Nanodiamond Modified Micron Alumina for Improved Breakdown Voltage and Thermal Conductivity of Epoxy Composites

The high power and miniaturised design of power equipment brings serious heat dissipation problems and better requirements for the thermal conductivity of epoxy composites. The high thermal conductivity epoxy composites often require the addition of a large amount of thermally conductive fillers, which can introduce interfacial defects to reduce the insulation performance, so it is important to improve the insulation performance of the material at high filler levels for safe equipment operation. In this paper, diamond was doped into the alumina/epoxy composites and the thermal conductivity reached up to 1.06 W/(m·K) and the breakdown voltage was increased by 2 kV compared to undoped diamond. Density functional theoretical (DFT) calculations verified the enhancement mechanism of diamond on the insulation performance of epoxy composites. This method enables an increase in the thermal conductivity of the material while ensuring that the breakdown voltage does not drop significantly.