A series of progress has been made in the research of functional lubricating materials for PTFE

Polytetrafluoroethylene (PTFE) is widely used in aerospace, automotive industry and other fields with its excellent self-lubricating properties, but its dispersion compatibility and wear resistance are still key problems that need to be solved urgently.

In recent years, the Research Group of The State Key Laboratory of Solid Lubrication of the State Key Laboratory of Solid Lubrication and the Research Group of Engineering Special Lubricating Materials of the Advanced Lubrication and Protective Materials R&D Center of the Advanced Lubrication and Protective Materials Research and Development Center have jointly devoted themselves to the systematic research of functional assembly strategies, structural regulation, performance optimization and tribological mechanisms of lubricating materials. The researchers prepared a series of PTFE-based composite lubricating materials through structural design and functional modification of PTFE and organic/inorganic materials, which solved the problems of uneven dispersion and phase separation when preparing composite materials by physical blending. The research results provide theoretical and experimental basis for the application of PTFE-based polymer composite lubricating materials, lubrication additives and coating materials.

In order to improve the problem of insufficient wear resistance when PTFE is used as a friction secondary element, the researchers prepared a core shell composite material (PTFE@PR, PTFE@PACR) with PTFE as the core, phenolic resin and polyacrylate as the shell, and obtained high load carrying and wear resistance under harsh working conditions (Figure 1). The excellent tribological properties are closely related to the uniformity and crystallinity of the transfer film and its binding to the substrate. Some of the results were published in Tribol Int (2020, 144, 1060922021, 154, 106718and J Appl Polym Sci (2019, 136, 47774On the relevant technology, it has been authorized by The Chinese Invention Patent (ZL 201911007819.X).

Figure 1 Structural design and performance study of PTFE-based core shell composites under different working conditions

In order to solve the problem of poor compatibility and dispersion of PTFE as a solid and liquid lubrication additive, the researchers prepared PTFE@SiO2, MXene@PTFE and GO@PTFE core shell particles by emulsion polymerization-sol gel method and electrostatic self-assembly method by means of rich functional groups on the surface of shell materials. The uniformity of the transfer film during friction and the strength of the binding to the substrate are the root causes of the excellent tribological properties of the composites in epoxy, PAO6 and water lubrication systems (Figure 2). Some of the results were published in Mater Design (2020, 195, 109069)、Carbon(2021, 184, 12-23)、Tribol Int(2021, 160, 1070162021,158, 1069302022, 169, 107485and journal of tribology (2021, 41, 522-531On the relevant technology, it has been authorized by China Invention Patent (ZL 202010092324.8).

Fig. 2 Structural design and performance regulation of PTFE solid and liquid lubrication additives

Based on the correlation between the excellent tribological properties of PTFE composites and the microstructure of the transfer membrane, the researchers prepared PTFE-based heterogeneous lubricating coatings (PTFE/Al3+-GS and PTFE/Al3+-MXene) under the inducement of friction, and simulated the theory of related transfer lubrication (Figure 3). Through structural analysis and molecular dynamics simulation, the formation mechanism, structural evolution and interfacial friction chemical reaction of the transfer membrane are revealed. Some of the results were published in Tribol Int (2022, 168: 107455and Chem Eng J(2022,10.1016/j.cej.2022.136238) , apply for a Chinese invention patent (CN 202111212961.5).

Fig. 3 Design and preparation of PTFE-based heterogeneous coatings and study of transfer lubrication mechanism

The above work was completed by Dr. Yang Yawen and Dr. Wang Na of Lanzhou Institute of Chemicals, and the supervisors were Researcher Wang Jinqing, Researcher Wang Honggang and Li Zhangpeng Distinguished Young Researcher.

The above research has been supported by the National Natural Science Foundation of China (51675509 and 52175203), the State Key Laboratory of Solid Lubrication of Lanzhou Institute of Chemicals, etc. (Source: Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences)

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