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Progress in Preparation of ZnO Based Varistor Ceramics

  • O. Milošević
  • D. Vasović
  • D. Poleti
  • Lj. Karanović
  • V. Petrović
  • D. Uskoković

Abstract

Chemical preparation methods were used to fabricate ZnO-based varistor ceramics having nonlinearity coefficients between 35–45, breakdown fields ranging from 400–1000 kV/m and leakage currents far less than 10−2 A/m2.The processing steps employed include (1) chemical synthesis of powders having a complex initial composition of the form (100−y) ZnO+y (additives) with y selected from the group of soluble salts of Bi, Sb, Co, Mn, Ni and Cr, then (2) calcination of as-prepared powders within the temperature interval from 373 to 1473K and (3) sintering at temperatures from 1373 to 1573K. Two different methods for powder preparation were used: 1) evaporation of ZnO suspensions with additive solutions and 2) coprecipitation of additive solution and afterwards by adding ZnO.

Various analytical methods such as optical and scanning electron microscopy, DTA, TGA, X-ray and EDAX were used in characterizing the powders and the resulting ceramics. Processes of formation of the main phases as well as their influence on resulting non-Ohmic behaviour, was investigated.

Keywords

Calcination Temperature Spinel Phase Nonlinearity Coefficient Additive Solution Breakdown Field 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer Science+Business Media New York 1989

Authors and Affiliations

  • O. Milošević
    • 1
  • D. Vasović
    • 1
  • D. Poleti
    • 1
  • Lj. Karanović
    • 1
  • V. Petrović
    • 1
  • D. Uskoković
    • 1
  1. 1.Institute of Technical Sciences of the Serbian Academy of Sciences and Arts and Belgrade UniversityYugoslavia

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