Transfer Behaviors of PFPE Lubricant from Disk Surface to Slider

Abstract

The rapid growth in storage areal density of hard disk drive (HDD) forces the flying height of slider has been currently reduced to less than 2 nm. In such a narrow spacing, perfluoropolyether (PFPE) lubricant is easier to transfer from disk surface to slider under fluid force field and heat transfer field, which is found to have a great effect on date storage reliability. Firstly, the lubricant transfer volume expression with respect to lubricant molecular weight is established. Secondly, the finite element models (FEM) of both Tri-pad positive pressure slider and flat slider are developed, and based on this, the PFPE lubricant transfer behaviors in HDD are investigated. Finally, four type unite cells composed of lubricant molecules and air molecules are established by using Materials Studio software, then both dynamic temperature and diffusion coefficients are researched based on molecular dynamics theory. Results show that the PFPE lubricant amount decreases with increasing pitch angles, rotation angles, slider flying height and disk rotation velocity, while it increases when heat source power increases. The diffusion coefficients of ZTMD lubricant is the maximum in the four lubricants we researched, while the temperature change ratio of Z-15 lubricant is the maximum.