Analysis of adhesion forces between particles and wall based on the vibration method

An indirect method for the measurement of adhesion forces between a particle and a wall is presented. The vibration method [1] is based on particle re-entrainment from a vertical-sinoidal vibrating surface caused by its inertia at a certain acceleration. Acceleration of the vibrating surface is measured and calibrated using a laser-scanning-vibrometer. Correlating particle re-entrainment events with acting acceleration permits the calculation of adhesion forces. For horizontal dislocation of re-entrained particles the vibrating surface is placed in a flow channel and exposed to a laminar air flow (Re-channel = 1514) parallel to the surface. Adhesion force measurements were carried out for glass spheres (20-30 and 60-70 mum), tin spheres (20-30 mum) and corn starch-fumed silica mixtures (10-20 mum) on a silicon wafer substrate at an air temperature of 20-25degreesC and relative humidity 8-14%. Experimentally obtained values were compared with a model presented by Rabinovich et al. [2] based on the Rumpf model, which integrates the r.m.s value of the contact surfaces measured with atomic force microscopy (AFM). It was found that adhesive force agreed approximately with the van der Waals force.