离心高速电镀镍工艺研究

为提高电镀镍的沉积速率以提高劳动生产率 ,采用自行研制的离心高速电镀镍装置。研究了电流密度与沉积速率、晶粒尺寸及镀层硬度的关系 ,结果表明 :采用此装置 ,镀液在阴极表面切向流速、极限电流密度及沉积速率均增大 ,使得镀层晶粒更细致 ,硬度更高。     

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。     

高速喷射电沉积镍工艺研究

利用自行研制的高速喷射电沉积装置电沉积镍。研究了电流密度与沉积速率的关系,并将所得沉积层与槽镀沉积层进行比较。结果表明：采用此装置,允许使用的极限电流密度及沉积速度均增大,所得沉积层硬度值（Ｈｖ）比一般槽镀层高出２００左右,镀层生形态由枝晶生长转变为柱状生长。     

脉冲电流密度对电沉积纳米晶镍织构和硬度的影响

采用脉冲电沉积法制备了韧性较好的纳米晶镍镀层。考察了脉冲峰值电流密度对纳米晶镍镀层织构和硬度的影响。结果表明,随着脉冲峰值电流密度的增加,Ni(111)晶面择优取向程度逐渐增强,晶粒显著减小,镀层的硬度逐渐增加。纳米晶镍镀层硬度与晶粒尺寸的关系符合经典的Hall—Petch效应。     

氨基磺酸盐镀镍的微观织构与硬度

采用氨基磺酸盐镀液电沉积镍层,通过WLI,SEM,XRD和MHT对镀层的三维形貌、微观织构及硬度进行分析。结果表明:在镀液中不含添加剂的情况下,随着阴极电流密度的增加,镀层晶粒细化,但镀层致密性变差且硬度呈近似线性关系降低;镀液中加入适量添加剂后,镀层衍射谱特征和各晶面的择优取向度无明显改变,但在相同阴极电流密度下所得镀层的晶粒更加细小且硬度有所提高。     

无氟稀土添加剂镀铬的研究

研究了无氟稀土添加剂镀铬的阳极腐蚀和镀液、镀层性能问题，并与常规镀铬、含氟稀土镀铬进行性能对比，实验结果表明，不含氟化物的稀土添加剂，能有效地提高镀层的沉积速度和硬度，使铬层表面微裂纹细密及表面结晶细致平整；改善镀液的分散能力和深镀能力及扩大电流密度光亮区范围；阳极不被腐蚀。     

脉冲喷射电沉积纳米晶镍工艺优化研究

采用脉冲喷射电沉积方法在钢基体表面制备了纳米晶镍镀层,研究了占空比、频率、平均电流密度对镀层硬度的影响,并通过正交试验对工艺参数进行优化,用扫描电镜和X-射线衍射仪对镀层表面形貌和晶粒尺寸进行分析。结果表明,制备纳米晶镍镀层的优化工艺参数为:平均电流密度39.8 A/dm2、频率1 000 Hz和占空比20%,此时镀层最致密,硬度最高(530.6 HV),纳米晶镍平均晶粒尺寸最小(13.7 nm)。     

硫酸盐镀液中紫铜电沉积Ni-Co/WC复合镀层的工艺条件优化

在硫酸盐镀液中加入纳米WC颗粒,通过电沉积在紫铜表面制备了Ni-Co/WC复合镀层.采用单因素分析法考察了镀液中纳米颗粒浓度、温度、阴极电流密度和搅拌速度对复合镀层硬度的影响,确定了电沉积Ni-Co/WC复合镀层的最佳工艺条件为:镀液中纳米颗粒浓度11 g/L、温度60℃、阴极电流密度5 A/dm2、搅拌速度450 r...     

电沉积Ni－Fe－P合金工艺研究

为改善Ｎｉ－Ｐ镀层性能，开发研究了Ｎｉ－Ｆｅ－Ｐ镀层。研究了镀液主要成分和工艺参数对镀层成分、沉积速度和显微硬度的影响。研究表明，Ｎｉ－Ｆｅ－Ｐ镀层中各元素的含量随镀液中相应盐浓度的增大而提高；低ｐＨ值和电流密度可适当提高镀层含磷量；高电流密度有利于铁的沉积；提高镀液温度和ｐＨ值加快沉积速度，却降低镀层硬度。较高的电流密度可获得较高的沉积速度和镀层硬度。     

峰值电流密度对脉冲电沉积Ni-Co-CNTs复合镀层机械性能的影响

研究了峰值电流密度对脉冲电沉积Ni-Co-CNTs复合镀层机械性能的影响。结果表明:当峰值电流密度升高时,镀层表面变得粗糙;随着峰值电流密度的增加,镀层中碳的质量分数先增加后下降,当峰值电流密度为80 A/dm~2时,镀层中碳的质量分数达到最大值;镀层的显微硬度和抗拉强度均在峰值电流密度为100 A/dm~2附近时达到其最大值,且高于直流电沉积时所得镀层的显微硬度值和抗拉强度值。说明采用脉冲电沉积工艺可以提高镀层的机械性能。     

低温镀铁时电流密度对镀层性能的影响

研究了不同电流密度下所得低温镀铁层的沉积速率、显微硬度和腐蚀速率。结果表明,当电流密度为14A/dm2时镀层可获得最佳的综合性能。电流密度过低时,镀层沉积速率慢,硬度低;电流密度过高时,镀层表面出现针孔,厚度不均。     

