金属镍电沉积中枝晶分形生长的研究

将分形几何与电化学原理相结合,通过改进的有限扩散凝聚模型(diffusion-limited aggregation,DLA),采用基于Microsoft Visual C 6.0的Open GL编程,对点电极为阴极进行二维电沉积时沉积产物的形貌进行了模拟.以环形金属镍为阳极,石墨为阴极,用自行设计的试验设备制备了二维的金属镍枝晶以验证模拟结果.结果表明,在保持电压恒定的条件下,镍沉积层的形貌特征为具有分形结构的枝晶,这与采用DLA模型模拟所得的二维枝晶形貌具有相似性,表明该模型对枝晶电沉积的实验研究具有很好的指导意义.     

温度对金属镍电沉积中枝晶分形生长的影响

将分形几何与电化学原理相结合,通过改进的有限扩散凝聚模型(diffusion-limited aggregation,DLA),采用基于Microsoft Visual C 6.0编程,模拟温度对点电极电沉积结果的影响.以环形金属镍为阳极,石墨为阴极,用自行设计的试验设备研究了不同温度时金属镍二维电沉积生长的行为特性,并与模拟结果进行比较.结果表明:在保持电压恒定的条件下,温度对点电极电沉积的影响与采用DLA模型模拟所得的结果具有相似性,表明利用DLA模型模拟的结果对枝晶电沉积的试验研究具有很好的指导意义.     

点阳极射流电沉积中二维枝晶的生长

将分形几何与电化学原理相结合,编程模拟了点阳极射流电沉积中枝晶的分形生长。用自行设计的实验设备研究了点阳极尺寸对点阳极射流电沉积中,金属镍枝晶二维电沉积生长行为特性的影响,并从分形维数的角度对其进行分析。结果表明:点阳极射流电沉积中的枝晶也是分形生长的,随着点阳极尺寸的增大,枝晶簇的形貌向致密型转变,分形维数也随之增加,模拟结果与实验结果具有极好的相似性,从而有力地促进了枝晶电沉积的分形研究。     

析氢对电沉积镍枝晶生长的影响

采用点电极电沉积的方法,在环形电解池中用自行设计的试验装置研究了不同电压和NiSO4质量浓度时,析氢对电沉积金属镍枝晶二维生长行为的影响。研究发现,析氢对沉积产物的形貌影响显著,氢气的大量析出有利于枝晶产生分枝,使沉积物的形貌趋于致密。     

多孔金属连续电沉积数学模型

采用电沉积方法制备连续多孔金属,通过把电流密度随时间的变化转换为镀区内的位置分布,建立了稳恒状态下高孔率带状多孔金属连续电沉积动态模型,推导出表观电流密度分布的数学表达式.并在多孔金属镍实际制备过程中对模型进行了验证,结果表明带状多孔金属与阳极配置满足一定角度时,实现阴极表观电流密度恒定,镍的结晶细致.这一工作为电沉积法制备多孔金属的在线控制提供了理论依据.     

喷射电沉积镍枝晶基础工艺研究

利用喷射电沉积工艺制备镍枝晶。试验在大电流脉冲电源作用下,通过改变溶液流量、电流、沉积时间、喷嘴与阴极距离,观察沉积物形态,研究各个参数对电沉积的影响。结果表明,随着溶液流量变大,阴极上长高的枝状晶根数变少,宏观上更疏松;随着电流增大,沉积形貌由圆柱体逐渐向倒圆锥过渡;沉积速度开始较慢,逐渐增加,最后保持稳定;喷嘴与阴极距离都对沉积物形态产生明显影响,试验测出了一个中间距离,在这个距离附近,沉积形状最接近圆柱。     

喷射速度对喷射电沉积多孔金属镍的影响

借助电化学技术,采用喷射电沉积的方法,直接制备出具有一定厚度、孔隙率较高、组织较均匀的多孔金属镍,并研究了不同喷射速度对喷射电沉积直接制备多孔金属镍的表面形貌和结构特征的影响。研究结果表明,多孔金属镍的孔隙率随喷射速度的增加先减小后增加。     

