An Adsorption of Perfluoropolyethers on SiO₂ Surfaces for Thin Film Magnetic Disk Overcoats

Abstract

Perfluoropolyethers (PFPEs) have been widely used as an excellent lubricant on magnetic disks. Sol-gel SiO₂ has been applied as a protective overcoat for plated magnetic disks. Adsorption of PFPEs on the surface of a protective overcoat is an important issue in evaluating lubrication characteristics, such as coefficient of friction, wear resistance, volatility, spin-off, etc. for magnetic disks. Molecular configuration and magnitude of adsorption between lubricants and protective overcoats were measured, using various analytical methods, i.e., diffuse reflectance IR spectroscopy, polarization reflection IR spectroscopy, refractive index analysis, flow micro-calorimetry, etc. Functional groups in PFPE molecules adsorb to silanol groups on the sol-gel SiO₂ surface. The main chain of PFPE molecule orients parallel to the sol-gel SiO₂ surface. The thickness of adsorbed PFPE agrees well with the diameter of the PFPE main chain. The heat of adsorption increases with increasing hydrophilic affinity of functional groups. The heat of adsorption decrecues with increasing baking temperature of sol-gel SiO₂, which corresponds to the decrease in silanol group density.

Presented as a Society of Tribologists and Lubrication Engineers paper at the ASME/STLE Tribology Conference in San Diego, California, October 19–21, 1992

KEYWORDS:

• Lubricant Properties and Problems
• Magnetic Data Storage

Notes

Presented as a Society of Tribologists and Lubrication Engineers paper at the ASME/STLE Tribology Conference in San Diego, California, October 19–21, 1992