| 摘要 |
<p>PURPOSE:To improve voltage-dependent nonlinearity and voltage application life characteristics by coating the side of the molded form or calcined one of a zinc oxide varistor element with magnesium, and then sintering it. CONSTITUTION:The side face of a molded form or calcined one is coated with 0.1-10mg/cm<2> of magnesium in terms of MgO, and sintered. That, is material powder is compression molded in size having approx. 40mm of diameter and approx. 30mm of thickness to obtain a molded form. Magnesium paste is formed by mixing 100g of organic binder made of ethylcellulose, n-butyl acetate, butyl carbitol with approx. 300g of MgO. The form is dipped in the magnesium paste to be coated. The coating weight is controlled by regulating viscosity by adding n-butyl acetate to the paste. The thus obtained form is exposed with the air to obtain a sintered one. Then, this material is heat treated, Al2O3 is plasma flame-sprayed on the side face, both edge faces are then polished, and aluminum flame-sprayed electrodes are provided. Thus, since the magnesium is diffused from the side faces of an element, its voltage-dependent nonlinearity is improved, and its voltage application life characteristic becomes satisfactory.</p> |
