The effects of graphene content on the corrosion resistance, and electrical, thermal and mechanical properties of graphene/copper composites

Graphene reinforced copper matrix (G/Cu) composites were prepared by temperature-programmed sintering of their mixtures in molds under pressure. The effects of graphene content on the microstructure, and electrical, thermal, mechanical and corrosion properties of the G/Cu composites were investigated. Results show that the hardness, tensile strength, yield strength, thermal and electrical conductivities, and corrosion resistance of the composites all reached maxima at a graphene content of 0.5 wt.%. The addition of graphene increased the thermal and electrical conductivities, tensile and yield strengths, and hardness of the composites, but led to defect formation in the graphene due to the thermal expansion mismatch between graphene and copper. Therefore, an optimal graphene content was needed to obtain the best improvement of these properties. Tafel and electrochemical impedance tests using the composite as the working electrode, Pt as the counter electrode and a saturated calomel electrode as a reference electrode showed that the composite with a graphene content of 0.5 wt% had the lowest corrosion current of 3.45×10−6 μA/cm2 and the highest charge transfer resistance of 1705 Ω·cm2.