Measurement of Adhesion Forces between Particles and Rough Substrates in Air with the Vibration Method

Abstract

Pull-off forces were measured using the vibration method at 30–50% relative humidity for glass and tin spheres on a variety of substrates. The results were compared with those obtained through the colloidal probe technique. Both methods show good agreement for small particle sizes. Since the vibration method causes sinusoidally alternating stresses, the method yields detachment and contact forces between particles and substrate of the same order of magnitude. Alternating contact forces of the vibration method can cause an increase in the adhesion force through flattening of asperities, which also depend on the surface roughness and the mechanical properties of particle and substrate.Pull-off force measurements with the colloidal probe technique and special attention to the influence of the contact force also show an adhesion force intensification with increasing contact forces depending on the surface roughness. No significant adhesion force intensification caused by increasing contact time to 30s at several contact forces was observed. For theoretical predictions based on van der Waals adhesion, an approach presented by Rabinovich and approximations of plastic micro-asperity flattening were combined.