Basic Research On Application Of Thermal Conductive Filler In Composite Insulating Silicone Rubber Composites

In recent years,with the continuous development of power systems,higher requirements have been placed on the insulation of composite insulators.To meet the equipment requirements,the umbrella material of silicone rubber composite insulators also needs to be optimizated.In this work,silicone rubber(SR)was choosed as the matrix,vinyl trimethoxysilane(A 171)was used as the coupling agent,and boron nitride(BN)and aluminum nitride(AlN)were used as the heat-conducting filler,which blends into matrix with aluminum hydroxide(ATH)to prepare SR/BN(AlN)/ATH and SR/BN(AlN)/ATH/A171 composites;On the premise that the amount of fillers kept constant,the mechanical properties,dielectric properties,breakdown strength and thermal conductivity of the silicone rubber composites before and after the modification of the filler were studied and analysed by regulating fillers ratio,and the cross-sectional morphology was observed to analyze the dispersion of the filler on the rubber matrix.For silicone rubber composites prepared by blending BN and ATH into matrix,the breakdown strength and thermal conductivity of silicone rubber composites increased with the content of BN fillers,when the number of BN reached 100 phr,the breakdown strength of the composite increased by 50%,and the thermal conductivity was also greatly improved;As the number of BN increased,the dielectric loss of the composite decreased,and the mechanical properties of the composite also increasingly deteriorated.Moreover,the addition of the coupling agent also improved the dispersion of the filler on the matrix,at the same filler fraction,the mechanical properties,breakdown strength and thermal conductivity of the composite modified by the coupling agent of the filler were improved compared with unmodified,and the thermal conductivity was increased by about 23%,while the dielectric loss became lower.Silicone rubber composites were obtained by replacing the ATH with AlN blending into silicone rubber.The mechanical properties of the composite decreased with the increase of the AIN fraction.When the AIN filler fraction was large,the viscosity of the composite became larger,resulting in reducation of processing performance and mechanical properties.The breakdown strength,dielectric loss and thermal conductivity of the silicone rubber composite increased with the increase of the AlN fraction,when the filling fraction of AlN changed from 0 phr to 150 phr,the thermal conductivity of the composite increased 35%,and the breakdown strength also increased from 22.1 kV/mm to 26.4 kV/mm,moreover,the dielectric loss of the composite decreased from 0.012 to 0.002 at 100Hz.All performance of the composite improved at the same filler fraction compared with unmodified ones,and the degree of deterioration of the mechanical properties is also suppressed.