Lubricant effect on noncontact-mode atomic force microscopy images of hard-disk surfaces

Abstract

In this paper we present our results of imaging ultrathin liquid films of perfluoropolyether (PFPE) lubricants on a hard-disk surface using the noncontact mode of atomic force microscopy (AFM). The presence of liquid films on the disk surface is reflected by features resulting from capillary interactions occurring when the AFM tip comes into contact with the lube layer. With the continually increasing tip-sample separation, the features of the capillary forces disappeared gradually and finally the images show a similar topography of the disk surfaces. The results demonstrate that the lubricants spread over the whole surface and coated surface grains of the carbon overcoats smoothly. More lubricants pool in the grain boundaries. The thickness is estimated in the range of 20-30 A.