电沉积-烧结法制备Y2O3：Eu 荧光薄膜的研究

平板显示是显示技术发展的方向,发光材料的薄膜化是显示技术发展的重要研究对象.本研究采用电沉积-烧结方法制备出了氧化钇铕红色荧光薄膜.在0.1 mol/L硝酸钇溶液中加入4%（摩尔分数）0.1 mol/L硝酸铕掺杂,用三电极体系进行阴极电沉积,工作电极的电位为-1.2 V（相对于Ag/AgCl电极）,温度65℃,沉积时间为400 s,500℃灼烧2 h,制备出的发光薄膜与高温固相法制备的薄膜对比,其发射光谱的峰位相同.XRD检测显示经不同温度灼烧后,随温度的升高,氧化钇晶相逐渐完整.经SEM扫描,薄膜沉积均匀平整.     

喷射电沉积枝晶生长数值模拟及实验研究

介绍了喷射电沉积的基本原理,并根据喷射电沉积原理对凝聚扩散模型进行了改进,对电铸过程中的二维枝晶生长过程进行了数值模拟,并进行了实验验证.结果表明,利用改进的凝聚扩散模型模拟得到的粒子簇与实验获得的枝晶相似度较高,用该模型来说明枝晶的生长规律是真实的、可靠的.随着粒子相对运动速度的加快,得到的粒子簇的形貌由疏松分枝逐步发展为致密结构;在不同的粒子数目模拟枝晶图中表现出了明显的屏蔽效应;结合概率越小,粒子越容易进入内层生长点,使枝晶结构较致密;喷射高度对枝晶形貌的影响没有明显规律,波动性很强.     

基于改进扩散限制凝聚模型的点电极金属二维分形生长模拟

采用VB编程软件对传统扩散限制凝聚模型进行改进,通过改变特定漂移概率下的粒子数和运动步长,模拟点电极金属二维分形生长的过程。采用MATLAB软件对分形图进行分析时发现,分形维数随着粒子数的增多而逐渐增大,随着运动步长的增大而逐渐减小。模拟的分形图与特定条件下铜电沉积物的形貌较为吻合,分形维数相近,说明通过计算机模拟点电极金属二维分形生长是可行的。     

几种多孔电极材料镓电沉积性能的研究

在工业上,稀散金属镓通常是从碱性溶液中电解提取得到的。在镓电解过程中,由于析氢副反应和传质速率低的原因导致镓电沉积的电流效率很低。本工作采用三维多孔电极电沉积镓,利用三维多孔电极发达的表面积促进镓电沉积过程,研究了不同电极材料(泡沫金属和多孔碳)的析氢特性,结合不同电解温度和电流密度下各材料的镓电沉积行为,揭示三维多孔电极上镓电沉积的特性规律。结果表明,泡沫铜和石墨毡(GF)具有较低的析氢活性,但两种电极的镓电沉积性能差别很大。其中泡沫铜表现出最佳的镓电沉积性能,在温度为40℃、电流密度为0.1 A/cm²条件下镓电沉积的电流效率(QE)达到22.5%,远高于铜片电极(10.7%);而相同条件下,GF电极的QE值仅为9.6%,低于铜片,这与电极表面的疏水性有关。具有较高析氢活性的泡沫铁、泡沫镍和网状玻璃碳(RVC)电极的镓电沉积过程受电解温度和电流密度的影响较大。在高电流密度下,泡沫铁电极表现出仅次于泡沫铜的QE值,在低电流密度下难以发生镓的电沉积;泡沫镍和RVC电极仅在低于镓熔点(20℃)的条件下发生镓的电沉积,在高于镓熔点(40℃)的条件下,由于电沉积的液态镓...     

