Fabrication of curved micro structures on photoresist layer

A novel fabrication process for micro patterns with curvature was introduced. The curved structures were made by compensating rectangular micro structures with liquid photoresist layer. Because of the surface tension of the liquid in micro scale, various shapes of meniscus can be made on the micro channels. The micro channels were made on the silicon substrate in advance, and then the liquid layer was coated on the micro channels. From the nature of liquid behavior, the curved patterns with smooth surface are obtained, which cannot be made easily with the conventional mechanical machining, as well as with the microfabrication processes, such as wet and dry etching. With this principle, it is expected that the smooth and curved surfaces can be made by simple processes and the results can be applied widely, such as optical patterns.     

Forming of Micro Channels with Ultra Thin Metal Foils

The objective of this paper is to investigate the feasibility of producing micro scale structures by forming ultra thin metal foils. During this investigation, flat rolled foils of AISI 304 stainless steel (2.5μm in thickness) and pure copper (3.0μm in thickness) were formed into channels of varying shapes. The shapes of these channels were straight lines, concentric circles, crosses, and other curved shapes. The cross sections of the channels ranged from 10∼20μm wide and 5-10μm deep. Forming was done by cold isostatic pressing. Two types of micro dies were used. One was made of SU-8 photo resist on a Si wafer, the other of dry etched (DRIE) Si wafer. The die and metal foil were vacuum packed in a bag made of multilayered film. The forming was conducted with a 240MPa cold hydrostatic press. The formed structures were examined in terms of their dimensions, surface qualities, and potential for defect. The fabrication results show that the sheet metal forming process can be applied to the manufacturing of micro scale structures.     

Micro patterning on curved surface with a fast tool servo system for micro milling process

Demand for generating functional micro patterns on a curved surface such as molds has increased in various industrial sectors. In order to meet the demand, it is important to develop advanced micro machining technology to generate curved form and fine patterns, simultaneously and efficiently. This paper presents a newly developed machining system equipped with a fast tool servo mechanism for milling process driven by a giant magnetostrictive actuator and evaluation of its basic machining performance. The results confirmed that the developed system has capability to position the end mill precisely during machining and to generate patterned curved surface.     

Development of deterministic-stochastic surface structures to improve the tribological conditions of sheet forming processes

In sheet-forming processes with mixed frictional state the tribological system is characterized to a great extent by the sheet-surface structure. This structure has the functions of storage, transport, and distribution of the lubricant, and take-up and transport of surface-abrasion particles. These functional characteristics are achieved by different of surface structure, the so-called stochastic and deterministic structures. The presence of micro channels connecting the surface pockets in stochastic structures allows the distribution of the lubricant in all directions but it is not possible to detain this lubricant in areas under high pressure, it simply flows aside. This ability is given by the isolated surface pockets (hydrostatic lubrication pockets) in deterministic structures. From this micro reservoirs the lubricant can be transported directly into the deformation zone by means of building up a hydrostatic pressure. However, because of the absence of micro channels it is not possible to transport the lubricant to all areas of micro contact between tool and sheet, the risk of cold-welding effects increases. Therefore, a new type of surface structure is developed by the combination of a deterministic and a stochastic sheet-surface structure. The results of strip-drawing experiments point out that the combination between isolated lubrication pockets and a network of micro channels to transport the lubricant in the space between these surface pockets leads to a improvement of the forming behaviour.     

微磨料水射流加工脆性玻璃的冲蚀机理研究

微磨料水射流加工技术正成为制造微细结构零件重要的经济高效的微细加工技术。作者在玻璃上进行微磨料水射流微细槽加工的实验基础上,对微磨料水射流加工的表面形貌、材料冲蚀去除机理及加工工艺性能进行了研究。结果表明,玻璃加工表面沿着槽道的方向形成了波纹状形貌,呈非对称或对称的波形,波纹表面很光滑,波纹图案沿着射流冲击区的径向方向发展。由于黏性流体的阻滞作用,脆性玻璃在微磨料水射流加工过程中,在黏性流区域没有发现任何裂纹,材料的冲蚀去除主要是以塑性断裂的方式为主,形成了光滑的加工表面。适当地控制加工工艺参数,在低压下,微磨料水射流加工是一种用于脆性材料上微细通道的加工切实可行的方法,并可获得良好的加工表面质量。     

