Direct Observation of PFPE Lubricants on Magnetic Disks

Tani, Hiroshi; Tagawa, Norio

doi:10.1109/tmag.2008.2010655

Cited by 11 publications

(9 citation statements)

References 11 publications

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“…The shoulder height was *1.7 nm. This value was in good agreement with the step height of Z-tetraol2000 obtained by AFM direct observation; it is suggested that this shoulder height corresponds to a monolayer film thickness of Z-tetraol2000 [8]. Figure 7 shows the spreading profiles of TA-30 which were measured by varying the disk substrate temperature from 20 to 80°C.…”

Section: Afm Observation Resultssupporting

confidence: 84%

Conformation and Fundamental Properties of Novel Lubricant TA-30 for Near Contact Magnetic Recording

Tagawa

Tani

2010

Tribol Lett

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A novel perfluoropolyether (PFPE) lubricant called TA-30 has been developed recently. We investigate the conformation of TA-30 on diamond-like carbon (DLC) thin films, by attempting the direct observation of a lubricant film by atomic force microscopy (AFM) using a fluoride probe. We investigate the fundamental properties of a TA-30 lubricant film, such as its spreading characteristics, and the film thickness dependence of surface energy. Considering these experimental results, we conclude that the conformation of TA-30 is considerably different from that of conventional Z-tetraol2000 whose molecular height is 1.7 nm and which was adsorbed on the DLC surface with the random coil. The TA-30 molecules are adsorbed rigidly to the DLC surface with double layers. The thickness of the first TA-30 layer is *0.9 nm (similar to diameter of the PFPE backbone) and that of the second layer from the DLC surface is 1.4 nm. Since TA-30 has a lower film thickness than Z-tetraol2000 on the DLC surface, it can have two layers, even if the film thickness is approximately of the order of 1 nm, whereas Z-tetraol2000 does not cover the DLC surface and does not form the complete first layer. In addition, we conduct slider touchdown and takeoff hysteresis tests by using TA-30 and Z-tetraol2000. It is confirmed that the use of TA-30 can improve the head-disk interface (HDI) reliability at lowfly-height conditions.

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Section: Afm Observation Resultssupporting

confidence: 84%

Conformation and Fundamental Properties of Novel Lubricant TA-30 for Near Contact Magnetic Recording

Tagawa

Tani

2010

Tribol Lett

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“…Therefore, Z-dol of experimental samples had double layers, approximately 1.2 nm, and that of Z-tetraol was approximately 1.7 nm [12] and only Z-tetraolt with 2.0 nm had double layers. It was estimated that the lubricant film with the double layers showed the stable second regime, because the second layer molecules on the first layer might add the hydrodynamic lubrication effect.…”

Section: A Slider Vibration Measurementsmentioning

confidence: 89%

“…Z-tetraol showed smaller TDPs and similar slope compared to Z-dol, when the lubricant thickness was thinner than 1.6 nm. This difference of TDPs was estimated to be affected from the difference of the lubricant film structure, because the monolayer thickness of Z-dol was approximately 1.1-1.2 nm [12].…”

Section: A Slider Vibration Measurementsmentioning

confidence: 99%

Experimental Study of Head-Disk Interface Instability on Light Contact Recording Using Dynamic Flying Height Control

2011

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The instability of the slider touchdown process was observed by the sensitive method that uses PZT ((Zr x Ti 1 x ) O 3 ) sensor mounted on a suspension. By using this method, we could differentiate from the contact between the slider and the lubricant surface, the stable regime beyond touchdown (surfing regime), and the final full contact with the disk surface. Z-dol2000S clearly showed the surfing regime, but Z-tetraol2000S did not show the surfing regime on a thin lubricant film with a thickness of less than 16 Å. In the case of Z-dol, the magnitude of the slider vibration at the contact on the lubricant surface depended on the lubricant thickness; in the case of Z-tetraol, a large vibration was observed only at 20 Å. We have tried to explain these phenomena with the help of potential energy curves that are based on intermolecular forces calculated by molecular dynamic simulations. Potential energy curves could be used to explain the stability of the touchdown process.Index Terms-Head-disk interface, lubricant, magnetic head, magnetic recording.

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“…The AFM probes were dipped into the solution (30 wt% concentration). This fluoride-coated probe was used to scan the surface of the lubricant film and measured the step height at the boundary of the lubricant film [7]. The step height corresponded to the molecular height of the lubricant monolayer.…”

Section: Afm Observationmentioning

confidence: 99%

Electric Field Assisted Dip-coating Process of Ultra-thin PFPE Lubricant Film on Magnetic Disks

Tani

Kubota

Kanda

et al. 2010

JAMDSM

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The influence of an electric field on the dip-coating process was studied by using the lubricants Z-tetraol, D-4OH, TA-30, and QA-40. The electric field facilitated the adsorption of lubricant molecules onto the disk surface. It also resulted in an increase in the lubricant film thickness. The surface free energy and molecular height of the Z-tetraol lubricant film were not affected by the electric field; however, they decreased in the case of other lubricant films. To elucidate these results, we estimated that the molecular conformation of the lubricants changed due to the electric field and that the OH end-groups aligned to the carbon surface. These results suggest the possibility of resistance to outgas contamination and humidity through electric field assisted dip (EFAD) coating.

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Direct Observation of PFPE Lubricants on Magnetic Disks

Cited by 11 publications

References 11 publications

Conformation and Fundamental Properties of Novel Lubricant TA-30 for Near Contact Magnetic Recording

Conformation and Fundamental Properties of Novel Lubricant TA-30 for Near Contact Magnetic Recording

Experimental Study of Head-Disk Interface Instability on Light Contact Recording Using Dynamic Flying Height Control

Electric Field Assisted Dip-coating Process of Ultra-thin PFPE Lubricant Film on Magnetic Disks

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