微弧氧化工艺过程的自动控制研究

针对轻金属微弧氧化工艺复杂,人工控制工艺重复性差的特点,设计了微弧氧化工艺过程的自动控制系统。分析了微弧氧化工艺过程各阶段的特点,对微弧氧化工艺过程涉及的电压、电流、工作时间、电解液温度、频率、占空比等参数,该自动控制系统能够按照预设的工艺曲线、手工给定方式自动处理,自动与手动之间能进行无扰动切换。实验表明,该微弧氧化控制系统工艺重复性好,工作可靠性较高。     

电参数对镁合金微弧氧化膜层厚度的影响

使用新型双端脉冲电源在镁合金AZ91D上制备微弧氧化膜。研究电压、频率、占空比和电流密度对微弧氧化膜层厚度的影响。结果表明:微弧氧化膜的厚度随电压、电流密度和占空比的升高而增厚,但频率对氧化膜厚度的影响不大。影响的主次顺序为:电压和电流>占空比>频率。     

铝合金表面改性技术研究进展

综述了近年来铝合金表面改性技术取得的研究进展,重点介绍了激光熔覆、阳极氧化和等离子体微弧氧化等方法在铝合金表面制备膜层的原理、特点及研究成果,并对等离子微弧氧化技术提出了展望。     

铝合金微弧氧化技术的研究及其应用

本文介绍了铝合金微弧氧化技术的工艺特点和氧化物陶瓷膜层性能。比较了微弧氧化技术和阳极氧化技术的工艺特点及其性能特征。分析了国内外微弧氧化技术的研究进展及其应用前景。     

镁合金的表面处理工艺选择

镁合金作为一种轻质合金,在航空航天领域得到广泛应用。目前便携红外产品也陆续采用了镁合金壳体。镁合金的表面防护工艺常用的有电泳涂装、化学氧化和微弧氧化。通过对三种处理工艺的说明和比较,确定了适合某些产品的表面处理工艺。化学氧化的颜色多样、处理简单、成本低、导电性能好、油漆附着力好,是一种具有相对优势的处理工艺。     

航空铝合金微弧氧化工程化应用研究

为实现微弧氧化技术在航空领域的应用,突破非微弧面的保护难题,以2A14航空铝合金零件为研究对象,主要研究了胶带、胶体及工装对保护效果的影响,结合微弧氧化反应特殊原理,强调了工装的设计要点、工装的材料及不同表面所用的工装类型。研究结果表明,胶带和涂胶的方式可在某种程度上达到防护功能,但不适合于航空产品;而专用工装在掌握设计要点的前提下可有效实现防护效果,可以满足大批量生产的要求且稳定性好、可控性强。     

铝合金型材的氧化与着色

铝对氧有很强的亲和力，甚至在空气中也能跟氧起反应，很快地在表面上生成一层致密的保护性氧化薄膜，这膜称为自然氧化膜，它的主要成分是Al2O3，厚度为几十到几百埃，能阻止内层的铝被氧化，从而将铝在常温下置于空气及水中，都处于稳定状态。     

垃圾渗滤液膜浓液处理研究进展

为满足《生活垃圾填埋场污染物控制标准》的要求,垃圾渗滤液大多采用膜分离技术进行有效处理。随之产生的成分复杂、可生化性差、污染浓度高的膜截留浓缩液极难处理,是制约膜技术应用的主要技术难题。国内外对膜浓缩液处理的研究还处于发展阶段,常用的回灌、氧化、蒸发和焚烧等方法均存在一定的缺陷,处理效果有限。文章通过对现行方法比较分析,指出高级氧化技术及其组合工艺效果明显、经济效益高,在将来有望得到广泛应用。建议从垃圾产生源头开始,实现垃圾及渗滤液的减量化,结合高级氧化组合工艺,以期从根本上解决膜浓缩液问题。     

浅议医用镁合金微弧氧化表面改性

镁及其合金作为一种重要的生物医用材料,在生理环境下较差的耐腐蚀性能已成为限制其发展与应用的重要因素。而微弧氧化技术作为一种重要的镁合金表面改性手段被广泛研究和应用。本文结合实验结果分析与论证,对医用镁合金微弧氧化表面改性技术进行探索与评价,以期拓展其在生物医学领域的发展和应用。     

哈尔滨工业大学

钕铁硼永磁合金上电镀高防护性锌镍合金镀层，纳米添加剂改性的镁合金表面微弧氧化陶瓷化新技术，生活污水处理及回用技术与成套设备，洗车废水回用设备，金属橡胶技术及金属橡胶构件：     

多媒体辅助数学教学的利弊分析及对策

随着科技的发展,计算机在社会的各个领域中得到广泛的普及和应用。多媒体技术作为一种有效的辅助教学手段,已被广大教师广泛使用,并产生了积极的作用,但在实践中也暴露出种种弊端。本文就多媒体辅助数学教学的利弊进行分析并提出对策。     

阳离子染料－蒙脱石化学修饰电极的电化学性质─—与Nafion膜化学修饰电极的比较

用蒙脱石与Ｎａｆｉｏｎ制备了阳离子染料中性红化学修饰电极（ＣＭＥ）．两种ＣＭＥ在支持电解质溶液中有相似的循环伏安行为．蒙脱石ＣＭＥ的峰电流随膜厚增加而增加，而ＮａｆｉｏｎＣＭＥ的峰电流随膜厚增加有所降低．阳离子染料在蒙脱石膜内的扩散系数比在Ｎａｆｉｏｎ膜中的扩散系数大一个数量级．阴离子电活性物以及不同的制备方法对两种ＣＭＥ的电化学响应有不同的影响．两种ＣＭＥ在性质上的差异反映了两种膜的微结构与通透性等方面的差别．蒙脱石用作制备化学修饰电极的表面层材料有一定吸引力．     

