Characteristic analysis of surface damage and bulk micro-cracks of SiR/SiO2 nanocomposites caused by surface arc discharges

Anti-pollution flashover coating made by room temperature vulcanized (RTV) silicone rubber (SiR) has been widely used in electrical equipment insulation. However, it faces many outstanding problems; for example, the erosion caused by surface arc discharges. This paper presents the characteristic analysis on surface damage and bulk microcracks of SiR/SiO
₂
nanocomposites caused by surface arc discharges in order to better understand the suppression mechanism of nano-SiO
₂
particles. The specimens were prepared by adding nano-sized SiO
₂
particles into neat RTV SiR with different weight ratio and the experiments were performed according to IEC 60587. During the experiments, a high-speed camera was used to record the discharge processes. After the experiments, the eroded parts of each specimen were dyed by methylene blue solution. Also, a high-power microscope was used to observe the bulk micro-cracks. Then, an image processing technology was used for processing the surface damage images, bulk cracks images, and discharge light images to analyze the effects of adding nano fillers in SiR. The results show that as the content of nano-SiO2 fillers increases, the distribution ranges of black solid residues and dry-band traces caused by surface arc discharges tend to decrease. It indicates the increasing resistance to surface damage. Moreover, the depth of bulk micro-cracks and their area ratio show a decreasing tendency. It reveals the decreasing propagation of bulk micro-cracks. In addition, the reducing total luminance of discharge light shows the decrease of discharge intensity. Therefore, at the certain weight ratios, the addition of nano-SiO
₂
particles can not only improves the resistance to surface damage, but also inhibits the propagation of micro-cracks tracking in SiR bulk.