Tribochemistry of phosphoric acid sheared between quartz surfaces: 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

34 Scopus citations

Abstract

Tribochemical processes have profound consequences on tribological performance. In the present paper, the tribochemical mechanism of low friction state in the silica/phosphoric acid system is elucidated by reactive molecular dynamics (ReaxFF) simulations. The friction coefficient is found having strong positive correlation with the number of interfacial hydrogen bonds, which suggests that a weaker interfacial hydrogen bond network would favor a lower friction. The friction reduction mechanisms have been analyzed in two temperature regimes: For 300 ≤ T ≤ 600 K, no indication of tribochemical reaction is observed, and the friction coefficient decreases because of the accelerated molecular rotational and translational motion and the corresponding weakened hydrogen bond network. For 800 K ≤ T ≤ 1400 K, the occurrence of tribochemical reactions leads to a clustering and polymerization of the phosphoric acid molecules and generation of a considerable quantity of water molecules distributed mainly in the sliding interface which could act as lubricant, and a low friction state is reached with a friction coefficient of 0.02.

Original languageEnglish (US)
Pages (from-to)25604-25614
Number of pages11
JournalJournal of Physical Chemistry C
Volume117
Issue number48
DOIs
StatePublished - Dec 5 2013

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Energy(all)
  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films

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