Comparison between silicone rubber containing micro- and nano- size silica fillers [insulating material applications]

In this study, the influence of nano-size silica filler is compared with micro-size filler in silicone rubber using the ASTM 2303 inclined plane tracking and erosion test. Silicone rubber samples filled with 5 μm mean size ground silica are compared with silicone rubber filled with 12 nm average size fumed silica. Both the low frequency components of leakage current and eroded volume are used to evaluate the performance of the two types of composites. While the fundamental component of leakage current does not correlate with the erosion, the third harmonic component of the leakage current shows good correlation to the erosion, in terms of volume, and for both composites. Based on the results of the eroded volume, it is observed that 10% by weight of nano-size filler in the silicone rubber gives a performance that is similar to that obtained with 50% by weight of micro-size filler. The paper discusses the merits of nano-size filler in silicone composites.