Tribological behaviour of silver based self-lubricating composite

Abstract

Silver based composites with varying concentration of graphite and/or MoS₂ were prepared by powder metallurgy method. Impacts of composition on the tribological performance of the composites in ambient air and vacuum were investigated. The lowest friction in air was achieved by Ag–20G (vol.-%) composite, while Ag–20MoS₂ exhibited the best lubricity in vacuum. XPS evaluation revealed the oxidation of MoS₂ in air and a decrease concentration of graphite on the surface of the wear tracks under vacuum. As the proportion of graphite to MoS₂ increased, the friction coefficient and the wear rates ascended gradually in air while decreased sharply under vacuum. As compared with other compositions, Ag–15MoS₂–5G exhibited a comparable stable and good tribological performance as the environmental condition changed for its friction coefficient and wear rate remained around 0·14 and 5×10⁻⁶ mm³ N⁻¹ m⁻¹.

Keywords:

• Silver based composite
• Solid lubrication
• MoS₂
• Graphite
• Wear
• Different composition

Acknowledgements

This work was financially supported by the Major Research Program of the National Natural Science Foundation of China (grant no. 91026018), the National Natural Science Foundation of China (grant no. 60979017) and the Doctoral Fund of Ministry of Education of China (grant no. 20110111110015)