| 摘要 |
PURPOSE:To decrease a leak current and limit voltage by calcining the molding obtd. by molding of a specific porcelain material in a nonoxidative atmosphere and heat-treating the sintered body obtd. in such a manner in the oxidative atmosphere. CONSTITUTION:A mixture (A) is obtd. by mixing 100mol parts oxide of Ti, 100mol parts SrCO3 or Sr compd. which is made into the oxide of Sr by high- temp. decomposition, and 0.001 to 2.500mol parts semiconductor additive consisting of >=1 kinds selected from respective metal oxides of Nb, W, La, Ta, Ce, Nd, Y, Sm, Dy, and Gd. The component A is then calcined at 800 to 1300 deg.C in the oxidative atmosphere to obtain the semiconductor porcelain material (B) contg. SrTiO3. The mixture for varistor is then obtd. by mixing 100mol parts component B in terms of the SrTiO3 and 0.020 to 2.000mol parts >=1 kinds of metal oxides (C) selected from respective oxides of Si, Al and Cu. This mixture is molded and is calcined in the nonoxidative atmosphere. The sintered body obtd. in such a manner is heat-treated at about 1100 deg.C in the oxidative atmosphere, by which the varistor porcelain 1 is produced. |
