Research Of The Insulation And Mechanical Properties Of Micron Al₂O₃/EP Composite Material Modified By Plasma

Because of its good mechanical and dielectric properties, micro-Al2O3/Epoxy (EP)composites were widely used in busbar connections, insulators, transformer insulation and other high voltage electrical equipments as solid organic insulation materials. However, condition of the interfacial bonding between Al2O3 inorganic filler and EP organic matrix would affect the insulation and mechanical properties of Al2O3/EP composites. In order to improve the surface activity of micron Al2O3 filler and strengthen the interface bonding between filler and matrix,which met the power industry's higher performance requirements for composites, the composite surface modification of low temperature plasma and coupling agent is introduced in this paper.In this paper, the low temperature plasma is formed by repeated pulse Dielectric Barrier Discharge (DBD) , and two kinds of surface modification methods are used to treat micron Al2O3 filler by modification of coupling agent and coupling agent combined with low temperature plasma. By scanning electron microscopy, Fourier Transform infrared spectrometer and X-ray photoelectron spectroscopy observing the surface morphology, chemical structure,element content of micron Al2O3 filler. Then, the Al2O3/EP composites of 10wt%?70wt% filler are prepared under two different modification methods, and the Fracture of composites is observed. Finally, the partial discharge inception voltage, transient AC breakdown voltage and tensile strength data of the composites are obtained by measurements.The results show that the coupling agent combined with low temperature plasma composite modification can effectively enhance the surface activity of micron Al2O3. Compared with single coupling agent modification, the grafting rate of the coupling agent on the filler surface is raised by 24.5%, and the content of oxygen-containing group is increased by 3.32%.The plasma produces severe etching on the surface of micron Al2O3, and the surface energy can be increased. The increase of surface activity promotes the bonding between the filler and the matrix, which makes the bonding between the two interfaces more solid and the dispersion of micron Al2O3 in the Al2O3/EP composites more uniform. Compared with coupling agent modification, when the filling amount of composite modified Al2O3 is 40wt%, partial discharge inception voltage and tensile strength of the Al2O3/EP composites reaches the highest, partial discharge inception voltage performance is increased by 22%, tensile strength is increased by 13.1%. when the filling amount of composite modified Al2O3 is 50wt%, breakdown voltage of the Al2O3/EP composites reaches the highest, performance is increased by 43.5%.In summary, the coupling agent combined with low-temperature plasma composite modification can effectively improve the agglomeration of micron Al2O3 in EP matrix by strengthening the chemical bonding between filler and substrate. Finally, insulation and mechanical properties of Al2O3/EP composites are improved by good interfacial bonding.