The Effects of Impurities and Vapors at Very Low Pressures on the Sliding Properties of Molybdenum and Tungsten Disulfide

Item

Title
The Effects of Impurities and Vapors at Very Low Pressures on the Sliding Properties of Molybdenum and Tungsten Disulfide
Report Number
AFML-TR-70-127 p. 67
Creator
Haltner, Arthur J.
Corporate Author
General Electric Company, Spaces Sciences Laboratory
Laboratory
Air Force Materials Laboratory
Date
1970
Date Issued
1970-07
Extent
56
Contract
AF33(615)-5278
DoD Project
7343
Abstract
The friction of molybdenite (naturally occurring molybdenum disulfide) sliding in ultrahigh vacuum is generally half that observed in air under comparable conditions. In contrast, synthetic molybdenum disulfide (three different preparations) and tungsten disulfide (from three sources) have been shown to have friction levels in ultrahigh vacuum that are as high as and often higher than values observed in air. When these samples are exposed to a gas mixture at 10<sup>-5</sup> torr containing significant concentrations of hydrocarbons, friction levels drop to levels similar to those observed for molybdenite in ultrahigh vacuum. Tungsten disulfide has been studied in the presence of controlled atmospheres of pure vapors at reduced pressurues. Of the vapors studied, most (water vapor, oxygen, mercury, ethylene, acetone, methyl ethyl ketone, ethyl acetate, and methanol) had little or no effect on friction. But at 10<sup>-5</sup> torr n-amyl or isoamyl alcohol lowered the friction coefficient to less than 0.09. When a specimen of molybdenite containing 10% by weight of molybdenum dioxide was studied in ultrahigh vacuum, the friction coefficient was near 0.25 and dropped to 0.07 when gas containing hydrocarbons was admitted to the chamber. These observations are consistent with the hypothesis that the high friction levels for synthetic dichalcogenides in ultrahigh vacuum are related to the presence of one or more impurities at the sliding interface.
Distribution Classification
1
Distribution Conflict
No
DTIC Record Exists
No
Illinois Tech Related
No
Photo Quality
Not needed
Type
article
Is Part Of
Proceedings of the AFML-MRI Conference on Solid Lubricants Held in Kansas City, Missouri, on (September 9-11, 1969)
Provenance
Lockheed Martin Missiles & Fire Control