超厚SU-8负胶高深宽比结构及工艺研究

采用新型SU-8光刻胶在UV-LIGA技术基础上制备了各种高深宽比MEMS微结构,研究了热处理和曝光两个重要因素对高深宽比微结构的影响,解决了微结构的开裂和倒塌等问题;优化了SU-8胶工艺,从而获得了最大深宽比为27：1的微结构。     

Microstructures of chafer cuticle and biomimetic design

Insect cuticle has high strength and high fracture-toughness. The superior material properties are closely related to the various particular microstructures in the cuticle, which has passed through natural optimization for thousands of years. In this work, a scanning electron microscope (SEM) was used for observing the various microstructures in a chafer cuticle. The observation revealed that there are several special microstructures that include helicoidal layups, round-hole-fiber arrangements and branched fibers in the cuticle. These microstructures were analyzed in order to learn more about the strength and toughness mechanisms of these microstructures. Several biomimetic composites were then designed and fabricated with special processes and moulds. Obtained biomimetic composites were tested for investigating their strength and toughness and then compared with those of conventional man-made composites. It was shown that the mechanical properties of the biomimetic composites are remarkably better than those of the corresponding conventional man-made composites.     

Area scalable optically induced photorefractive photonic microstructures

A convenient approach to fabricate area scalable two-dimensional photonic microstructures was experimentally demonstrated by multi-face optical wedges. The approach is quite compact and stable without complex optical alignment equipment. Large-area square lattice microstructures are optically induced inside an iron-doped lithium niobate photorefractive crystal. The induced large-area microstructures are analyzed and verified by plane wave guiding, Brillouin-zone spectroscopy, angle-dependent transmission spectrum, and lateral Bragg reflection patterns. The method can be easily extended to generate other more complex area scalable photonic microstructures, such as quasicrystal lattices, by designing the multi-face optical wedge appropriately. The induced area scalable photonic microstructures can be fixed or erased even re-recorded in the photorefractive crystal, which suggests potential applications in micro-nano photonic devices.     

Cryogenic deformation microstructures of 32Mn–7Cr–1Mo–0.3N austenitic steels

The cryogenic deformation microstructures of impact and tensile specimens of 32Mn–7Cr–1Mo–0.3N austenitic steel were investigated using light microscopy and transmission electron microscopy. The results show that the deformation microstructures of the impact specimens are mainly composed of stacking faults, network dislocation, slip bands, and a few mechanical twins and -martensite. These microstructures cross with each other in a crystal angle. The deformation microstructures of the tensile specimens consist only of massive slip bands, in which a few mechanical twins and -martenite are located. Because of the larger plastic deformation the slip band traces become bent. All the deformation microstructures are formed on the {111} planes and along the <110> orientation.     

自然材料微结构的几种特征

自然材料微结构是仿生机械结构设计的灵感来源.利用激光扫描共聚焦显微镜分析了鸭子下层绒毛、水稻叶毛、松针维管束鞘、水稻侧根和松针的微结构;用扫描电镜分析了黄瓜外表皮、仙人掌表皮组织、水稻叶脉、蚊子复眼、仙人掌组织、鹌鹑蛋蛋壳、水稻根和贝壳的微结构．结合前人对其它自然材料微结构的研究,总结了自然材料的结构特征,典型微结构特征有分形结构、分级结构、多尺度结构、多孔结构、梯度结构和整合结构;并且讨论了典型生物微结构原型在仿生结构设计方面的应用．分析了自然材料微结构特征的一般性特征,即对称性和自相似性．     

Betrachtungen zur Gefügesystematik

Considerations on Mircostructural Systematics Many terms of modern engineering materials science have been defined by metal science and metallurgy. Their transmission to other materials as ceramic needs adaption. But also the original content of the terms undergoes timedepending variations according to the nowadays state-of-the-art. This is why the definition and the relation of scientific-technical terms to each other has to be reconsidered again and again. In this context related to microstructure the present paper discusses terms as adhesion, agglomeration, alloys and anisotropy, cohesion, cristallites, directionally solidified eutectics, disordered and duplex microstructures. Engineering materials, grains and grain boundaries are also put into this frame as well as heterogenity, homogenity, incoherence, inhomogenity, in-situ- and interconnected microstructures, isotropy, material and matrix microstructures. Microstructural elements and microstructural levels, microstructural modelling and microstructural parameters are related to microstructure-property-correlations and by multiphased microstructures, ordered microstructures, orientation factors, phases, pores, shape factors, single phase and synthetical microstructures as finally textures and types of microstructures the sequence of terms is completed. What they mean, how they belong together and why microstructure needs them is subject of the constribution.     