Micro electrochemical machining for complex internal micro features

In this paper, the application of micro electrochemical machining (ECM) for the micromachining of internal features is investigated. By controlling pulse conditions and machining time, micro features are machined on the side wall of a micro hole. These methods can easily machine a micro hole with larger internal diameters than the entrance diameter, which is very difficult to do by the conventional processes. A micro disk-shaped electrode with an insulating layer on its surface is also introduced to machine microgrooves inside the hole. This method is similar to the turning lathe process. The purpose of this study was to confirm the various possibilities of making complex internal structures in a micro hole by micro ECM.     

室温盐液渗硫

介绍了室温盐液渗硫新工艺，采用SBR系列硫化液对淬火45钢表面进行了室温硫化处理，借助SEM、EDAX和XRD研究了渗硫层的结构和形貌，分析了渗硫层显微硬度的分布。结果表明，室浊盐液渗硫层呈片状结构，主要由FeS相组成，其硬度仅为63HV；适当调整硫化盐液浓度将有利于提高渗速，一般经（0.5-1)h处理可获得10μm左右厚度的渗硫层。     

矿用链轮链窝电弧增材制造路径规划

针对曲率较大的链窝表面的增材制造,提出了曲面分层的方案。对即将增材的区域进行分层设计和施焊路径规划,得到的路径点平滑连续,能够很好地适应链窝曲面。结果表明,施焊时机器人各轴运动平缓,焊枪行走平稳,不存在速度突变。堆敷层表面均匀平整,与链窝曲面吻合度高,边缘焊道与周围轮廓相适应好,未出现缺肉及超出轮廓边缘的情况,表明路径规划算法能较好地适用于链窝曲面增材制造过程。     

马鞍形板件冲压成形新工艺

曲面板件在冲压成形时常常发生起皱现象。从曲面板件的几种冲压成形方法出发,讨论了各自的特点,提出了一种新型的曲面板件冲压成形技术,其为多点压板成形冲压工艺与杆系柔性成形模具。杆系柔性成形模具由可重构的杆系组成,若干个可更换的冲压头构成模具冲压型面;冲压过程中模具对板料实施压边、压板与成形,板面压板力提升了板料的抗失稳能力,保证复杂曲面板件的顺利成形。     

晶体塑性模型分析微圆柱墩粗变形尺寸效应机理(英文)

为了分析单个晶粒变形行为对微成形的影响,将自由表面的晶粒看作单晶体构建晶体塑性模型。基于率相关晶体塑性理论,考虑试样尺寸、初始晶体取向及其分布,分析微圆柱体墩粗变形中尺寸效应机理。结果表明,流动应力随着试样尺寸的减小而明显减小,晶体取向的分布对试样流动应力具有显著影响,并随着塑性变形的进行而减小。由于单晶体的各向异性,在试样表层发生了明显的非均匀变形,这将导致表面粗糙度的增加,小尺寸试样则更加明显。过渡晶粒的存在使得晶粒各向异性对表面形貌的影响减小。模拟结果得到了实验验证,这表明所建立的模型适合于以尺寸依赖性、流动应力分散性和非均匀变形为特点的微成形工艺分析。     

