Influence of nanometer scale film structure of ZDDP tribofilm on Its mechanical properties: A computational chemistry study

Tasuku Onodera, Takanori Kuriaki, Yusuke Morita, Ai Suzuki, Michihisa Koyama, Hideyuki Tsuboi, Nozomu Hatakeyama, Akira Endou, Hiromitsu Takaba, Carlos A. Del Carpio, Momoji Kubo, Clotilde Minfray, Jean Michel Martin, Akira Miyamoto

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

We investigated the influence of a nanometer scale film structure of a tribofilm generated from zinc dialkyldithiophosphate (ZDDP) anti-wear additive on its mechanical properties using a combined molecular dynamics (MD) and finite element (FE) method. The frictional behavior of an interface between a native iron oxide layer on steel surface and zinc metaphosphate - regarded as a model material of ZDDP tribofilm - was firstly studied using the MD method. The results showed that the iron atoms in the oxide layer diffused into the phosphate layer during the friction process. The zinc atoms in the phosphate layer also diffused into the oxide layer. Significant interdiffusion of iron and zinc atoms was observed with increasing simulation time. Thus, metallic phosphate with a gradient composition of iron and zinc atoms was formed on the phosphate/oxide interface. We then constructed an axisymmetric nanoindentation simulation model from the MD-derived structures at a certain simulation time and carried out a FE calculation. As a result, we found that the rubbed ZDDP tribofilm, including the phosphate with the gradient composition of metallic atoms, showed larger contact stiffness and hardness. The combined MD/FE simulation indicates that the tribofilm becomes stiffer and harder due to the interdiffusion of iron and zinc atoms on the tribofilm/oxide interface. We have found that the gradient composition formation in ZDDP tribofilm during friction process influences on its mechanical properties.

Original languageEnglish
Pages (from-to)976-979
Number of pages4
JournalApplied Surface Science
Volume256
Issue number4
DOIs
Publication statusPublished - 2009 Nov 30

Keywords

  • Computational chemistry
  • Gradient composition
  • Mechanical properties
  • ZDDP

ASJC Scopus subject areas

  • Chemistry(all)
  • Condensed Matter Physics
  • Physics and Astronomy(all)
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films

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  • Cite this

    Onodera, T., Kuriaki, T., Morita, Y., Suzuki, A., Koyama, M., Tsuboi, H., Hatakeyama, N., Endou, A., Takaba, H., Del Carpio, C. A., Kubo, M., Minfray, C., Martin, J. M., & Miyamoto, A. (2009). Influence of nanometer scale film structure of ZDDP tribofilm on Its mechanical properties: A computational chemistry study. Applied Surface Science, 256(4), 976-979. https://doi.org/10.1016/j.apsusc.2009.04.205