MEMS微结构旋转角度的快速测量方法

可运动的微结构是MEMS器件的重要单元,其运动特性与器件的性能和可靠性是密切相关的.针对频闪成像技术获得的微结构运动图像序列,提出一种微结构旋转角度的快速测量方法.该方法利用运动微结构上普遍存在的释放工艺孔结构作为目标特征,对其中两个释放工艺孔的图像特征分别求取质心和两质心连线的斜率,最后比较运动图像序列中质心斜率的变化,得到各运动状态下的旋转角度.实验结果表明,该测量方法的运算时间小于0.5s,角度测量分辨率可达到0.01°.     

光学微结构的超精密加工技术

微结构光学元件在光电产品及光通讯产品中的应用日益广泛，采用多轴超精密机床加工光学微结构，可达到亚微米级形状精度和纳米级表面光洁度的高精度水平，详细介绍了光学自由曲面及光学微结构的超精密加工技术，并开发了适合超精加工微型槽和微透镜列阵的刀具轨迹自动生成软件。     

微结构光学元件快速伺服刀架加工技术研究

微结构光学元件是一种微小的拓扑元件,通常分为微沟槽列阵、锥形列阵以及微透镜列阵等.这些微结构光学元件能在一些手持装置（例如手机）的平板显示器上得到先进的光学应用.由于产品微型化的需求越来越紧迫,传统的刻蚀方法不再适用于加工高质量的光学微结构产品,为此,提出了一种新型的加工高质量光学微结构元件的技术.该技术以快速伺服刀架加工系统为基础,并结合新开发的刀具轨迹生成器.该刀具路径生成器主要是针对快速伺服刀架加工系统而开发的,它可以根据光学微结构元件的设计直接生成加工所需的刀具轨迹,而不需要进行任何的后续处理.最后,通过加工实例证明了上述加工系统的可行性并得到了符合要求的加工效果.     

Micro-mechanical properties of calcium sulfoaluminate cement and the correlation with microstructures

To investigate the micro-mechanical properties of calcium sulfoaluminate cement and the correlation with the microstructures, we apply a variety of advanced techniques of microstructural and micro-mechanical characterization, including scanning electron microscopy with backscattered electron and energy-dispersive X-ray spectroscopy detectors, X-ray fluorescence, X-ray diffraction and nanoindentation. For the first time, the micro-mechanical properties of material microstructures present in a calcium sulfoaluminate cement are estimated. In the calcium sulfoaluminate cement used in this research, two type of hydration product microstructures with the differentiable microstructural morphologies, compositions and micro-mechanical properties are identified and investigated. The correlation of the micro-mechanical properties with the microstructures shows that the hydration product microstructure containing more ettringite has lower indentation modulus and hardness than that containing more aluminum hydroxide.     

Computer simulations of realistic microstructures of coarse constituent particles in a hot-rolled aluminum alloy

Computer simulations of realistic microstructures of coarse constituent particles in hot-rolled 7075 Al-alloy plate are presented. These simulations incorporate realistic complex morphologies/shapes of the constituent particles as well as their spatially clustered non-uniform arrangements and partially anisotropic morphological orientations. The methodology permits simulations of sufficiently large microstructural windows that incorporate short-range (on the order of particle/feature size) as well as long-range (few hundred times the particle/feature size) microstructural heterogeneities and spatial patterns. Two-point correlation functions are used for microstructure representation. The two-point correlation functions of the simulated microstructures are closely matched with those of the corresponding real microstructures. The simulation parameters enable simulations of virtual microstructures of the alloy that cover a range of different volume fractions and average sizes of the constituent particles.     

微粉增强水泥基复合材料的早期界面显微结构研究

介绍了粉煤灰、硅灰、纳米SiO₂与水泥水化反应产物的早期界面显微结构,探讨了三种微粉与水泥水化反应的机理及对改善界面结构的作用,并提出了"二级界面"的概念。研究表明,三种微粉对界面的改善呈递增趋势,单一微粉中纳米SiO₂的水化产物结构最致密、均匀,微粉复合有效改善二级界面显微结构,有效提高水泥基材料性能。     

Comparison of mechanical properties of martensite/ferrite and bainite/ferrite dual phase 4340 steels

Different microstructures were produced by heat treatment of 4340 steel. These microstructures are bainite, martensite, ferrite–martensite and ferrite–bainite. Mechanical tests were carried out at room temperature. The results showed that steel with bainite–ferrite microstructure has better ductility and charpy impact energy than steels with martensite–ferrite and full bainite microstructures. But yield and tensile strengths of this steel are less than the yield and tensile strengths of the other two steels. Hardness measurements showed that their hardness is the same. Fracture surface observations of tensile specimens showed increase in toughness of bainite–ferrite in comparison to martensite–ferrite and full bainite microstructures.     

