ZINC OXIDE-BASED SINTERED COMPACT, ZINC OXIDE VARISTOR, AND LAMINATION TYPE ZINC OXIDE VARISTOR

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PROBLEM TO BE SOLVED : To solve the problems in firing of the conventional zinc oxide varistor that the firing generates a pyrochlore phase and the like being solid at low temperature and results in high-temperature sintering and therefore electric power consumption is heretofore high and the materials liable to evaporate at elevated temperature are heretofore wasted. SOLUTION : Cr2O3-containing Bi2O3 compound synthetic powder is prepared by previously mixing Cr2O3 and Bi2O3 so as to attain a molar ratio of 1 : 02 to 0.15 and heat treating the mixture. A ZnO-based sintered compact is obtained by adding at least 0.05 to 5.0 parts by weight the Bi2O3 compound synthetic powder, 0.1 to 10.0 parts by weight at least one oxide selected from the group consisting of respective oxides of Sb, Ti, Sn, Zr, Nb, Ta, V, Mo, W, Si, and rare earths, and 0.5 to 7.0 parts at least one compound selected from the group consisting of respective oxides of Bi, Co, Mn, Ni, and B, and boric acid and Al salt, to 100 parts by weight ZnO and mixing the mixture, then molding the mixture and firing the molding at 700 to 980°C. An electrode and side face insulation coating are formed therefrom and the zinc oxide varistor having excellent electric characteristics is thus obtained.