摩擦诱导发动机碳烟微粒摩擦学功能转化机制研究

It is significant to focus on the engine soot not only in controlling the engine exhaust emissions but also in improving the tribological performance of engine. The present project is based on the idea to control the abrasive wear behaviour of soot particles from biomass fuel by way of tribocatalytic process according to the detailed effect of soot particles from diesel and biomass fuel on the tribological performance of engine respectively. It will be characterized the relation among the biomass fuel soot, engine working conditions and tribological performance by studying the effects of the composition, structure, morphology and surface defects of soot particles on the catalytic effect and wear resistance and friction reduction. It is also studied the tribocatalysis reaction conditions of transform tribological function of soot particles during friction process, and the formation mechanism of antiwear and antifriction film derived from the soot particles from biomass fuel because of tribocatalysis induction as well. The mechanisms of friction and wear of soot particles are summarized at micro- and nano- scales by way of modern surface analysis methods. The wear model of soot particles from biomass fuel is also proposed. The present researches will develop the tribological theory of engine fuel and provide the theoretical and technical supports for the application of biomass fuel in the engine in the future.

发动机燃油碳烟不仅关系到发动机排放，而且影响到发动机的摩擦学性能。本项目在系统研究柴油和生物质燃油碳烟微粒对发动机摩擦学特性影响的基础上，立足利用摩擦诱导的催化效应控制生物质燃油碳烟微粒磨粒磨损的思路，从研究生物质燃油碳烟微粒的组成、结构、形态与表面状况-催化效应-抗磨减摩性能之间关系的角度，来实现如何使得生物质燃油碳烟与发动机工况条件及其摩擦学性能更好地协调和统一；探讨控制生物质燃油碳烟微粒摩擦学功能转变的摩擦催化反应条件，揭示摩擦催化诱导碳烟微粒由磨粒磨损功能转变成抗磨减摩功能的作用机理；利用现代表面分析技术，深入分析碳烟微粒在微纳尺度的摩擦状态和磨损机制的变化规律，发展生物质燃油碳烟微粒的磨损模型，丰富发动机燃油摩擦学的基本理论，为高性能生物质燃油在发动机上的应用提供必要的理论支撑和技术指导。

本项目研究不同生物质热解燃油碳烟微粒的组成、结构、形态与表面状况，探讨不同碳烟微粒的摩擦磨损行为与作用机理。通过不同的催化剂摩擦诱导的催化效应，掌握生物质燃油碳烟微粒在发动机摩擦副中作用机理转换的摩擦催化反应条件与规律。首次发现：（1）生物质燃油碳烟微粒平均直径约为30~50 nm，生物质燃油碳烟微粒表面含有-C-OH和C≡C等活性官能团；生物质裂解燃油碳烟微粒表面含有较多的酸碱位点。（2）TiF3对液体石蜡和全配方柴油机润滑油CD SAE 15W-40均有良好的抗磨减摩效果，其作用机理在于在摩擦表面形成了含有二氧化钛与氟化物的边界润滑薄膜。（3）生物质燃油碳烟微粒摩擦磨损机制不同于传统发动机柴油碳烟，其生物质燃油碳烟会参与边界润滑膜形成，生物质燃油碳烟会提升润滑油的油膜强度。（4）摩擦催化材料TiF3可以抑制全配方润滑油因生物质燃油碳烟污染润滑功效降低 （5）TiF3和FeF3在一定条件下会催化碳烟微粒结构转变，而且摩擦热和碳烟微粒初始结构是决定摩擦诱导碳烟结构转变的关键因素。(6)碳烟颗粒的抗磨减摩机制归于摩擦诱导铁基材料氧化，生成的铁基氧化物与碳烟颗粒在摩擦副接触表面形成复杂的润滑和防护膜。生物质燃油碳烟颗粒的抗磨减摩效果优于柴油碳烟，原因归于其石墨化程度较高。（7）二烷基二硫代磷酸锌(ZDDP) 摩擦反应膜因碳烟的介入而出现分布不均的现象；相应磨损表面的硬度H 降低、弹性模量E 升高，H/E 值降低。上述结果为提高生物质燃油发动机的抗磨减摩特性，提供必要的理论支撑和技术指导。