Study On Nonlinear Conductivity And Insulation Properties Of Epoxy Resin Based Micro Nano Composites

High-voltage motor anti-corona technology is an important aspect in the field of insulation,which is directly related to the safety,reliability and service life of the unit.High-voltage motor anti-corona technology is an important aspect in the field of insulation,which is directly related to the safety,reliability and service life of the unit.In order to improve this problem,it is particularly important to produce composite materials with good nonlinear electrical conductivity properties.In this paper,micro,nano and micro-nano composite samples were prepared with epoxy resin as matrix and silicon carbide and silicon dioxide as inorganic fillers.The micro-morphology of inorganic particles and the dispersion of micro-nano fillers in composites were characterized by PLM and SEM;The electrical conductivity properties of composite materials under different field strengths and temperatures are analyzed,the change law of nonlinear properties of composite materials is studied,and the method of improving nonlinear coefficient at high temperature is obtained.Then,the breakdown field strength of the material and the dielectric constant and loss tangent at different frequencies were tested,and the polarization form and the motion of polymer macromolecular chains after doping nanoparticles were analyzed.The research results show: If the content of nanoparticles is too high,there will be obvious agglomeration.For micron Si C composites,the increase in Si C concentration leads to an increase in electrical conductivity and an increase in nonlinear coefficient;The increase in the particle size of silicon carbide leads to an increase in the electrical conductivity and an increase in the nonlinear coefficient.The electrical conductivity and nonlinear coefficient of the β-crystal silicon carbide composites are higher than those of the α-crystal type.Compared with micro-silicon carbide and nano-silicon carbide composites at the same concentration,the conductivity and nonlinear coefficient of nano-silicon carbide composites are slightly higher than those of micro-silicon carbide,and the breakdown field strength of nano-silicon carbide composites is slightly lower.The electric constant and dielectric loss are slightly higher.When nano-silica particles are added,the nonlinear coefficient of the material decreases significantly,but the breakdown field strength increases.Due to the high surface energy of nano-silica,it will be adsorbed on the molecular chain of epoxy resin,which will cause the polarization of the macromolecular chain to deteriorate and inhibit the dielectric constant and loss tangent of the material.When nano-silicon carbide is added,the nonlinear coefficient and electrical conductivity of the material will be improved.with the increase of temperature,the material expands due to thermal expansion,the Si C particles inside the matrix are in poor contact,the conductive path is unstable,and the nonlinear coefficient of the material decreases at high temperature.When nano-silicon carbide and silicon dioxide are added in a certain proportion,the composite material has better nonlinearity and higher breakdown field strength.With the increase of temperature,the electrical conductivity of the composite material will increase,and the nonlinear coefficient of the material will gradually decrease with the increase of temperature.The existence of nano-silica will have a certain inhibitory effect on it and slow down the decline of the nonlinear coefficient.