Role of interphase on the resistance to high-voltage arcing, on tracking and erosion of silicone/SiO2 nanocomposites

In this study a two kinds of silicone/SiO₂ nanocomposites were tested with respect to their resistance to high-voltage arcing, the resistance to tracking and erosion and their TGA performance. The silicones with filler type F1 show a high improvement of the resistance to high-voltage arcing and the resistance to tracking and erosion at very low filler contents. Furthermore, a maximum resistance to high-voltage arcing is observed for these nanocomposites at a filler content of 5% wt. In contrast to that the silicones with filler type F2 show no significant improvement for both resistances. The effects are explained by the ratio of interphase to matrix material, which is estimated by the Interphase Volume Model. The thermogravimetric analysis (TGA) shows that the resistance to thermal degradation is significantly higher for the silicones with filler type F1 already at a filler content of 0.5 wt.% compared to the material without any fillers. The resistance to thermal degradation for the materials with filler type F2 is significantly lower. This result is also explained by the high interphase content.