A Model for Lubricant Transfer from Media to Head During Heat-Assisted Magnetic Recording (HAMR) Writing
- 191 Downloads
One of the challenges in heat-assisted magnetic recording (HAMR) is the creation of write-induced head contamination at the near-field transducer. A possible mechanism for the formation of this contamination is the transfer of lubricant from the disk to the slider (lubricant pickup) due to temperature-driven evaporation/condensation and/or mechanical interactions. Here we develop a continuum model that predicts the head-to-disk lubricant transfer during HAMR writing. The model simultaneously determines the thermocapillary shear stress-driven deformation and evaporation of the lubricant film on the disk, the convection and diffusion of the vapor phase lubricant in the air bearing and the evolution of the condensed lubricant film on the slider. The model also considers molecular interactions between disk–lubricant, slider–lubricant and lubricant–lubricant in terms of disjoining pressure. We investigate the effect of media temperature, head temperature and initial lubricant thickness on the lubricant transfer process. We find that the transfer mechanism is initially largely thermally driven. The rate of slider lubricant accumulation can be significantly reduced by decreasing the media temperature. However, as the amount of lubricant accumulation increases with time, a change in the transfer mechanism occurs from thermally driven to molecular interactions driven. A similar change in transfer mechanism is predicted as the head–disk spacing is reduced. There exists a critical value of head lubricant thickness and a critical head–disk spacing at which dewetting of the disk lubricant begins, leading to enhanced pickup.
KeywordsHard disk drives Heat-assisted magnetic recording (HAMR) Lubricant Disjoining pressure Evaporation Contamination Smear
This work was supported by the Computer Mechanics Laboratory at University of California, Berkeley, Mechanical Engineering Department.
- 2.Marchon, B., Guo, X.C., Pathem, B.K., Rose, F., Dai, Q., Feliss, N., Schreck, E., Reiner, J., Mosendz, O., Takano, K., Do, H., Burns, J., Saito, Y.: Head-disk interface materials issues in heat-assisted magnetic recording. IEEE Trans. Magn. (2014). https://doi.org/10.1109/TMAG.2013.2283068 Google Scholar
- 8.Yang, Y., Li, X., Stirniman, M., Yan, X., Huang, F., Zavaliche, F., Wang, H., Huang, J., Tang, H., Jones, P.M., Kiely, J.D., Brand, J.L.: Head disk lubricant transfer and deposition during heat-assisted magnetic recording write operations. IEEE Trans. Magn. (2015). https://doi.org/10.1109/TMAG.2015.2434826 Google Scholar
- 22.Batchelor, G.: An Introduction to Fluid Dynamics. Cambridge University Press, Cambridge (1967)Google Scholar
- 30.Israelachvili, J.N.: Intermolecular and Surface Forces: Revised, 3rd edn. Academic Press, Cambridge (2011)Google Scholar
- 32.Karis, T.: Lubricants for the disk drive industry. In: Rudnick, L. (ed.) Lubricant Additives: Chemistry and Applications, chap 22, p. 523584. CRC Press, Boca Raton (2009)Google Scholar
- 33.Carey, V.P.: Liquid–Vapor Phase-Change Phenomena, 2nd edn. Taylor and Francis Group LLC, New York (2008)Google Scholar
- 38.Patankar, S.: Numerical Heat Transfer and Fluid Flow. Hemisphere Publishing Corporation, New York (1980)Google Scholar
- 40.Aoki, T.: Multi-dimensional advection of CIP (cubicinterpolated propagation) scheme. Comput. Fluid Dyn. J. 4(3), 279–291 (1995)Google Scholar
- 41.Jones, P.M., Yan, X., Hohlfeld, J., Stirniman, M., Kiely, J.D., Zavaliche, F., Tang, H.H.: Laser-induced thermo-desorption of perfluoropolyether lubricant from the surface of a heat-assisted magnetic recording disk: lubricant evaporation and diffusion. Tribol. Lett. (2015). https://doi.org/10.1007/s11249-015-0561-y Google Scholar