W-Cu Composites Reinforced by Copper Coated Graphene Prepared using Infiltration Sintering and Spark Plasma Sintering: a comparative study

In order to solve problems of significant interfacial reactions and agglomeration in graphene reinforced W-Cu composites, powders of copper coated graphene (Cu@Gr) were pre-mechanically mixed with tungsten and copper powders, and then graphene doped W-Cu composites were sintered using two different methods, e.g., spark plasma sintering (SPS) and infiltration sintering. Microstructural analysis showed that the doped Cu@Gr powder can effectively inhibit the interfacial reaction between graphene and tungsten, prevent the segregation of graphene, and evenly distribute the copper in the binder phase. When the mixed concentration of Cu@Gr was 0.45wt.%, uniform distributions of W phase and Cu phase were obtained in the composite, and the mechanical properties and conductivity of this composite achieved their best results. When the doping content was further increased to 0.8%, WC phase was found in all alloys, thus resulting in poor mechanical and physical properties. Comparing the microstructures produced using these two methods, the composites prepared using the infiltration sintering method showed network distribution of copper phase and segregation of copper, whereas the composites prepared using the SPS method showed network skeleton phase of tungsten. Although the SPS process was performed in a much shorter time, the mechanical properties of the composites sintered using the SPS process did not show much differences with those sintered using the infiltration sintering method.