The influence of lubricant recovery on the coefficient of friction of lubricated metal-particulate flexible disks

We studied the relationship between the removal/recovery behavior and the chemical and physical properties of perfluoropolyether lubricants with different functional groups in metal-particulate flexible disk systems. The rotational speed dependence of the coefficient of sliding friction between disks and a spherical glass slider were measured. The dependence was found to be described by a simple equation in consideration of the removal/recovery behavior of the lubricant. The time constants in the equation were found to be almost proportional to the inverses of the extraction lifetimes estimated from the solvent-extraction profiles of lubricants on the disk surface. This result indicates that the affinity of the lubricant to the disk surface dominates the rate of recovery.