Study On The Fabrication And Wear Properties Of Copper Matrix Composite Reinforced By In-situ Al₂O₃ Particle

With the development of modern industry,the performance requiments of materials are more and more higher.Pure copper has good performance of plastic deformation,conductivity and thermal conduction;but of low strength and poor wear resistance.It is difficult for the traditional copper alloys to have good strength and conductivity,it can not satisfy the devmoelopment of modern industry.The copper composites prepared by artifitial composite have good strength as well as high conductivity and high temperature properties.In this thesis,Cu/Al₂O₃ composite reinforced by Al₂O₃ particle gained from in-situ reaction,was prepared by combining methods of self-propagating high-temperature synthesis(SHS) with the traditional foundry process.Thus, making the incorporation of alumina-surface strengthening and part fabrication come true,as a result,create a new way for the industrialized application of copper-based composite.The process parameters such as reaction temperature,pressure for formation of the precast block,the ratio of aluminum powder and copper oxide powder etc have great influence on the microstructure and properties of the composites.The results indicate that the appropriate process parameters are as follows:the ratio of aluminum powder and copper oxide powder(mass ratio) is 2:1,the copper powder addition amount accounts for 5%of the total mass, precast block forming pressure is 12MPa,and point of pouring is 1120℃。The performances of composite were also investigated such as micro-hardness,microstructure,phase composition,surface and interfacial distribution and electrical conductivity etc.The results showed that,the interfaces of the composite prepared by the process mentioned above were distinct,the base is copper,the composite layer is composed of the Alumina and Copper,and their distribution was homogeneous.The electrical conductivity of the Copper base is 92%IACS,and the composite layer is 47%IACS, Micro-hardness of the composite is increased by 130%compared with pure copper.The fretting wear behavior of pure copper and composites in ball-surface approach was studied on condition of dry friction and oil-lubricated.The relative wear resistance improved about 2～5 fold in the air,and 2～7 fold in the oil compared to that of pure copper.The wear mechanism of composite is adhesive associate with abrasive in the air,as load increase,the wear mechanism changed into fatigue;while it is abrasive under low load and associate with slight fatigue under high load in the oil.