EFFECT OF RELATIVE-HUMIDITY ON FRICTION BEHAVIOR OF THE HEAD DISK INTERFACE

The effect of relative humidity on friction behavior of the head/disk interface was investigated experimentally. Thickness of adsorbed water on both head and disk surfaces was measured at various relative humidities using an ellipsometer. Lubricated disks adsorbed less water than unlubricated disks, and an optimal thickness of lubricant was found for the least water adsorption. It was found that total liquid thickness (lubricant and adsorbed water) on both contacting surfaces was better correlated with static friction coefficient, compared with total liquid thickness on the disk surfaces only or total water thickness only at the head/disk interface.