Mechanism of action of WS2 lubricant nanoadditives in high-pressure contacts

Monica Ratoi, Vlad Bogdan Niste, John Walker, Jurgita Zekonyte

    Research output: Contribution to journalArticlepeer-review


    Because of their excellent tribological properties and potential to replace problematic lubricant additives currently in use, WS2 nanoparticles have spurred considerable interest over the last two decades from academia and industry to decipher their mechanism of action. To elucidate the mechanism, this study carried out tribological tests at low and high temperatures and investigated the wear track and friction properties. It was found that in high-pressure, high-temperature sliding contacts, WS2 nanoadditives react with the metal substrate to generate thick chemical tribofilms which account for their excellent tribological properties. Based on XPS and FIB/SIMS results, a layered structure was proposed for the chemically formed tribofilms. The large amount of W in the composition of the reacted tribofilm could explain the excellent mechanical and antiwear properties, while the exfoliated squashed WS2 NPs which fill the gaps and cover the reacted tribofilm account for the striking reduction in the boundary friction.
    Original languageEnglish
    Pages (from-to)81-91
    JournalTribology Letters
    Issue number1
    Early online date21 Aug 2013
    Publication statusPublished - Oct 2013


    • WS2 nanoparticles
    • Mechanism of action
    • Tribofilm
    • Composition
    • Hardness
    • Friction modifiers
    • Antiwear additives


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