Abstract
Nanometer-thick liquid lubricant films are used for lubrication of miniaturized mechanical systems such as hard disk drives and microelectromechanical systems. In particular at the head–disk interface of hard disk drives, the lubricant thin film is coated on a diamond-like carbon surface, and the films are usually composed of both chemically and physically adsorbed lubricant molecules. The combination of these two types of molecules leads to high lubrication performance. However, the detailed mechanism is not fully understood. The aim of this study was to clarify the effect of chemically adsorbed lubricant molecules on the viscous friction of lubricant films. Two different samples were tested: One was the lubricant film composed of both chemically and physically adsorbed molecules, and the other was the lubricant film with only physically adsorbed molecules. We used a fiber wobbling method (FWM), which we developed in our previous study, to measure the viscous friction. The FWM uses a spherical-ended glass fiber as a shearing probe and enables friction forces in the order of 0.1 nN to be measured at precisely controlled nanometer-scale gap widths. For the fair comparison of friction forces between the samples with different compositions, the contact area between the probe tip and the lubricant film must be the same. To determine the contact area in the friction measurement, we improved the FWM system to enable simultaneous measurement of friction force and contact area. Experimental results showed the 1-nm-thick layer of chemically adsorbed molecules in the lubricant film effectively reduced the viscous friction.
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Rymuza, Z.: Control tribological and mechanical properties of MEMS surfaces. Part 1: critical review. Microsyst. Technol. 5(4), 173–180 (1999)
Eapen, K.C., Patton, S.T., Zabinski, J.S.: Lubrication of microelectromechanical systems (MEMS) using bound and mobile phases of Fomblin Zdol®. Tribol. Lett. 12(1), 35–41 (2002)
Gui, J.: Tribology challenges for head–disk interface toward 1Tb/in2. IEEE Trans. Magn. 39(2), 716–721 (2003)
Marchon, B., Pitchford, T., Hsia, Y.-T., Gangopadhyay, S.: The head–disk interface roadmap to an areal density of Tbit/in2. Adv. Tribol. 2013(521086), 1–8 (2013)
Zhao, Z., Bhushan, B.: Effect of bonded lubricant films on the tribological performance of magnetic thin-film rigid disks. Wear 202(1), 50–59 (1996)
Chen, C.-Y., Bogy, D., Bhatia, C.S.: Effect of lubricant bonding fraction at the head–disk interface. Tribol. Lett. 10(4), 195–201 (2001)
Junho, C., Kawaguchi, M., Kato, T.: The surface coverage effect on the frictional properties of patterned PFPE nanolubricant films in HDI. IEEE Trans. Magn. 39(5), 2492–2494 (2003)
Zhang, H., Mitsuya, Y., Fujikawa, Y., Fuwa, A., He, Y., Fukuzawa, K.: Changes in friction properties of monolayer lubricant films induced by development of molecules’ bonding. Tribol. Lett. 28(2), 163–170 (2007)
Hedong, Z., Mitsuya, Y., Fuwa, A., Fujikawa, Y., Fukuzawa, K.: Effect of thermal bonding on frictional properties of monolayer lubricant films coated on magnetic disk surfaces. IEEE Trans. Magn. 44(11), 3637–3640 (2008)
Lu, R., Zhang, H., Mitsuya, Y., Fukuzawa, K., Itoh, S.: Contributions of mobile and bonded molecules to dynamic friction of nanometer-thick perfluoropolyether films coated on magnetic disk surfaces. Tribol. Lett. 54(3), 237–247 (2013)
