Lubricant thickness modulation and recovery for contact and near contact recording conditions

Lubricant distribution and recovery for near contact and contact recording conditions are experimentally investigated using Thermal Fly-height Control (TFC) sliders. Contact between the protruded center pad and the lubricant layer causes a thickness modulation together with lubricant depletion that grows with contact duration. In experiments using Z-dol+A20H and Z-tetraol+A20H with different thicknesses, a larger depletion is observed for the thicker lubricant of each type for a given TFC power. Lubricants with lower bonded fraction recover more quickly after the slider is unloaded. From the current experiments it is extrapolated that Z-dol+A20H (30% bonded) lubricant recovers in a time scale of a few hours to a day, while Z-tetraol+A20H (60% bonded) lubricant of comparable thickness takes a few days to fully recover.