Fretting behavior of gold flashed palladium, palladium nickel and palladium silver contact materials

Palladium and palladium-alloy contact materials manufactured by both electroplating and skive inlay cladding technologies were evaluated for adhesive and abrasive wear behavior. The contact materials were coated with 0.1- mu m-thick hard gold electroplate and tested again to determine the effect of the coating on wear behavior. Selected contact finishes with the gold flash were subjected to fretting conditions in the presence of organic vapors to determine susceptibility to frictional polymer formation. It was found that, in general, palladium and palladium-alloy 'flats' cause rider wear, and the durability of wrought Pd-Ag was significantly improved by alloying with small amounts of Ni. The gold flash altered the wear behavior of plated Pd-Ni and clad Pd-Ag but not plated Pd-Ag and clad Pd-Ag-Ni. Type-I frictional polymers were produced on the gold flashed Pd-Ag electroplates and gold flashed Pd-Ag-Ni inlays but not on the gold flashed Pd-Ni electroplates. It was determined that the wear mechanism and therefore the resultant contact surface materials controlled the formation of frictional polymer. The increase in contact resistance at end of test was attributed to rider wear and the exposure of the nickel underplate.<>