Research On The Forming And Sintering Process Of High Gradient Zinc Oxide Resistor

With the rapid development of the electrical industry, except the good reliability of zinc oxide arrester, the requirement of the economic and miniaturization in the zinc oxide arrester become higher and higher.Because of zinc oxide resistor served as the core part of zinc oxide arrester, people paid attention to the high potential gradient and high electrical properties of the zinc oxide resistance plates.The basement of zinc oxide resistor plate is formulation, which is achieved by preparing technologies. The electrical properties of the resistor disc mainly depend on its composition of the synthetic resistor disc, manufacturing process and the microstructure. In this paper, in the premise of determining the novel formulation about the high gradient of zinc oxide resistance plates, by the application of a traditional manufacturing process, all kinds of factors have been analyzed, which appears in the processes of zinc oxide resistance plates forming and sintering can affects its electrical properties. By improving of the preparing technology, the potential gradient of the zinc oxide resistance plates will be increased and the reliability of all kinds of electric properties can be guaranteed.Firstly, the cause of generating defects of molding process about high gradient of zinc oxide valve element have been investigated. By comparing with the reason of conventional molding process defects on the zinc oxide resistance plates of the routine potential gradient is 200V/mm, the influence of the molding process on the defects has been researched. Optimizing the molding process, using the proper molding machine, controlling the quality indicators of molding powder particles and exploring the forming mechanism and defects influence mechanism, all of those work have been done for determining the best molding process.Secondly, the cause of the defects of firing processes about high gradient of zinc oxide resistance plates have been investigated. By comparing analysis, the reasons of firing process defects on the zinc oxide resistance plates of the routine potential gradient is 200V/mm and the influence of the atmosphere, temperature, time and speed etc in the firing process on the defects have been researched. The best firing process has been determined based on the analyzing of the microstructure and the firing mechanism and defects influence mechanism.Finally, the electrical properties of zinc oxide varistor are tested. The influences of the forming technologies of the conventional zinc oxide varistor and high gradient zinc oxide varistor on the defect mechanisms are analyzed and the influence of forming and sintering process on the high gradient ZnO varistors are discussed.