Charging characteristics of some powders used in electrostatic coating

Preliminary studies have been carried out on charging characteristics of two epoxy powders and a polytetrafluoroethylene (PTFE) by measuring charge-to-mass ratios (Q/m). The epoxy powders were charged by corona current and the PTFE by triboelectric. The results indicate that for the PTFE powder, the mean Q/m is inversely proportional to the particle radius, whereas for epoxy powders the pigmentation and the surface chemistry of the particles have a dominant effect on the mean Q/m values. The deposition efficiencies of the epoxy powders were found to be a function of the mean Q/m.