Jeffrey Lince - Tribological and chemical effects of long term humid air exposure on sputter-deposited nanocomposite MoS2 coatings

Document created by Jeffrey Lince on Sep 21, 2019Last modified by Jeffrey Lince on Sep 21, 2019
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  Publication Details (including relevant citation   information):

  J. R. Lince, C. S. Clark and S. H. Loewenthal, “Degradation of   Sputter-Deposited Nanocomposite MoS2 Coatings for NIRCam during   Storage in Air,” Proceedings of the 43rd Aerospace Mechanisms   Symposium; NASA Conf. Publ. NASA/CP-2016-219090, May 2016.

  Abstract: Sputter-deposited nanocomposite MoS2-based lubricant coatings have attractive properties for niche spacecraft applications, because they are thinner, exhibit lower friction, have excellent endurance, and can handle higher loads than bonded coatings. However, questions have been raised regarding the potential degradation of their tribological performance due to oxidation during prelaunch storage in air. We have studied the tribological and surface chemical changes occurring for coatings stored in air at 59% RH for extended periods. Pin-on-disk friction testing showed that the endurance of Ni–MoS2 coatings dropped significantly during storage of up to 4.2 years, but Sb2O3-containing coatings (Sb2O3–MoS2 and Au–Sb2O3–MoS2) exhibited much smaller drops in endurance over the same period. The differences in endurance correlate with X-ray Photoelectron Spectroscopy results that measured the conversion of MoS2 to nonlubricating MoO3 during storage.

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