Major effects on varistor properties and impulse aging behavior of Zn–V–Mn–Co–Dy ceramics with small sintering changes

Abstract

The effect of sintering temperature on varistor properties and impulse aging behavior of ZnO–V₂O₅–MnO₂–CoO–Dy₂O₃ ceramics was systematically investigated. As the sintering temperature increased, the average grain size increased from 5.8 to 10.8 μm, whereas the sintered density decreased from 5.56 to 5.47 g/cm³. The breakdown field and the nonlinear coefficient increased from 1,812 to 3,379 V/cm and from 11 to 36, respectively, with an increase in the sintering temperature up to 925 °C. The varistor ceramics sintered at 950 °C exhibited the best clamp characteristics for the impulse-current of 1–50 A, with the clamp voltage ratio of K = 1.63–2.31. The varistor ceramics sintered at 925 °C exhibited the strongest stability against an impulse-current, with $\% \,\Updelta {\text{E}}_{{ 1 {\text{ mA}}/{\text{cm}}^{2} }} = - 8. 1 \,\% ,\;\%\, \Updelta \alpha = - 4 4. 4\, \% ,{\text{ and}}\;\%\, \Updelta {\text{J}}_{\text{L}} = 3 8. 9\, \%$ after applying the multi-impulse-current of 400 A.