Study on the microstructure and properties of copper/graphite composites with two-step method and copper-modified graphite

Abstract

In this experiment, copper was coated on the surface of graphite by chemical process. Besides, the microstructure and crystal structure of copper-coated graphite were characterized by SEM and XRD. Copper-plated C/Cu composite was prepared by SPS sintering technique of powder mixture by two-step method. In order to test the dispersion state of graphite in the composites and the phenomenon of interfacial dispersion, the effect of graphite content on the properties of copper-coated C/Cu composites was also an important point. Therefore, the microscopic characterization and performance test were carried out. The results show that magnetic stirring and high-energy ball milling ensure the uniformity of copper-coated graphite in copper matrix, and conducted structural grain refining. The grain size of copper, and the properties of composite materials decreased with the increase of graphite content, such as relative density, conductivity and hardness. However, the further increase of graphite content leads to excessive grain size, the relatively long time of ball milling makes the fine grain become larger after sintering. When the graphite content is 1.0wt.%, the relative density, conductivity and hardness are 99.91%, 92.1%IACS and 67.7 HV, respectively. It is proved that copper-coated graphite and two-step powder mixing play an important role on improving the properties of the composites.