Preparation of Spherical Bi_2O_3 Powder by Plasma and Precipitation Processes

摘要

Spherical Bi_2O_3 powder prepared by plasma chemical vapor reaction and aqueous chemical precipitation is studied. The superfine spherical Bi_2O_3 powder with an average diameter of 1 μm is made by plasma process. During the precipitation process, the micrograph of the Bi_2O_3 powder can be controlled through the reaction temperature, the rate of addition of the precipitation reagent, the reaction time and the amount of the dispersant. Accordingly, spherical Bi_2O_3 powder with diameters ranging from 2 μm to 3 μm is prepared. The spherical Bi_2O_3 particles have such advantages as uniform size distribution and excellent dispersing property. ZnO varistors made from the resultant powder exhibit properties of a low discharge voltage ratio, great eligibility coefficient measured by a rectangle wave of 2 ms 800 A and good stability in the above characteristics.