Basic Study Of Preparing Insulating Pouring Sealant Of Alumina

Inorganic non-metallic mineral filler is an important component of insulating pouring sealant,it not only can reduce the cost,but also can improve the dielectric properties,thermal conductivity and mechanical properties of the pouring sealant.Having an excellent chemical stability,especially in resisting SF₆,alumina was widely used by SF₆ switch.Having an extremely high insulation resistance and low dielectric loss,muscovite minerals were widely used in the insulation material.Mixed well with resin and the pouring sealant had good mechanical properties and excellent dielectric,quartz silica powder is commonly used filler.Those three kinds of mineral filler in the pouring sealant has its own merits.In order to provide the scientific basis for insulation pouring sealant preparation,application and to provide reference information of choosing which filler and so on,using the planetary ball mill,spetrum One type of Fourier transform infrared spectroscopy,NXS-11B type rotary viscometer,Z323K refrigerated centrifuge,PC68 digital high resistance meter,a self-made miniature electrode,WE-100 hydraulic universal testing machine,JSM-7500F scanning electron microscope and other equipments,focus on the effects of modified alumina by different couling agents,at the same time,focus on researching insulation properties and compressive strength of modified alumina and non-modified alumina in insulating pouring sealant,and the dispersibility and settleability in epoxy resin f modified alumina and non-modified alumina,the last,those have been comparison with other fillers.The results have been made as follows:?1?Modified alumina experiment:Hydrophobic experimental result showed that modified alumina by KH-570 and NDZ-311 have been changed from hydrophilic to hydrophobic.Infrared spectroscopy analysis confirmed that the surface of alumina powder have been changed by KH-570 and NDZ-311.The X-ray diffraction analysis shows modified alumina by the coupling agent did not change its peak.The result of the resistivity of those mineral powder filler showed:KH-570 modified alumina>NDZ-311 modified alumina>alumina.?2?The dispersibility of the alumina and the modified alumina in the epoxy resin:The result showed that the dispersibility of alumina in the epoxy resin at the condition of 60?was better than under the condition of 25?.At the same temperature,the dispersibility of the modified alumina by the coupling agent in epoxy resin was better than the unmodified alumina,the muscovite minerals and quartz silica powder.?3?The settling property of the modified alumina and the alumina in the epoxy resin:The result showed that coupling agent stopped alumina to settle,the natural sedimentation time of the modified alumina and the alumina in epoxy resin was 1098days,732 days,and the corresponding natural sedimentation rate was 7.691×10^-7mm/s,8.381×10^-6mm/s,but the settling property of modified alumina was less than the microcrystal muscovite.?4?The influence on the insulation resistance of the modified alumina and the unmodified alumina:The result showed that modified alumina by NDZ-311 had adversely affect on resistivity of insulating pouring sealant.Volume resistivity and surface resistivity of alumina insulating pouring sealant improved in some extent.The surface resistivity of insulating pouring sealant was 9.54×10¹³?,volume resistivity of insulating pouring sealant was 8.3×10¹⁵?·cm,while the amount of the modified alumina by KH-570 was 80phr,and the modified alumina insulating pouring sealant volume resistivity was obviously better than the unmodified alumina insulating pouring sealant.The modified alumina by KH-570 surface resistivity of insulating pouring sealant was less than the microcrystal muscovite insulating pouring sealant While they were at the same dosage.The volume resistivity of the modified alumina insulating pouring sealant have been greatly improved,it is better than the microcrystal muscovite?5?The influence on the compressive strength of the modified alumina and the unmodified alumina:The result showed that modified alumina by NDZ-311 had little affect on the compressive strength of insulating pouring sealant.The compressive strength of insulating pouring sealant had been little improved while the amount of the alumina was under and equal to 60phr.When the amount of alumina is between60phr and 140phr,compressive strength of unmodified alumina insulating decreased,while modified alumina has obvious effect on compressive strength.While the amount of the modified alumina by KH-570 was 100phr,compressive strength of insulating pouring sealant was 110.77 Mpa,but the compressive strength of the modified alumina by KH-570 insulating pouring sealant was less than silica powder.