EFFECT OF BONDED LUBRICANT FILMS ON THE TRIBOLOGICAL PERFORMANCE OF MAGNETIC THIN-FILM RIGID DISKS

Polar perfluoropolyether lubricants are widely used for topical lubric ation of thin-film rigid disks. However, little is known about the rol e of bonded lubricant on tribological performance. In this study, as-a pplied lubricant films, after thermal treatment and after thermal trea tment and washing to remove unbonded fraction, have been studied. The bonded fraction of lubricant films on coated disks made with Al-Mg and glass substrates was measured at various applied lubricant thicknesse s, soaking times and thermal treatments, with silicon wafer as a refer ence. Friction and wear performance of lubricated disks against Al2O3- TiC microsliders was measured. Results show that bonded lubricant thic kness increases initially with increasing soaking time, baking tempera ture and baking time, and then levels off. Bonded lubricant thickness also increases initially with increasing applied lubricant thickness a nd levels off above a certain film thickness. A critical lubricant thi ckness exists above which coefficients of static and kinetic friction increase rapidly and durability decreases rapidly, and this thickness increases with disk roughness. A rise in static and kinetic friction a bove a critical value of film thickness is associated with meniscus fo rces. The drop in the disk durability above a critical level may resul t from the observed stick/slip phenomena and erratic friction at lubri cant thicknesses which is thick as compared to disk surface roughness. It is further noted that lubricant film with mobile and immobile frac tions is important for the disk to have a long life.