Investigation of the Insulating Properties of Si–Al–B/Epoxy Nanocomposites

Epoxy resin (EP) faces significant limitations in electronic applications due to its short corona resistance lifetime, while nanomaterial modification technology offers new avenues for enhancing its performance. This study synthesized a composite oxide (organic Si-Al-B composite oxide) using phenyl triethoxysilane (PTES), tributyl borate, and aluminum isopropoxide as monomers via a hydrolytic condensation reaction. By adjusting different doping levels, a series of epoxy resin composites (Si-Al-B/EP composites) were prepared. This study aimed to enhance the material's corona resistance while maintaining other electrical properties. The epoxy composite was systematically characterized and evaluated through X-ray photoelectron spectroscopy (XPS), dielectric property testing, breakdown field strength testing, volume resistivity measurement, and corona life testing. Results indicate that the Si-Al-B/EP composite exhibits optimal comprehensive performance when the molar ratio of Si:Al:B is 9:2.5:1 and the doping level is 8 wt %. Compared to pure EP, this composite demonstrates an approximately 13-times higher corona resistance lifetime and a 35% increase in breakdown field strength, while achieving a slight reduction in both dielectric constant and dielectric loss.