Tribological implications of solvents in dip-coating lubrication of thin film magnetic disks

Gao, Chao; Lee, Y.C.; Chao, J.; Russak, M.

doi:10.1109/20.538808

Cited by 10 publications

(3 citation statements)

References 3 publications

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“…The dip coating solution concentration, draw rate, vapor head space, and solvent also play a role in determining the properties and performance of the film. Both Gao et al [18] and Waltman et al [19] studied the effect of dip coating solvent on tribological performance. Only Gao et al [16] reported some effect of the film microstructure on tribological performance at the relative humidity of 80%.…”

Section: Experimentation and Mesoscopic Analysismentioning

confidence: 98%

Spreading and dewetting in nanoscale lubrication

Karis

Kim

2005

Tribol Lett

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This article critically reviews the fundamental scientific tools, as well as constructs cohesive schemes for potential applications, relevant to the molecularly-thin liquid film technology. Our focus is to understand the nanoscale dynamic behavior of thin lubricant films, relevant to the emerging field of nanotechnology, especially for achieving durability and reliability in the nanoscale devices. Our goal is to present a unified and hybrid description of perfluoropolyether (PFPE) experiment, mesoscopic interpretation, microscopic simulation tools, and molecular design tools available up to now. The experimentation and theory for the physicochemical properties of ultra-thin PFPE films are used to examine liquid film in the sub-monolayer to multilayer regime. Methods for extracting spreading properties from the scanning microellipsometry (SME) for various PFPE/solid surface pairs and the surface rheological characterization of PFPEs are examined. The interrelationships among SME spreading profiles, rheology, surface energy, and tribology, are given. Mesoscopic theories, including thermodynamics of evaporation and flow, stability analysis, microscale mass transfer, and capillary waves are introduced to describe thin PFPE film dynamics. Estimation of thin film viscosity enhancement from vapor pressure suppression by dispersion force is reviewed. The method for experimental derivation of lubricant spreading profiles from contact angles is summarized. The implications of capillary waves, or thermal fluctuations, at the surface of polymeric lubricant films are also discussed. The lattice-based, simple reactive sphere Monte Carlo (MC) technique for examining the fundamentals of PFPE dynamics is illustrated. An off-lattice based bead-spring MC model is also introduced to capture a detailed internal structure of the PFPE molecules, and the molecular dynamics method is implemented for a full-scale nanostructural analysis of PFPE ultra-thin films. By systematically tuning the endgroup strengths of PFPE, we examined the physicochemical properties for thin liquid films of the various PFPE/solid surface pairings. These tools accurately describe the static and dynamic behavior of ultra-thin liquid films consistent with experimental findings and thus are suitable for examining the fundamental mechanisms of lubrication in nanoscale devices. Application of the next generation head-disk interface design in information storage device is briefly considered.

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Section: Experimentation and Mesoscopic Analysismentioning

confidence: 98%

Spreading and dewetting in nanoscale lubrication

Karis

Kim

2005

Tribol Lett

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“…They attributed the difference to the microstructure and/or orientation of the lubricant molecules affected differently by the solvent [1]. Lubricants topi- Figure 7.…”

Section: Summary and Concluding Remarksmentioning

confidence: 98%

“…Most intriguingly Chao et al reported that, keeping all other factors constant, the disk performance (measured by the CSS test) could vary significantly depending on the choice of the solvent used in the dip-coating process. They attributed the observed difference to the microstructure and/or orientation of the lubricant molecules affected differently by the solvent employed in the dip-coating process [1].…”

Section: Introductionmentioning

confidence: 98%

Interaction Between Disk Lubricants and Solvents in the Dip-Coating Process

Kasai

Spiese

2004

Tribology Letters

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It has been reported earlier that, keeping all other factors fixed, the disk performance could vary significantly depending on the choice of solvent used in the dip-coating process. We surmised that the difference in the ability of solvent to disrupt the intermolecular hydrogen bonding between hydroxyl units of Z-dol or Z-tetraol would lead to a different structure or arrangement of the lubricant molecules as the solvent evaporated in the dip-coating process. Using proton NMR and IR spectroscopy, four solvents, hexafluorobenzene, Vertrel-XF, HFE7100, and FC72, were examined for their ability to disrupt the hydrogen bonding of Z-dol and Z-tetraol. The study has revealed that the said ability increases in the order of FC72 < HFE7100 < hexaflurobenzene < Vertrel-XF. Z-dol molecules, for example, are completely separated from each other in Vertrel-XF, but maintain their intermolecular hydrogen bonding in FC72. It has also revealed an extraordinary formation of complexoid between HFE molecules and Z-tetraol with MW n of~2000. The complexoid has a specific stoichiometry of (Z-tetraol) n (HFE)~15 n and is not miscible with HFE. The formation of such complexoid was not observed for Z-tetraol of larger MW n ( ‡3000).

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