Bonding and tribological properties of perfluorinated lubricants and hydrogenated amorphous carbon films

Molecular properties of perfluorinated lubricants and amorphous carbon films relevant to the tribological performance of hard disk drives have been measured. The bonding of water and model perfluorinated lubricants to amorphous carbon surfaces has been studied by thermal desorption spectroscopy. Binding energies consistent with a physisorbed state are found for each of these small molecules. Binding energies are found to increase with increasing molecular weight and polarity of the adsorbate as well as increasing surface free energy of the carbon film. Adhesion forces and coefficients of friction have been measured with atomic force microscopy at hydrogenated amorphous carbon surfaces as a function of hydrogen content. An increase in both adhesion and friction forces is observed with increasing hydrogen contents and is attributed to changes in the surface free energy of the carbon films.