Hardness, friction and wear of multiplated electrical contacts

Abstract

Full interpretation of the composite (e.g. Vickers) microhardness is given for typical multilayer platings used for electrical contacts. For relatively thick layers plated on a Cu substrate, an effective highly stressed region (delimited by the "plastic boundary") is identified, which introduces a significant modification in the prior interpretive theory of thin platings (P. A. Engel, A. R. Chitsaz and E. Y. Hsue, Interpretation of superficial hardness for multilayer platings, Thin Solid Films, 207 (1992) 144-152). An approximate computation for the internal plastic work is devised. The work done on the underlying substrate is shown to correlate well with findings of the subsurface deformation theory of multiplated contacts. (R. G. Bayer, E. Y. Hsue and J. Turner, A motion-induced subsurface deformation wear mechanism, Wear, 154 (1992) 193-204; R. G. Bayer, A general model for sliding wear in electrical contact, Proc. Wear of Materials Conf., San Francisco, CA, 1993). In particular, wear and friction are shown to be, respectively, proportional and inversely proportional, to the plastic work done on the substrate during multiple passes of a slider. © 1993.