Relationship Between the Integrity of Lubricating Film and the Tribological Behavior on TiAl-Ag Self-Lubricating Composi
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JMEPEG DOI: 10.1007/s11665-017-3056-1
Relationship Between the Integrity of Lubricating Film and the Tribological Behavior on TiAl-Ag Self-Lubricating Composites Zengshi Xu, Shiyang Hua, and Ming Zhan (Submitted January 20, 2017; in revised form August 10, 2017) To explore the relationship between the integrity of the lubricating film and the tribological behavior of a metal matrix self-lubricating composite, the friction and wear experiments of TiAl-Ag self-lubricating composites were carried out with a ball-on-disk configuration. Besides, an approximate model was developed for analyzing the relationship based on BlauÕs theory. The research results suggest that the friction and wear behavior of the TiAl-Ag self-lubricating composites changes in accordance with the formation conditions of the Ag-rich lubricating film. Specifically, the friction coefficients and wear rates of the TiAl-Ag self-lubricating composites decreased from high levels at full composite–counterface ball contact to low levels at full-film lubrication. Hence, the integrity of the lubricating film is a possible criterion for the selflubricating property of the self-lubricating composites. Keywords
lubricating film, metal matrix self-lubricating composite, solid lubricant additives, solid lubrication
1. Introduction The demand for metal matrix self-lubricating composites (MMSCs), with excellent anti-friction and anti-wear performance, has been driven by the advancements in the jet engine and aerospace technology (Ref 1-3). Consequently, developing many kinds of MMSCs has become an active research field for researchers working in the field of tribology (Ref 4, 5). Shi et al. (Ref 6) studied the tribological behavior of TiAl matrix selflubricating composites containing Ag at high temperatures and observed that the Ag-rich lubricating films with different percentages of coverage smeared the worn surfaces. The films played an important role in improving the tribological behavior of the composites. Li and Xiong (Ref 7) researched the tribological properties of nickel-based self-lubricating composites reinforced by graphite under different experimental conditions and found that the graphite-rich lubricating films with different percentages of coverage formed on the worn surfaces. The films resulted in lower friction coefficients and less wear rates of the composites. Zhu et al. (Ref 8) explored the tribological properties of NiAl matrix self-lubricating composites incorporated with ZnO or CuO under different temperatures and observed that the ZnO-rich or CuO-rich lubricating films with different percentages of coverage smeared the worn surfaces. The films were responsible for the excellent tribological properties of the composites. Xu et al. (Ref 9) investigated the friction and wear behavior of TiAlWS2 self-lubricating composites at elevated temperatures and found that the WS2-rich lubricating films with different percent-
ages of coverage smeared the worn surfaces. The films ameliorated the anti-friction and anti-wear properties of the composites. The aforementioned
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