Spreading Properties of Monolayer Lubricant Films: Effect of Bonded Molecules

• Published in: IEEE transactions on magnetics Vol. 45; no. 11; pp. 5055 - 5060
• Main Authors: Itoh, S., Takahashi, K., Fukuzawa, K., Amakawa, H., Hedong Zhang
• Format: Journal Article Conference Proceeding
• Language: English
• Published: New York, NY IEEE 01.11.2009; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Atomic measurements; Bonding; Chain entanglement; Cross-disciplinary physics: materials science; rheology; Diffusion bonding; Diffusion coefficient; Exact sciences and technology; Force measurement; Hard disks; Head-disk interface; Lubricant films; Lubricants; Magnetic films; Magnetic heads; Magnetism; Materials science; monolayer lubricant film; Monolayers; Other topics in materials science; perfluoropolyether; Physics; Reptation; Rough surfaces; Spreading; Spreads; Surface roughness; Surface topography; Head disk interface; Lubricants; perfluoropolyether; Monolayers; Head-disk interface; monolayer lubricant film; spreading; Disks; Magnetic properties
• ISSN: 0018-9464; 1941-0069
• DOI: 10.1109/TMAG.2009.2029605

Monolayer lubricant films applied to head-disk interface of hard disk drives consist of bonded and mobile molecules. We measured the diffusion coefficient of mobile molecules that spread through the spaces not covered with bonded molecules and revealed its dependence on the coverage fraction. The diffusion coefficient gradually decreased with increasing coverage from 0.2 to 0.8, and its trend was well represented by reptation theory. However, the diffusion coefficient significantly decreased at a coverage higher than 0.8, in contrast to the prediction of reptation theory. The reason for this decrease is thought to be the disappearance of minimum spaces required for mobile molecules to spread through.