Itoh, S., Fukuzawa, K., Hamamoto, Y., Zhang, H.D., Mitsuya, Y.: Fiber wobbling method for dynamic viscoelastic measurement of liquid lubricant confined in molecularly narrow gaps. Tribol. Lett. 30(3), 177–189 (2008)
Itoh, S., Fukuzawa, K., Takahashi, K., Ando, T., Zhang, H., Mitsuya, Y.: Optimization of dynamic shear force measurement for fiber wobbling method. Microsyst. Technol. 11(8–10), 894–900 (2005)
Itoh, S., Ishii, K., Fukuzawa, K., Zhang, H.: Shear thinning of nanometer-thick liquid lubricant films measured at high shear rates. Tribol. Lett. 53(3), 555–567 (2014)
Fukuzawa, K., Itoh, S., Suzuki, K., Kawai, Y., Zhang, H., Mitsuya, Y.: Diffusive motion of molecules in submonolayer liquid films on a solid surface. Phys. Rev. E 72(6), 061602 (2005)
Itoh, S., Takahashi, K., Fukuzawa, K., Amakawa, H., Zhang, H.: Spreading properties of monolayer lubricant films: effect of bonded molecules. IEEE Trans. Magn. 45(11), 5055–5060 (2009)
Itoh, S., Hamamoto, Y., Ishii, K., Fukuzawa, K., Zhang, H.D.: Detection of asperity contact for precise gap determination in thin-film nanorheometry. Tribol. Lett. 49(1), 1–10 (2013)
Vurens, G.H., Gudeman, C.S., Lin, L.J., Foster, J.S.: The mechanism of ultraviolet bonding of perfluoropolyether lubricants (used in magnetic recording). IEEE Trans. Magn. 29(1), 282–285 (1993)
Tyndall, G.W., Waltman, R.J., Pocker, D.J.: Concerning the interactions between Zdol perfluoropolyether lubricant and an amorphous-nitrogenated carbon surface. Langmuir 14(26), 7527–7536 (1998)
Waltman, R.J., Pocker, D.J., Tyndall, G.W.: Studies on the interactions between ZDOL perfluoropolyether lubricant and the carbon overcoat of rigid magnetic media. Tribol. Lett. 4(3/4), 267–275 (1998)
Chiba, H., Takeda, M., Nakamura, N., Watanabe, K.: Improvements of lubricant performance in hard-disk media by vacuum ultraviolet irradiation. Tribol. Int. 36(4–6), 367–369 (2003)
Zhang, H., Mitsuya, Y., Imamura, M., Fukuoka, N., Fukuzawa, K.: Effect of ultraviolet irradiation on the interactions between perfluoropolyether lubricant and magnetic disk surfaces. Tribol. Lett. 20(3–4), 191–199 (2005)
Gennes, P.-G.D., Brochard-Wyart, F., Quere, D.: Capillarity and wetting phenomena: drops, bubbles, pearls, waves. Springer, New York (2003)
Luengo, G., Israelachvili, J., Granick, S.: Generalized effects in confined fluids: new friction map for boundary lubrication. Wear 200(1–2), 328–335 (1996)
Ruths, M., Granick, S.: Tribology of confined Fomblin-Z perfluoropolyalkylethers: molecular weight dependence and comparison between unfunctionalized and telechelic chains. Tribol. Lett. 7(4), 161–172 (1999)
Yamada, S.: General shear-thinning dynamics of confined fluids. Tribol. Lett. 13(3), 167–171 (2002)
Pit, R., Hervet, H., Leger, L.: Direct experimental evidence of slip in hexadecane: solid interfaces. Phys. Rev. Lett. 85(5), 980–983 (2000)
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The present research was partially supported by the Storage Research Consortium and the Asahi Glass Foundation.
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This article is part of the Topical Collection on STLE Tribology Frontiers Conference 2014.
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Itoh, S., Norizuki, Y., Fukuzawa, K. et al. Effect of Chemically Adsorbed Molecules on the Viscous Friction of Nanometer-Thick Liquid Lubricant Films Coated on a Diamond-Like Carbon Surface. Tribol Lett 60, 7 (2015). https://doi.org/10.1007/s11249-015-0583-5
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DOI: https://doi.org/10.1007/s11249-015-0583-5