Capillary-Induced Crack Healing between Surfaces of Nanoscale Roughness


Soylemez E. , de Boer M. P.

LANGMUIR, vol.30, no.39, pp.11625-11633, 2014 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 30 Issue: 39
  • Publication Date: 2014
  • Doi Number: 10.1021/la5026284
  • Title of Journal : LANGMUIR
  • Page Numbers: pp.11625-11633

Abstract

Capillary 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, (v) over bar, between clean hydrophilic polycrystalline silicon surfaces of nanoscale roughness is measured. A plot of (v) over bar versus energy release rate, G, reveals log-linear behavior, while the slope vertical bar d[log((v) over bar)]/dG vertical bar 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.