Surface roughness change of epoxy/TiO2 nanocomposites due to partial discharges

Partial discharge degradation of an epoxy nanocomposite with 5 weight % additions of nanoscale TiO₂ particles was investigated in comparison with that of an epoxy resin without nanofillers. Such materials were subjected to PDs under the IEC(b) electrode configuration for evaluation. Surface roughened by PD attack was inspected by a mechanical surface profilometer and a scanning electron microscope. Erosion depth and surface roughness were selected as indexes of surface degradation in this research. It is elucidated that surface degradation of the nanocomposite due to PDs is caused by erosion of epoxy matrix around the nanofillers. As the surface degradation proceeds, large agglomerates of the nanofillers appear on the eroded surface. Erosion depth and Surface roughness are far smaller in the specimens with nanofillers than those without nanofillers. This result indicates that the epoxy/TiO₂ nanocomposite is more resistant to PDs than that without nanofillers.