(Dr. Steven Danyluk, advisor)

"Non-Vibrating Kelvin Probe Detection of Monolayer Thick PFPE Lubricant on a Magnetic Disk Surface"

Abstract

This thesis focuses on the detection of monolayer thick Perflouropolyether (PFPE) lubricants on a magnetic disk surface using a non-vibrating Kelvin probe.  Magnetic disks were partially dipped in a PFPE lubricant to create lubricated and non-lubricated regions on the disk surface.  The lubricant thickness was varied between 2 and 40 nm.  The non-vibrating Kelvin probe measures an electrical signal proportional to the surface charge density at the interfaces between the lubricated and non-lubricated regions, and linearly related to the scanning velocity.  The probe was placed at a data track radius of 30 mm and the disk spun at three scanning velocities (9, 12, and 15 m/s).  The surface charge at the non-lubed/lubed regime is calculated from the integration of the probe output signal and related to the corresponding lubricant thickness.  Results exhibit an exponential decay of probe output with decreasing lubricant thickness and scanning velocities.  This trend is related to the dipole moment generated in the lubricant.  Experimental results are compared with an analytical simulation of the probe signal output.