Effect of Low-Temperature Sintering on Electrical Properties and Aging Behavior of ZVMNBCD Varistor Ceramics

Choon-Woo Nahm

Korean Journal of Materials Research, Vol.30, No.10, 502-508, October, 2020

DOI10.3740/MRSK.2020.30.10.502 Export Citation

Effect of Low-Temperature Sintering on Electrical Properties and Aging Behavior of ZVMNBCD Varistor Ceramics

Choon-Woo Nahm^†

Department of Electrical Engineering, Dongeui University, Busan 47340, Republic of Korea

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This paper focuses on the electrical properties and stability against DC accelerated aging stress of ZnO-V2O5-MnO2- Nb2O5-Bi2O3-Co3O4-Dy2O3 (ZVMNBCD) varistor ceramics sintered at 850 - 925 °C. With the increase of sintering temperature, the average grain size increases from 4.4 to 11.8 mm, and the density of the sintered pellets decreases from 5.53 to 5.40 g/ cm3 due to the volatility of V2O5, which has a low melting point. The breakdown field abruptly decreases from 8016 to 1,715 V/cm with the increase of the sintering temperature. The maximum non-ohmic coefficient (59) is obtained when the sample is sintered at 875 °C. The samples sintered at below 900 °C exhibit a relatively low leakage current, less than 60 mA/cm2. The apparent dielectric constant increases due to the increase of the average grain size with the increase of the sintering temperature. The change tendency of dissipation factor at 1 kHz according to the sintering temperature coincides with the tendency of the leakage current. In terms of stability, the samples sintered at 900 °C exhibit both high non-ohmic coefficient (45) and excellent stability, 0.8% in ΔEB/EB and -0.7% in Δα/α after application of DC accelerated aging stress (0.85 EB/85 °C/24 h).

Keywords:Zn-V-based ceramics;sintering;electrical properties;aging behavior;varistors

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