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Capillary-Induced Crack Healing between Surfaces of Nanoscale Roughness
journal contribution
posted on 2014-10-07, 00:00 authored by Emrecan Soylemez, Maarten P. de BoerCapillary forces are important in
nature (granular materials, insect
locomotion) and in technology (disk drives, adhesion). Although well
studied in equilibrium state, the dynamics of capillary formation
merit further investigation. Here, we show that microcantilever crack
healing experiments are a viable experimental technique for investigating
the influence of capillary nucleation on crack healing between rough
surfaces. The average crack healing velocity, v̅, between clean hydrophilic polycrystalline silicon surfaces of nanoscale
roughness is measured. A plot of v̅ versus
energy release rate, G, reveals log–linear
behavior, while the slope |d[log(v̅)]/dG| decreases with increasing relative humidity. A simplified
interface model that accounts for the nucleation time of water bridges
by an activated process is developed to gain insight into the crack
healing trends. This methodology enables us to gain insight into capillary
bridge dynamics, with a goal of attaining a predictive capability
for this important microelectromechanical systems (MEMS) reliability
failure mechanism.