Effect of alumina types on properties of epoxy resin casting materials for ultra-high voltage (UHV) electrical applications

Al₂O₃ is more economical and easier to be physically doped to prepare epoxy resin (EP) composites for actual production. The effect of various alumina types on the properties of epoxy resin casting materials intended for Ultra-High Voltage (UHV) electrical applications was investigated. The electrical and mechanical properties of epoxy resin casting materials were examined. Based on the assessment of physical and chemical properties, as well as electrical and mechanical characteristics, A-Al₂O₃/EP exhibited the highest glass transition temperature (<i>T_g</i>) and the most efficient curing process, with its viscosity changing at the fastest rate. The tensile strength, flexural strength, impact strength (7.5 J), compressive strength and elongation (tensile and flexural) tests demonstrated that A-Al₂O₃/EP possessed commendable mechanical properties. Furthermore, A-Al₂O₃/EP displayed superior electrical properties, according to the evaluations of electric breakdown strength, dielectric constant, and volume resistivity. The viscosity growth of A-Al₂O₃/EP was the fastest at 110 and 120 °C, and the <i>T_g</i> of A-Al₂O₃/EP was the highest in the three samples, displaying both mechanical and electrical tests. It could be concluded that A-Al₂O₃ significantly facilitated the curing reaction. Moreover, GIS units incorporating epoxy resin casting materials were developed using A-Al₂O₃ as the filler.