In this paper, we study the role of ductile separation on the evolution of gold-on-gold micro-contacts. A specially designed SPM contact test station has been used to conduct the cycling tests. The evolution of contacts is studied by monitoring the characteristics of the pull-off force. The magnitude of the pull-off force, the force vs. displacement curves, and the rate-dependent pull-off force are sampled during cycling. It is found that ductile separation causes significant and random modification of the contact surfaces. The magnitude of the pull-off force also changes due to the variation of surface morphology. Significant plastic deformation during ductile separation can form a plateau region in the force-displacement curve which is characteristic of ductile separation. This deformation can also contribute to a higher pull-off force when the contacts are cycled at 300Hz compared with cycling at 0.5Hz. The difference between these rate-dependent pull-off forces can be used to indicate the degree of plastic dissipation during each separation.

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