高钴低镍合金电沉积工艺

介绍了一种氨基磺酸盐镀钴镍合金工艺,镀液组成为:Co(NH2SO3)2·4H2O 450 g/L,Ni(NH2SO3)2·4H2O 150 g/L,NiC12·6H2O18 g/L,H3BO3 35 g/L,十二烷基硫酸钠(K12) 0.04 g/L,丁二酸二己酯磺酸钠(MA80) 0.08 g/L,苯亚磺酸钠0.4 g/L,羟甲基磺酸钠0.25 g/L.用扫描电镜及能谱考察了阴极电流密度和镀液中Co/Ni质量比对钴镍合金镀层微观形貌及化学成分的影响,用表面张力仪测试了湿润剂(即K12和MA80)对镀液界面张力的影响,用极化曲线测量法分析了柔软剂(即苯亚磺酸钠和羟甲基磺酸钠)对镀液性能的影响,并研究了Co-Ni合金镀层的热稳定性.结果表明,电流密度对合金镀层成分的影响较大,镀液中Co/Ni质量比对镀层形貌的影响较小,Co-Ni合金遵循异常共沉积规律,所开发的添加剂效果良好.所得Co-Ni合金镀层结晶细致、韧性好,平整而无脆性及针孔,高温耐热性良好.     

镍基TiO2复合电极的制备及电催化析氢性能

在含有TiO₂颗粒的氨基磺酸体系镀镍液中通过电沉积制备了Ni/TiO₂复合镀层。采用扫描电子显微镜(SEM)、红外吸收光谱(FTIR)和X射线衍射(XRD)对镀层进行表征的结果显示,TiO₂颗粒成功地沉积在镍镀层中,并改变了镍镀层的表面微观形貌和相结构。通过极化曲线、塔菲尔曲线、电化学阻抗谱(EIS)、计时电位曲线等电化学测试考察了不同TiO₂质量浓度下所得Ni/TiO₂复合镀层的析氢活性和稳定性。与Ni镀层相比,Ni/TiO₂复合镀层显示出更高的析氢催化活性。TiO₂表面存在的羟基有利于析氢反应中氢吸附原子的形成,提高了析氢反应速率。在10 mA/cm²的阴极电流密度下,以6 g/L TiO₂制备的复合镀层表现出较低的析氢过电位(310 mV),具有最高的析氢活性。     

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.     

电沉积镍阳模

方法一 :用于电沉积无残余应力镍的电解液的 p H值先用酸调整至低于电沉积所需的 p H值以下 ,然后用镍的碱式盐调整至电沉积镍的正常值。经上述方法调整的电解液中所得镍镀层无残余应力 ,且表面光滑 ,槽液中无杂质产生。一个例子如下 :该实例主要用于电沉积镍阳模 ,首先将玻璃基体光精饰 ,再经光阻喷涂 ,激光切割 ,溅射 0 .0 5～ 0 .1 0μm的镍层 ,然后按下述电解液组成及工艺条件进行电沉积 :Ni( NH2 SO3 ) 2 · 4H2 O40 0 g/L;Ni Cl2 · 6H2 O 4g/L;H3 BO3 40 g/L;p H=4;温度为 5 5℃ ,电解液的总体积为 40 0 L。连续过滤的速度…     

电化学阻抗谱在电沉积研究中的应用(二)

