Fabrication And Properties Of Copper Matrix Composite Reinforced By Cu-coated Graphite And Nano-sicp

Pantograph slide is the most important part of electric locomotive. with the development of railway electrization, the requirment about the capablity of slide is improving. A kind of preparation technology-powde metallurgy technology was developed, and a copper matrix composite material slider with low attrition rate and high conductivity was fabricated. In term of the slider material, copper powder was used as conduction phase, graphite powder was used as self-lubrication phase and nano-SiCp was used as reinforment phase. By increasing the graphite content and doing the surface modification of graphite powder, we can adjust the mechanical and wear properties of composite material.Graphite and copper are not wet in high and low temperature. In order to enhance the bonding strength of graphite and copper, the basic techniques of copper coating on graphite particls was discussed. The copperizing technique of loading capacity of 4g/L, pH value of 12.5 to 13, temperate of 60 to 65 and initial concentration of HCHO 15ml was chosen. Analysis results show that the surface of Gr was successfully coated with copper layer.The copper materix composite was made by sintering-hot repressing. The volume fraction of nano-SiCp was 3%, the volume fraction of graphite by copper coating was 5%,10%,15% respectively. To compare, Two copper materix composite was made, as the volume fraction of Gr was 10%, the volume fraction of nano-SiCp were 0% and 3%. The microstructure of copper matrix composite was observed by means of OM, SEM and TEM. The mechanical property at room temperature, the electronic conductivity and friction wear performance were also studied.The results show that: Copper plating could improve the wettability and infercial boding between matrix and particles. By copper coating, Graphite particles can more evenly distributed in the copper matrix composite, the material is more compact, the material has higher room temperature mechanical properties and conductivity than uncoated. With the increasing of Gr/Gr(copper plating) volume fraction, the room temperature mechanical properties and conductivity is graduately decreasing.By copper plating, the material has better wear performance. In the same wear condition, With the increasing of Gr/Gr(copper plating) volume fraction, the friction coefficient and wear volume graduately decreased. Under the same sliding speed condition, with the load increasing, the friction coefficient and wear volume graduately decreased too.