The Improvement Of The Performance Of The Low-voltage ZnO Varistors

ZnO varistors boast the excellent nonlinear volt-ampere characteristic, sound surge absorption, and quite a low current leakage under steady-state voltage circumstances.(low energy consumption). With these features it can be used in over voltage protection, lightning arresting, surge absorption etc. With the advancement of computers, household appliances, communication technology, the demand for low voltage varistors is in a great increase to ensure the normal operation of these systems. However, the whole industry sees a low rate of finished product in low voltage ZnO varistors, and the existent ones are easy to absorb moisture and show poor performance in dealing with high-current shocks. Based on the above mentioned situation, our lab have carried out exploring research works to solve these problems.This paper would introduce the idea of the research works and the methods we have adopted in our lab. We have replaced the traditional solid-phase preparation method with wet chemical preparation methods. Through the introduction of TiO₂ sol, ZnO seed, Co,Mn,Bi co-precipitation powders , an encouraging improvement has been made in the 8/20μs surge current absorption and the withstanding rectangular current pulse (2ms) capability of ZnO varistors. Then the paper would as well elaborate the full-sol method which makes the most additives of varistors be sol, enhances by a large margin the performance of high current impact and displays extraordinary characteristics of limited voltage which could help the average 8/20μs surge current climb to 1000A (the sample diameter is 8.8mm) and get the limited voltage ratio to range from 3 to 4. Resorting to the analysis of SEM,XPS,TG-DTA and some other materials to tackle problems occuring in the process of the experiments would meanwhile be illustrated in the paper, and so would the evidence of the experimental results .