Study Of Nano Diamond On Mechanical Properties And Electrical Insulation Properties Of Epoxy Resin Composites

With the rapid development of UHV in China,UHV basin-type insulators need to bear greater mechanical and electrical stress.Epoxy resin composite is made of epoxy resin,inorganic filler and curing agent.It is the key material to prepare basin-type insulator and directly affects the performance of basin-type insulator.The results show that the properties of epoxy resin composites can be effectively improved by adding inorganic nanoparticles as fillers.Nano diamond not only has high mechanical strength,excellent insulation performance,excellent thermal conductivity,negative electron affinity and low field emission threshold,but also has mature preparation process and low cost,so it is suitable to be used as inorganic nano filler to enhance the properties of epoxy resin composites.It meets the needs of the development of UHV in China that studying the influence of nano diamond on the mechanical properties and electrical insulation properties of epoxy resin composites and preparing epoxy resin composites with high mechanical strength,good toughness and strong electrical insulation ability.Therefore,the following work has been carried out in this paper.(1)In order to avoid the influence of the dispersion of epoxy resin composite on the research of nano diamond,the composite curing agent was used to reduce the dispersion of epoxy resin composite.In this paper,PA and HHPA were compounded to prepare epoxy resin / compound curing agent composite cured samples,and their mechanical strength and breakdown strength were tested.The results show that the compound curing agent can reduce the melting point of anhydride,so that the temperature window of epoxy resin mixture during curing is expanded,and the control difficulty of curing process is reduced.The dispersion of material properties is greatly reduced while the maximum mechanical strength and breakdown strength are hardly reduced.(2)In order to explore the influence of nano diamond on curing characteristics and mechanical properties of epoxy resin composites,the curing exothermic,viscosity change,tensile and bending properties of epoxy resin / nano diamond composites were tested.The results show that the addition of nano diamond can reduce the exothermic peak of epoxy resin curing,reduce the rate of viscosity growth,and improve the mechanical strength of epoxy resin composites.When the amount of nano diamond is 6 phr,the tensile strength and bending strength of epoxy resin composites are improved to the maximum,in which the tensile strength is increased by 11%,and the bending strength is increased by 7.8%.At the same time,the yield point was found in the stress-strain curve,which indicated that the toughness of epoxy resin composites was enhanced by adding nano diamond.(3)In order to explore the influence of nano diamond on the electrical insulation properties of epoxy resin composites,the electrical properties of epoxy resin / nano diamond composites were tested.The results show that with the addition of nano diamond,the shallow trap energy density increases,the surface resistivity decreases,the surface charge dissipation rate increases,and the surface flashover voltage increases.When the amount of nano diamond is 8 phr,the surface flashover voltage increases by 17.6%,while the volume resistivity and breakdown voltage increase first and then decrease When the content of nano diamond is 8 phr,the arc resistance is increased by 211.25%.