Study On The Amelioration Of The Formula Of ZnO Varistor

ZnO varistor boast excellent non-linear volt-ampere characteristics, the large surgeabsorption capacity; they have been widely used as the over-voltage protection device invarious electronic devices, electronic equipment, lightning surge, load switching surgeabsorption and other electronic devices. With the development of the computer, homeappliances, communications technology and other aspects, the demand of the normaloperation of protection system components will continue to increase.But domesticmanufactures of pressure-sensitive resistor has a high cost, low profit margins and ahigh residual pressure radio （about2.3-2.6）. The purpose of this issue is to study andsolve the current problems.This dissertation describes doping SnO₂in the ZnO varistors and the changes ofthe formula after the adding of SnO₂, and the system process adapted with the newformula （mainly about the sintering temperature）.The result shows that after addingSnO₂the total additive system has been effectively reduced, the new formula has ahigher breakdown voltage gradient than the current commercial ZnO varistors andfinally the new formula has a lower voltage residual radio. So it has a better protectionof electronic devices. After this the paper introduces the reason of the higher breakdownvoltage and lower voltage residual radio. After adding SnO₂the O ions between grainboundaries have a more complete ionization and the grain resistance has beeneffectively reduced, so the new formula has a higher breakdown voltage and a lowervoltage residual radio. Finally this paper introduce some other work （mainly about thepreparation of additive components use Sol-Gel）, the result shows that the currentcapacity of ZnO varistors can be effectively improved by the introduction of Sol-Gel.