Interaction Force Between Thin Film Disk Media and Elastic Solids Investigated by Atomic Force Microscope

Abstract

Atomic force microscopy is used to investigate the interaction force between the sharp tips of various elastic solids and four different samples. The samples are: thin film disk media coated with functional liquid lubricant having diol end groups, unlubricated disk media, a single-crystal silicon wafer, and Au evaporated onto single-crystal silicon. Relationships between the interaction and static friction force of disk media and a taper flat type head slider are examined. The interaction force between a disk medium coated with a functional liquid lubricant greater than 11.0 nm thick and tungsten tips with radii of 5 μm-100 μm is caused by the functional liquid lubricant meniscus, as pointed out by McFarlane and Tabor. However, at a thickness of several nanometers, the interaction force has a lower value than that for lubricant thicknesses above 11.0 nm. The interaction force has a minimum value of 0.4 μN at the functional liquid lubricant thickness of 2.0 nm. Mean interaction forces of the tungsten, Al2 O3 − TiC and Si3 N4 tips on a disk medium coated with a 2.0-nm-thick functional liquid lubricant are less than 0.1 times those for an unlubricated disk medium. Interaction forces of the SiC tip show very low values, even when the disk medium is unlubricated. Static friction force between a thin-film disk medium and a head or sphere is dependent on the interaction force between the medium and a tip that is made of the same material as the head or sphere. The use of an atomic force microscope (AFM), may allow the surface structure to be more thoroughly analyzed.