Adhesion of solids

We report results of studies of adhesion of two solids on a microscopic level. We show that the Johnson-Kendall-Roberts theory [Proc, R. Soc. London A 324, 301. (1971)] remains valid even at this level, and that the effects of roughness and an intervening fluid can be accounted for by adjusting the value of the work of adhesion. We study adhesion hysteresis and demonstrate that, in our system, it arises from bulk effects. We also find that the detachment of spherical particles from solid surfaces occurs at smaller values of the shear rate than predicted by continuum theory, due to slip between the particle and the solid surface which is not taken into account by continuum theories.