Surface-force-induced nonelastic deformations between micrometer size glass particles and silicon substrates

Glass beads having radii between 3 mu m to 25 mu m were gently deposited onto a polished silicon wafer, and the surface-force-induced particle-substrate contact radii were determined using scanning electron microscopy. The contact radii were found to vary as the particle radii to the 0.42 power (+/- 0.14), which is consistent with the plastic deformation model of Maugis and Pollock,(10) but inconsistent with the predictions of the elastic-response based adhesion models proposed by Johnson, Kendall, and Roberts(5) or Dejaguin, Muller, and Toporov.(6) Estimates of the stresses due to the surface forces suggest that they exceed the tensile strength of glass and that the observed deformations can arise from these tensile stresses.