Theoretical Model for Lubricant Pickup Considering Disjoining Pressure of Nanometer Thick Film

Abstract

In recent magnetic storage systems, the spacing between the flying head and the disk has been drastically decreased to less than 5 nm in order to realize ultrahigh density recording. Lubricant on the disk is picked up to the flying head slider as a result of the intermittent contact between the slider and the disk, or due to condensation of the lubricant vapor. We propose a model for the breakage of a liquid meniscus bridge based on the mass conservation of a liquid droplet and derive the volume fraction of the lubricant pickup. In this study, the basic characteristics of lubricant pickup caused by the breakage of a liquid meniscus bridge are investigated theoretically considering the disjoining pressure for a nanometer thick film. The balanced equation for the Laplace pressure and the disjoining pressure is introduced to obtain the liquid meniscus bridge shape and to determine the breakage point of the liquid meniscus bridge. The effects of the radius of curvature of a sphere surface, the receding contact angle, and the thickness of the ultrathin liquid film are discussed.