| In order to avoid the effects of oil leakage and harmful lubrication additives on the environment,it is of great significance to develop friction pairs materials that work under water lubrication conditions.However,there is a big difference between the viscosity of the water and of the lubricant,and the motion mechanism is frequently operated in the mixed or even boundary lubrication under water lubrication condition.The solid-solid contact of the friction pairs bears quite or even most of the load.This poses a severe challenge to the service life and reliability of friction pair materials.Polymer and polymer composites have the advantages of self-lubrication,high chemical stability and performance designability,so having application prospects as water-lubricated materials.In this work,the macroscopic tribological behavior of a series of eposy(EP)-based polymer composites under water lubrication is studied,which provides a research idea for obtaining polymer composites with optimal tribological properties.On this basis,the effects of fillers and their coupling on the tribological properties of composites are analyzed.Advanced research methods are used to deeply study the nanostructure of the tribofilm formed at the interface,and to deepen the understanding of the complex physical and chemical effects of the water-lubricated interface.The main research in this article is as follows:(1)Through a one-step hydrothermal synthesis reaction,about 130nm carbon spheres(CSs)were synthesized and added as fillers to the EP matrix.It was found that the addition of CSs can greatly reduce the friction and wear of the materials.The presence of protective tribofilm during the surface friction process has greatly reduced the frictional oxidation of the steel ring surface.CSs-reinforced EP-based composites have broad application prospects in the development of high-performance friction pairs suitable for harsh water lubrication conditions.(2)The synthesized CSs and oxide nanoparticles(Al2O3 and SiO2)were added to the EP matrix as double fillers.Experiments have shown that the addition of double fillers can greatly reduce the friction of composites and show the best tribological properties.It is proved that the existence of CSs and oxide nanoparticles in the tribofilm is beneficial to the improvement of the lubrication performance of the material under water lubrication conditions to a certain extent.CSs and other nanoparticle-reinforced EP-based composits are also suitable for the study of high-performance friction pairs under harsh water lubrication conditions.(3)One-step hydrothermal synthesis of spherical copper sulfide/carbon quantum dots/carbon spheres(CuS/CQDs/CSs)hybrids were added as fillers to the EP matrix.The research results show that the addition of low content(0.1wt.%)of CuS/CQDs/CSs greatly improves the wear resistance of EP-based composites.However,EP-based composites that continue to increase the fillers content(up to 1.0wt.%)show good anti-friction properties,and the wear resistance has not been significantly improved.The improvement of these properties is mainly due to the formation of tribofilm during friction process.Therefore,the addition of CuS/CQDs/CSs can be adjusted according to the requirements of the working conditions to control the formation of the tribofilm,and EP-based composites with different tribological properties(low wear rate or low friction coefficient)can be obtained that can apply to different working conditions.In this paper,by studying the tribological behavior of polymer composites under water lubrication conditions and the related mechanisms of the structure and formation process of tribofilms,it is helpful to explain the macroscopic phenomena from a microscopic perspective,and to a certain extent provides a reference way for the development of water-lubricated friction materials. |
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