Stability Model for a Lubricant Film With a Slider

The thermodynamic stability model of perfluoropolyether (PFPE) lubricants is developed and extended to include the interaction between surfaces of slider and lubricant film as a function of molecular weights, film thickness, and fly heights. Surface energies of PFPEs and a hydrogenated carbon overcoat were calculated from measured contact angles. The model predicts instability for the lower fly heights. The relationships among the stability, the molecular weights of lubricants, and the film thickness were investigated. It was shown that thinner lubricant film and smaller surface free energy of the slider enhance the stability of the film