Study On Preparation And Performance Of Graphene Reinforced Copper Matrix Composites By One-step In-situ Reduction Method

Due to its excellent intrinsic properties and mechanical properties,graphene is widely used as a reinforcement in the preparation of copper-based composites.However,graphene is prone to agglomeration,and it is difficult to disperse evenly in the copper matrix.It is also difficult to disperse it uniformly using the traditional powder metallurgy process;To some extent,the quality of the interface combination also basically determines the performance of the composites,while the interface of graphene and copper is poorly wetted,making it difficult to exert the desired reinforcement effect in the copper matrix.In this paper,GO,which can be stably dispersed in solution,is used as a precursor to prepare graphene-supported copper(Cu@RGO)and graphene-supported cobalt(Co@RGO)powders by one-step in-situ reduction mehod.Ultrasonic dispersion combined with wet grinding is used to mix it with ultra-fine copper powder.Compared with direct ball milling,this method of mixing powder in solution is more convenient and has little damage to the graphene structure.Finally,spark plasma sintering(SPS)was used to prepare graphene-loaded copper/cobalt reinforced copper matrix composites(Cu@RGO/Cu,Co@RGO/Cu),and their morphology observation and performance analysis were carried out.The results show that:(1)The prepared GO is in the form of pleated tulle,and its surface contains a large number of hydrophilic oxygen-containing groups and defects,which provide nucleation points for the subsequent loading of metal particles;(2)Cu@RGO and Co@RGO powders were successfully prepared by one-step in-situ reduction method.The reduced Cu and Co particles are all nano-sized and more evenly distributed in the graphene sheet structure,which can inhibit the graphene in reunion under vander waals forces;(3)Ultrasonic dispersion combined with wet grinding can make the proper amount of Cu@RGO and Co@RGO powders evenly dispersed in the copper matrix;(4)With the increase of Cu@RGO contents,the density and electrical conductivity of Cu@RGO/Cu composites gradually decrease,the hardness increases first and then decreases,and the friction coefficient gradually decreases.The wear mechanism is mainly changed from adhesive wear and abrasive wear to delamination wear;when the contents of Cu@RGO is 0.45 wt.%,the microhardness of the composites is 123 HV,which is 40%higher than that of pure copper,the density is 96.95%,and the electrical conductivity 93.86%IACS;The friction and wear performance is the best when the contents of Cu@RGO is 0.60 wt.%.Under the friction condition of 6 N,the average friction coefficient is 0.34 and the wear rate is 5.89×10~-99 mm~3/(N·M),compared with pure copper,reduced by 52%and 73%respectively;(5)The density,hardness,and friction coefficient of Co@RGO/Cu composites increase first and then decrease as the sintering temperature increases,and the electrical conductivity gradually decreases;when the sintering temperature is 700℃,the microhardness of the composites is126 HV,and the density is 97.39%,the conductivity is 88.12%IACS,the friction coefficient is the smallest,the wear morphology is mainly furrows and pits,the wear form is mainly abrasive wear,delamination wear and oxidative wear,the composites have the best comprehensive performance;(6)The hardness and density of graphene-loaded with metal particles reinforced copper matrix composites are better than graphene/copper composites,indicating that loading copper or cobalt particles on the surface of graphene can enhance the interface between graphene and copper,and to a greater extent,the loaded copper and cobalt particles are similar to micro-rolling bearings,which can improve friction performance.