Invited Paper TR+AS+HI+NS+SS-WeA7
Fundamental Understanding of Interfacial Adhesion and Tribochemistry by Ab Initio Calculations

Wednesday, November 1, 2017, 4:20 pm, Room 10

Tribologically-induced chemical modifications of surfaces interacting with lubricant additives or other molecules present in the environment surrounding the sliding media can substantially change the adhesion and friction of materials in contact. Therefore, is highly desirable to understand how they take place. However, tribochemical reactions are difficult to monitor in real-time by experiments, which leaves a gap in the atomistic understanding required for their control.

We apply ab initio molecular dynamics to monitor chemical reactions involving common solid lubricants, namely molybdenum disulfide, graphene/graphite and carbon-based films, interacting with water molecules in the presence of mechanical stresses. Our simulations elucidate atomistic mechanisms relevant to understand the effects humidity on the lubricating properties of these materials.[1,2]

As second issue, we investigate the tribochemistry of sulfur, phosphorus and graphene on iron and discuss the role of metal passivation in reducing the interfacial adhesion and shear strength. We generalize the result by establishing a connection between the tribological and the electronic properties of interfaces. This adds a new piece of information for the ultimate understanding of the fundamental nature of frictional forces. [3,4]

[1] P. Restuccia, G. Levita and M. C. Righi Graphene and MoS2 interacting with water: a comparison by ab initio calculations Carbon 107, 878 (2016).

[2] S. Kajita and M. C. RighiA fundamental mechanism for carbon-film lubricity identified by means of ab initio molecular dynamics, Carbon 103, 193 (2016).

[3] M. C. Righi, S. Loehlé, M. I. De Barros Bouchet, S. Mambingo-Doumbeand J. M. Martin A comparative study on the functionality of S- and P-based lubricant additives by combined first principles and experimental analysis RSC Advances, 6, 47753 (2016).

[4] P. Restuccia and M. C. Righi Tribochemistry of graphene on iron and its possible role in lubrication of steel Carbon 106, 118 (2016).