Study On The Formula And Preparation Technology Of ZnO Varistor

ZnO varistors, whose most representative products including multilayer chipvaristor and extra-high voltage znic oxide arrester recently, have been widely used inelectronic protection area with excellent electrical properties. Especially outstandingperformance and large surge absorption capacity of the protective components arehighly required with the rapid development of China’s economy. Currently commercialZnO varistors, which are produced at home, have the characteristics of lowerbreakdown voltage, comparatively high residual voltage ratio and high cost. So theresearch is carried out under the situation.The dissertation focus on the improvement of the electrical performance of thevaristor on the base of the formula of SnO2doped ZnO varistor. The experiment ismainly done in the following two aspects: On one hand, the formula adjustment trend isdetermined through the factor test method, the result optimized is listed below: additivequantity of manganese and cobalt should be improved while stannum should be reduced,and bismuth’s content remains unchanged. On the other hand, preparation process ofSol state compound additive of Co,Mn,Bi,Ni is explored, and it is found thatcomponents prepared by Sol state compound additive method(Sol-method) have bettermicrostructure uniformity. The experiment result shows that the agglomerationphenomenon decreased, additives distribute more uniform in the grain boundary.Meanwhile, better consistency and more stable performance were obtained after testing.Furthermore, breakdown voltage was up to449.6V/mm, nonlinear coefficient was47,and leakage current was0.76μA. The surge absorption capability value can achieveabout107%of national standard when the voltage variation being10%, with residualvoltage ratio being1.92. The phenomenon of slightly decreasing of the doped ZnO’sdiffraction angle is observed when using XRD for phase analysis. Manganese, whichmakes interplanar spacing increase and the diffraction angle decrease, is supposed toplay a leading role in causing lattice distortion according to the comparison betweenCASTEP simulation and experiment result.