脉冲电沉积钴镍合金层微观结构的研究

研究了钴镍合金镀液中Co^2 浓度与镀层中钴含量的关系,并采用XRD,TEM分析了不同钴含量合金镀层的微观结构。结果表明,沉积层中的钴含量随电解液中Co^ 浓度的增大而显著增大,当镀层中的钴含量为69．8％－78．9％（质量分数）时,镀层为面心立方晶格的α－Co相和排六晶格的ε－Co相组成;钴含量低于69．8％时为α－Co相,钴含量大于78．9％时为ε－Co相,钴含量增大,晶粒尺寸明显减小,合金点阵参数增大。     

添加剂对喷射电沉积纳米晶Co-Ni合金的影响

在氯化镍-硫酸钴体系电解液中采用添加剂喷射电沉积纳米晶Co-Ni合金,测定了其阴极极化曲线.研究了添加剂对阴极过电位、电流效率、镀层中Co含量、镀层的相结构、晶粒尺寸、表面形貌及显微硬度、软磁性能等影响.结果表明:添加剂增加了极化作用,影响了Co、Ni电沉积的动力学过程.当添加剂为2.5g/L时,与未加添加剂相比较,阴极过电位从3.594V增大到4.755 V,电流效率和沉积层中Co含量变化不大,但沉积层晶粒尺寸从12.8 nm明显降低到5.5 nm,维氏硬度从423升高到511,同时Co-Ni合金的软磁性能得以提高.     

喷射电沉积纳米晶镍的研究

用喷射电沉积法制备纳米晶镍,研究了电解液喷射速度、电流密度、沉积速度等工艺参数之间的关系,分析了沉积层的组织结构。结果表明：电解液喷射速度为２～５．５ｍ／ｓ,电流密度在８０～１６０Ａ／ｄｍ＾２之间时,最大沉积速度为１４～３２μｍ／ｍｉｎ,沉积层外观光亮。ｘ－射线衍射谱观察和透射电镜的分析表明：沉积层平均晶粒尺寸为２０～３０ｎｍ,且存在（２２０）结构。     

射流电沉积工艺优化对铜镀层形貌及微观结构的影响

射流电沉积技术具有特殊的定域性和材料特性,可用于磨损机械零件的修复,但因为边缘效应,沉积层的分布均匀性和质量需要改善。考察了沉积形貌、微观结构与射流电沉积电解液流速、喷嘴扫描速度及电流密度等关键参数的关系。结果表明,喷射流速在1~10 m/s范围,随着流速的增加沉积层表面质量及微观结构逐渐致密;扫描速度在1~15 mm/s范围,随着速度的加快沉积层表面质量及微观结构逐渐致密;电流密度在100~600 A/dm~2范围内,随着电流的增大沉积层表面质量及微观结构逐渐改善,晶粒尺寸逐渐增大。     

电沉积纳米晶镍涂层的微结构与性能

采用电沉积法制备了纳米晶镍涂层，讨论了镀液中硼酸浓度对涂层晶粒尺寸的影响，并分别分析了显微硬度与平均晶粒尺寸、磨损体积及摩擦因数的关系。测试了微晶和纳米晶镍涂层的抗高温氧化性。结果表明：当硼酸在镀液中未达到饱和之前，镍的晶粒尺寸随硼酸浓度的增加而减小；当晶粒尺寸在8～20nm范围时，随着晶粒尺寸的减小，涂层的显微硬度增大，滑动摩擦因数和静摩擦因数均有所减小．耐磨性能提高，抗高温氧化性能增强。     

电沉积法制备纳米晶Ni-Co合金镀层

在氨基磺酸盐镀液体系中,采用电沉积法制备了纳米晶镍镀层和四种纳米晶Ni-Co合金镀层,采用FESEM、EDS和XRD表征了镀层的表面形貌、成分和晶体结构。结果表明,镍镀层和四种Ni-Co镀层的晶体结构都是简单面心立方结构;与镍镀层相比,Ni-Co合金镀层的平均晶粒尺寸减小,且当镀层钴含量为41.3%时,Ni-Co合金的平均晶粒尺寸最小为14.6 nm。在一定范围内,钴含量的增加有利于改善Ni-Co合金镀层的表面质量以及实现晶粒细化。     

硫酸钴浓度对电沉积Co-W-P薄膜结构与磁性能的影响

在20#钢基体上电沉积Co-W-P薄膜，并研究镀液中硫酸钴浓度对Co-W-P薄膜的结合强度、结构、成分、厚度和磁性能的影响。结果表明：Co-W-P薄膜与20#钢基体结合紧密，随着硫酸钴浓度从5 g/L增至25 g/L,Co-W-P薄膜的结构和物相无明显变化，但平均晶粒尺寸呈现先减小后增大的趋势，Co元素的质量分数呈现先升高后降低的趋势，导致不同Co-W-P薄膜的致密性和磁性能存在差异。当硫酸钴浓度为15 g/L时，Co-W-P薄膜的平均晶粒尺寸仅为40.6 nm,Co元素的质量分数达到64.19%，具有最大的矫顽力（932 A/m）和饱和磁化强度（100.7 A·m2·kg-1），其结构致密并且展现出良好的磁性能。在一定范围内硫酸钴浓度的增加，降低了成核过电位，使晶粒细化且结合紧密，同时提高了钴还原沉积效率，使Co元素的质量分数升高。研究表明：晶粒细化、致密性改善以及磁性元素的协同作用进一步提高了Co-W-P薄膜的磁性能。     

