PURPOSE: To form a dense layer at a high yield rate, and to improve environmental resistance by a method wherein the molded body of a zinc oxide type lightning arrester element is dipped into a borasic acid solution, and after the molded body has been dried up and calcined, primary firing is conducted, and secondary firing is conducted by coating a highly resistant layer forming material on the side face of the molded body.
CONSTITUTION: The title lightning arrester element is mainly composed of zinc oxide, and bithmuth oxide, antimony oxide, cobalt oxide, manganese oxide, chromium oxide, silicon oxide of 0.1 to 2.0mol% respectively, for example, are added as additives, also aluminum nitride of 0.01 to 0.1mol% is added as an additive, and they are crushed, mixed, granulated and molded. The molded material is dipped into a supersaturated borasic acid (H3BO3) aqueous solution, it is dried up, and after it has been calcined, a primary firing is conducted at 1010°C. Then, the sintered material is coated with a mixture of ZnO-SiO2-Bi2 O3-Sb2O3 to be used for formation of a side face high resistance layer, a secondary firing is conducted at 1190°C, and polishing and electrode attaching operations are conducted.
KOBAYASHI MASAHIRO
FUJIWARA YUKIO
