Microelectromechanical system devices (MEMS) suffer from severe wear and short lifetimes from high pressure asperity-asperity contacts due to the nature of their rough surfaces.  Recently nanoscale carbon lubricants, such as graphene, are of interest as protective surface coatings for MEMS.  Here, Atomic Force Microscopy (AFM) has been used to investigate the frictional properties of graphene on hydrophilic and hydrophobic nanoparticle films, which model the nanoscaled asperities found on realistic surfaces.  These AFM studies revealed that graphene partially conforms to the rough surfaces and as the number of layers increase, conformity decreases due to stiffening of the thicker layers, but increases under mechanical loading.  Friction nominally decreases as a function of layer thickness, but was also found to depend on contact area of the tip and interfacial shear strain of the graphene associated with its adhesion to the substrate.

Frictional properties of graphene on hydrophilic and hydrophobic silica surfaces with nanoscale roughness

248th National Meeting (2014)

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