Measurement of the Deformation and Adhesion of Rough Solids in Contact

Abstract

A contact mechanics approach is used to study the impact of deformations on the adhesion between microscopically rough gold and molecularly smooth mica. The surface forces apparatus was used to directly measure deformations at the interface and in the bulk, while also controlling applied loads. Surface forces and applied loads act to deform gold asperities in an unrecoverable fashion. Concurrent bulk deformations, namely the nominal area of contact, are also nonreversible. Using Johnson−Kendall−Roberts theory to interpret these findings illustrates how adhesion between the bodies effectively increases with increasing load. Correlating this phenomenon to deformations at the interface details how adhesion varies when multiple metallic asperities contact and deform under external stress. Moreover, observed hysteresis is explained.