Perfluorocyclobutyl Copolymers for Microphotonics

The copolymerization of aryl bis‐ and tris‐trifluorovinyl ether monomers yields aromatic perfluorocyclobutyl (PFCB) polymers, via thermally initiated step‐growth cycloaddition chemistry. PFCB polymers and their copolymers enjoy a unique combination of attributes well suited for applications in photonic technologies, such as broad tailorability of refractive indices and thermo‐optic coefficients, low transmission losses at 1300 and 1550 nm, high thermal, mechanical, and optical stability, and excellent melt and solution processability. Planar PFCB structures can be processed by direct micro‐transfer molding, which is a first step towards rapid soft‐lithographic fabrication of polymer planar lightwave circuits. Copolymerization chemistry and processing parameters and characterization, including thermal (T_g = 120–350 °C) and optical properties (refractive indices from 1.443 to 1.508 at 1550 nm; thermo‐optic coefficients dn/dT = –7×10^–5 K^–1 to –1.5 × 10^–4 K^–1), birefringence (< 0.003), and temporal stability of refractive index, are described.     

超声辅助悬浮固化液液微萃取-液相色谱荧光法测定血清中阿齐沙坦

建立一种悬浮固化分散液液微萃取-液相色谱荧光法测定血清中阿齐沙坦含量的新方法.在超声辅助下,乳化后的萃取剂1-十一醇高效快速萃取溶液中的阿齐沙坦,将萃取液离心后冰水浴中冷却,萃取剂凝固漂浮在水面而与溶液分离,分离后的1-十一醇用乙醇溶解后利用液相色谱荧光法测定其中阿齐沙坦的含量.实验中对液相色谱测定条件、萃取条件进行了...     

焊接微缺陷磁光成像检测有限元分析

目的 研究铁磁材料焊接微缺陷的磁光成像规律.方法 运用漏磁检测原理和法拉第磁致旋光效应,建立微缺陷三维有限元模型,分析微缺陷磁光成像过程与磁场之间的关联,研究不同提离值、励磁电流、缺陷宽度、缺陷深度下的磁光成像,以及探索这些因素对磁光图像特征的影响.在此基础上,对最小宽度为0.05 mm的微缺陷进行磁光成像检测实验,并...     

基于高压扭转法制备SiCp/Al基复合材料

基于高压扭转法制备SiCp/Al基复合材料(SiC体积分数为8.75%),采用排水法、金相显微镜、数字式显微硬度计,研究SiCp/Al基复合材料致密度、显微组织分布和硬度等性能。结果表明,基于高压扭转法可制备致密度高的SiCp/Al基复合材料,随着扭转半径的增加,SiC颗粒团聚现象减小,颗粒分布越均匀。材料的显微硬度呈先增加后减小的趋势。     

电压对微弧氧化膜抑制7050铝合金氢脆敏感性的影响

为进一步探究微弧氧化膜和7050铝合金的氢脆敏感性之间的关系,采用了湿空气中的慢应变速率拉伸、拉伸断口形貌分析、微弧氧化试样表面形貌分析及氢含量测试等表征手段,验证了微弧氧化膜抑制7050铝合金在湿空气中发生氢脆的机制。结果表明,不同微弧氧化电压下制备的膜层对7050铝合金具有不同的抑制氢脆效果,抑制机制主要由膜阻氢进入试样和膜致附加压应力两个方面组成。     

硅烷偶联剂对表面微坑复合PTFE的减摩及缓释性能影响研究

目的探究硅烷偶联剂对缸套表面微坑复合PTFE微粒的减摩和缓释性能的影响。方法利用激光刻蚀机在缸套表面加工不同参数的微坑,并依据摩擦系数对表面微坑参数进行优化。选取最佳表面微坑参数,进行加工,并机械涂覆经硅烷偶联剂修饰的PTFE,制备复合润滑结构。采取往复式摩擦磨损试验机对复合润滑结构的减摩性能进行分析。利用SEM和EDS研究摩擦副的表面形貌和成分,采用三维共聚焦显微镜研究微坑内PTFE的释放情况。结果在热压复合方法下,直径为0.4 mm、深度为120μm的微坑复合PTFE具有最佳的减摩效果。硅烷偶联剂的加入会进一步改善摩擦副之间的减摩性能,其摩擦系数为0.1248。与未处理缸套试样、微坑处理缸套试样、热压复合PTFE缸套试样进行对比,其摩擦系数分别降低了24.3%、18.8%和11.2%。另外,硅烷偶联剂还可以减缓表面微坑内PTFE的释放,延长作用时效,与热压复合方法相比,微坑内PTFE颗粒的释放速率约降低96.3%。结论复合润滑结构能够改善摩擦副之间的摩擦状况,其减摩和缓释机理是固体自润滑材料、表面微坑和硅烷偶联剂协同作用的结果。     

