Microsystem Technologies

, Volume 21, Issue 7, pp 1501–1511 | Cite as

Optimization of molecularly thin lubricant to improve bearing capacity at the head-disk interface

  • Shahla Chowdhury
  • Antonis I. Vakis
  • Andreas A. Polycarpou
Technical Paper


A molecularly thin lubricant layer (of the order of 1–2 nm thick) has been shown to provide bearing forces at the interface between contacting solid surfaces under light loads and high shear rates. This phenomenon is important, for example, in the head-disk contact in magnetic storage hard disk drives to ensure that some of the contact is sustained by the lubricant layer and thus avoiding damage of the solid surfaces. The magnitude of the normal and tangential bearing forces that the lubricant layer can provide depends on temperature, viscosity of the lubricant, sliding velocity and radius of gyration of the lubricant molecules. This study shows that viscosity has the greatest effect on the load bearing capacity of the molecularly thin lubricant. Thus, by controlling the flash temperature and the ratio of molecularly thin lubricant-to-bulk viscosity, the bearing load carrying capacity of the layer can be controlled. This would allow for the contact to be sustained within the mobile lubricant layer, avoiding solid contact so as to protect the diamond-like carbon coating, and thus reduce wear and potential catastrophic failures.


Bulk Viscosity High Shear Rate Lubricant Layer Lubricant Thickness Flash Temperature 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.



The motivation of this work was through a sponsored research program from Seagate Technology LLC, through Grant No. SRA- 32724.


