| 摘要 |
A zinc oxide varistor comprises a sintered body (1), the side surfaces of which are coated by a high-resistance layer (2). The major component of (1) is zinc oxide. (1) has itself varistor characteristics. (2) is composed of a crystallised glass contg., as major component, SiO2 (6.0-15.0 wt.%). The high resistance layer of the side surfaces comprises PbO (50.0-75.0 wt.%), ZnO (10.0-30.0 wt.%), B2O3 (5.0-10.0 wt.%) and SiO2 (6.0-15.0 wt.%). This compsn. is the crystallised glass coating compsn. The zinc oxide varistor is produced by coating a glass plate contg. the above-mentioned crystallised glass and an organic cpd. on the side surfaces of the sintered body (10.0-150.0 mg/cm2 thick) and heating at 450-650 deg.C. The linear expansion coefft. of the crystallised glass is 65 x 10 power (-7) to 90 x 10 power (-7)/deg.C. The high resistance layer coated on the side surfaces of the sintered body can be PbO contg. molybdenum oxide (0.1-10.0 wt.% calculated as the MoO3) or a PbO-ZnO-B2O3-MoO3 system crystallised glass having the compsn.: PbO (50.0-75.0 wt.%), ZnO (10.0-30.0 wt.%), B2O3 (5.0-15.0 wt.%), SiO2 (0-15.0 wt.%) and MoO3 (0.1-10.0 wt.%). |