The effect of the surface functionalization and the electrolyte concentration on the electrical conductance of silica nanochannels

It is known that the conductance of nanochannels as a function of electrolyte concentration deviates from a linearly proportional relationship and approaches a value independent of the concentration as the electrolyte concentration is lowered. Most of the proposed models account for this behavior by considering a constant surface charge density and an ideal electrolyte solution. However, at low electrolyte concentrations, the ideal electrolyte approximation is no longer valid because the ions that result from the atmospheric carbon dioxide dissolution in water dominate the ionic concentration. In this paper, arrays of silica nanochannels were electrically characterized via conductance measurements. The conductance at low salt concentrations is modeled by a variable surface charge model that accounts for all ionic species in solution. This model was used to determine the variable surface charge of the bare silica nanochannels as well as of chemically modified nanochannels. The model correctly predicted the variation of the nanochannel conductance observed after silane (aminopropyldimethylethoxysilane) functionalization and single-strand DNA immobilization. Finally, pH modification of bulk KCl solutions was employed as an alternative method of changing the surface charge of silica nanochannels. Surface charge calculated from conductance measurements performed at different bulk pH values confirmed that the surface charge of the silica nanochannel walls is sensitive to the H⁺ concentration.     

Isotachophoresis with emulsions

An experimental study on isotachophoresis (ITP) in which an emulsion is used as leading electrolyte (LE) is reported. The study aims at giving an overview about the transport and flow phenomena occurring in that context. Generally, it is observed that the oil droplets initially dispersed in the LE are collected at the ITP transition zone and advected along with it. The detailed behavior at the transition zone depends on whether or not surfactants (polyvinylpyrrolidon, PVP) are added to the electrolytes. In a system without surfactants, coalescence is observed between the droplets collected at the ITP transition zone. After having achieved a certain size, the droplets merge with the channel walls, leaving an oil film behind. In systems with PVP, coalescence is largely suppressed and no merging of droplets with the channel walls is observed. Instead, at the ITP transition zone, a droplet agglomerate of increasing size is formed. In the initial stages of the ITP experiments, two counter rotating vortices are formed inside the terminating electrolyte. The vortex formation is qualitatively explained based on a hydrodynamic instability triggered by fluctuations of the number density of oil droplets.     

Microfluidics based on ZnO/nanocrystalline diamond surface acoustic wave devices

Surface acoustic wave (SAW) devices with 64 μm wavelength were fabricated on a zinc oxide (ZnO) film deposited on top of an ultra-smooth nanocrystalline diamond (UNCD) layer. The smooth surface of the UNCD film allowed the growth of the ZnO film with excellent c-axis orientation and low surface roughness, suitable for SAW fabrication, and could restrain the wave from significantly dissipating into the substrate. The frequency response of the fabricated devices was characterized and a Rayleigh mode was observed at ∼65.4 MHz. This mode was utilised to demonstrate that the ZnO/UNCD SAW device can be successfully used for microfluidic applications. Streaming, pumping, and jetting using microdroplets of 0.5 and 20 μl were achieved and characterized under different powers applied to the SAW device, focusing more on the jetting behaviors induced by the ZnO SAW.     

Enabling Mg metal anodes rechargeable in conventional electrolytes by fast ionic transport interphase

Rechargeable magnesium batteries have received extensive attention as the Mg anodes possess twice the volumetric capacity of their lithium counterparts and are dendrite-free. However, Mg anodes suffer from surface passivation film in most glyme-based conventional electrolytes, leading to irreversible plating/stripping behavior of Mg. Here we report a facile and safe method to obtain a modified Mg metal anode with a Sn-based artificial layer via ion-exchange and alloying reactions. In the artificial coating layer, Mg₂Sn alloy composites offer a channel for fast ion transport and insulating MgCl₂/SnCl₂ bestows the necessary potential gradient to prevent deposition on the surface. Significant improved ion conductivity of the solid electrolyte interfaces and decreased overpotential of Mg symmetric cells in Mg(TFSI)₂/DME electrolyte are obtained. The coated Mg anodes can sustain a stable plating/stripping process over 4000 cycles at a high current density of 6 mA cm⁻². This finding provides an avenue to facilitate fast ion diffusion kinetics of Mg metal anodes in conventional electrolytes.     

掺加氧化铁的彩色沥青混合料配合比设计

本文介绍了等同于建筑图谱色彩体系中（C0/M0-100/Y20/B0-100）范围内的彩色沥青混合料配合比设计,确定了即满足路用要求,又在标准比色卡（C0/M0-100/Y20/B0-100）范围内的氧化铁掺量范围.     

高Tc铜氧化物超导体中氧的作用特征

本文应用二流体模型、超导体的双体结构模型和德拜晶体震动模型对氧在高TC铜氧化物超导体中的作用特征作了分析讨论。结合氧在高TC铜氧化物超导体中的同位素效应实验结果,得出的结论是：氧的作用特征是影响晶体结构和载流子的浓度;参与了电声子成对。     

基于HSV空间的彩色图像直方图检索技术

传统彩色图像的直方图检索技术基于RGB空间,但研究发现,RGB空间不符合人眼的视觉感应。因此本文提出的算法是在HSV空间上计算彩色图像的三维直方图,通过非均匀的划分三个分量色相H(Hue)、饱和度S(Saturation)和亮度V(Value)的采样区间,得到不同的检索结果。实验结果分析表明,在HSV空间,不同的分量在不同类型的图像中的作用是不一致的。     

Zinc phosphate dental cements

A spectrophotometric method of determining total visual transmission and visual density of non-neutral light filters is described. In addition, this method is utilized in determining density and gamma intensification produced by tones in color motion picture work and the importance of intensification control is emphasized.