Zinc Oxide Varistor Prepared by Low-Temperature Sintering of ZnO Nano-Powder and its Electrical Properties

Influence of particle size of starting material, mixing time by ball mill and sintering atmosphere on microstructure and electric property was investigated. Two kinds of ZnO powders with particle sizes of 0.8 *mm and 50 nm were used as starting materials. They were mixed with oxide additives by ball mill for 18-200 h respectively. And then, they were sintered at 800-1100DGC in O2 gas atmosphere or in air. The discs sintered from normal powder (0.8 *m) showed better electric property than those sintered from nano-powder ZnO(50 nm). Electric property was stabilized by ball mill mixing for long time. Densities of samples sintered in O2 atmosphere were higher than those of samples sintered in air.