HARDNESS, FRICTION AND WEAR OF MULTIPLATED ELECTRICAL CONTACTS

Full interpretation of the composite (eg. Vickers) microhardness is gi ven 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, I nterpretation of superficial hardness for multilayer platings, Thin So lid Films, 207 (1992) 144-152). An approximate computation for the int ernal plastic work is devised. The work done on the underlying substra te is shown to correlate well with findings of the subsurface deformat ion theory of multiplated contacts. (R. G. Bayer, E. Y. Hsue and J. Tu rner, A motion-induced subsurface deformation wear mechanism, Wear, 15 4 (1992) 193-204; R. G. Bayer, A general model for sliding wear in ele ctrical contact, Proc. Wear of Materials Conf., San Francisco, CA, 199 3). In particular, wear and friction are shown to be, respectively, pr oportional and inversely proportional, to the plastic work done on the substrate during multiple passes of a slider.