Z-DOL and carbon overcoat: bonding mechanism

Magnetic layers of hard storage disks are usually coated with a thin of sputter-deposited carbon in order to protect them from corrosion and abrasive impacts of the slider of the head. A thin layer of lubricant is applied over the carbon overcoat to further dampen the tribological impact of the slider. The lubricant of topical choice for this application is a PFPE (perfluoropolyether) known by the brand name Z-DOL. It has been known that, when a layer of Z-DOL is applied atop a carbon overcoat, a certain fraction of Z-DOL becomes bonded such that it can not be removed by rinsing with fluorinated solvents. In this paper we attempt to correlate chemical features of the carbon surface with the Z-DOL bonding process.