Study On Copper Based Electrical Contact Composites Modified By Multi Component

The electrical contact is the key device of the electrical switch,and its performance will directly affect the reliability of the switch operation and the life of the switch.Most of the electrical contact materials are processed by the silver based composites in the low voltage apparatus.But silver,as a precious metal,is very expensive and limited in production.Because copper has excellent electrical conductivity and low cost,copper based contact is very promising in place of silver based electrical contact.However,when copper is used as an electrical contact material,it is easy to be oxidized to form non-conductive oxide film,and the tendency of arc erosion and fusion welding is more serious,which seriously affects the stability of contact material performance.In this paper,the problems of copper based electrical contact materials are studied.Because the electrical contact materials are diverse in performance when applied to practical applications,a metallic material cannot be satisfied at the same time.Usually two or more metals or nonmetals are combined to make composite materials.Therefore,this paper attempts to add different components to the design of material components and make full use of the advantages of each added component to improve the comprehensive performance of the material.In this experiment,the effects of carbon nanotube,graphene and nano carbon powder with excellent properties on the microstructure and properties of copper are studied The effects of carbon content,ball milling time and adding ingredients on the properties of copper were investigated by orthogonal test.The results show that with the increase of carbon content,the hardness increases first and then decreases,while the conductivity decreases gradually.Through the comprehensive analysis,the better performance of the carbon nanomaterials is determined as graphene,and the milling time is 4h.Then the copper based electrical contact material reinforced with graphene was discussed.Due to the large surface area of graphene,it is easy to be reunion and is poor in compatibility with copper matrix.Therefore,graphene is coated with silver on the surface to enhance the wettability of graphene and copper based electrical contact materials.Meanwhile,chemical silver plating is applied to improve the oxygen resistance of copper powder and explore the effect of different silver content on its properties.After the pretreatment of coarsening,sensitization,activation,and electroless plating,a layer of metal silver was successfully coated on the surface of graphene.At the same time,two methods were used to electroless silver plating on the surface of copper powder.The results show that the silver plating effect of sensitized and activated pre treated samples is obviously better than that of electroless plating on the surface of copper powder.Copper based electrical contact materials were prepared by powder metallurgy,and the results show that with the increase of graphene content,the relative density and hardness of the two groups increase first and then decrease,while the conductivity decreases gradually.Compared with all aspects of the contact material,the silver plating samples were superior to those of the untreated samples.Through the comprehensive analysis of the structure and properties of the materials,when the addition amount of graphene is 0.2wt.%,the performance is the best.The relative density,hardness,oxidation weight gain and IACS of the materials obtained by the optimum process parameters were 90.0%,53.4HB,1.6mg/cm2 and 76.2%,respectively.In order to improve the anti arcerosion and welding properties,contact materials,experimental study on different metal oxides?ZnO,SnO₂?with different silver content of silver plated copper powder on the properties of materials,through the comparative analysis of the results:with the increase of silver content,sample density and hardness increased first and then decreased,and the electrical conductivity decreased graduallyIn order to improve the mechanical properties,arc erosion resistance and fusion welding performance of materials,the effects of different metal oxides?ZnO and SnO₂?on the properties of materials were studied.comparison and analysis of the results,it is found that the density and hardness of the sample increase first and then decrease with the increase of silver content,and the The addition of MeO can greatly reduce the friction coefficient of copper based materials,and make the material's friction and wear capacity improved significantly.The friction resistance of SnO₂ sample is better than that of ZnO.conductivity decreases gradually.The addition of MeO can effectively improve the anti arc erosion ability of the material.The arc erosion resistance between the two groups is almost the same,but the effect is higher than that of pure copper.When two conductors contact each other,an arc is generated,which makes the surface of the specimen warm up instantly and melt into a molten pool in the contact area of the contact.Due to the dispersion of SnO₂ and ZnO particles in the matrix,the viscosity of the molten pool increases,so that the droplet splashing decreases under the action of viscous force,which can significantly improve the arc erosion resistance of the material.The comprehensive analysis shows that when the silver plating content is3wt.%,the sample with SnO₂ has excellent performance.By adding rare earth elements?Pr,Nd,Sm?to improve the oxidation resistance of copper and to study the effects of different rare earth and content on the properties of copper based electrical contact materials.The rare earth can greatly reduce the oxidation of the material,and the range is 24.4%,which can effectively improve the antioxidant capacity of the material.This is mainly due to the active chemical properties of rare earth,which can impede the diffusion process of copper ions and oxygen through the oxide layer by solid solution and forming a dense and continuous oxide layer on the surface of copper,thus reducing the oxidation rate of copper based contact materials.The antioxidant capacity of the materials is from high to low order as:Nd,Pr,Sm added sample.The rare earth can refine the grain.With the increase of rare earth content,the hardness of the sample increases gradually,and the friction coefficient decreases gradually,which greatly improves the mechanical properties of the material.However,with the increase of the content of rare earth,the conductivity of the sample decreased.