Electrostatic Charges of Abrasive Powders: The Role of Particle Size and Humidity

Electrostatically coated abrasives have drawn vast attention in many industrial applications. Therefore, influence of humidity on the electrical properties of alpha-SiC and alpha-Al2O3 abrasive powders with three mu m-range particle sizes are here investigated using electrostatic charge and DC resistivity analysis. From the three particle size ranges used, 15-16 mu m, 60-63 mu m and 153-156 mu m, the intermediate one (60-63 mu m) is found to be associated with the highest charge values, measured using a double Faraday cup method, as well as the highest resistivity for both materials. However, comparing SiC and Al2O3 powders, the latter ones present about twice larger charges in dry and normal humidity states accompanied by several orders of magnitude larger resistivity. Under humid conditions all the powders reveal diminishing charge and resistivity values.