Tuning the adhesion of diamond/copper interfaces through surface chemical modifications and reconstruction

Diamond and diamond-like carbon (DLC) coatings are well-known for their exceptional combination of tribological and mechanical properties, such as low friction coefficients and wear rates, together with high hardness and elastic modulus. A significant limitation in their employment concerns their spallation from the substrate; it is thus interesting to explore how DLCs adhesion can be tuned through chemical modifications of its surfaces. We employ ab initio simulations to study the effect of surface reconstruction and chemical species intercalation (B, P, O, F, N, S, H) on the adhesion of non-reconstructed and Pandey-reconstructed C(111)/Cu(111) interfaces. We found that the increment of graphitization at the diamond surface decreases the adhesion. Moreover, when a high degree of surface graphitization is present the best way to increase adhesion is to select atoms able to act as chemical bridges (e.g., B and N), compensating for the lack of interaction between the surfaces. Conversely, adhesion reduction of ∼100% can be achieved, regardless of the degree of surface graphitization, by intercalating an atomic species that does not bond with the countersurface and prevents the interaction between the slabs, i.e. F and S.