文章的第二部分介绍了电化学阻抗谱在金属(包括锌、铜、镍、铅、铬)及合金(锌–铁、钴–镍、镍–钼)电沉积研究中的应用。     

梯度电流密度下电沉积制备铜-镍-钼合金电极及其性能研究

采用梯度电沉积法制备铜基Cu–Ni–Mo合金电极,电流密度参数为:10 mA/cm^2×5 min+30 mA/cm^2×40 min+50 mA/cm^2×5 min。通过扫描电子显微镜(SEM)、能谱仪(EDS)、X射线衍射仪(XRD)和X射线光电子能谱仪(XPS)分析了Cu–Ni–Mo合金镀层的表面形貌、元素组成、相结构和各元素的化学价态,并通过线性扫描伏安曲线(LSV)、电化学阻抗谱(EIS)和计时电流法对比了Cu–Ni和Cu–Ni–Mo合金电极在1 mol/L KOH溶液中的析氢性能和稳定性。结果表明,所得Cu–Ni–Mo合金镀层是呈花椰菜多孔形貌的非晶态结构。与Cu–Ni合金电极相比,Cu–Ni–Mo合金电极具有更大的比表面积,可为析氢反应提供更多活性位点,表现出更好的析氢性能,稳定性也更好。     

一步水热法制备钴镍氢氧化物及其电容性能研究

本文采用一步水热法制备泡沫镍基钴镍双金属氢氧化物。通过调节Co-Ni摩尔比制备不同形貌的金属氢氧化物。并通过SEM和XRD进行了微观形貌和晶型的分析。最后将不同形貌的产物用于超级电容器电极材料,用电化学工作站进行测试分析其电化学性能。测试结果表明,当Co-Ni摩尔比为6︰4时得到的氢氧化物电化学性能最佳。     

碳毡基体上电沉积Ni-Mo合金及其催化析氢性能

以碳毡为基体,采用瓦特型镀镍工艺电沉积镍,获得碳镍（C-Ni）电极,然后在离子液体体系中以C-Ni为基体电沉积Ni-Mo合金。采用扫描电镜和X射线衍射仪对合金电极的表面形貌和结构进行了表征,通过阴极极化曲线、交流阻抗等电化学测试研究了其析氢催化性能。实验结果表明,制得的Ni-Mo合金中Mo的质量百分含量约为5.12%,平均晶粒尺寸约为2.2 nm,为纳米晶结构;极化曲线测试表明,当电流密度为0.1 A·cm^-2时,Ni-Mo/C-Ni合金电极催化析氢电位较C-Ni电极正移108 mV,较碳毡正移557 mV,较水溶液中沉积的紫铜基Ni-Mo合金电极正移约50 mV;连续电解和断电流实验结果表明Ni-Mo/C-Ni合金电极具有良好的电化学稳定性,实用前景广阔。     

电化学交流阻抗在量子点敏化太阳电池中的应用

研究量子点敏化太阳电池(QDSSCs)电极界面电荷转移,抑制电极界面电荷复合,促进电荷的正向流动成为提高QDSSCs效率急需解决的问题。特别是寻找一种能有效研究光阳极/电解液界面的电荷转移和复合以及对电极催化活性的表征方法。电化学交流阻抗(EIS)是一种常用的研究电极界面阻抗和电容的分析方法。利用EIS可以对QDSSCs光阳极/电解液界面电荷转移,对电极催化活性进行有效的评价。     

硼酸盐电化学还原特性研究

在NaOH水溶液中利用三电极体系对硼砂在阴极上电化学还原生成硼氢化钠的特性进行了研究，评价了Ni、Cu—Hg、Ag电极的还原活性。电化学测试表明，BO2^-在阴极还原是间接的电化学还原过程，阴极反应的本质是H2O的电化学还原，由于电荷的排斥作用，BO2^-阴离子难于接近阴极表面，研究发现利用脉冲电源产生的适量正脉冲，可以实现BO2^-阴离子在阴极表面的吸附，使还原易于进行。     

The role of anion additives in the electrodeposition of nickel-cobalt alloys from sulfamate electrolyte

