Lubricant flow under a flying head on a thin-film disk

Pouwer, A.; Kawakubo, Y.; Tsuchiyama, R.

doi:10.1109/20.950993

Cited by 21 publications

(17 citation statements)

References 6 publications

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“…However, the difference in the viscosity between the two layers is about 20 times, a much lower value than that measured by Scarpulla et al [3]. In spite of the fact that the diffusion behaviors of both the functional and nonfunctional lubricants were studied in detail, there are some earlier studies on the flow behavior in spin-off of very thick films of the nonfuncational lubricant, for which the solid surface effect is limited [8][9][10].…”

Section: Introductionmentioning

confidence: 81%

The Rheological Behavior of the Nano-Meter Film of Non-Functional PFPE on Hard Disk Surfaces during Spin-Off

2009

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Spin-off experiments were conducted at different temperatures for a nonfunctional PFPE Z25 film with an initial thickness of 2.4 nm, and comparison with the diffusion experiments was carried out. It is found that PFPE Z25 shows completely different rheological behaviors in spin-off and diffusion. Theoretical model based on the Fick law of diffusion was proposed, which is called the Layer Molecular Dynamic Diffusion (LMDD) model. The proposed model results in a much better agreement with the spin-off experimental results than the continuum theory being used at present. Contrary to the results in the diffusion experiment, the nanometer film of nonfunctional PFPE Z25 also shows a layered structure in the spin-off.

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Section: Introductionmentioning

confidence: 81%

The Rheological Behavior of the Nano-Meter Film of Non-Functional PFPE on Hard Disk Surfaces during Spin-Off

2009

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“…Spin-off of thick films (on the order of 2-10 nm) from magnetic recording disks was in good agreement with the continuum hydrodynamic calculation. However, when a slider was being accessed over the disk surface [105], lubricant removed more rapidly than expected from the continuum theory. An MC simulation faithfully replicated the reflow profile observed after removing the lubricant in a 1.4 mm wide region of the disk surface.…”

Section: Simulationmentioning

confidence: 84%

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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“…However, the pressure distribution under the head used in the experiment [8] was not known to us. We then defined the distribution of s head numerically.…”

Section: Simulation Modelmentioning

confidence: 99%

“…In this study, we first simulated lubricant movement under flying heads with centrifugal force and air shear stress and compared our results with published experimental data of a 10-nm PFPE lubricant under a 77 nm flying height taper-flat slider by Pouwer et al [8]. Then, we added the effects of diffusion to the model.…”

Section: Introductionmentioning

confidence: 94%

“…Ishii et al [5,6] et al [7] studied the change in lubricant thickness during pin-on-disk wear tests and showed the effects of lubricant viscosity and pin shapes. Pouwer et al [8] tried to simulate the lubricant movement under a tworail taper-flat flying head taking into account the centrifugal force and the shear stress by the air flow due to disk rotation and flying head. They reported an oscillating lubricant pattern and concluded that they failed to obtain results similar to their experiments.…”

Section: Introductionmentioning

confidence: 99%

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Effects of diffusion on lubricant distribution under flying headon thin-film disks

2005

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Lubricants on thin-film disks have large effects on head-disk interface characteristics. They reduce head and disk wear while thick lubricant film increases friction force between them and lubricant transfer onto head surfaces. Therefore, we have to know the lubricant behavior in many cases. Lubricant depletion due to disk rotation has been studied very well. However, the effects of flying heads have not been understood systematically until now. We developed a simulation program to numerically calculate the change in lubricant thickness under a flying head on a thin-film magnetic disk. The program included the effects of centrifugal force, shear stress from the air due to disk rotation with a flying head, and the effect of lubricant diffusion. We first calculated a change in lubricant thickness under a flying head using previously published data without the effect of diffusion. Calculated results showed fairly good agreement with the published experimental data with very high peaks on both sides of the flying head rails. With the introduction of diffusion effects, these peaks became moderate and the calculated result agreed very well with the experimental data. The coefficient of diffusion obtained to best fit to the experimental data was close to that reported in a literature. We analyzed the effects of air shear stress patterns under flying head on the change in lubricant distribution. We found that the side shapes had large effect on the distribution. We also confirmed that our program could calculate lubricant depletion on rotating disks without a flying head.

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Lubricant flow under a flying head on a thin-film disk

Cited by 21 publications

References 6 publications

The Rheological Behavior of the Nano-Meter Film of Non-Functional PFPE on Hard Disk Surfaces during Spin-Off

The Rheological Behavior of the Nano-Meter Film of Non-Functional PFPE on Hard Disk Surfaces during Spin-Off

Spreading and dewetting in nanoscale lubrication

Effects of diffusion on lubricant distribution under flying headon thin-film disks

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