【作者】 孟小霞；

【导师】 王霄；

【作者基本信息】 江苏大学 ， 机械制造及其自动化， 2007， 硕士

【摘要】 随着摩擦学理论和实验研究的深入，规则表面微造型作为显著改善摩擦副表面的摩擦学性能的可控技术日益成为国际研究的热点，研究不同形状的规则表面形貌造型及其摩擦学性能，对根据润滑摩擦性能要求设计并制造出与之匹配的摩擦副表面微观几何形貌，具有重要的理论研究价值与广阔的应用前景。激光表面微造型技术以其制造加工速度快，对环境无污染以及优良地对形状和尺寸的控制能力被认为是表面微造型领域颇为成功的造型方法之一。本课题主要工作是对纳秒和皮秒激光微造型加工质量进行性能对比，研究适用于工业应用的激光微造型方法，然后设计了三种微造型形貌并进行激光加工，再对这三种表面微造型形貌的表面摩擦性能进行研究。本文首先在现有理论研究的基础上，建立了激光与物质相互作用时的热传导和温度场的数学模型，为课题组的后续研究二级管泵浦YAG激光器和Nd：YVO₄皮秒激光加工灰铸铁提供理论指导。其次分别运用纳秒和皮秒激光器进行凹坑和凹槽形貌加工，对纳秒和皮秒激光器的表面微造型加工质量进行了对比试验，选用WYKO轮廓仪和电子探针扫描电镜（JXA—840A型，美国）对这两种加工方法下的凹坑微观组织进行表征与分析，结果表明：纳秒激光器由于脉冲宽度较大，与被加工材料接触时间较长，形成较大的热影响区，产生较严重的损伤区域，这些损坏区域将产生反复的热融化、再凝固现象、形成裂缝和残渣等；而超短激光脉冲加工—皮秒激光加工则可以克服这种现象，可以实现冷加工，大大提高加工质量。通过激光加工对比实验得出皮秒激光加工有着优于纳秒激光加工的性能，进而设计了三种微造型（凹坑、网纹、断纹），并用皮秒激光器加工。紧接着对皮秒激光加工下的三种微造型进行UMT-2摩擦磨损实验研究，并与未造型的光滑面进行比较。实验主要分为干摩擦实验和润滑摩擦实验，通过研究不同润滑条件，不同载荷，不同表面造型的摩擦系数的变化趋势，分析规则表面微形貌对摩擦性能的影响。实验结果表明：在干摩擦低载荷的同等工况条件下，造型面的摩擦性能相比未造型面有明显提高，在三种造型中以凹坑的表面摩擦性能最优；在润滑低载荷条件下，造型面的摩擦性能相比未造型面也有一定的提高，但是稳定值相差不是很明显，同样在三种形貌中以凹坑的表面摩擦性能最优。更多还原

【Abstract】 As the development of tribology theories and experimental research, regular surface micro texturing as a controllable technique ,which can remarkably improve surface tribological performance, has been the focus for the international research increasingly. It has significant value of research and application prospect for designing suitable surface micro pattern to study the different kinds of regular surface micro patterns and its tribological performance.Laser surface texturing （LST） has been one of the most successful ways in surface texturing because of its good performance such as high speed, non pollution and excellent control ability for shape and size. The chief work of my paper includes that comparing the machining quality between nanosecond and picosecond laser texturing, studying a suitable LST for industry application, designing three kinds of micro patterns for laser texturing and comparing their tribological performance.In this dissertion, firstly a mathematic model of heat exchange and temperature field during laser machining is established based on vested theoretical research. It offers theoretical instruction for the subsequent research in laser surface texturing byYAG and Nd: YVO₄. Secondly, a contrast test is given to analyze the differencesbetween nanosecond laser surface texturing and picosecond laser surface texturing. WYKO profile testing instrument and SEM （JXA-840A, the USA） are chosen to character the crater micro-structure in two different laser machining methods. The result shows that: because of the larger pulse width, nanosecond laser texturing has a longer contact time with work material, and then forms larger heat-affected zone and produces serious damage zone. These damage zones would bring repeating hot melting and resolidification, come into being split and residue. Contrarily, ultrashort laser pulse-picosecond laser texturing could conquer this phenomenon, carry out cold-working and improve the machining quality remarkably. Thirdly, three kinds of micro patterns are designed for laser texturing. Then an experimental device—UMT-2 is used to conduct comparative experiments among three kinds of micro patterns in picosecond laser texturing and untextured surface. It includes dry friction test and lubrication test. The effect to surface friction behavior caused by microstucture is analyzed through studying the trend of friction coefficient under different lubricated conditions, loads and micro patterns. The result shows that: on the condition of dry friction and low load, the tribological performance of textured surface improves remarkably comparing with untextured surface, the crater has the best tribological performance among three micro patterns ; In the case of lubrication and low load , an improvement in tribological performance could be achieved. But it didn’t have a obvious difference in steady-state value, similarly, the crater had the best tribological performance among three micro patterns.更多还原