Effect of Cr coating on microstructure and properties of graphite flake/Cu composites

Cr coating was successfully deposited on the graphite flake surface by salt bath plating, and then the Cr-coated graphite flake/Cu composites were prepared by vacuum hot pressing. The morphology and phase composition of Cr coating were studied, and the effects of Cr coating on the microstructure and properties of graphite flake/Cu composites were analyzed, including interface structure, thermal conductivity, and bending strength. The results indicate that the Cr coating synthesized by salt bath plating is mainly composed of Cr₃C₂ and Cr₇C₃, however, Cr₇C₃ is reacted with graphite to form Cr₃C₂ during vacuum hot pressing sintering. Cr coating deposited on the graphite flake surface can evidently reduce the pores and gaps in the interface, resulting in an improvement on the thermal conductivity and bending strength. Compared with the uncoated graphite flake/Cu composites, the thermal conductivity of Cr-coated composites increases from 594 W·m^-1·K^-1 to 625 W·m^-1·K^-1 when the Cr-coated graphite flakes content is 60% by volume, and the bending strength is increased by 58%.