Microwave Sintering and Electric Properties of ZnO Varistor Ceramics

Abstract

The ZnO varistor ceramics were fabricated through microwave sintering at 800~1150°C using ZnO powder doped and undoped TiO2 prepared by planetary ball mill. And the effects of milling time, sintering temperature and doping on microwave sintering technique have been studied. The result shows that the powder is more homogeneously and with smaller particle size with the increasing of milling time, therefore the electric properties is improved. However the particle size and the electric properties tend towards stability after 20h milling time. The density and electric properties increase with the increasing of sintering temperature, but decrease sharply at 1100°C, so the best sintering temperature is 1100°C. Doping TiO2 improves the electric properties of ZnO, however the electric properties decrease with more than 2.5% doping.