All the systems were constructed using the Materials and Processes Simulations (MAPS) platform from Scienomics SARL. The three model surfaces were native iron, cementite, and magnetite. Symmetrical contacts were used with the same material for the upper and lower surface. Native iron surfaces were considered due to the possibility that they are exposed to the additive following removal of surface oxides in rubbing steel contacts. Cementite was chosen as a representative iron carbide surface because it was identified in previous thermal degradation experiments using TCP. Magnetite was selected since previous experiments have shown that it is the major oxide formed on the surface of bearing steel following tribometer experiments. We used an α-Fe(110) for the iron surface, Fe 3 C(010) as the cementite surface, and Fe 3 O 4 (001) with a subsurface cation vacancy (SCV) reconstruction as the magnetite surface due to their relatively low surface energies.