Nickel-cobalt alloys have been deposited from sulfamate electrolyte with acetate and citrate-anion additives and evaluated for structure and properties, such as microhardness, tensile strength, internal stress and high-temperature oxidation. XRD data show that at low Co content, the alloys exhibit face-centered cubic (fcc) growth orientations. Above 60% Co, the deposit is completely hexagonal close packed (hcp) with pronounced (100) and (110) lines. It seems likely that the Ni-Co deposits from typical sulfamate electrolyte at pH 5, as well as at current density higher than 5 A/dm², include metal hydroxides. This is followed by the formation of a more strained structure. The high-temperature oxidation rate of the Ni-Co coating from sulfamate electrolyte at pH 5 is twice that of the alloy deposited from the electrolyte with anion additives. We believe that, citrate complexes of Ni and Co, which are assumed to be involved in alloy deposition, eliminate the incorporation of hydroxides into the deposits and enable low-internal-stress coating. The anion-modified bath offers stability of structure and properties of the alloy over a wide range of acidity and current density.     

Nanocrystalline Ni–Co alloy coatings: electrodeposition using horizontal electrodes and corrosion resistance

Nanocrystalline Ni–Co alloy coatings containing 0–45 wt% Co were electrodeposited using horizontal electrodes in a modified Watts bath. Different techniques including scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction, microindentation, and potentiodynamic polarization were used to characterize the alloy coatings. Properties of the alloy coatings were investigated as a function of the cobalt ion concentration (Co²⁺) in the bath. It was observed that the alloy codeposition exhibits anomalous behavior. Co content in the alloy coatings increases with increasing Co²⁺ in the bath and with electrolyte agitation. Morphology and grain size of alloy coatings are greatly affected by Co content. By increasing Co content, surface morphology of the alloy coatings changes from pyramidal to spherical. Microhardness of the alloy coatings increases with increasing Co content mainly due to decreasing grain size that follows the Hall–Petch relation. In addition, Ni–17 wt% Co alloy exhibits better corrosion resistance compared to pure Ni and other Ni–Co alloy coatings. The higher corrosion resistance of Ni–17 wt% Co coating is discussed based on its phase structure, grain size, and preferred orientation.     

Anomalous codeposition of Co–Ni: alloys from gluconate baths

Thin films of cobalt–nickel alloys were galvanostatically deposited onto steel substrates from gluconate baths. Cathodic polarization curves were determined for the parent metals and Co–Ni alloy. The effects of bath composition, current density and temperature on cathodic current efficiency (CCE) and alloy composition were studied. The deposition of Co–Ni alloy is of anomalous type, in which the less noble metal (Co) is preferentially deposited. The CCE of codeposition is high and increases with increase in temperature and current density, but it decreases as the [Co²⁺]/[Ni²⁺] ratio in the bath increases. The percentage of Co in the deposit increases with increasing cathodic current density, temperature and increasing Co²⁺ ion concentration. The structure and surface morphology of the deposit were studied by XRD, ALSV and SEM. The results showed that the alloys consisted of a single solid solution phase with a hexagonal close packed structure.     

Influence of Co and Cu on the phase composition of Zn-Ni alloy

Influence of Co²⁺ and Cu²⁺ on codeposition of Zn-Ni in acetate-chloride electrolyte have been investigated by the potentiodynamic stripping and XRD methods. In our earlier work it has been determined that the quantity of the η-phase in the alloy increased with decrease in the quantity of Ni when codeposition of Zn-Ni took place in acetate-chloride electrolyte. Meanwhile, both the quantity of Ni and that of the η-phase in the alloys decreased, when Co or Cu were incorporated in the alloy. Data of XRD have shown that the quantity of γ-phase in the alloy increased with increase in the quantities of Co²⁺ or Cu²⁺ in acetate-chloride electrolyte. When concentration of [Co²⁺] (0.15 mol dm⁻³) was approximately 19 times as high as that of [Cu²⁺] (0.008 mol dm⁻³), the influence of Co²⁺ and that of Cu²⁺ on the phase composition of alloys were nearly similar.     

