Lubricant Transfer Model at the Head-Disk Interface in Magnetic Storage Considering Lubricant–Lubricant Interaction

Abstract

Interactions among molecularly thin lubricant–solid and lubricant–vapor interfaces become increasingly strong when the slider approaches closer to the disk (or media) surface, which is desirable for higher storage areal densities. Lubricant transfers from the disk to the slider as the head-media spacing decreases below a critical value, leading to loss of protection for the solid thin films. The present work proposes a new criterion for lubricant pickup to occur by improving the lubricant transfer model via considering interactions between the lubricant films, in addition to lubricant–solid interaction. The effect of lubricant roughness is also included in the proposed model, which is then used to predict critical solid distances as a function of lubricant roughness and average lubricant thickness. It is found that the interaction force between the slider solid and the disk lubricant plays a weaker role than that between the lubricant on the slider and the lubricant on the disk in determining the critical solid distance. The physics for the dependence of the critical clearance on the bonding ratio is explained, and a linear model is developed.