RESISTANCE TO SLIDING ON ATOMIC SCALES IN THE ADHESIVE CONTACT OF 2 ELASTIC SPHERES

The structure and stability of agglomerates of micron-sized particles is determined by the mechanical properties of the individual contacts between the constituent particles. In this paper we study the possibil ity of aggregate rearrangements by sliding. Since the contacts between (sub)micron particles are only a few hundred atoms in diameter, proce sses on atomic levels will play the dominating roll. We study a theore tical model of sliding friction for surfaces that are either flat or c ontain steps in their grids. The results shows that sliding over hat s urfaces may produce a large range of friction coefficients, including zero if the adhesive forces are small compared to the binding forces i nside a body. However, both grid alignment and steps in the surface wi ll lead to high values for friction. These processes combined virtuall y eliminate the possibility of sliding in a collision of two (sub)micr on-sized particles at velocities low enough for sticking to occur. On the other hand we show that in collision between aggregates sliding ma y be an important factor for energy dissipation and compaction.