Sliding and rolling of individual micrometre sized glass particles on rough silicon surfaces

Abstract

Access to the tribological contact behaviour of individual small particles is crucial with respect to many applications in particle technology. In this paper, we present a simple nanoindentation based approach to study the rolling friction of micrometre sized spherical particles. The results are compared to sliding friction tests, which are carried out by a nanoindentation based colloid probe technique. The potential of the approach is evaluated for borosilicate glass spheres featuring nominal radii of 2·5 and 10 μm in contact with silicon surfaces. The roughness of the latter is modified by a plasma etching process. Significant differences of sliding and rolling friction with respect to roughness are observed even though the variation of root mean square roughness only ranges from 0·3 to 2·7 nm respectively.