(Dr. Steven Danyluk, advisor)
"Non-Vibrating Kelvin Probe Detection of Monolayer Thick PFPE Lubricant on a Magnetic Disk Surface"
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.