Insight into the graphitization mechanism of the interface between iron and diamond: A DFT study

It is an important topic in the manufacturing research field to understand the mechanisms for the wear of diamond surfaces. The density functional theory (DFT) methods have served as useful tools for studying chemical reaction mechanisms in processing. In this work, we studied the changes in the diamond structure during the interface contact between the iron and diamond. The iron-diamond contact area is simplified to different coverage rates of Fe atom, corresponding to different numbers of adatom. With the different numbers of the Fe adatoms, the interlayer C C bonds have different changes. Below the Fe adatom region, the interlayer C C bonds are strengthened, inhibiting the graphitization. It is noteworthy that the C C bonds became significantly weakened or even broken at the boundary of the interface contact. Moreover, the interface sliding simulation verifies that the graphitization preferentially occurs at the edge of the interface between iron and diamond. The actual cause of graphitization is the synergistic effect of the charge transfer of the Fe C bonds and the asymmetric contraction and stretching on the diamond surface. Our work provides a theoretical basis for suppressing excessive diamond tool wear and polishing the diamond surfaces. • The graphitization mechanism of the interface between iron and diamond was concluded. • The graphitization preferentially occurs at the edge of the interface. • The charge transfer of the Fe C bonds and the asymmetric surface contraction and stretching are the causes of graphitization.