The degradation of silicone rubber composites with ZnO microvaristors under impulse voltage

Abstract

Abstract In this study, the degradation behavior of silicone rubber (SiR) composites with ZnO microvaristors under impulse voltage was investigated. Typical impulse voltages with different amplitudes were applied to the samples, and the degraded threshold electric field (E b) and nonlinear coefficient (α) of the samples were obtained by conductivity test after every impulse was applied. Scanning electron microscope and energy dispersive spectroscopy were used to characterize the micro performance of the samples. The failure of the SiR composites was found to be attributed to the aging behavior in the microstructure of ZnO microvaristors, which was divided into four stages caused by the precipitation of Bi2O3 and the dissipation of the honeycomb grain-boundary structure. The mechanism of degradation was internal local heat accumulation and damage of the microelement caused by the thermal stress, generated by impulse voltage. This work is helpful to develop smart composite materials with self-adaptive capability to control high electrical field and increase the stability and durability of power apparatus and electronic devices.