The interactions that occur between the hydroxyl-terminated perfluoropolyethers Zdol 2000/4000 and an amorphous-nitrogenated carbon surface (CNx) were studied via surface energy measurements, kinetic measurements, and ab initio calculations. The results of these measurements are compared with those of previous studies on the Zdol/amorphous-hydrogenated carbon (CHx) system and the major differences identified. The thickness dependence of the dispersive surface energy for the Zdol/CNx system can be fit using a repulsive van der Waals potential. Effective Hamaker constants determined for both the Zdol/CNx and Zdol/CHx systems demonstrate that Zdol is less effective at covering CNx as compared to CHx due to less favorable interactions between the Zdol backbone and the CNx surface. The Zdol thickness dependence of the polar surface energy for the Zdol/CNx system indicates that very few strong polar interactions are present between the initially applied Zdol and the CNx surface. A substantial decrease in the polar surface energy of the first Zdol monolayer however occurs on a time scale of 1-5 weeks after lubricant application. The attractive well that develops in the free energy versus thickness curve reflects the formation of attractive interactions between the polar hydroxyl end groups of Zdol and the polar entities on the CNx surface. A kinetic analysis of the Zdol + CNx system reveals that the rate at which the adhesive interactions are formed is limited by diffusion of the polar end groups to the surface active sites. Ab initio calculations indicate that attractive hydrogen-bonding interactions between the hydroxyl end groups of Zdol and imine (basic) sites on the CNx surface may be responsible for the Zdol adhesion. These calculations further suggest that the appearance of the diffusion step in the bonding kinetics and the less efficient coverage of Zdol on CNx are manifestations of repulsive interactions that exist between the basic imine surface sites and the basic perfluorinated Zdol backbone.

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TiSiN ultrathin films (10–50 Å) deposited by reactive magnetron sputtering from TixSiy targets were used as anticorrosion overcoats to protect Co-containing recording media. Films’ growth, structure, composition, resistance against hydrolysis, and anticorrosion performances were studied by spectroscopy (x-ray reflectivity and diffraction, ellipsometry, x-ray photoelectron spectroscopy, Fourier transform infrared reflection–absorption spectroscopy) and simulated by molecular dynamics (using modified Tersoff-type interatomic interactions). TiSiN ultrathin overcoats were found to be dense amorphous oxynitrides containing Ti–O–Si linkages. The conversion of SiNx into SiOx by hydrolysis was prevented by introducing less than 20 at. % of Ti in the films. Thanks to the formation of Ti–O–Si linkages which densify the films and reduce oxygen diffusion, good corrosion protection of the magnetic media was achieved down to 28 Å TiSiN overcoat thickness.

Ultra-thin films of titanium silicon carbide (TiSiC) were deposited by magnetron sputtering (using Ti2SiC3 targets) to form protection overcoats (OCs) onto magnetic recording media of hard disk drives. The chemico-physical properties (composition, optical constants, electrical resistivity, mass density, and surface energy) of titanium silicon nitride (TiSiN) films were measured and correlated to their OC performances in terms of protection against Si oxidation, Co corrosion, and Co diffusion. Performances of TiSiC OCs were compared to those of silicon carbide (SiC), silicon nitride (SiN), and TiSiN OCs. It was found that Ti incorporation into SiC and SiN considerably densifies the films, reduces their surface energy, and renders them more metallic. 25 Å thick TiSiC OC forms stable protecting barriers than can sustain hydrolysis conditions without growth of surface silicon oxide or cobalt diffusion or oxidation in the underlying recording magnetic medium. Overall, TiSiC OCs outperformed TiSiN, SiC, and SiN OCs as disk protection layers. We could directly correlate good protection against surface silicon oxide formation with film's lower surface energy, and good protection against Co diffusion with film's higher mass density.

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