选择相溶解技术制备微/纳结构的研究进展

选择相溶解技术是一种简单、经济、有效的微/纳结构制备方法,尤其是在超长径比、超深宽比和单晶微/纳结构制备方面具有独特的优势。其原理是提取两相或多相合金中的微/纳结构,尺寸调控主要在预制合金形成的过程中进行。本文在明确区分选择相溶解技术和去合金化的基础上,首次详细综述了选择相溶解技术在纳米颗粒、微/纳丝、微/纳米孔和微/纳通道制备方面的研究进展,并结合本课题组研究工作完善了其工艺流程,拓宽了其应用范围,丰富了微/纳结构种类,为该技术在微/纳结构制备领域的广泛应用奠定了基础。     

Structural Color Boosted Electrochromic Devices: Strategies and Applications

Electrochromic devices (ECDs) have attracted substantial attention on account of their unique characteristics and prosperous applications. However, their monotonous color modification remains a momentous challenge that significantly restricts their application scope. Integrating structural colors that arise from the interaction between light and periodic micro/nanostructures with electrochromic materials (ECMs) turns out to be an effective approach to enhancing the comprehensive performance of ECDs more than the coloration effectiveness. This review provides an overview on the recent burgeoning development of structural color ECDs regarding strategies and applications. The performance parameters of ECDs and physical principles regarding the generation of structural colors are introduced. Then, strategies that introduce structural colors into ECDs are discussed according to the category of chromogenic micro/nanostructures, namely, gratings, (single-layer and multilayer) thin films, photonic crystals, plasmonic metasurfaces, and composite structures. The current state-of-the-art research activities of structural color ECDs for display application including segmented and pixelated devices are also presented. Additionally, the future perspective of structural color ECDs with respect of major challenges and potential solutions is proposed.     

Optimal shape design of three‐dimensional MEMS with applications to electrostatic comb drives

A comb drive is one of the most important microactuators in Microelectromechanical (MEM) systems. In a standard comb drive, the capacitance varies linearly with displacement, resulting in an electrostatic driving force which is independent of the position of the moving fingers (relative to the fixed ones) except at the ends of the range of travel. It is of interest in some applications to have force profiles such as linear, quadratic or cubic. Such shaped comb drives could be useful, for example, for electrostatic tuning or to get actuators with longer ranges of travel than those of standard comb drives. This paper presents a methodology for solving three‐dimensional design (inverse) problems in MEM systems. Design of variable shape comb drives (shape motors) is presented as an application of the general methodology. It addresses issues of simulation, sensitivity analysis and then design of three‐dimensional comb drives. Direct simulation is carried out by the exterior, indirect boundary element method and shape sensitivities are obtained by the direct differentiation approach. The inverse problem determines the height profile of the moving fingers of a comb drive such that the driving force is a desired function of its travel distance. An available optimization code (‘E04UCF’ from the NAG package) is used to solve the inverse problem. Numerical results are presented for shape motors that produce linear or cubic force profiles as functions of travel of the moving fingers. Copyright © 1999 John Wiley & Sons, Ltd.     

微小型零件的微细切削加工工艺研究

文章研究了微小型零件的微细切削加工工艺,微细切削加工微小型零件具有较大的工艺和成本优势,适应微小型零件产品批量化、加工柔性化、材料多样化的发展趋势.微小型零件按照加工工艺特征大致可分为微小型轴类、三维结构件、板类和齿轮类零件,总结和分析了上述零件的工艺特征和加工方式,介绍了微小型加工机床和刀具的选用原则,包括如何合理选择微细切削刀具的材料、特征尺寸和结构.微小型零件必须根据机床功能和零件自身结构特点确定装夹方式,并进行准确定位.最后,归纳和总结了微小型零件进行微细切削数控加工工艺设计时应遵循的原则,并进行了详细论述.微细切削加工中,采用合理的数控加工工艺和走刀路线,可以实现微小型零件的精确、高效加工,适应批量化的产品需求.