Lubricant behavior and pin wear on thin-film magnetic disks

Transparent-pin wear tests with in-situ microellipsometer measurement were performed on thin-film magnetic disks with different lubricants. We found that pin wear started when the decrease in the lubricant thickness at the pin slide-path leveled-off and that pin wear sometimes started when the lubricant thickness was still larger than that of the adsorbed lubricant. These mean that the free lubricant on the disk surface is not replenishing the real points of pin-disk sliding. Consequently, we considered that the replenishment of free lubricant to the real points of pin sliding is more important than the fact whether the average lubricant thickness exceeds the adsorbed lubricant thickness or not. Tests on disks with different lubricants show that the lower the lubricant viscosity, the greater the lubricant loss and the smaller the pin wear. We find that a low-viscosity-lubricant is better in replenishing free lubricant to the real points of sliding than high-viscosity-lubricant is.