Cy. Chen et al., Lubricant thickness effect on tribological performance of ZDOL lubricated disks with hydrogenated overcoats, TRIBOL LETT, 7(1), 1999, pp. 1-10
Tribo-chemical studies of the lubricant thickness effect on the tribology o
f the head/disk interface (HDI) were conducted using hydrogenated (CHx) car
bon disk samples coated with perfluoropolyether ZDOL lubricant. The studies
involved drag tests with uncoated and carbon-coated Al2O3-TiC sliders and
thermal desorption experiments in an ultra-high vacuum (UHV) tribochamber.
The studies showed that the lubricant interaction with the carbon overcoat
varies as a function of lubricant thickness. Wear durability improves consi
derably for thicknesses more than a monolayer. However, in the sub-monolaye
r thickness regime, the adhesion of the lubricant to the carbon overcoat is
much stronger, as indicated by the fact that a much higher temperature is
required to desorb the lubricant. When the lubricant thickness is around or
above a monolayer, cohesion among the lubricant molecules plays a greater
role and a much lower temperature is needed for lubricant desorption.