Self-assembly of pillars modified with vapor deposited polymer coatings

In this paper, we demonstrate that thin layers of polymer coatings can be used to self-assemble pillars into stable microstructures. Polymer coatings are deposited onto elastomeric pillars using solventless initiated chemical vapor deposition and capillary forces are used to collapse the coated pillars into microstructures. The location of pillar collapse can be controlled by patterning regions of hydrophilicity and hydrophobicity. Poly(hydroxyethyl methacrylate) and poly(methacrylic acid) coatings stabilize the self-assembled microstructures by providing an adhesive force through solvent bonding. These solvent bonds allow the response of the microstructures to be tuned by varying the thickness of the polymer coating and the solubility parameter of the solvent. The coating process described in this paper is substrate-independent and therefore can be applied to pillars composed of any material.     

Effect of cathodic potential on stress corrosion cracking behavior of different heat-affected zone microstructures of E690 steel in artificial seawater

In this work,the stress corrosion cracking(SCC)behavior of E690 steel base metal(BM)and different heat-affected zone(HAZ)microstructures,i.e.,coarse grain HAZ(CGHAZ),fine grain HAZ(FGHAZ),and intercritical HAZ(ICHAZ),was investigated at different cathodic potentials in artificial seawater by slow strain rate tensile tests,scanning electron microscopy and electron back-scattered diffraction measurements.The results show that the HAZ microstructures and BM exhibit different SCC susceptibilities:FGHAZ相似文献   

C／C复合材料的显微结构及其与工艺、性能的关系

对化学气相渗透（CVI）C／C复合材料在偏振光下的显微结构（偏光显微结构）类型、结构的形貌特征及对应炭的基本物理性能、材料的制备工艺参数－结构－性能之间的关系进行了综述。C／C复合材料具有三种基本偏光显微结构,即RL、SL和ISO。这三种基本偏光结构的炭对应于不同的形貌特征,可从消光十字形、旋光性、光学反射性、生长特征、表面织构、择优取向性和环形裂纹等特征将其分辨出来。工艺参数对沉积炭偏光显微结构的影响没有一成不变的规律可循,影响因素除了温度、压力、气体成分、气体流速外,还与炉子的几何尺寸及试样的堆积尺寸有关,对不同的CVI体系,都应当摸索出一套适合其运行的最佳工艺参数。C／C复合材料的偏光显微结构与材料的性能有着密切的联系,不同的结构下,材料的物理性能、力学性能和热性能都表现出明显的差异。通过归纳与分析,获得了对C／C复合材料偏光显微结构全面、系统的认识,明确了它在C／C复合材料研究中的重要性,为制备具有单一、均匀偏光显微结构及所需性能的C／C复合材料指明了方向。     

Influence of microstructure on the dynamic fatigue properties of injection-moulded polypropylene

A polypropylene copolymer was injection-moulded using several processing conditions and with different gating systems to produce a range of typical spherulitic microstructures. In addition to internal weld lines, some specimens were joined to form external mirrorplate butt-welds. The effect of the different microstructures on the fatigue and impact properties as a function at two test temperatures of 23 and – 10° C are reported. The influence of the different microstructures resulted in significant differences in load-bearing ability.     

An efficient novel low voltage field electron emitter with cathode consisting of template synthesized copper microarrays

Synthesis of copper microstructures was done using the electrochemical template technique using the NTF (Nuclear Track Filter). The NTF was fabricated using the polycarbonate SSNTD (Solid State Nuclear Track Detector) which was created by irradiation of Uranium ions. The synthesized copper microstructures were further used to fabricate a novel low voltage field electron emitter. As compared to traditional technique of lithography-based nano/micro fabrication, template synthesis is a simple technique, where pores of NTFs are used as templates and by using a suitable electrochemical cell design, any type of nano/microstructures can be fabricated. The present paper envisages the production of nuclear track filters and fabrication of copper microstructures through galvanic replication. The studies also reports first time, a excellent low voltage field electron emitter fabricated by using copper microstructures in comparison to the earlier work. This low voltage field electron emitter being a novel cold cathode emitter can be a potential candidate for an energy saving devices.     

Studying the influence of initial powder characteristics on the properties of final parts manufactured by the selective laser melting technology

Selective laser melting (SLM) is an additive manufacturing process that enables direct manufacturing of 3D complex shape parts and internal architecture from powder materials. The SLM technology is characterised by high temperature gradients and solidification rates that have a significant effect on the microstructures and properties of final parts. The present paper aims at understanding the influence of the initial properties of various martensitic stainless steel powders on the final microstructures and mechanical properties of parts manufactured using the same optimised SLM process parameter settings. The results obtained show that for applied optimum process parameters, the thermal effects are the same for all martensitic powders used. Besides, the final microstructures and properties are different. The results clearly show the effect of the initial complex chemical composition of the martensitic precipitation hardening powder on the microstructures of final parts, and consequently, on their properties.