The Korean Journal of Ceramics

The Korean Ceramic Society (한국세라믹학회)
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The Effect of Additives on Twining in ZnO Varistors

  • Han, Se-Won (Department of Electrical Engineering, Hanyang University, Division of electrical materials, Korea Electrotechnology research Institute) ;
  • Kang, Hyung-Boo (Department of Electrical Engineering, Hanyang University)
  • Published : 1998.09.01
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Abstract

By comparison of the experimental results in two systems of ZnO varistors, it's appear that Sb2O3 is the indispensable element for twining in ZnO varistors and the Zn7Sb2O12 spinel acts as the nucleus to form twins. Al2O3 is not the origin of twining in ZnO varistor, but it was found that Al2O3 could strengthen the twining and form a deformation twining by ZnAl2O4 dragging and pinning effect. The inhibition ratios of grain and nonuniformity of two systems ZnO varistors increase with the increase of Al2O3 content. The twins affect the inhibition of grain growth, the mechanism could be explained follow as: twins increase the mobility viscosity of ZrO grain and grain boundary, and drag ZrO grain and liquid grain boundary during the sintering, then the grain growth is inhibited and the microstructure becomes more uniform.

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