电沉积Ni—Ce—S非晶态合金

研究了镀液组成和工艺条件对Ｎｉ—Ｃｅ—Ｓ非晶态合金沉积层的影响，结果表明，镀层中的Ｓ含量随电流密度、镀液的ｐＨ值和硫代硫酸钠浓度的变化而变化，但与镀液中的氯化钾浓度无关；Ｘ射线衍射图说明，当镀层中的Ｓ含量超过３０％时，镀层为非晶态结构；扫描电子显微镜表明，当镀层中Ｓ含量增加时，镀层的微裂纹减少且变细，当镀层中Ｃｅ含量增加时，晶粒会细化。     

射流电沉积工艺参数对沉积层形貌的影响

射流电沉积技术具有特殊的定域性和材料特性,可用于机械零件修复,但沉积层的均匀性和质量需要改善。研究了电解液喷射流速、电流密度、沉积层数等对沉积层形貌的影响。结果表明:喷射流速在1~10m/s范围内,随着喷射流速的增大,沉积层的表面质量逐渐改善;电流密度在100~600A/dm2范围内,随着电流密度的增大,沉积层形貌逐渐恶化,产生析氢副反应;沉积层数在400~1 600层范围内,沉积层的表面质量随层数的增加而逐渐恶化。得到了一系列的优化参数,有助于改善沉积层的质量。     

脉冲喷射电沉积镍工艺的研究

由于直流电沉积镍使用极限电流密度下,沉积速度低。本文介绍脉冲喷射电沉积的方法制备镍镀层。研究了脉冲频率、占空比、电流密度及糖精对镀层晶粒尺寸的影响。结果表明：镀层晶粒尺寸随脉冲频率、平均电流密度的增大而减小;随空比的增大而增大。少量糖精的加入能有效降低镀层晶粒尺寸。     

脉冲电镀中脉冲参数对镍镀层显微硬度的影响

采用传统的瓦特镀液通过脉冲电镀制得纯镍镀层。研究了脉冲参数对镀层微观形貌与显微硬度的影 响。结果表明:镀层表面形貌为胞状结构;随着脉冲峰值电流密度的增加,胞状结构的尺寸逐渐变小,镀层显微硬度先增 加后减小;随着占空比的减小,最大显微硬度值对应的峰值电流密度增大,占空比减小到一定值后,峰值电流密度的改变 对显微硬度影响不再明显。     

Study of gold deposition on copper by electrochemical and microscopic techniques

Deposition of gold on copper from acid gold bath was investigated using electrochemical and microscopic techniques. The growth morphology of both soft and hard gold deposits was characterized using scanning electron microscopy (SEM) and atomic force microscopy (AFM). Analysis of chronoamperometric transients showed that the mechanism of nucleation and growth of hard gold is three-dimensional progressive nucleation and growth of right-circular cones. This was further confirmed by SEM and AFM measurements. The grain size of hard gold deposit was shown to be much smaller than that of soft gold, indicating that nickel in deposit acts as a grain refiner. The mean roughness of hard gold deposit increases with deposition time, and with an increase of negative potential from --0.5 to --0.70V (vs SCE), however, the surface becomes more uniform at --0.80V. Similarly, the maximum height of clusters increases as potential is made more negative between --0.50 and --0.65V, while it decreases steeply at potentials from --0.65 to --0.80V. The inhibition of crystal growth in gold deposition at certain potentials was observed electrochemically and corroborated by microscopic techniques.     

峰值电流密度对脉冲镀镍钴合金纳米镀层机械性能的影响

研究了峰值电流密度对脉冲镍钴合金纳米镀层的成分、晶粒尺寸、显微硬度、抗拉强度的影响.结果发现:在一定范围内,峰值电流密度的增大,可以降低镀层钴含量、表面粗糙度和晶粒尺寸,使菜花胞状结构更明显,提高镀层显微硬度(最高可达600 kg/mm2)和抗拉强度(最高可达1 200 MPa).然而,峰值电流密度太大又会使显微硬度和强度下降.与采用类似方法制得的纯镍纳米镀层相比,镍钴镀层的显微硬度并未明显升高.这说明在该纳米材料中,固溶强化效果并不很明显,而以细晶强化为主.     

