燃油润滑状态下聚合物-金属摩擦副反应边界膜的形成与作用机理

Utilization of low-sulfur fuels in response to more and more critical environmental regulations leads to lubrication problems, e.g. occurrence risk of seizure of metal-metal friction components in an engine system, which are lubricated by fuel itself. To replace conventional metal-metal sliding pairs by using a high-performance polymer composite-metal pair is proven to be effective for avoiding the occurrence of seizure. It was demonstrated recently that the tribological performance of polymer composites under fuel boundary lubrication conditions is closely related to the formation of a boundary reaction layer. Up to now, the composition and micro/nanostructure of the boundary layer is not known and the mechanisms of friction and wear reduction are not understood. In order to find answers to these questions, it is of fundamental importance to deeply investigate the structures and properties of the boundary reaction layers. This project will address at least three brand new issues: Firstly, the thin and nano-structured boundary layers will be characterized by analytical transmission electron microscopy and tribo-chemical reactions dominating the formation of the surface layers will be analysed. Secondly, the micro/nano-scale mechanical and tribological properties of the boundary layers will be studied by employing advanced techniques. Thirdly, effects of matrix molecular structures and multiple fillers, especially new functional fillers, on structures/properties of boundary layers will be investigated. Objectives are not only to establish a boundary lubrication model of polymer composites taking into account the micro/nano-scale structures/properties of boundary layers, but also to pave a theory route for tailoring high-performance boundary layers under fuel lubrication conditions. The outputs of this project are expected to lead to major breakthroughs in the fields of fuel-lubricated systems in engine systems.

降低燃油中含硫量，是实现减少汽车污染物排放、改善空气质量，重大战略的有效途径。然而,由于采用脱硫工艺，使得燃油中的有效润滑性组分减少，导致常规金属-金属摩擦副的摩擦磨损甚至咬合问题。本研究针对未来强制使用低硫燃油以后必然出现的润滑难题,立足于采用聚合物-金属摩擦副的新途径，研究聚合物-金属摩擦副在低硫燃油边界润滑条件下的摩擦学机理。通过有机融合聚合物-钢的摩擦学机理和边界润滑理论，本选题将深入探讨基体的分子结构、常规及功能填充物对聚合物复合材料燃油边界摩擦特性的影响机理，重点研究反应边界膜的纳米结构及其微/纳尺度力学和摩擦学性能，旨在揭示反应边界膜的形成和作用机理,建立考虑反应边界膜结构和性能的聚合物复合材料燃油润滑条件下边界摩擦学模型，为高性能反应边界膜的可控构筑奠定基础。研究结果预计将为解决相关领域的低硫燃油润滑难题提供理论指导，具有重要的理论和现实意义。

低硫燃油的采用可减少内燃机污染物排放，改善空气质量。然而，脱硫工艺的采用使得燃油中的有效润滑性组分减少，可加剧常规金属-金属摩擦副的摩擦磨损甚至导致咬合发生。本研究立足于采用聚合物-金属摩擦副的新途径，深入研究聚合物-金属摩擦副在低硫柴油边界润滑条件下的摩擦学机理，定量表征了金属对偶表面生成反应边界膜的纳米结构与性能，深入分析了界面的摩擦化学，揭示了纳米结构反应边界膜生长机理及其改变聚合物材料宏观摩擦学性能的微观作用机制，获得了高性能反应边界膜的可控构筑原则，完成了预定目标。具体研究进展如下：（1）以分子结构迥异的环氧树脂、聚苯硫醚和聚醚醚酮作为树脂基体，系统考察了基体树脂分子结构对低硫柴油润滑条件下复合材料摩擦学特性的影响规律，探讨了聚合物基体分子结构影响界面摩擦化学以及反应边界膜生长的机理；（2）系统考察了多种增强相、固体润滑剂和纳米陶瓷颗粒对复合材料摩擦系数和磨损率的影响，阐明了功能性填料物化性质对反应边界膜生成的影响机制；（3）利用多种先进的研究手段定量表征了反应边界膜的纳米力学结构与纳米尺度性能，深入分析了界面摩擦化学，阐明了高性能反应边界膜的生长机制，揭示了反应边界膜纳米结构影响其承载能力和边界润滑特性的微观机制；（4）对比研究了聚合物纳米复合材料在干摩擦、水润滑和燃油润滑条件下的摩擦学行为，深化理解了润滑介质物化性质对反应边界膜生长的影响；（5）设计制备了适用于低硫燃油润滑工况且在极端贫油状态表现出极低摩擦磨损的多元纳米复合材料。相关研究结果在ACS Sustainable Chemistry & Engineering、Carbon和Tribology International等本领域知名期刊发表SCI论文15篇，申请国家发明专利5项，其中1项已授权。本项目研究成果对低硫燃油润滑运动机构的摩擦学设计提供了理论支撑，对深入理解边界润滑聚合物-金属界面作用本质具有重要科学意义。