Effect of graphene on the microstructure, thermal conductivity, and tribological behavior of cast B319 Al alloy

In this research, the effect of adding 0.1 – 0.7 wt% of graphene on the microstructure, hardness, thermal conductivity, and tribological response of cast B319 Al alloy was investigated. Addition of 0.1 wt% graphene increased the hardness of cast B319 alloy from 77 to 92 HV, which was the result of grain refinement and the modification of the Si phase. At 0.3 wt% graphene, the composite achieved optimal wear resistance, as the average coefficient of friction (CoF) decreased from 0.42 to 0.20, a ∼52% reduction with respect to the base B319 alloy. Similarly, the average wear volume and specific wear rate of 0.3 wt% graphene composite showed a ∼36% (measured by weight loss) and ∼32% (measured by the laser microscopy) reduction compared to the base alloy. The improved wear resistance of the composite was attributed to its higher hardness caused by microstructural refinement, high stability of the mechanically mixed layer (MML), and the formation of a graphene-rich lubricating layer on the contact surfaces. The results obtained from this study on B319-graphene composites could pave the way for developing lightweight and high-performance wear-resistant components for next-generation automotive applications.