ag-Pd 70% contacts measured with I_m =0.1 A remains low through 500000 operations, despite some palladium oxides being formed. Dissimilar materials mating tests are done and influences of contact materials on the phenomena, such as effect of material transfer due to difference of hardness, are studied