Corona resistance performance of epoxy resin modified by hydrophobic fumed SiO₂

The hydrophobic fumed SiO₂ particles were dispersed in solvent-free epoxy resin (EP) by sand milling, hydrophobic fumed SiO₂/EP composites with different hydrophobic fumed SiO₂ mass fractions were prepared by heating and curing. The results of XRD detection and SEM observation confirm that the hydrophobic fumed SiO₂ nanoparticles are uniformly dispersed in EP in amorphous form. The results of the physical and chemical properties of the hydrophobic fumed SiO₂/EP composites show that the thermal stability, dielectric constant, dielectric loss and electrical conductivity of the hydrophobic fumed SiO₂/EP composites increase with the increase of the doping amount of SiO₂ nanoparticles. The breakdown field strength reaches the maximum value of 24.66 kV/mm with 2wt% nanoparticle addition, which is 21.35% higher than the pure EP. When the doping amount of SiO₂ nano particles is 8wt%, the corona life of the hydrophobic fumed SiO₂/EP can reach 42.7 h, which is 18.9 times that of the pure EP.