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Title: Impact of Microstructure on MoS 2 Oxidation and Friction

In this work, we demonstrate the role of microstructure in the friction and oxidation behavior of the lamellar solid lubricant molybdenum disulfide (MoS 2). We report on systematic investigations of oxidation and friction for two MoS 2 films with distinctively different microstructures—amorphous and planar/highly-ordered—before and after exposure to atomic oxygen (AO) and high-temperature (250 °C) molecular oxygen. A combination of experimental tribology, molecular dynamics simulations, X-ray photoelectron spectroscopy (XPS), and high-sensitivity low-energy ion scattering (HS-LEIS) was used to reveal new insights about the links between structure and properties of these widely utilized low-friction materials. Initially, ordered MoS 2 films showed a surprising resistance to both atomic and molecular oxygens (even at elevated temperature), retaining characteristic low friction after exposure to extreme oxidative environments. Finally, XPS shows comparable oxidation of both coatings via AO; however, monolayer resolved compositional depth profiles from HS-LEIS reveal that the microstructure of the ordered coatings limits oxidation to the first atomic layer.
Authors:
 [1] ;  [2] ;  [3] ;  [4] ;  [2] ;  [2] ;  [5] ; ORCiD logo [5]
  1. Lehigh Univ., Bethlehem, PA (United States). Department of Mechanical Engineering and Mechanics; Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Materials Science and Engineering Center
  2. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Materials Science and Engineering Center
  3. Lehigh Univ., Bethlehem, PA (United States). Surface Analysis Facility
  4. Lehigh Univ., Bethlehem, PA (United States). Materials Science & Engineering Department
  5. Lehigh Univ., Bethlehem, PA (United States). Department of Mechanical Engineering and Mechanics
Publication Date:
Report Number(s):
SAND-2017-11202J
Journal ID: ISSN 1944-8244; 657854
Grant/Contract Number:
AC04-94AL85000; NA0003525
Type:
Accepted Manuscript
Journal Name:
ACS Applied Materials and Interfaces
Additional Journal Information:
Journal Volume: 9; Journal Issue: 33; Journal ID: ISSN 1944-8244
Publisher:
American Chemical Society (ACS)
Research Org:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org:
USDOE National Nuclear Security Administration (NNSA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; aging; friction; HS-LEIS; MoS2; nitrogen spray; orientation; oxidation; wear
OSTI Identifier:
1429653