Effects Of Sintering Process And Doping Pre-Composite Additives On Properties Of ZnO Varistors

Since the discovery of ZnO varistors in the 1970s,Because of its unique volt ampere characteristics and excellent current capacity,it is widely used in high voltage arresters and inrush current protection devices.At present,it plays the part of significant role in many fields,such as electrical system,power electronics,building disaster avoidance,military radar and so on.How to obtain ZnO varistors with excellent performance and wide application is the focus of scholars all over the world.The purpose of writing this article to discuss the sintering process of ZnO varistors and the influence of pre composite additives on their properties,so as to prepare ZnO varistors with excellent comprehensive properties.Firstly,the optimum sintering process of ZnO varistor and the importance of each process were studied,The effect of temperature rising speed,sintering temperature,holding time and cooling speed on the electrical performance and density of ZnO varistor was considered.The results of the study show the best sintering process factors and influencing factors are sintering temperature 1150℃,holding time 4h,cooling rate60℃/h and heating rate 30℃/h.Then,the effect of doping pre composite additives on the properties of ZnO varistors was studied.the pre synthesized Bi Sb O₄和Zn₂Si O₄were doped into ZnO varistors,The influence of doping ratio in the micro aspect,electrical properties and current-pass ability of ZnO varistors are studied.the research findings suggest ZnO varistor can effectively inhibit the ZnO grain size,the crystal structure becomes compact and uniform,and the densification is improved after doping Bi Sb O₄and Zn₂Si O₄,and the pressure-sensitive property and the flow-pass ability are effectively improved.When the doping ratio of Bi Sb O₄and Zn₂Si O₄is 3:1,the density of the sample is 5.58 g/cm³,the varistor voltage gradient is 425 V/mm,the nonlinear coefficient is 70,the leakage current is 0.12×10^-6A/cm²,the residual voltage ratio is2.5,and the varistor voltage change rate is 4.8%.