Comparative evaluation of long-term corona- and environmentally-aged high-temperature vulcanized silicone rubber nano-composites

This study presents an aging evaluation of high-temperature vulcanized silicone rubber nanocomposites subjected to corona-induced deterioration over different durations, as well as their retardation through the incorporation of nanosized fillers to improve high-voltage insulation performance. In addition to performing corona aging using a multi-needle electrode test system for 72, 172, and 272 h, the test samples were aged in a specially constructed chamber for 5040 h under AC voltage and different environmental stresses, including temperature, humidity, ultraviolet radiation, and acidic and salt fog. Following these different aging treatments (corona/environmental stress), diagnosis based on surface partial discharge and volume/surface current was performed to determine modifications in the electrical properties of the materials under investigation. As a result, the deterioration of the tested samples’ surface properties was indicated by an increase in the mean partial discharge magnitude. Furthermore, a significant change in surface conductivity was noticed at high ambient temperature and test voltage. The results showed that under the given experimental arrangement, corona discharge for about 272 h is adequate to cause considerable degradation of the material properties. Overall, the sample containing 5 wt% of boron nitride demonstrated consistent performance under all investigated conditions, leading to improved aging resistance against different stresses.