【作者】 李劲峰；

【导师】 王晓雷；

【作者基本信息】 南京航空航天大学 ， 机械设计及理论， 2009， 硕士

【摘要】 近年来,表面织构技术因其具有的降低摩擦、减小磨损和提高承载能力等特点,引起了人们的极大关注,在汽车发动机、滑动轴承、人工关节以及磁介质存储等许多领域中有着极其广泛而重要的应用。目前对表面织构技术的研究,主要集中在硬质材料方面,如陶瓷、钢等;而对于由低弹性模量柔性材料所组成的摩擦副,表面织构的研究还未见有报导。因此,探讨因柔性材料表面织构的接触弹性形变而引起的润滑液流动对其摩擦特性的影响规律成为掌握和丰富表面织构设计原则的关键。本文采用光刻—复模的微细表面加工技术,在聚二甲基硅氧烷(PDMS)柔性材料表面加工了微小凹坑阵列;并对材料的相关机械性能,如硬度、弹性模量、表面粗糙度和表面接触角等参数进行了测试;最后,以不同几何参数的微小凹坑阵列表面织构PDMS材料/GCr15轴承钢球作为配对摩擦副,在自制的摩擦实验机上测试滑行速度、表面织构几何参数对水润滑下摩擦因数的影响,并进行了相关的润滑理论数值计算,初步探讨了柔性材料表面织构的润滑机理。本文获得的主要结论和创新性成果如下:第一,运用软光刻技术中具有代表性的复制模塑法在PDMS柔性材料表面制备了规整的微小凹坑阵列,轮廓仪照片显示:光刻—复模法制备的凹坑阵列图案清晰而均匀,表面平整无缺陷。第二,考察了PDMS材料制备工艺对其机械物理特性的影响,并初步研究了本研究所设计的各种几何参数的表面织构微小凹坑阵列对PDMS材料表面浸润性的影响。第三,研究了表面织构PDMS材料/GCr15轴承钢球的摩擦学特性,并与无织构光滑表面PDMS/GCr15轴承钢球的摩擦学特性作了对比,结果表明:表面织构的存在,具有优异的减摩效果,如在滑行速度v = 40 mm /s,凹坑直径d = 100μm,深径比h / d = 0.05,面积率r =4.9%时,出现摩擦因数的最小值0.112,相比光滑表面PDMS的摩擦因数减小了88.81%;同时,在一定条件下,表面织构又能够起到增加摩擦的作用,如在滑行速度v = 60 mm /s时,在凹坑直径d = 50μm,深径比h / d = 0.01,面积率r = 10.4%时,出现摩擦因数的最大值1.409。本文首次对柔性材料表面织构的宏观摩擦学特性进行了水润滑条件下的实验研究,研究结果丰富了表面织构技术在改善材料摩擦学特性方面的作用机理,并为表面织构技术在改善低弹性模量材料(橡胶、塑料)摩擦学特性的工程应用提供了相关设计依据。更多还原

【Abstract】 Recently, more attention has been paid on surface texture technology. Due to its advantages in improving tribological performances, such as friction and wear reduction, high load-carrying capability, surface texture technology has wide and important engineering applications in a variety of fields ranging from engine components, sliding bearings, artificial joints and magnetic storage devices, etc.. Researches are now mainly focused on hard materials (like ceramic, steel, etc.). However, the lubrication effect of micro-texture on surfaces of soft material friction pairs has not been reported previously. Therefore, it becomes the most important problem to investigate the effect of lubricant flow behavior on the tribological properties caused by textured tribo-pairs soft elastic contact.In this thesis, patterns of micro-dimples were created on Poly (dimethylsiloxane) (PDMS) surfaces using the Lithography & Replica Molding technique. The mechanical properties such as hardness, elastic modulus, surface roughness and contact angle were measured. The macroscale tribological experiments were carried out in water-lubricated condition by using tribo-meter. The numerical calculation results and tribological mechanism were discussed. The main research results and some innovative achievements are showed as follows:Firstly, typical Lithography & Replica Molding (RM) technique of soft lithography was used to fabricate patterns of micro-dimples on the surface of PDMS. The surface profiler images demonstrate the high fidelity and facility of RM for the patterns of micro-dimples fabrication process.Secondly, the influence of PDMS preparation process on its mechanical properties was studied, and the wettability of textured surfaces with different geometrical parameters was also analyzed.Thirdly, compared with untextured surface, the tribological properties of textured PDMS surfaces were researched. The experimental results show that textured surface has superior tribological properties. The pattern with dimple diameter of 100μm, and area density of 4.9% has an obvious friction reduction at the sliding velocity of 40mm/s, the friction coefficient is 0.112 which is 88.81% lower than that of untextured surface. But the pattern with dimple diameter of 50μm and area density of 10.4% has a high friction coefficient about 1.409 at the sliding velocity of 60mm/s, exhibiting an obvious friction increase effect.It is the first efforts to experimental investigate the macroscale tribological performances of textured soft material under water lubrication. The results of this study enrich the mechanism of surface texture in improving tribological properties, and provide some design basis for engineering application of low elastic modulus materials (like rubber, plastic etc.).更多还原