Tribochemical mechanism of amorphous silica asperities in aqueous environment: A reactive molecular dynamics study

Da Chuan Yue, Tian Bao Ma, Yuan Zhong Hu, Jejoon Yeon, Adri C.T. Van Duin, Hui Wang, Jianbin Luo

Research output: Contribution to journalArticlepeer-review

29 Scopus citations

Abstract

Reactive molecular dynamics (ReaxFF) simulations are used to explore the atomic-level tribochemical mechanism of amorphous silica (a-SiO2) in a nanoscale, single-asperity contact in an aqueous environment. These sliding simulations are performed in both a phosphoric acid solution and in pure water under different normal pressures. The results show that tribochemical processes have profound consequences on tribological performance. Water molecules could help avoid direct adhesive interaction between a-SiO2 surfaces in pure water under low normal load. However, formation and rupture of interfacial siloxane bonds are obviously observed under higher normal load. In phosphoric acid solution, polymerization of phosphoric acid molecules occurs, yielding oligomers under lower load, and tribochemical reactions between the molecules and the sliding surfaces could enhance wear under higher load. The bridging oxygen atoms in silica play an important role in the formation of interfacial covalent bonds, and hydrogen is found to have a weakening effect on these bonds, resulting in the rupture during shear-related loading. This work sheds light on tribochemical reactions as a mechanism for lubrication and wear in water-based or other tribological systems.

Original languageEnglish (US)
Pages (from-to)1429-1436
Number of pages8
JournalLangmuir
Volume31
Issue number4
DOIs
StatePublished - Feb 3 2015

All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Spectroscopy
  • Electrochemistry

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