表面微织构对45#钢摩擦副表面摩擦学性能影响的实验研究

目的 通过在摩擦副表面进行激光微织构加工,研究不同分布形式的微织构对摩擦副的减摩作用效果,为微织构摩擦副在实际工程应用中的设计与选用提供参考。方法 选取45#钢作为摩擦材料制备环环接触的摩擦副,通过激光微雕刻在试件表面加工一定尺寸的微织构,在油润滑条件下,利用万能摩擦磨损试验机进行摩擦磨损实验,并通过超景深三维显微镜观察磨损表面,研究不同微织构在油润滑方式下对摩擦副的减摩作用机理及具体影响规律。结果 带有合理分布形式微织构的摩擦副接触表面能产生明显的动压润滑效应,其中径向沟槽微织构和凹坑状微织构在稳定磨损阶段的摩擦系数明显小于光滑表面,分别能减小摩擦系数16%和11%,局部网状微织构的摩擦系数与光滑表面没有明显差异,周向沟槽微织构的摩擦系数大于光滑表面。带有径向沟槽和凹坑微织构的摩擦副相比于光滑表面,温升有所降低,而周向沟槽和局部网状微织构随着摩擦表面磨损的加剧,温升更加明显,下试件分布有微织构的摩擦副接触表面摩擦系数要明显小于上试件分布有微织构的摩擦副。磨损局部放大图中,凹坑状微织构表面产生的磨粒剥落痕迹要明显浅于光滑试件表面,说明微织构能有效存储磨损磨粒,减少二次磨损对摩擦表面的破坏。结论 表面微织构能有效改善摩擦副的润滑性能,合理选择微织构分布形式和分布位置,才能最大限度地发挥微织构的减摩效果。     

Surface treatment of 3D outside serrated integral-fin tube manufactured by rolling and extrusion

The outside serrated integral-fin tubes fabricated by rolling-plowing-extrusion processing were surface-treated through different processes of annealing in hydrogen atmosphere, electrochemical corrosion or sandblasting. The purpose was to eliminate residual stress, clear secondary micro-fins and enhance heat transfer performance. By comparing the surface characteristics, it is found that the finned tubes treated by electrochemical corrosion have the most glabrous surfaces where the fins are almost perfectly reserved. Clear layer cracks can be observed on the top of the fins. These structures are effective in enhancing heat transfer performance when being applied to flow heat exchange. Therefore, the finned tubes treated by electrochemical corrosion are proper for the tubular exchanger with water coolant. The finned tubes treated by sandblasting have rougher surfaces with layer cracks and micro gaps removed. As these structures are useful to clearing adhesive feculence, the tubes are more suitable for the tubular heat exchanger with oil coolant.     

基于曲面分层的大型螺旋桨GMA增材制造

为了实现曲面复杂零件的高精度高效率增材制造,开发了高适应性的曲面分层算法.采用从空间角加权法向方向平移三角网格控制点的策略,生成与初始分层曲面等距的曲面簇,与模型求交运算,从而获得了每层曲面切片轮廓.在此基础上,使用基于体素化和曲面积分思想的曲面等距路径规划算法,获得了分层曲面上的等距轮廓偏置路径,保证了零件曲面轮廓的成形精度并进行了试验验证. 试验采用六轴机器人与旋倾变位机作为运动机构,使用熔化极气体保护电弧(gas metal arc,GMA)增材制造方法,在一个外径为0.2 m的圆柱金属管上,实际堆敷了直径1 m的扭转棱形螺旋桨.经过扫描检测和模型比对,得到桨叶的成形尺寸标准偏差为1.1 mm,最大偏差在3.0 mm以下.结果表明,对于特定曲面零件如螺旋桨的增材制造,曲面分层算法可以提高成形的效率和表面质量.     

机械研磨对电沉积镍镀层晶粒生长过程的影响

在Watt镀液中加入玻璃球,玻璃球以不同频率垂直撞击试样表面形成机械研磨.考察了震荡频率和球直径对镍镀层晶粒细化的影响以及机械研磨对晶粒生长的影响.SEM表面观察表明,机械研磨改变了镀层晶粒的生长方式,使镀层晶粒明显细化,镀层表面光滑.在电沉积过程中施加机械研磨,玻璃球的撞击会在镀层表面产生宏观和微观缺陷,增加形核中心,提高形核速率;玻璃球撞击晶粒尖端,使得镀层表面变得平整,有利于电力线均匀分布,促进形核,避免了晶粒不均匀长大.     

