Lubricant-Induced Spacing Increases at Slider-Disk Interfaces in Disk Drives

• Published in: Tribology letters Vol. 37; no. 3; pp. 581 - 590
• Main Authors: Mate, C. Mathew, Marchon, Bruno, Murthy, Aravind N, Kim, Sang-Hoon
• Format: Journal Article
• Language: English
• Published: Boston Boston : Springer US 01.03.2010; Springer US; Springer Nature B.V
• Subjects: Chemistry and Materials Science; Computer simulation; Corrosion and Coatings; Disk drives; Drying; Lubricant films; Materials Science; Nanotechnology; Original Paper; Physical Chemistry; Recording heads; Slippage; Surfaces and Interfaces; Theoretical and Applied Mechanics; Thick films; Thickness; Thin Films; Tribology; Viscosity; Viscous flow; Viscosity; Magnetic data storage; Boundary lubrication; Magnetic data recording heads
• ISSN: 1023-8883; 1573-2711
• DOI: 10.1007/s11249-009-9555-y

In this article, we explore the physical mechanisms for lubricant migration on recording head slider surfaces and how this migration leads to increased slider-disk spacing during disk drive operations. This is done using both a new experimental methodology, called the “droplet stress test,” and through simulation. In our simulations, we compare the air shear-induced lubricant migration modeled either as viscous flow of a continuum liquid film with zero slip or as wind driven slippage of molecules across the surface. The experimental data are best fitted using the viscous flow model to determine an effective viscosity for the sub-nanometer thick lubricant films. This effective viscosity tends to be somewhat less than the lubricant bulk viscosity due to air shear promoting the slippage of lubricant molecules across the surface. Our experimental results also indicate that the potential spacing increase from the pickup of disk lubricant on the slider is limited by the mobile fraction of the dewetting thickness of the lubricant film on the slider.