Superlubricity

[10] A state of ultralow friction can also be achieved when a sharp tip slides over a flat surface and the applied load is below a certain threshold.

Such a "superlubric" threshold depends on the tip-surface interaction and the stiffness of the materials in contact, as described by the Tomlinson model.

[12] Superlubricity was also observed between a gold AFM tip and Teflon substrate due to repulsive Van der Waals forces and hydrogen-bonded layer formed by glycerol on the steel surfaces.

Formation of the hydrogen-bonded layer was also shown to lead to superlubricity between quartz glass surfaces lubricated by biological liquid obtained from mucilage of Brasenia schreberi.

Superlubricity is more analogous to phenomena such as superelasticity, in which substances such as Nitinol have very low, but nonzero, elastic moduli; supercooling, in which substances remain liquid until a lower-than-normal temperature; super black, which reflects very little light; giant magnetoresistance, in which very large but finite magnetoresistance effects are observed in alternating nonmagnetic and ferromagnetic layers; superhard materials, which are diamond or nearly as hard as diamond; and superlensing, which have a resolution which, while finer than the diffraction limit, is still finite.

Potential applications include computer hard drives, wind turbine gears, and mechanical rotating seals for microelectromechanical and nanoelectromechanical systems.