The degradation behavior of high-voltage SnO2 based varistors sintered at different temperatures

摘要

In this research, for the first time, the stability of SnO(2)( )based varistor ceramics sintered in the range of 1250-1350 degrees C against DC-accelerated aging and impulse surge current tests, was systematically studied. Microstructural study of the sintered samples by XRD and FESEM indicated that the sintering temperature only affects densification and grain size, while phase composition remains intact. With the increase of sintering temperature from 1250 degrees C to 1350 degrees C, the mean grain size increased from 1.6 to 8 The maximum nonlinear coefficient of 50 and the minimum leakage current density of 1.5 mu A/cm(2) were obtained in the sample sintered at 1300 degrees C. The breakdown electric field decreased from 800 V/mm to 270 V/mm, when sintering temperature increased from 1250 degrees C to 1350 degrees C. The samples sintered at 1250 degrees C did not show stability against neither of DC-accelerated aging and impulse current tests. The varistors sintered at 1300 degrees C exhibited the excellent resistance to DC-accelerated aging degradation, while ceramics sintered at 1350 degrees C showed the best resistance to impulse current degradation.