Advanced Powder Technology, Vol.26, No.2, 454-461, 2015
Advanced characterization of particles triboelectrically charged by a two-stage system with vibrations and external electric fields
In this study, we propose a new method to effectively characterize particle tribocharging caused by repeated contact with a wall in an external electric field. We perform experiments using a two-stage system consisting of two inclined vibrating plates and electrodes. The mass flow rate and charge of particles were controlled at the first vibrating plate, and the charge that was transferred from the plate to the particles was obtained from the difference between the charges on particles at the lower and upper ends of the second vibrating plate. In addition, electric currents generated by the charge transfer were simultaneously measured at the second vibrating plate. From these measurements, we verified that the charge balance in this system holds. Furthermore, we found that the charge transfer depends on various factors, such as the initial charge, chemical and electrical properties, travel length of particles, and the external electric field. We also found that the equilibrium charge of particles depends on the chemical property and external electric field. The equilibrium charge and the rate of tribocharging were evaluated analytically from the relationship between the initial and transferred charges without changing the travel distance of particles. This method enables the rapid and reliable analysis of the particle tribocharging process. (C) 2014 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.