基于第三体的制动材料摩擦磨损行为研究进展

Research Progress on Friction and Wear Behavior of Brake Materials Based on the Third Body

制动系统是交通运输和工业设备的重要组成部分,在高速、高载、高温的摩擦工况下,接触表面会因剧烈磨损而产生磨屑,并在复杂的摩擦化学反应下形成厚度为几微米至几十微米的摩擦膜,其被称为“第三体”。制动时,第三体经历了塑性变形、氧化、粘附、分层等变化,对制动材料的摩擦磨损性能产生重要影响,即制动材料的摩擦磨损性能取决于第三体的性质。因此,掌握第三体的组织结构、形成及演变机制有利于对制动材料摩擦磨损性能及机理的深入研究,从而为新型制动材料的研制提供依据。第三体的早期研究主要集中在采用SEM、EDX、TEM等手段分析其组成、形成与运动机制方面,并取得了较为丰富的成果。随着表征方式的发展,研究人员开始尝试从应力、纳米结构、化学键等更为微观、本质的角度阐述第三体的运动、演化和作用机制,进一步将第三体与摩擦条件及磨损机理相关联。第三体对材料摩擦磨损性能影响的研究,已由传统的摩擦系数、磨损率逐步扩展到选择性转移、界面化学反应、摩擦功率损耗等方面。但上述研究大多采用非原位法,只能间接获取摩擦表面信息,存在局限性和滞后性。为分析第三体的动态特性,近些年开发了外源第三体实验法和基于第三体的建模仿真,对澄清第三体中各组元作用、探索第三体微观演化规律具有重要意义,特别是以离散元法(DEM)、可移动元胞自动机法(MCA)为代表的非连续介质模拟,可针对第三体的位移变化、力学性能变化及受力状况进行大规模仿真。本文归纳了第三体组成、形成和运动机制,阐述了第三体对制动材料摩擦磨损性能的影响,总结了外源第三体实验法和第三体建模仿真方面的研究进展,重点对可移动元胞自动机法进行了介绍,最后结合当前第三体研究中出现的问题提出了改进方向,并对未来发展趋势进行了展望。

The braking system is an important part of transportation and industrial equipment.Under the friction conditions of high speed,high load and high temperature,the contact surface will produce debris due to severe wear,and form a friction film of several microns to dozens of microns under the complex friction chemical reaction,which is called the“third body”.During braking,the third body undergoes plastic deformation,oxidation,adhesion,delamination and other changes,which have an important impact on the friction and wear performance of the brake material,that is,the friction and wear performance of the brake material depends on the nature of the third body.Therefore,mastering the orga-nization structure,formation and evolution mechanism of the third body is beneficial to the in-depth study of the friction and wear performance and mechanism of brake materials,and provides a basis for the development of new brake materials.The early research of the third body mainly focused on the analysis of its composition,formation and movement mechanism by means of SEM,EDX,TEM,etc.,and achieved relatively rich results.With the development of characterization methods,researchers begin to try to explain the movement,evolution and mechanism of the third body from a more microscopic and essential perspective such as stress,nanostructure,and chemical bonds,and further correlate the third body with friction conditions and wear mechanisms.The study of the influence of the third body on the friction and wear properties of materials has gradually expanded from traditional friction coefficients and wear rates to selective transfer,interface chemical reactions,and friction power loss.However,most of the above-mentioned studies adopt the ex-situ method,which can only obtain the friction surface information indirectly,so it has limitations and hysteresis.In order to analyze the dynamic characteristics of the third body,the external third body experiment method and the modeling simulation based on the third body have been developed in recent years.It is of great significance to clarify the role of each component in the third body and explore the micro-evolution law of the third body,especially the discontinuous medium simulation represented by the discrete element method(DEM)and movable cellular automata(MCA).Large-scale simulations are carried out for the third body’s displacement changes,mechanical performance changes and force conditions.This article summarizes the third body composition,formation and movement mechanism.The influence of the third body on the friction and wear performance of brake materials is described.The research progress of the exogenous third-body experimental method and the third-body modeling and simulation are summarized,and the mobile cellular automata method is mainly introduced.Finally,combined with the current problems in the third-body research,the improvement direction is proposed,and the future development trend is prospected.