Electrodeposition of Rhodium and Ruthenium for Slip-ring Surfaces

Abstract

The mechanical wear of rhodium and ruthenium electrodeposits operating as slip-ring surfaces with palladium-silver alloy brushes is shown to be a function of electrolyte composition, plating conditions, and thickness of coating. Within selected thickness ranges the deposits function very satisfactorily and are resistant to wear. Types of roughness which should be avoided are discussed, and methods of measuring and controlling these are recommended. It is concluded that for slip-rings a thickness of 40 x 10⁻⁶ in should be sufficient to withstand the conditions involved in the majority of applications, and that for such duty ruthenium provides a more suitable surface than rhodium.