Lubricant bonding and orientation on carbon coated media

The bonding characteristics of perfluoropolyether lubricants with functional end groups have been studied on carbon-overcoated thin-film recording media. Two types of bond energies were measured for these lubricants, indicating that they chemically bond to carbon while physically bonding to themselves. Grazing-angle FTIR (Fourier-transform infrared) techniques were utilized to show that the orientation of the Fomblin Am2001 lubricant is consistent with a π-bonding model between the neutral planar ring groups and the carbon overlayer. Neither the chemically nor the physically bonded lubricant layers were removed from disks lubricated with Z-DOL after spinning at 6000 r/min for three months at 60°C. This indicates that lubricant spin-off itself should not be a concern for the smaller-diameter disks. Localized depletion of lubricant at the landing zone during contact-start-stop testing was found to occur with the physically bonded lubricant layers, while the chemically bonded layer remained in place. This suggests that the use of chemically bonded lubricants on carbon-coated media is important to ensure good tribological performance over the lifetime of the drive