Study On Dielectric Properties Of SiC/SiO₂/EP Micro-nano Composites

Epoxy resin(EP)is widely used in aerospace,electronic instruments,insulation materials and other fields because of its high insulation,mechanical properties,thermal and chemical stability.With the continuous development of science and technology,many high-tech fields put forward higher requirements for the performance of epoxy resin materials.Therefore,how to obtain better performance of epoxy resin has become a research hotspot of scholars at home and abroad.Due to their special properties,micro and nano particles can change many properties of the matrix when combined with epoxy resin.Researchers have gradually carried out the research on the properties of micro nano composite.Therefore,this paper prepared the micro-nano composite based on epoxy resin and studied its dielectric properties.In this paper,silicon carbide(SiC)particles with a particle size of 2?m are selected as inorganic micro fillers,and silicon dioxide(SiO2)particles with a particle size of 80nm treated by KH550 are selected as inorganic nano fillers,The samples of EP and SiC/SiO2/EP micro-nano composite with different proportion of inorganic dispersion phase were prepared by melt blending;The micro structure of the composite was characterized by scanning electron microscopy(SEM);The alternating current breakdown characteristics of EP and its composites were tested by power frequency alternating current test platform;The volume conductivity of epoxy resin and its composites under different field strength different temperature was measured by high voltage direct current conductivity testing equipment;The dielectric constant and loss of epoxy resin and its composites at different frequencies and temperatures were measured by broadband dielectric spectrometer and high voltage Xilin bridge.The experimental results show that in the alternating current breakdown test,the introduction of micro particles and nano particles with low content will reduce the breakdown field strength of epoxy resin,and the high content of nano particles will increase the breakdown field strength of epoxy resin;The test of electric conductivity changing with electric field strength shows the conductivity of epoxy matrix increases with the addition of inorganic particles,M2N3 and M3N2 in the composite samples show good nonlinear characteristics with the increase of electric field strength;The test of conductivity changing with temperature shows in the whole temperature range,the total conductivity barrier characteristic value of epoxy resin sample is the largest.The effect of micron silicon carbide particles on the decrease of ion transport barrier is the most obvious.With the increase of the content of nano silica particles and the decrease of the content of micro silicon carbide particles,the characteristic value of the total electric conductivity barrier increases gradually;The dielectric spectrum test shows that the relative permittivity of all samples decreases with the increase of frequency,The addition of inorganic particles increases the relative dielectric constant of epoxy,In the micro-nano composite,the higher the content of silicon carbide particles,the larger the relative permittivity.The loss factor of all samples decreases first and then increases with the increase of frequency,When the frequency is low,the higher the content of silica particles,the greater the loss factor of the sample;The dielectric temperature spectrum test shows that the relative dielectric constant and loss factor of the composite are larger than that of the epoxy resin,and the change rule is similar;When the temperature is less than 120?,the relative permittivity and loss factor of all samples have little change,When the temperature reaches 120?,the relative permittivity and loss factor of all samples increase rapidly;In all composites,the higher the content of silicon carbide particles,the larger the relative dielectric constant of the samples,When the temperature is in the range of 20??120?,the higher the content of silica particles,the greater the loss factor of the sample.