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Tribological performance of MoS2B2O3compacts

Authors
Journal
Tribology International
0301-679X
Publisher
Elsevier
Publication Date
Volume
23
Issue
1
Identifiers
DOI: 10.1016/0301-679x(90)90068-z
Keywords
  • Lubrication
  • Solid Lubricants
  • Molybdenum Disulphide
  • Boric Oxide

Abstract

Abstract A recent investigation suggests that selected oxides perform well as additives in molybdenum disulphide (MoS 2) because of their ability to soften at asperity contacts with the result that the solid lubricant can attain and retain a preferred tribological orientation. This research determined the effectiveness of boric oxide (B 2O 3), when used as an additive in MoS 2, for substrate temperatures ranging from 21°C to 316°C. This range was used to allow the asperity contact temperature to vary below and above the softening point of B 2O 3. It was found that a moderate friction coefficient and high wear, which is attributed to the additive acting abrasively, occurred when the asperity contact temperature was well below the softening point of the oxide. When the asperity contact temperature neared the softening point of the oxide, the friction coefficient increased dramatically and wear volume was reduced. It is postulated that B 2O 3 acted adhesively at the interface resulting in a higher coefficient of friction, and wear decreased due to an attainment of a preferred orientation by the MoS 2. For asperity contact temperatures significantly above the softening point of B 2O 3, the friction coefficient returned to about the same value as for temperatures below the softening point. It is speculated that wear continued to increase moderately because of localized melting of the B 2O 3, permitting the MoS 2 to be removed from the interface. These observations support a hypothesis that an additive, such as boric oxide, can soften as the asperity contact temperature approaches the softening point temperature of the additive so that the overall tribological conditions may be improved resulting in reduced interfacial wear. Significant changes in temperature, load or sliding velocity would, of course, dramatically alter the wear characteristics observed at the interface.

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