Microtribology of aqueous carbon nanotube dispersions

Kai Kristiansen, Hongbo Zeng, Peng Wang, Jacob N. Israelachvili

Research output: Journal article publicationJournal articleAcademic researchpeer-review

27 Citations (Scopus)

Abstract

The tribological behavior of carbon nanotubes (CNTs) in aqueous humic acid (HA) solutions was studied using a surface forces apparatus (SFA) and shows promising lubricant additive properties. Adding CNTs to the solution changes the friction forces between two mica surfaces from "adhesion controlled" to "load controlled" friction. The coefficient of friction with either single-walled (SW) or multi-walled (MW) CNT dispersions is in the range 0.30-0.55 and is independent of the load and sliding velocity. More importantly, lateral sliding promotes a redistribution or accumulation, rather than squeezing out, of nanotubes between the surfaces. This accumulation reduced the adhesion between the surfaces (which generally causes wear/damage of the surfaces), and no wear or damage was observed during continuous shearing experiments that lasted several hours even under high loads (pressures â∼10 MPa). The frictional properties can be understood in terms of the Cobblestone Model where the friction force is related to the fraction of the adhesion energy dissipated during impacts of the nanoparticles. We also develop a simple generic model based on the van der Waals interactions between particles and surfaces to determine the relation between the dimensions of nanoparticles and their tribological properties when used as additives in oil- or water-based lubricants.

Original languageEnglish
Pages (from-to)4555-4564
Number of pages10
JournalAdvanced Functional Materials
Volume21
Issue number23
DOIs
Publication statusPublished - 6 Dec 2011
Externally publishedYes

Keywords

  • aqueous lubricant
  • carbon nanotubes
  • microtribology

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics

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