Topographical and tribo-chemical studies of contact sliding on ultra-thin perfluoropolyether film

This paper presents data from topographical (using ellipsometer and optical surface analyzer) and tribo-chemical (using X-ray photoemission spectroscope (XPS)) measurements that were carried out after wear tests on perfluoropolyether (PFPE) films dip-coated on diamond-like-carbon (DLC). The wear experiments were carried out using a glass ball slider sliding on PFPE lubricated (/spl sim/2 nm) magnetic hard disks (having DLC overcoat) under a normal load of 20 mN and at different sliding speeds. The test conditions were maintained such that only the PFPE film was worn and no wear of either the DLC or the magnetic layer of the disk was observed. From the test results we conclude that contact sliding removes the PFPE film causing some chemical compositional changes which might be related to tribo-chemistry of the surface. On the topography, there is a large roughening of the PFPE film due to sliding. This increased roughness of the film is stable even after a rest of several weeks.