Wear and degradation mechanisms of magnetic thin-film rigid disks with different lubricants using mass spectrometry

Wear and degradation mechanisms of perfluoropolyether (PFPE) lubricants are studied using mass spectrometry and friction measurements during sliding in a high vacuum environment. Three kinds of lubricants with nonpolar and polar ends and with and without thermal treatment are applied over a thin-film disk with diamondlike film (DLC) overcoat. The results show that fluorocarbon fragments are generated from lubricants during a period of sliding with a low and stable coefficient of friction, followed by a sharp rise in frictional force and generation of gaseous products of DLC overcoat material. Increase in the friction is associated with lubricant depletion leading to intimate contact of the slider with the DLC overcoat. It is concluded that decomposition of PFPEs begins from the onset of sliding, and the DLC overcoat starts to wear simultaneously from the beginning of the sliding for untreated lubricants, but was well protected in the case of chemically bonded lubricants. Fully bonded lubricants better protect the DLC followed by partially bonded lubricants. Two bonded lubricants tested, exhibited similar performance. (C) 1997 American Institute of Physics.