Laminated alumina/zirconia ceramic composites prepared by electrophoretic deposition

The electrophoretic deposition of alumina and zirconia powders from isopropanolic suspension in the presence of monochloroacetic acid was studied in the constant-current regime. The different levels of electric current during deposition from 250 μA to 48 mA were used. The green density of the deposit depends on the current density and then on the particle velocity during deposition, reaching values from 58% to 61% according to the electric current used. It was found that the lower the green density of the green deposit, the larger the pores. The low green density led to low final fired density and subsequently to the low Vickers hardness HV5 ranging from 2000 to 1650 depending on electric current used. Based on these findings microlaminates having various thickness ratios to achieve different residual stress levels were prepared consisting of alternating layers of alumina and zirconia.     

pH对低温镀铁组织形貌及性能的影响

介绍了低温镀铁的工艺配方及流程.利用扫描电镜观察了镀层的组织形貌,利用硬度计测试了镀层硬度,利用锉刀法和热震法检验了镀层的结合强度,考察了pH对沉积速率、显微硬度和耐蚀性能的影响.结果表明,所得镀层结合力良好,pH为1.0时,沉积速率最高,耐蚀性能最好;镀层硬度随pH的升高而增大,最大值为587.43 HV.     

电流密度对氨基磺酸镍电镀镍镀层的影响

为了解不同电流密度对氨基磺酸镍镀层的影响,分析了电流密度在0.1～20A/dm2时,氨基磺酸镍镀镍层的外观、硬度、应力和沉积速率。在工艺范围内,随电流密度的增加沉积速率增加、镀层硬度降低、孔隙率变大、表面出现针孔缺陷、应力变大,随后讨论了出现各种情况的原因。     

Growth of electrodeposited γ-manganese dioxide from a suspension bath

The addition of solid particles of manganese oxides to the electrolyte of a manganese dioxide production bath (suspension bath process=SBP) allows the anodic current density to be increased to values more than twice that used in the conventional EMD process. This is possible even with the use of titanium anodes which are sensitive to passivation if the current density exceeds critical values. Analysis of deposition conditions and properties of the SBP-EMD shows that the SBP-EMD resembles and EMD which has been deposited at very low current densities. These low current densities are realized by the adsorption of the suspended particles on the anode surface, thereby promoting dendritic crystal growth on the adsorbed particles and increasing the real anode surface by up to a factor of ten. This assumption is able to explain most of the properties found for the SBP-EMD, e.g. X-ray pattern, potential drop, hardness of the deposit, low specific surface area, low content of combined water and high electronic conductivity.     

在以EDTA和柠檬酸为配位剂的酸性硫代硫酸盐-亚硫酸盐镀液中电沉积金

以乙二胺四乙酸或柠檬酸作配位剂,在无氰的硫代硫酸盐–亚硫酸盐体系中研究了金在镀镍铜基底上的电沉积。在温度为60°C,pH为6和电流密度为2A/dm2的条件下,研究了不同配位剂对电流效率、镀速、镀层硬度及镀液分散能力的影响。最佳的镀液组成为0.5mol/L硫代硫酸钠–亚硫酸钠 0.2mol/L乙二胺四乙酸(或0.3mol/L柠檬酸)。该镀液具有良好的分散能力及高达98%的电流效率。采用扫描电镜、原子力显微镜及X射线衍射分析了镀态金镀层的表面形貌和晶体结构。所得的金镀层几乎无孔(孔隙率<2~4个/cm2),结合力良好,硬度适中(80~130HV)。     

新型化学镀镍工艺

介绍了一种新型化学镀镍工艺.分析了各单因素及组合方案对镀速、镀液稳定性及镀层性能的影响.结果表明,使用组合光亮剩的镀液镀速高,稳定性好,获得的镀层孔隙率低、耐蚀性好、硬度高.     

Effect of organic extractants on the electrocrystallization of nickel from aqueous sulphate solutions

The effect of the presence of commercial organic extractants LIX 84I, Cyanex 272, D2EHPA, Versatic 10 and TBP with or without Mg²⁺ on various electrodeposition parameters for nickel deposition on stainless steel cathode from aqueous sulphate solutions was investigated. The parameters included cathodic current efficiency, deposit morphology, crystal orientation and cathodic polarization. There was no significant variation in the current efficiency in the presence of these additives, but changes were observed in the deposit morphologies and crystal orientations even though all the deposits were bright, smooth and coherent. Changes were also observed in the cathodic polarization behaviour during nickel electrocrystallization in the presence of these additives. The effect of the additives on the electrokinetic parameter, exchange current density (i ₀) has also been investigated.     

An electrochemical quartz crystal microbalance study into the deposition of manganese dioxide

An electrochemical quartz crystal microbalance (EQCM) has been used to study the effects of electrolyte composition (MnSO₄ and H₂SO₄ concentrations) and anodic current density on the electrodeposition of manganese dioxide. The EQCM, in tandem with the electrode voltage during deposition, has been used to characterize features of the deposition mechanism such as the relative lifetime of the Mn(III) intermediate, the rate of soluble Mn(III) hydrolysis to form MnOOH, and the porosity of the resultant manganese dioxide deposit as a function of crystal nucleation. The connection between the results obtained here and commercial electrodeposition of manganese dioxide were also discussed.