Study on ZnO Varistors Doped with Y2O3 by Microwave Two-step Sintering

Abstract

The zinc oxide varistor prepared in this paper is mainly composed of submicron zinc oxide powder and dopants, and is prepared by two-step sintering method, which is in contrast with traditional sintering method and ordinary microwave sintering method. The effects of microwave sintering temperature and holding time on the microstructure and electrical properties of ZnO varistors were investigated. The results show that the potential gradient of microwave sintering is higher than that of traditional sintering, but the leakage current also increases. Compared with ordinary microwave sintering, the two-step sintering can further effectively reduce the grain size, enhance densification, not only improve the potential gradient, but also reduce leakage current. In two-step sintering, increasing sintering temperature can effectively reduce leakage current and non-linear coefficient, but the potential gradient is also greatly reduced. When the holding time is more than 1 hour, there is little difference in electrical performance. When the holding time is too small, its electrical performance is weak overall.