| LIU Cong,YIN Yanguo,ZHANG Guotao,MA Shibang,ZHANG Congzheng,YE Tie.Synergistic Lubrication Mechanism of FeS and Bi Phases in Lead-free Copper Based Self-lubricating Materials[J],54(7):118-128 |
| Synergistic Lubrication Mechanism of FeS and Bi Phases in Lead-free Copper Based Self-lubricating Materials |
| Received:June 11, 2024 Revised:August 22, 2024 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2025.07.010 |
| KeyWord:lead-free copper based self-lubricating material multiphase solid lubrication antifriction and wear resistance tribofilm synergistic mechanism |
| Author | Institution |
| LIU Cong |
School of Intelligent Manufacturing and Electrical Engineering, Nanyang Normal University, Henan Nanyang , China |
| YIN Yanguo |
Institute of Tribology, Hefei University of Technology, Hefei , China |
| ZHANG Guotao |
School of Mechanical Engineering, Anhui University of Technology, Anhui Maanshan , China |
| MA Shibang |
School of Intelligent Manufacturing and Electrical Engineering, Nanyang Normal University, Henan Nanyang , China |
| ZHANG Congzheng |
School of Intelligent Manufacturing and Electrical Engineering, Nanyang Normal University, Henan Nanyang , China |
| YE Tie |
School of Intelligent Manufacturing and Electrical Engineering, Nanyang Normal University, Henan Nanyang , China |
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| Abstract: |
| Although copper-lead alloy materials have good antifriction properties, lead is highly toxic. Cu-Bi materials developed by replacing lead with green, nontoxic bismuth with a low melting point have good antifriction properties. However, bismuth is brittle and easily peels off from friction surfaces due to shear force during friction, resulting in a remarkable decrease in the wear resistance of materials. Similar to graphite, FeS has a stable structure and properties and does not react with the copper matrix during sintering. Therefore, it is a good solid lubricant. FeS can improve the peeling of the bismuth phase. An appropriate content of FeS and Bi can confer copper-based composites with good antifriction and wear resistance. In this work, a tribological experimental research on materials containing single and FeS/Bi composite lubricants is conducted. The synergistic lubrication characteristics of FeS and bismuth phases are explored by characterizing friction coefficients, wear rates, friction interface microstructures, and chemical compositions. Results indicate that the bismuth phase with a low melting point can effectively fill the pores formed by the weak interface between FeS and the copper matrix, thereby improving the density of the material surface in microstructures. At the same time, the presence of FeS refines the network distribution of the bismuth phase in the copper matrix. The FeS/Cu-Bi self-lubricating material prepared with the FeS/Bi composite component can reduce the adhesion of the copper matrix on the surfaces of counterparts, thereby forming a thin transfer film. The presence of FeS in FeS/Cu-Bi materials slows down the formation and propagation of cracks between the Bi phase and the matrix, reducing the peeling off of the Bi phase, strengthening the worn surface of the material, and promoting enrichment of more Bi phases at the friction interface. Meanwhile, the existence of Bi rich phase promotes the retention and enrichment of FeS at the friction interface. Both of these promote each other to form a friction interface between a lubricating film rich in Bi and FeS and a transfer film rich in Bi and FeS, thereby improving the antifriction and wear resistance of the material. The forms of FeS and Bi present in the lubricating film of materials containing a single lubricant and FeS/Bi composite lubrication components do not seem to differ. However, in the lubricating film formed by FeS/Cu-Bi self-lubricating materials, the content of FeS and Bi is significantly higher than that of single Cu-FeS and Cu-Bi materials on the worn surface. At the same time, the degree of the frictional chemical reaction between FeS and Bi reduces. That is, the coexistence of FeS and Bi phases in the copper matrix can reduce the degree of their participation in frictional chemical reactions, thus improving the preservation rate of FeS and Bi on the worn surface, forming a lubricating film with rich FeS and Bi phases and good thickness, and causing the disappearance of the interface between the original sliding contact surfaces. A friction interface dominated by lubricating film–transfer film is reformed. The research results provide a theoretical basis for the multiphase synergistic effect in solid self-lubricating materials and guide the development of high-performance lead-free FeS/Cu-Bi self-lubricating materials. |
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