Study On Corona Aging And Modification Of Epoxy-based Nonlinear Composite

At the three junction points of gas insulated lines,motors,and other power equipment,the electric field is usually concentrated,which is prone to cause corona discharge and threatens the safe operation of power equipment.Nonlinear composites have the characteristic of uniform electric field distribution,which plays a good role in suppressing corona discharge in gas insulated lines and motor ends.However,the influence and mechanism of corona discharge on nonlinear composites are still unclear.Therefore,it is necessary to conduct research on the corona aging performance of nonlinear composites.This article uses silicon carbide as the filler and epoxy resin as the matrix to prepare silicon carbide/epoxy resin nonlinear composites,and conducts corona aging treatment on them.Firstly,the influence of corona aging time on the microstructure and electrical properties of 40wt% silicon carbide/epoxy resin nonlinear composites was investigated.Then,the influence of filler loading(i.e.30,40,and 60wt%)on the corona aging characteristics of nonlinear composites was studied.Finally,the influence and mechanism of the loading(i.e.1,2,and 5wt%),molecular weight,and type(i.e.APEG,OP,and OPP)of organic small molecule fillers on the corona aging resistance of nonlinear composites were investigated.The experimental results indicate that corona aging can cause the oxidation and decomposition of hydroxyl groups in nonlinear composites,while also causing the fracture of C-H bonds.Corona aging leads to a more irregular surface structure of nonlinear composites.As the corona aging time increases,the relative dielectric constant and loss tangent of nonlinear composites gradually increase,the shallow trap density gradually increases,the breakdown strength decreases,and the nonlinear coefficient and switching electric field of nonlinear conductivity characteristics also decrease.With the increase of silicon carbide filler loading,the impact of corona aging on the electrical properties of nonlinear composites is becoming smaller and smaller.APEG help to reduce the relative dielectric constant and loss tangent of nonlinear composites after corona aging,and reduce their shallow trap density.It also helps to improve the nonlinear coefficient of nonlinear composites after corona aging.The OP reduces the relative dielectric constant and loss tangent of the nonlinear composites after corona aging,and increases its nonlinear coefficient.Compared with APEG and OP,the addition of OPP with the same loading reduces the relative dielectric constant of the nonlinear composites after corona aging,increases its shallow trap density,and reduces its breakdown strength and nonlinear coefficient.The influence of different types of organic small molecule fillers on the electrical properties of nonlinear composites is different.