Adhesion measurements for electrostatic powder coatings using drop test rig and virtual oscilloscope

The total forces holding a layer of electrostatically charged powder onto a work piece result from the combination of an interfacial electrochemical phenomenon at the surface, inter particle/particle cohesion and a bulk electrostatic attractive force. An attempt has been made to obtain the total integrated effect by assessing the force that is required to selectively remove the powder layer from a metal substrate. This is a destructive measurement that disrupts the powder layer. All the measurements are taken with the powder layer before fusing. Powder adhesion measurements have been obtained from an impulse drop test, incorporated with a charge pick up device (CPD), Faraday cup, micro balance, Keithley Electrometer and CVI National Instrument Virtual Oscilloscope. Sample results are presented for powder coating using standard tribo and negative corona gun.