Additive mechanism investigation of perfluoropolyether lubricants with a phosphazene additive

The tribological characteristics of magnetic thin film media coated with perfluoropolyether (PFPE) lubricants (ZDOL and AM3001) and a phosphazene additive (X-1P) were investigated in this study. The drag test results show that under ambient and hot/wet conditions the media coated with AM3001 lubricant have higher retention on the test track than those coated with ZDOL 2000 PFPE lubricant. The phosphazene additive X-1P was observed to strongly anchored to the surface and was not as easily removed as PFPE lubricants alone. The retention characteristics of X-1P are independent of either AM or ZDOL. Secondary Ion Mass Spectroscopy (SIMS) depth profile data and Angle-Resolved X-Ray Photo-electron Spectroscopy (XPS) reveal that X-1P molecules were distributed near the disk surface in the X-1P and PFPE lubricants mixed layer, indicating a strong bonding/adhesion of X-1P to the disk surface. Together with the drag testing data, the authors conclude that the preferential distribution of X-1P close to the disk surface in the mixed layer helps to improve lubricant retention performance at the head-disk interface.