Influence of Treatment Sequence on Tribological Performance of Duplex Surface-Treated AISI 1045 Steel

The surface of AISI 1045 steel specimens was modified via two duplex surface treatments of(i) titanium diffusion coating followed by plasma nitriding(Ti–PN) and(ii) plasma nitriding followed by titanium diffusion coating(PN–Ti). A comparative study on the microstructure and wear properties of the fabricated TiN coatings was conducted. A scanning electron microscope equipped with energy-dispersive X-ray spectroscopy, X-ray diffractometer(XRD), and pin-on-disk wear test was utilized to evaluate the microstructures, phases, and wear properties of the coatings. XRD patterns of duplex-treated specimens illustrated that the modified layer consisted of nitride and carbo-nitride phases such as TiN and TiC_(0.7)N_(0.3). The results also showed that Ti–PN treatment led to a low friction coefficient and the lowest wear factors, as compared with the PN–Ti treatment. Oxidation and mild fatigue fracture wear were found to be the main wear mechanism of the Ti–PN coating. The wear mechanism in the PN–Ti specimen involved a higher oxidative wear regime followed by plastic deformation wear regimes.     

飞秒激光刻蚀氧化锆表面微纳结构及其润湿与抗菌性能

目的 构筑氧化锆表面微纳结构,提高表面疏水性能。方法 用飞秒激光在氧化锆表面刻蚀网格结构,随后用硬脂酸修饰所得表面,系统研究了激光能量密度、激光扫描速度对氧化锆表面形貌及润湿性的影响,分析不同处理条件下氧化锆的表面形貌和润湿性,通过润湿模型进一步揭示润湿性转变内在机理。进一步通过在饱和大肠杆菌溶液中浸泡的试验,对不同处理条件下氧化锆表面的抗菌性能进行了测试和分析。结果 在9.6 J/cm²的过高能量密度以及10 mm/s的过小扫描速度下会导致氧化锆表面过度烧蚀,破坏表面微结构,不利于提高表面疏水性。发现激光纹理化氧化锆的最佳参数为激光能量密度8.3 J/cm²,扫描速度20 mm/s,制备的微凸起结构为表面覆盖大量纳米结构的周期性锥状阵列,凹槽的平均宽度和平均深度分别为(27.598±1.376)μm和(33.825±0.559)μm,此时表面粗糙度最大为9.556 μm,随着表面粗糙度的增加,微纳复合结构可以截留更多的空气,减少固液接触面积,表面具有最大的水接触角为(163.9±1.5)°,最小的水滚动角为(4.3±0.8)°。平板菌落计数法测定结果显示,此时硬脂酸修饰的激光纹理化氧化锆超疏水表面的抗菌率最高,为(89.1±3.6)%。结论 采用飞秒激光刻蚀结合硬脂酸修饰的方法,通过激光参数优化,可在氧化锆表面产生微纳复合结构,增加其表面粗糙度,从而制备得到疏水甚至超疏水的氧化锆表面,超疏水氧化锆表面截留的空气层对大肠杆菌的黏附具有很好的抑制作用,表现出明显的抗菌性,有望扩展氧化锆在牙科领域的应用。     

基于激光表面微纳结构的胶接性能研究进展

胶接具有独特的性能而被广泛关注,但在实际应用中往往由于界面结合强度不足而导致接头在服役过程中过早失效。激光表面处理是一种能够有效提高胶接接头表面性能的方法,通过激光表面处理会使黏接材料表面形成不同的表面微纳结构,从而改善接头的性能。首先介绍了激光表面处理原理及激光器分类,对比了不同激光器的优缺点及加工质量特性,分析了激光加工参数对接头强度的影响。其次从激光加工不同表面微纳结构入手,阐述了不同表面微纳结构的加工方式,分析了不同表面微纳结构对不同材料接头强度的影响。此外,针对不同的表面微纳结构,其结构参数有所不同,导致接头表面化学成分和润湿性能也有所不同,使得接头强度有所差异,在此基础上分析了微纳结构参数对接头强度的影响及原因。同时,胶层间的作用机制与接头强度具有密不可分的联系,研究表明,不同的表面微纳结构对胶层的作用机制具有明显的不同,归纳总结发现,经激光表面处理形成表面微纳结构后接头表面粗糙度、化学性质、润湿性能及胶层间裂纹的扩展对接头强度的提升具有一定作用。最后,对激光表面处理微纳结构的研究进行了展望。     

