View in EDS

Surface and Subsurface Contributions of Oxidation and Moisture to Room Temperature Friction of Molybdenum Disulfide.

Saved in:
Bibliographic Details
Title: Surface and Subsurface Contributions of Oxidation and Moisture to Room Temperature Friction of Molybdenum Disulfide.
Authors: Khare, H.1, Burris, D.1 dlburris@udel.edu
Source: Tribology Letters. Jan2014, Vol. 53 Issue 1, p329-336. 8p.
Subjects: Molybdenum disulfide, Moisture, Temperature effect, Solid lubricants, Water chemistry, Friction
Abstract: Molybdenum disulfide (MoS), a lamellar solid lubricant, is used extensively in space applications due to its exceptional performance in vacuum and inert environments. The friction and wear of MoS, however, increase in the presence of atmospheric contaminants, such as water. Despite numerous studies of the moisture-sensitive friction response of MoS over the decades, important fundamental questions remain unanswered. Two leading hypotheses suggest that water affects friction by causing the MoS to oxidize or by physically bonding to edge sites, and thereby disrupting easy lamellar shear. This paper presents a parametric study to (1) isolate the effects of water and oxygen on ambient MoS friction, (2) identify the effect of water and oxygen on MoS oxidation, and (3) distinguish between the effects of water diffusion and surface oxidation on the frictional response of MoS coatings. The experimental findings were used to develop a qualitative model for the effects of environment on MoS friction; the model is used to explain transients, hysteretic effects, oxidation effects, and effects of physically bound water. [ABSTRACT FROM AUTHOR]
Copyright of Tribology Letters is the property of Springer Nature and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
Database: Engineering Source
Description
Abstract:Molybdenum disulfide (MoS), a lamellar solid lubricant, is used extensively in space applications due to its exceptional performance in vacuum and inert environments. The friction and wear of MoS, however, increase in the presence of atmospheric contaminants, such as water. Despite numerous studies of the moisture-sensitive friction response of MoS over the decades, important fundamental questions remain unanswered. Two leading hypotheses suggest that water affects friction by causing the MoS to oxidize or by physically bonding to edge sites, and thereby disrupting easy lamellar shear. This paper presents a parametric study to (1) isolate the effects of water and oxygen on ambient MoS friction, (2) identify the effect of water and oxygen on MoS oxidation, and (3) distinguish between the effects of water diffusion and surface oxidation on the frictional response of MoS coatings. The experimental findings were used to develop a qualitative model for the effects of environment on MoS friction; the model is used to explain transients, hysteretic effects, oxidation effects, and effects of physically bound water. [ABSTRACT FROM AUTHOR]
ISSN:10238883
DOI:10.1007/s11249-013-0273-0