Effects of nano-SiO2 particles on surface tracking characteristics of silicone rubber composites

Compared with neat silicone rubber composites (SiRCs), SiRCs filled with nano-sized SiO2 particles at weight ratios from 0.1 to 1.0 wt. % exhibit a higher surface flashover voltage and a greater resistance to surface tracking. Scanning electron microscopy images of tracking morphologies indicate that the SiO2 particles are situated in close proximity to the polymeric chains and act as bridges to stabilize the chains and maintain the structure of the composite. Higher concentrations of nano-sized SiO2 particles, however, (above 0.3 wt. %) produce defects in the molecular network which lead to reductions in both the surface flashover voltage and the resistance to surface tracking, although these reduced values are still superior to those of neat SiRCs. Therefore, SiRCs filled with nano-sized SiO2 particles, especially at an optimal weight ratio (0.1 to 0.3 wt. %), may have significant potential applications as outdoor insulators for power systems.