1304 Bonding mechanism by UV treatment of ultra thin PFPE lubricant films on disk surface

Spring constants and damping coefficients of a thin lubricant bridge of a perfluoropolyether (PFPE) lubricant intervening between a diamond probe tip and a diamond-like carbon (DLC) surface of a magnetic disk are identified through regression analysis of tip damping vibration. PFPE lubricants with functional end groups were used to form a lubricant bridge between the DLC surface and a probe tip with a notably small curvature radius of 0.1μm. The tip was both retracted from and extended toward the disk surface at four different progressive distances to attain varied elongation of the bridge. It was also vibrated at each step to provide damping waveforms. By applying regression analysis to the observed waveforms, the spring constant and the damping coefficient of the lubricant bridge were identified within an elongation range from 50nm to 800nm. Spring constant of the lubricant bridge kb had a negative value varying from −0.15N∕m to −0.1N∕m. The damping value expressed in the form of frequency-multiplied damping cb×ω ranged from 0.02N∕m to 0.06N∕m. Note that both the absolute value of spring constant ∣kb∣ and frequency-multiplied damping cb×ω exhibited U-shaped variation with lubricant bridge elongation; that is, those values decrease with bridge elongation and they begin to increase after reaching the minimum. The variation in the spring constant was found to be in good accordance with the quasi-static stiffness of the lubricant bridge, and variation in the damping coefficient was explained by energy loss arising in the vibrating lubricant bridge.

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HDI-06 EFFECT OF ULTRAVIOLET IRRADIATION ON ADHESIVE FORCE AND ELONGATION OF MONOLAYER LUBRICANT FILMS COATED ON MAGNETIC DISK SURFACE(Head/Disk Interface and Tribology II,Technical Program of Oral Presentations)

Proceedings of JSME-IIP/ASME-ISPS Joint Conference on Micromechatronics for Information and Precision Equipment IIP/ISPS joint MIPE ◽

10.1299/jsmemipe.2009.111 ◽

2009 ◽

Vol 2009 (0) ◽

pp. 111-112

Author(s):

Yasuji OHSHIMA ◽

Takashi SUMI ◽

Hedong ZHANG ◽

Yasunaga MITSUYA ◽

Kenji FUKUZAWA

Keyword(s):

Ultraviolet Irradiation ◽

Disk Surface ◽

Adhesive Force ◽

Head Disk Interface ◽

Technical Program ◽

Magnetic Disk ◽

Disk Interface ◽

Lubricant Films ◽

Oral Presentations

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Molecular orientation of PFPE lubricant films and its quantification

IEEE Transactions on Magnetics ◽

10.1109/20.617863 ◽

1997 ◽

Vol 33 (5) ◽

pp. 3118-3120 ◽

Cited By ~ 15

Author(s):

C. Gao ◽

P. Dai

Keyword(s):

Molecular Orientation ◽

Pfpe Lubricant ◽

Lubricant Films

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Synthesis of tri-functional PFPE lubricant and its spreading characteristics on a hard disk surface

Micro-Nanomechatronics and Human Science, 2004 and The Fourth Symposium Micro-Nanomechatronics for Information-Based Society, 2004. ◽

10.1109/mhs.2004.1421315 ◽

2005 ◽

Cited By ~ 3

Author(s):

H. Chiba ◽

Y. Oshikubo ◽

K. Watanabe ◽

T. Tokairin ◽

E. Yamakawa

Keyword(s):

Hard Disk ◽

Disk Surface ◽

Pfpe Lubricant

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Spreading Characteristics of Monolayer Lubricant Films on Surfaces With Lube Textures

Journal of Tribology ◽

10.1115/1.1843828 ◽

2005 ◽

Vol 127 (1) ◽

pp. 164-170 ◽

Cited By ~ 9

Author(s):

Hedong Zhang ◽

Yasunaga Mitsuya ◽

Natsuko Fukuoka ◽

Kenji Fukuzawa

Keyword(s):

Diffusion Coefficients ◽

Surface Characteristics ◽

Disk Surface ◽

Ultraviolet Rays ◽

Monolayer Film ◽

Magnetic Disk ◽

Surface Energies ◽

Angle Measurements ◽

Contact Angle Measurements ◽

Lubricant Films

In this paper, we investigate the effect of lube textures from the viewpoint of lubricant spreading. Lube textures, designating a patterned distribution of bonding strength between lubricant molecules and disk surface, were formed by irradiating ultraviolet rays through a stripe-patterned mask onto a magnetic disk surface which was partially coated with one-monolayer film of perfluoropolyether. Surface characteristics of the lube textures were evaluated by surface energies ascertained from contact angle measurements. Spreading of the lubricant film was measured by scanning microellipsometry on the striped lube textures in the directions parallel and perpendicular to the stripes. The thickness-dependent diffusion coefficients extracted from the spreading profiles show that lubricant spreading in the regime of film thickness less than 0.2 nm is faster along the stripes, indicating the possibility of controlling the behavior of lubricant films with lube textures.

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Stiffness and Damping of Molecularly Thin PFPE Lubricant Bridging Between Magnetic Disk and Diamond Probe Tip

World Tribology Congress III, Volume 1 ◽

10.1115/wtc2005-63058 ◽

2005 ◽

Author(s):

Yasunaga Mitsuya ◽

Yasuji Ohshima ◽

Hedong Zhang ◽

Kei Aoyama ◽

Toshiyuki Kawai ◽

...

Keyword(s):

Regression Analysis ◽

Liquid Bridge ◽

Disk Surface ◽

Spring Constant ◽

Curvature Radius ◽

Magnetic Disk ◽

Pfpe Lubricant ◽

Stiffness And Damping ◽

Diamond Probe ◽

Spring Constants

Spring constants and damping coefficients of a molecularly thin liquid bridge of PFPE lubricant intervening between a diamond probe tip and diamond like carbon (DLC) surface of a magnetic disk are identified through regression analysis of tip damping vibration. Perfluoropolyether (PFPE) lubricants having functional end groups were used to form the liquid bridge between the DLC surface and a probe tip with the notably small curvature radius of 0.1 μm. The tip was both retracted from and extended toward the disk surface at four different, progressive distances to attain varied elongation of the bridge, and was made to vibrate at each step to provide damping waveforms. By applying regression analysis to observed waveforms, the spring constant and the damping coefficient of the liquid bridge were identified. It is interesting to note that both the absolute value of the spring constant and the frequency-multiplied damping decrease with bridge elongation, and after reaching the minimum, those values begin to increase.

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