Experimental Study of Stationary Head-Disk Contact in Magnetic Disk Drives

Magnetic disk drives are vulnerable to “stiction” a contact phenomenon in which static friction greatly exceeds kinetic friction. Stiction tends to increase dramatically with time of stationary contact. Thus, processes leading to stiction in the stationary head-disk contact are an important subject of tribological studies. Measurements of the static friction force are accompanied in this work by measurements of the capacitance between a resting slider and a thin-film rigid disk. Capacitance provides a sensitive measure of the surface separation and allows in-situ monitoring of the stationary contact. The experiments have shown that if the disk is covered with a thin film of a mobile lubricant, the adhesion growth with time measurably pulls the slider nearer to the plane of the disk (“slider microdescent”), and both the stiction and capacitance increase. If there is no mobile lubricant film, there is no growth of either stiction or capacitance. Thus, the stiction phenomenon is connected strongly with the slider microdescent. Their time dependence is likely governed by the capillary force increase caused by redistribution of the mobile lubricant toward the newly formed menisci.