Investigation on the electric charge decay of micropowder prepared by jet milling/electrostatic dispersion

The micropowders prepared by the combination method of jet milling and electrostatic dispersion (jet milling/electrostatic dispersion, J/E) show the good dispersibility, but the electric charge carried by particles will vanish gradually in air, making the dispersion effect of particles weaken and even disappear. Using CaCO₃ powder and barium ferrite powder as the raw materials, a novel non-contact method was designed to measure the electric charge decay of the charged particles in this paper, and the charge decay process of two different powders was investigated. The results indicate that, the attenuation of charge to mass ratio (q/m) of the charged particles presents the exponential relationship in air. The higher the charging voltage is, the larger the initial rate of decay is, and the charge to mass ratio is larger at the same time of repose during the whole decay process. In addition, the charge storage performance of powders is related to the particle size and the relative permittivity, the smaller the particle size is and the larger the relative permittivity is, the better the charge storage performance shows.