Schaefer DM, Carpenter M, Reifenberger R, DeMejo LP, and Rimai DS.
Dept. of Phys., Purdue Univ., West Lafayette, IN, USA.
Surface roughness and its influence on particle adhesion using atomic force techniques.
Journal of Adhesion Science & Technology, vol.9, no.8, 1995, pp.1049-62. Netherlands.
The surface force interactions between individual 8 mu m diameter spheres and atomically flat substrates have been investigated using atomic force techniques. The lift-off force of glass, polystyrene, and tin particles from atomically smooth mica and highly oriented pyrolitic graphite substrates was determined as a function of the applied loading force in an inert nitrogen environment. While the relative magnitudes of the measured lift-off force were found to scale as expected between the various systems studied, the absolute values were a factor of approximately 50 smaller than expected from the Johnson, Kendall, and Roberts theory. The surface topography of representative spheres was characterized with atomic force microscopy, allowing a quantitative assessment of the role that surface roughness plays in the adhesion of micrometer-size particles to substrates. Taking into account the radius of curvature of the asperities measured from the atomic force scans, agreement between the measured and theoretical estimates for the lift-off forces was improved, with the corrected experimental forces about a factor of 3 smaller than theoretical expectations. (28 References).