Polarization curves in the ohmic controlled electrodeposition of metals

The conditions under which ohmic controlled metal electrodeposition occurs are discussed using a simple mathematical model. It is shown that ohmic controlled electrodeposition can be operative if the value of the exchange current density for the electrodeposition process is more than 10 times larger than the corresponding value of the limiting diffusion current density. In this case, a linear dependence of the current density on overpotential up to the value of the limiting diffusion current density can be observed. On the other hand, the initiation of dendrite growth under these circumstances is possible, even at very low values of overpotential, at the moment when the limiting diffusion current density is attained in potentiostatic electrodeposition. In this way, instead of a limiting diffusion current density plateau, an inflection point on the polarization curve can be observed, since dendritic growth is followed by an increase in the deposition current density. At the same time, it is shown that the ensemble of tips of dendrites can behave as an ensemble of microelectrodes working independently under mixed or activation control due to the absence of a common diffusion layer. This was confirmed by deposition of copper on a copper dendritic electrode and by silver electrodeposition from a silver nitrate solution onto a graphite substrate.     

Application of elimination voltammetry in the study of electroplating processes on the graphite electrode

The electrode reaction mechanism of electrolytical coating by nickel on paraffin impregnated graphite electrode (PIGE) was investigated by cyclic voltammetry (CV) and elimination voltammetry with linear scan (EVLS). The EVLS, a relatively new method of processing electrochemical signals obtained by voltammetry, is able to eliminate some individual chosen currents from total voltammetric currents measured at different scan rates. During the electrodeposition of metals on the graphite electrode, hydrogen evolved from aqueous acidic solutions interferes with the plating process. The elimination of kinetic current arising due to hydrogen evolution enables one to study other processes proceeding at the electrode. Cyclic voltammograms for metal coating deposition/dissolution on the graphite electrode were measured at three scan rates (12.5, 25 and 50 mV/s) and the EVLS functions were calculated for one or two eliminated currents. The results indicate the occurrence of surface reactions with the adsorption of intermediates on graphite. The application of EVLS provides deeper insight into the mechanism of electrode reaction during metal deposition.     

High-density gold nanowire arrays by lithographically patterned nanowire electrodeposition

Here we describe a new method for preparing multiple arrays of parallel gold nanowires with dimensions and separation down to 50 nm. This method uses photolithography to prepare an electrode consisting of a patterned nickel film on glass, onto which a gold and nickel nanowire array is sequentially electrodeposited. After the electrodeposition, the nickel is stripped away, leaving behind a gold nanowire array, with dimensions governed by the gold electrodeposition parameters, spacing determined by the nickel electrodeposition parameters, and overall placement and shape dictated by the photolithography.     

The preparation of high surface area nickel oxide electrodes for synthesis

A study of the electrodeposition of nickel onto copper and graphite is described; the objective was to prepare high surface area, i.e. microrough, but stable deposits which could be used as nickel oxide anodes in aqueous base. It is shown that such electrodes may be prepared by electrodeposition at a high current density (200 mA cm^–2) from a Watts bath and that they give useful apparent current densities for a model synthetic reaction, the oxidation of ethanol to acetic acid.     

双极Electro-Fenton法降解水中苯酚的研究

设计了一种双极电化学芬顿方法(Bipolar Electro—Fenton;BEF)并对水中的苯酚进行了降解研究。采用热压法制备了多孔气体扩散碳电极。在无分隔槽反应装置中,以多孔气体扩散碳电极为阴极将氧气还原产生过氧化氢,铁板作阳极产生Fe2 ,直接利用两电极产物发生芬顿(Fenton)反应对苯酚进行降解。TOC、COD的检测结果表明,BEF法中所采用的气体扩散电极对苯酚的降解程度较通常废水处理中以石墨为阴极的电芬(Electro-Fenton;EF)更为彻底;而且BEF法对苯酚的降解速率比传统芬顿法更快。     

凹凸棒土/石墨复合材料电极的制备及性质

以酸化处理的凹凸棒土粉和膨胀处理的石墨粉为原料、环氧树脂为粘合剂,制得凹凸棒土/石墨复合材料电极。采用扫描电镜、红外光谱等对其形貌和结构进行表征。探讨了电极材料类型、富集时间、平行测定次数对模拟苯酚废水峰电流的影响。研究结果表明,凹凸棒土/石墨复合材料电极比普通石墨电极对峰电流的响应更明显,且稳定性好,无二次污染。