流化床垃圾焚烧炉飞灰沉积实验

在自行搭建的小型流化床积灰试验台上选用流化床垃圾焚烧炉对流管束浮灰,模拟焚烧炉烟气环境下开展飞灰沉积实验。首先分析浮灰理化特性,结果表明：随着粒径增大,浮灰中CaO和SO₃含量逐渐降低,而SiO₂和Al₂O₃的含量逐渐增加;碱金属Na和K以及卤素Cl的含量在粒径较小的浮灰中含量最高。其次重点研究了浮灰粒径、烟气温度和换热管表面温度对飞灰沉积特性的影响规律,结果表明：积灰中主要富含Ca、S、Si和Al等元素,积灰中CaO和SO₃含量比浮灰高,而Al₂O₃和SiO₂含量比浮灰低;积灰量随着烟气温度升高而增加;粒径对灰沉积影响作用显著,大粒径灰颗粒难沉积而小粒径灰粒易沉积;管壁温度在600℃时,积灰量最小。积灰中CaO和SO₃的含量随着管壁温度升高而减少,而难熔Al₂O₃和SiO₂的含量随着管壁温度升高而增加。     

Properties and paper sizing application of waterborne polyurethane emulsions synthesized with isophorone diisocyanate

In this work, a two-step synthesis methodology has been used to synthesize a series of waterborne polyurethane (WPU) emulsions with isophorone diisocyanate (IPDI), poly-caprolactone diol (PCL) and dimethylol propionic acid (DMPA) as monomers and ethylenediamine (EDA) as the chain extender, respectively. The influences of the NCO/OH molar ratio, DMPA content, chemicals-adding sequence, and acetone content on the physical properties of the resultant emulsions have been investigated in detail. The results show that the emulsion viscosity increases with an increase in the NCO/OH molar ratio or DMPA content whereas it declines sharply as the acetone amount increases. The emulsion particle size is seen to increase with the NCO/OH molar ratio but it decreases as the DMPA content increases. The chemicals-adding sequence is observed to strongly affect the particle size and viscosity of the resultant emulsions. For cast films, with an increase in the NCO/OH molar ratio, the elongation monotonically decreases while the tensile strength is seen to increase at first and then deceases. The film water absorption capacity is found to go up as the DMPA content increases. Furthermore, after sized with the emulsions, the paper water resistance is markedly improved and the 30s Cobb value is seen to decrease by 63% as compared to the unsized counterpart. The paper folding resistance and the tensile index are also improved to certain extents. For producing well-performed WPU emulsions for sizing paper sheets, an NCO/OH molar ratio of 1.6–1.8 and a DMPA content of 6.0–7.0 wt.% are preferably chosen.     

The effect of cadmium on zinc deposit structures obtained from high purity industrial acid sulphate electrolyte

The effect of cadmium on cathodic zinc crystal growth was studied in high purity industrial electrolyte, with and without additives, in an attempt to establish a correlation between morphology, polarization and the extent of cadmium contamination. Cadmium additions to acid zinc sulphate electrolyte did not have a significant effect on the zinc deposit orientation but did substantially refine the deposit grain size. The refinement in deposit grain size is directly related to the level of cadmium in the zinc deposits. Cadmium, in combination with glue and optimum amounts of glue and antimony, also reduced the deposit grain size: the preferred deposit orientation remained (1 1 2) with a slight tendency to (1 0 1) at high glue concentrations. Cadmium in combination with antimony resulted in an increased depolarization of zinc deposition and a basal (0 0 2) deposit orientation. Lead additions to zinc electrolyte containing cadmium resulted in increased deposition overpotentials and intermediate to vertical deposit orientations.     

电沉积Ni-Co合金的研究

研究了氨基磷酸盐电沉积Ni-Co合金电解液组成及工艺条件对沉积层中Co含量的影响.并测定了Ni-Co合金沉积层中Co含量与Ni-Co与硬度的关系,以及影响Ni-Co合金沉积层内应力的因素.实验结果表明,将一定量的Co引入Ni沉积层,可以显著地提高其硬度;当在电解液中添加一定量的Ni-1添加剂后,能使Ni-Co合金沉积层的内应力为零.这些有益的实验结果为电铸加工使用寿命长、机械性能好的模具提供了一定的依据.     

Effects of thiourea and urea on zinc–cobalt electrodeposition under continuous current

The effect of thiourea and urea on zinc-cobalt alloys obtained from chloride baths under continuous current deposition are described and discussed. The deposit morphology was analyzed using Scanning Electron Microscopy (SEM) and an X-Ray Diffraction (XRD) was used to determine the preferred crystallographic orientations of the deposits. The use of additives does not refine the grain size of the Zn–Co alloy and an especially porous alloy was produced in the presence of urea. The preferred crystallographic orientations of zinc–cobalt alloys do not change in the presence additives. Zinc–cobalt alloys were without texture in the presence and absence of additives. Also, in the absence of additive and in the presence of urea, the XRD lines of the Zn–Co alloys are slightly shifted with respect to the pure zinc XRD lines, whereas, in the presence of thiourea, the XRD lines are not shifted. The alloy composition was examined using Energy Dispersive X-ray Fluorescence Spectroscopy (EDXRF). The percentage of cobalt in the alloy decreases slightly from 1.04 to 0.91 wt.% in the presence of urea and in the presence of thiourea it increases from 1.04 to 7.70 wt.%. Voltammetric studies show that thiourea increases the reduction rate of cobalt. This explains the increase in cobalt percentage in the alloy in the presence of thiourea.