Quantitative evaluation of nano-silica dispersion in silicone nanocomposites and its resistance to erosion and tracking

Silicone rubber nanocomposites were newly prepared for outdoor insulation in laboratory scale. This paper deals with the effects of addition of nano scale silica filler on tracking and erosion resistance of silicone rubber. Silica (SiO₂) particles of 7 nm, 40 nm, 0.5 μm and 22 μm in average of primary particle size were used as silica fillers. For effective mixing nano filler, an ultrasonic homogenizer was used. Aluminum trihydrate (Al(OH)₃ or ATH) particle of 10.5 μm in average of primary particle size was used as micro filler for comparison. Filler content was mainly fixed in 5 weight (wt) % in all composites. The dispersion state of nano filler in specimens was observed by scanning electron microscopy and then evaluated quantitatively by an imaging analysis. Inclined plane tracking and erosion test according to the IEC 60587 and arcing resistance test according to the IEC 60621 were performed to investigate effects of nano silica dispersion for erosion resistance property.