Orientation-dependent tribological behavior of the graphite-diamond composite

Coherent interfacial graphite-diamond composite (Gradia) is superhard and conductive, promisingly applied as electric contact material. In this work, large-scale atomistic simulations were performed to investigate its tribological behavior. Depending on the orientation between graphite-diamond interface and loading direction, three structural evolution modes were observed under compression, featuring Gradia to diamond, Gradia to graphite, and Gradia to defective carbon. Coefficient of friction and wear rate were found orientation-dependent. Orientations of graphite-, diamond-, and defective-preferred structural evolution showed different performance. A satisfied balance between tribological performance and conductivity (rich of sp2-carbon) is obtained in the defective-preferred orientation. These results demonstrate the great potential for Gradia using in dynamic electrical contact and provide a theoretical basis for further material design.