Nonlinear friction characteristics between silica surfaces in high pH solution

Elena Taran, Yoichi Kanda, Ivan Uriev Vakarelski, Ko Higashitani*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

27 Scopus citations

Abstract

Molecular-scale characteristics of friction forces between silica particles and silica wafers in aqueous solutions of the normal (pH 5.6) and high pH (pH 10.6) are investigated, using the lateral force measuring procedure of the atomic force microscope (AFM). Various significant differences of friction characteristics between solutions of normal and high pH's are found. In the case of solutions of normal pH, the friction force increases linearly with increasing loading force, as the Amonton's law for solid bodies indicates. However, in the case of high pH solutions, the increasing rate with the loading force is considerably reduced in the low loading region, but the value increases abruptly above a critical loading force to overcome the magnitude of friction force of normal pH above the region of very high loading. It is very interesting to know that this nonlinear force curve at high pH is independent of the atomic-scale roughness of surfaces, although the magnitude of friction is greatly influenced by the roughness in the case of normal pH. The reason why the friction at high pH is independent of the surface roughness is postulated to be due to the hairy-like layer formed on the silica surface. The existence of hairy-like layers at high pH is proven directly by the dynamic method of normal force measurements with AFM and the thickness is estimated to be at least ca. 1.3 nm.

Original languageEnglish (US)
Pages (from-to)425-432
Number of pages8
JournalJournal of Colloid And Interface Science
Volume307
Issue number2
DOIs
StatePublished - Mar 15 2007

Keywords

  • CMP
  • Friction
  • Hairy layer
  • High pH
  • Lubrication
  • Silica surface

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Biomaterials
  • Surfaces, Coatings and Films
  • Colloid and Surface Chemistry

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