MODELING OF AMORPHOUS CARBON OVERCOAT FOR INVESTIGATION OF LUBRICANT TRANSFER AT THE HEAD-DISK INTERFACE

In current hard disk drives, the spacing between the slider and the disk is reduced to the order of 1-2 nm. At such a narrow spacing, intermolecular forces at the head-disk interface play an important role in achieving a stable slider-disk interface. Even in the absence of actual head-disk contact, lubricant transfer between a slider and a disk may occur. Transferred lubricant can change the flying characteristics of the slider in subsequent read-write operations. It is therefore apparent that lubricant transfer at the head-disk interface is undesirable. In this paper, molecular dynamics simulations were performed to investigate lubricant transfer between a slider and a disk. A so-called coarse-grained bead spring (CGBS) model was implemented. In this model, the Lennard-Jones potential, the short-range polar attractive potential, and the finitely extensible nonlinear elastic potential functions were used to describe the intermolecular interactions at the head-disk interface. Also, in order to develop a realistic model of the carbon overcoat, different modeling approaches are discussed, including the use of rigid coarse-grained beads and a 3-body Tersoff potential function.