Experimental Study On Space Charge And Dielectric Properties Of Micro-or Nano-Inorganic Particles/Epoxy Resin Composites

It is becoming increasingly difficult for ordinary expoxy to meet the current requirements,because of the higher demand of the industry on the electrical insulation properties of epoxy resin.It is one of the hot research topics that polymer properties are changed to meet the industry and research needs by adding inorganic nanoparticles into it.Epoxy resin composites prepared by adding BN or Al₂O₃ into epoxy matrix material have increasingly attracted industry concern for the wide application prospect in high-power power electronics device insulation substrate.We hope to research the effects of BN and Al₂O₃ particles on the electrical insulation properties of epoxy resin composites in this paper,based on the experiment of the electrical insulation properties.In order to research the effects of different BN particle contents,different BN diameters and coupling agent on space charge and dielectric property of high temperature curable epoxy resin composites,micro-,untreated nano-and surface treated nano-BN/epoxy resin composites were prepared in laboratory.The microscope analysis,breakdown strengths,broadband dielectric spectrum,temperature dielectric spectrum and space charge of experimental samples were measured in this paper.The experiment shows that micro-BN can decrease the breakdown strength of BN/epoxy resin composite;nano-BN can increase the breakdown strength of BN/epoxy resin composite;and the breakdown strength of BN/epoxy resin composites decrease with the increasing of micro-or nano-BN concentration.The adding of micro-and nano-BN can decrease the average space charge density of BN/epoxy resin composite under high DC electric field,and they increase with the increasing of micro-or nano-BN concentration.The average space charge densities of untreated nano-BN/epoxy resin composites are more than micro-BN/epoxy resin composites during the polarization and less than micro-BN/epoxy resin composites during the depolarization.Meanwhile,the adding of coupling agent can decrease the average space charge density of nano-BN/epoxy resin composite during the polarization and increase the Space charge dissipation rate during the depolarization.The permittivity,dielectric loss and conductivity of BN/epoxy resin composites decreased comparing with neat epoxy resin.Permittivity of micro-and untreated nano-BN/epoxy resin composites decreased with the increasing of BN particles content.Permittivity of surface treated nano-BN/epoxy resin composites increased with the increasing of BN particles content.Permittivity of neat epoxy and BN/epoxy resin composites increased with the increasing of temperature under 10?¹10?.Dielectric loss of neat epoxy and BN/epoxy resin composites increase significantly with the increasing of temperature under 50?¹10?.In order to research the effects of different Al₂O₃ particle contents,different Al₂O₃ diameters and room temperature curing on space charge and aging resistance of room temperature curable epoxy resin composites,micro-and nano-BN/epoxy resin composites were prepared in laboratory by adding Al₂O₃ into epoxy resin.The space charge and AC aging in high hygrothermal environment of experimental samples were measured in this paper.It is found that more space charges appeared in micro-composites and nano-composites comparing with neat epoxy resin,which increased with alumina particles content.It's discovered that micro-alumina particles have an obvious sedimentation phenomenon in samples of micro-alumina/epoxy resin composites which were prepared with room temperature curable epoxy resin.The samples of micro-alumina/epoxy resin composites show different contents of micro-alumina between the up and down layer.The space charges were detected again after AC aging at 20kV/mm under the environment of 80?,90%RH.It is found that the ability of withstanding aging of nano-composite is stronger than that of neat epoxy and micro-composite.