Composition control of ternary FeCoNi deposits using cyclic voltammetry

Ternary FeCoNi alloys were electroplated through mean of cyclic voltammetry in simple chloride baths with pH of 2.0. The anodic process in the voltammetric curves was found to completely depress the anomalous deposition of binary alloys while this anomaly was still obvious for the deposition of ternary FeCoNi alloys. From the energy-dispersive X-ray results, the Fe/Co ratio in the ternary FeCoNi deposits was equal to the Fe²⁺/Co²⁺ ratio in the deposition solutions when the Ni²⁺ content was continuously changed. The composition of ternary FeCoNi deposits could be precisely predicted and easily controlled by adjusting the Ni²⁺/(Fe²⁺+Ni²⁺+Co²⁺) ratio in the plating solutions although a synergistic effect in depressing the codeposition of Ni onto the FeCoNi matrix due to the coexistence of Co²⁺ and Fe²⁺ was clearly demonstrated in this work.     

Electrodeposition of Co-Ni and Co-Ni-Cu systems in sulphate-citrate medium

Electrodeposition of Co-Ni and Co-Ni-Cu alloys was performed in a sulphate-citrate medium. Experimental electrodeposition parameters (pH, cobalt(II), nickel(II) and citrate concentrations) were varied in order to analyse their influence on the deposition. Anomalous Co-Ni codeposition occured in the citrate medium. High [Ni(II)]/[Co(II)] ratios (above 5) were suitable for the preparation of homogeneous magnetic Co-rich Co-Ni deposits of hexagonal close-packed (hcp) structure or face centred cubic (fcc) structure as a function of the deposition potential.The presence of very low copper(II) concentrations (<10⁻² mol dm⁻³) in the nickel-cobalt bath makes it possible to incorporate copper in the deposits in amounts ranging from 5 to 60% Cu, although uniform deposits are obtained only for low copper percentages. These ternary deposits are solid solutions with fcc structure and magnetic behaviour both dependent on the deposition potential.     

Low temperature electrochemical properties of LaNi4.6−xMn0.4Mx (M = Fe or Co) and effect of oxide layer on EIS responses in metal hydride electrodes

Iron is a key element in the development of Co-free AB₅-type hydrogen storage alloys. The aim of this work is to systematically investigate the effects of Fe and Co on the electrochemical properties of LaNi_4.6−xMn_0.4M_x (M = Fe or Co, x = 0, 0.25, 0.5 and 0.75) hydrogen storage alloys under relatively low temperatures (273, 253 and 233 K). The results showed that substitution of Fe for Ni reduced the low temperature electrochemical performance much more seriously than that of Co. Exchange current density (I₀), charge-transfer resistance (R_ct) and hydrogen diffusion coefficient (D) were determined based on the study of linear polarization, electrochemical impedance spectrum (EIS) and galvanostatic discharge, respectively. Both the hydrogen diffusion in the bulk of alloy particles and the electrochemical reaction at the alloy electrolyte interface were found to be greatly limited as the decrease of temperature. During the EIS analysis, interestingly, we found that the semicircle in the high frequency region increased dramatically with the decrease of temperature. The electrochemical process corresponding to this semicircle was proposed to be related to the oxide layer on the surface of alloy particles. Novel explanations of EIS response in metal hydride electrodes were proposed accordingly.     

Electrochemical deposition and characterization of ZnCo alloys and corrosion protection by electrodeposited epoxy coating on ZnCo alloy

ZnCo alloys electrochemically deposited on steel under various deposition conditions were investigated. The influence of deposition current density, temperature and composition of deposition solution on the phase structure and corrosion properties of ZnCo alloys were studied. It was found that ZnCo alloy obtained from chloride solution at 5 A dm⁻² showed the best corrosion properties, so this alloy was chosen for further examination. Epoxy coating was electrodeposited on steel and steel modified by ZnCo alloy using constant voltage method. The effect of ZnCo alloy on the corrosion behavior of the protective system based on epoxy coating is interpreted in terms of electrochemical and transport properties, as well as of thermal stability.