Tribo-induced melting and temperature gradients at sliding asperity contacts

Tribo-induced nanoscale surface melting mechanisms have been investigated by means of a combined QCM-STM technique [1] for a range of Au and Au-Ni alloys with varying compositional percentages and phases. The QCM-STM setup allows studies to be performed at sliding speeds of up to m/s, and also reveals valuable information concerning tip-substrate temperature gradients.[3] A transition from solid-solid to solid-``liquid like'' contact was observed for each sample at sufficiently high asperity sliding speeds. Pure gold, solid-solution and two-phase Au-Ni (20 at.{\%} Ni) alloys were compared, which are materials of great relevance to MEMS RF switch technology.[2] The transition points agree favorably with theoretical predictions for their surface melting characteristics. We acknowledge NSF and AFOSR support for this research. \\[4pt] [1] B. D. Dawson, S. M. Lee, and J. Krim, Phys. Rev. Lett. 103, 205502 (2009) \\[0pt] [2] Zhenyin Yang; Lichtenwalner, D.J.; Morris, A.S.; Krim, J.; Kingon, A.I, Journal of Microelectromechanical Systems, April 2009, Volume: 18 Issue:2, 287-295 \\[0pt] [3] C.G. Dunkle, I.B. Altfeder, A.A. Voevodin, J. Jones, J. Krim and P.Taborek, J. Appl. Phys., 107, art{\#}114903, (2010)