What force causes particles to stick to surfaces ?

International audienceParticle adhesion to conducting surfaces is of broad concern in industrial systems where particles can stick to the metal walls of reactors, pipes, etc. We are particularly interested in dust adhesion in Tokamak fusion reactors, where the adhesion of oxide coated particles to reactor walls prevents dissemination of radiologically and chemically hazardous dust into the environment during loss of vacuum scenarios (Rondeau et al. 2015).In dry systems, particle adhesion is governed by van der Waals (vdW) forces and electrostatic forces. For a charged particle in contact with a conducting surface, an image charge of opposite polarity is induced in the conductor causing an attractive electrostatic force. It is commonly assumed that vdW forces dominate adhesion and electrostatic forces are of second order importance and can be neglected (Bowling, 1988). This is unambiguously the case for particles contacting flat surfaces where vdW forces are up to thousands of times larger than electrostatic forces for small particles (~1 µm). However, this simple analysis neglects the complexities of real systems