AVS 46th International Symposium
    The Science of Micro-Electro-Mechanical Systems Topical Conference Monday Sessions
       Session AS+MI+VM-MoM

Invited Paper AS+MI+VM-MoM9
Tribo-Chemistry of the Head-Disk Interface in Hard Disk Drives

Monday, October 25, 1999, 11:00 am, Room 610

Session: Magnetic Recording: Chemical Integration and Tribology
Presenter: D.B. Bogy, University of California, Berkeley
Authors: D.B. Bogy, University of California, Berkeley
C.S. Bhatia, IBM SSD
C.-Y. Chen, University of California, Berkeley
W. Fong, University of California, Berkeley
Correspondent: Click to Email
Tribo-chemical studies of the lubricant thickness effect on the tribology of the head/disk interface (HDI) were conducted using hydrogenated (CHx) carbon disk samples coated with perfluoropolyether ZDOL lubricant. The studies involved drag tests with uncoated and carbon-coated Al@sub 2@O@sub 3@-TiC sliders and thermal desorption experiments in an ultra-high vacuum (UHV) tribochamber. The studies showed that the lubricant interaction with the carbon overcoat varies as a function of lubricant thickness. Wear durability improves considerably for thicknesses greater than a monolayer. However, in the sub-monolayer thickness regime, the adhesion of the lubricant to the carbon overcoat is much stronger, as indicated by the fact that a much higher temperature is required to desorb the lubricant. When the lubricant thickness is around or above a monolayer, cohesion among the lubricant molecules plays a greater role and a much lower temperature is needed for lubricant desorption. In addition, we observed that hydrogen evolution from CHx overcoat initiates lubricant catalytic decomposition, forming CF3 and C2F5. The generation of HF during the thermal desorption experiments provides the formation mechanism of HF, which is the necessary component for catalytic reaction.