  1. Archard JF (1958) The temperature of rubbing surfaces. Wear 2:438–455CrossRefGoogle Scholar
  2. Cho YK, Cai L, Granick S (1997) Molecular tribology of lubricants and additives. Tribol Int 30(12):889–894CrossRefGoogle Scholar
  3. Demirel AL, Granick S (1998) Transition from static to kinetic friction in a model lubricated system. J Chem Phys 109(16):6889–6897CrossRefGoogle Scholar
  4. Deolalikar N, Sadeghi F (2008) Numerical modeling of mixed lubrication and flash temperature in EHL elliptical contacts. J Tribol. doi: 10.1115/1.2805429 zbMATHGoogle Scholar
  5. DeVor RE, Chang TH, Sutherland JW (1992) Statistical quality design and control: contemporary concepts and methods. Prentice-Hall, Upper Saddle RiverGoogle Scholar
  6. Fisher LR, Israelachvili JN (1979) Direct experimental verification of the Kelvin equation for capillary condensation. Nature 277:548–549CrossRefGoogle Scholar
  7. Fukuzawa K, Hayakawa K, Matsumura N, Itoh S, Zhang H (2009) Simultaneously measuring lateral and vertical forces with accurate gap control for clarifying lubrication phenomena at nanometer gap. Tribol Lett 37(3):497–505CrossRefGoogle Scholar
  8. Greenwood JA, Williamson JB (1966) Contact of nominally flat surfaces. Proc R Soc. doi: 10.1098/rspa.1966.0242 Google Scholar
  9. Guo XC, Marchon B, Wang RH, Mate CM, Dai Q, Waltman RJ, Deng H, Pocker D, Xiao QF, Saito Y, Ohtani T (2012) A multidentate lubricant for use in hard disk drives at sub-nanometer thickness. J Appl Phys 111:024503CrossRefGoogle Scholar
  10. Hiroshi T, Tagawa N (2012) Adhesion and friction properties of molecularly thin perfluoropolyether liquid films on solid surfaces. Langmuir 28:3814–3820CrossRefGoogle Scholar
  11. Karis TE (2009) Lubricants for the disk drive industry. In: Rudnick L (ed) Lubricant additives: chemistry and applications, 2nd edn. CRC Press, FL, pp 523–584CrossRefGoogle Scholar
  12. Kogut L, Etsion I (2004) A static friction model for elastic-plastic contacting rough surfaces. J Tribol T ASME 126:34–40CrossRefGoogle Scholar
  13. Kunkel GH, Lou H, Macken D, Stoebe TW (2014) Resistance temperature sensors for head-media and asperity detection. Patent No: US 8,737,009 B2Google Scholar
  14. Lee SC, Polycarpou AA (2005) Microtribodynamics of pseudo-contacting head–disk interfaces intended for 1 Tbit/in2. IEEE Trans Magn 41(2):812–818CrossRefGoogle Scholar
  15. Lee SC, Strom BD (2008) Characterization of thermally actuated pole tip protrusion for head-media spacing adjustment in hard disk drives. J Tribol-T ASME 130(2):022001Google Scholar
  16. Marchon B, Saito Y (2009) Lubricant design attributes for subnanometer head-disk clearance. IEEE Trans Magn 45(2):872–876CrossRefGoogle Scholar
  17. Martini A, Hsu HY, Patankar NA, Lichter S (2008) Slip at high shear rates. Phys Rev Lett. doi: 10.1103/PhysRevLett.100.206001 Google Scholar
  18. Mate CM, Lorenz MR, Novotny V, Sanders IL, Lin LJ (1989) Tribological studies of storage media by atomic force microscopy. IEEE GA–7Google Scholar
  19. Muller VM, Yushchencko VS, Derjaguin BV (1980) On the influence of molecular forces on the deformation of an elastic sphere and its sticking to a rigid plane. J Coll Interface Sci 77(1):91–101CrossRefGoogle Scholar
  20. Persson BNJ (1997) Molecular tribology of lubricants and additives. Tribol Int 30(12):889–894CrossRefGoogle Scholar
  21. Rong J, Thomas L, Chong TC (2008) TOF-SIMS analysis for thermal effect study of hard disk lubricant. Appl Surface Sci 255(4):1490–1493CrossRefGoogle Scholar
  22. Scarpulla MA, Mate CM (2003) Air shear driven flow of thin perfluoropolyether polymer films. J chem phys 118(7):3368–3375CrossRefGoogle Scholar
  23. Seagate technology (2014), What is the normal operating temperature for seagate disk drives? Accessed 20 March 2014
  24. Spikes HA, Olver AV (2009) Compression heating and cooling in elastohydrodynamic contacts. Tribol Lett 36(1):69–80CrossRefGoogle Scholar
  25. Stanley HM, Etsion I, Bogy DB (1990) Adhesion of contacting rough surfaces in the presence of sub-boundary lubrication. J Tribol 112(1):98–104CrossRefGoogle Scholar
  26. Suh AY, Polycarpou AA (2005) Adhesive contact modeling for sub-5-nm ultralow flying magnetic storage head-disk interfaces including roughness effects. J Appl Phys. doi: 10.1063/1.1914951 Google Scholar
  27. Suh AY, Polycarpou AA (2008) Design optimization of sub-5 nm head–disk interfaces using a two-degree-of-freedom dynamic contact model with friction. Int J Prod Dev 5(3–4):268–291Google Scholar
  28. Suh AY, Mate CM, Payne RN, Polycarpou AA (2006) Experimental and theoretical evaluation of friction at contacting magnetic storage slider-disk interfaces. Tribol Lett 23(3):177–190CrossRefGoogle Scholar
  29. Vakis AI, Polycarpou AA (2010) Head-disk interface nanotribology for Tbit/in2 recording densities: near-contact and contact recording. J Phys D Appl Phys. doi: 10.1088/0022-3727/43/22/225301 Google Scholar
  30. Vakis AI, Polycarpou AA (2012) Modeling sliding contact of rough surfaces with molecularly thin lubricant. Tribol Lett 45(1):37–48CrossRefGoogle Scholar
  31. Vakis AI, Polycarpou AA (2013) An advanced rough surface continuum-based contact and sliding model in the presence of molecularly thin lubricant. Tribol Lett 49(1):227–238CrossRefGoogle Scholar
  32. Vakis AI, Lee SC, Polycarpou AA (2009) Dynamic head–disk interface instabilities with friction for light contact (surfing) recording. IEEE Trans Magn 45(11):4966–4971CrossRefGoogle Scholar
  33. Vakis AI, Eriten M, Polycarpou AA (2011) Modeling bearing and shear forces in molecularly thin lubricants. Tribol Lett 41(3):573–586CrossRefGoogle Scholar
  34. Vakis AI, Hadjicostis CN, Polycarpou AA (2012) Three-DOF dynamic model with lubricant contact for thermal fly-height control nanotechnology. J Phys D Appl Phys 45:135402CrossRefGoogle Scholar
  35. Wietzel U (1993) Significance of temperature effects for the behavior of thin lubricant films in an oscillating contact. Wear 169(1):59–62CrossRefGoogle Scholar
  36. Wood RW (2002) Recording technologies for terabit per square inch systems. IEEE Trans Magn 38(4):1711–1718CrossRefGoogle Scholar
  37. Yeo CD, Sullivan M, Lee SC, Polycarpou AA (2008) Friction force measurements and modeling in hard disk drives. IEEE Trans Magn 44(1):157–162CrossRefGoogle Scholar
  38. Zhu Y, Granick S (2004) Superlubricity: a paradox about confined fluids resolved. Phys Rev Lett. doi: 10.1103/PhysRevLett.93.096101 Google Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 2014

Authors and Affiliations

  • Shahla Chowdhury
    • 1
    • 2
  • Antonis I. Vakis
    • 1
    • 3
  • Andreas A. Polycarpou
    • 1
    • 2
  1. 1.Department of Mechanical Science and EngineeringUniversity of Illinois at Urbana-ChampaignChampaignUSA
  2. 2.Department of Mechanical EngineeringTexas A&M UniversityCollege StationUSA
  3. 3.Faculty of Mathematics and Natural SciencesUniversity of GroningenGroningenThe Netherlands

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