DeMejo LP, and
Dept. of Phys., Purdue Univ., West Lafayette, IN, USA.
Surface roughness and its influence on particle adhesion using atomic force
Journal of Adhesion Science & Technology, vol.9, no.8, 1995, pp.1049-62.
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).