Topographical changes in perfluoropolyether and organosilane monolayer in contact sliding

This paper compares the topographical features of two ultra-thin lubricants when slid against a glass ball at light normal load. Perfluoropolyether (PFPE), a liquid lubricant, and organosilane monolayer, a solid-like lubricant, were tested. 1-2 nm thick lubricants were deposited on Diamond-Like-Carbon (DLC) overcoated magnetic hard disks. Sliding tests were conducted on a spin-stand using 3 mm diameter glass ball under a normal load of 20 mN. The lubricant thickness profile was measured using ellipsometer and optical surface analyzer (OSA). Our initial results show that in the case of PFPE the lubricant topography becomes rougher due to sliding contact whereas in the case of organosilane the worn part of the lubricant show topography which is even smoother than the unworn area. It is concluded that strong anchoring of the molecules of organosilane to the substrate helps in smoothening of the lubricant. Organosilane shows good promise for its use as nano-lubricant in data storage application.