Numerical analysis of residual stress distribution generated by welding after surface machining based on hardness variation in surface machined layer due to welding thermal cycle

Recently, stress corrosion cracking (SCC) has been observed near the welded zone of the primary loop recirculation pipes made of low-carbon austenitic stainless steel type 316L in boiling water reactors. SCC is initiated by superposition effect of three factors. They are material, environmental and mechanical factors. For non-sensitized material such as type 316L, residual stress as a mechanical factor of SCC is comparatively important. In the joining processes of pipes, butt welding is conducted after surface machining. Surface machining is performed in order to match the inside diameter and smooth surface finish of pipes. Residual stress is generated by both processes. Moreover, residual stress distribution generated by surface machining is varied by subsequent welding processes, and it has the maximum residual stress around 900 MPa near the weld metal. The variation of metallographic structure, such as recovery and recrystallization, in the surface machined layer due to the welding thermal cycle is an important factor for this residual stress distribution. In this study, thermal ageing tests were performed in order to evaluate hardness variation due to the thermal cycle in the surface machined layer. Results of thermal ageing tests were applied to the finite-element method as the additivity rule of the hardness variation. Varied hardness was converted into equivalent plastic strain. Then, thermo-elastic-plastic analysis was performed under residual stress fields generated by surface machining. As a result, analytical results of surface residual stress distribution generated by bead-on-plate welding after surface machining show good agreement with measured results by the X-ray diffraction method. The maximum residual stress near the weld metal is generated by the same mechanism as in the both-ends-fixed bar model in the surface machined layer that has high yield stress.     

用表面活化处理法提高立方氮化硼与镀层的结合性能

将立方氮化硼（CBN）磨料依次浸泡于敏化液和活化液中，进行表面活化处理。分别用经过和未经过活化处理的CBN磨料制作电镀磨具。SEM观察结果表明，磨具电镀过程中，在CBN与镀层的结合面上形成了分散的连接点，从而改善了镀层与CBN的结合性能。用经过活化处理CBN制作电镀磨具，加工耐磨铸钢的材料去除体积是未活化处理的CBN电镀磨具的1．5倍，明显提高了电镀CBN磨具的使用寿命。在电镀过程中，应严格控制CBN活化表面钯质点的数量，使其保持在合适范围内，避免CBN颗粒相互粘结和成块现象。     

铁基金属摩擦副表面自修复层分析

目的分析不同工况对表层自修复层的影响,探究羟基硅酸镁纳米管在摩擦磨损过程中的作用机理。方法以人工合成的羟基硅酸镁纳米管Mg3Si2O5(OH)4为自修复添加剂,在油润滑实验条件下进行铁基金属摩擦副摩擦磨损实验。利用SEM、EDS、激光拉曼光谱仪及显微维氏硬度计分别对自修复层厚度、自修复层元素组成、自修复层表面结构及自修复层表面显微硬度进行表征。结果在转速为1000、2000 r/min时,载荷为200、300、400 N的实验条件下,表层均有自修复层的生成。在转速为2000 r/min、载荷为400 N时,表层自修复层的厚度最大。实验过程中,摩擦副得到修复,出现负磨损,自修复层的主要元素为C、O、Fe等。高转速载荷工况下,其摩擦系数相比基础油下降0.008。自修复层为类金刚石结构,其平均硬度值在673HV左右,为基体的1.87倍。结论羟基硅酸镁、基础油及磨屑三者共同作用,在高能摩擦作用下合金化,形成高硬度的类金刚石结构修复层,能有效保护摩擦副工作面,并延长寿命。加大实验载荷与实验转速,能加速自修复层的形成,实现摩擦副负磨损,并降低摩擦系数。