酸性氯化物体系电镀锌铁合金及镀后处理

以30CrMnSiA钢作为基材,先采用酸性氯化物体系电镀锌铁合金,再进行磷化或六价铬钝化.对比了Zn–Fe合金镀层及其磷化试样和钝化试样的外观、表面形貌、耐蚀性和电泳漆膜附着力.结果表明,本工艺所得的锌铁合金镀层更适合磷化后处理.     

Effect of diethanolamine and triethanolamine on the properties of electroplated Zn–Ni alloy coatings from acid bath

In the present work, zinc–nickel alloy coatings have been produced under direct current conditions from an acid bath with different concentrations of diethanolamine (DEA) and triethanolamine (TEA). The produced coatings were analysed through chronopotentiometry, microhardness, X‐ray diffraction and MEB techniques. The compositional analysis of the films showed that the Zn–Ni electrodeposition is anomalous for all the systems. Ethanolamines augmented the anomalous behaviour. The hindering in the Ni (II) reduction will be more effective due to complexation of Ni (II) catalyst with ethanolamines. Electrochemical and structure analysis of deposits indicated the presence of γ and highly Zn‐enriched phases. The presence of these additives resulted also in coatings with finer grains. The behaviour of modified Zn–Ni alloy coatings in corrosion solution of 3% NaCl was investigated through potentiodynamic polarisation and electrochemical impedance spectroscopy. It was found that the obtained Zn–Ni/3 mM TEA alloy exhibited better corrosion resistance compared to pure Zn–Ni alloy electrodeposited at similar conditions. © 2012 Canadian Society for Chemical Engineering     

Influence of variables in nickel-manganese-zinc alloy plating from a sulphate bath

An Ni-Mn-Zn alloy has been satisfactorily electrodeposited from a sulphate bath containing nickel sulphate (20–23 g dm⁻³), manganese sulphate (76–88 g dm⁻³), zinc sulphate (18–24 g dm⁻³), ammonium sulphate (30 g dm⁻³), thiourea (18g dm⁻³) and ascorbic acid (0.8 g dm⁻³) under various plating conditions, namely, current density 1.0–3.0 A dm⁻²; temperature 30–45° C; pH 2.7–4.2 and duration of electrolysis 15–30 min. Semibright, blackish-grey, thin films were generally deposited with the proportion of nickel and manganese in the deposits increasing with increasing current density, temperature and duration of electrolysis. However, the amount of zinc increased as the pH of the solution was raised. The cathode efficiency for alloy deposition increased linearly as the temperature or the pH of the solution was decreased, whereas at any particular pH and temperature it continuously rose with increasing current density or the time of deposition. The cathode polarization shifted to more negative values on increasing the current density and to less negative values at higher pH values and temperatures which consequently lowered the throwing power under the latter conditions.     

Electrodeposition of zinc-cobalt alloy from a complexing alkaline glycinate bath

The influence of cobalt on the electrodeposition of zinc onto AISI 1018 steel was studied in weakly alkaline glycine solutions. Thermodynamic calculations were performed to construct predominance-zone diagrams to identify the stability of the zinc and cobalt glycine complexes, and experimental studies of electrochemical behavior and deposit properties were conducted. When zinc is present, cobalt deposition shifts to more negative potentials, producing ZnCo alloys. Two main reduction steps were observed for electrodeposition from the ZnCo bath: the first at low potentials was due to ZnCo electrodeposition. In the second, at more negative potentials, cobalt content in the deposit increased forming a range of intermediate phases, and the hydrogen-evolution reaction became significant. The presence of Co(II) in the bath modified the morphology of the deposits as well as reducing the faradaic metal-deposition efficiency. ZnCo-deposit morphology was modified by the applied current density as well as the metal composition of the coating. X-ray diffraction studies revealed that cobalt oxide or hydroxide is formed during ZnCo electrodeposition, indicating that an elevation of the interfacial pH plays a role in the alloy deposition process.     

碱性锌镍合金电镀白钝化工艺的研究

研究了不同镍含量的锌镍合金镀层低铬白钝化工艺,通过中性盐雾试验。比较了不同钝化工艺对不同镍含量的锌镍合金镀层耐蚀性的影响,结果表明,不同镍含量的锌镍合金镀层需采用不同的白钝化工艺。     

Electrowinning of cobalt from a sulphate bath containing H3BO3 and NaF

Electrowinning of cobalt from a sulphate bath containing Na₂SO₄, NaF and H₃BO₃ individually and H₃BO₃ in combination with NaF and Na₂SO₄ was studied. From the preliminary study it was observed that a sulphate bath containing both NaF and H₃BO₃ gave the best results. The effects of various parameters, namely NaF, H₃BO₃ and cobalt concentrations, current density, bath temperature, bath pH, etc. on cathode current efficiency and on the nature of the deposit were studied. The results indicate that both H₃BO₃ and NaF in the sulphate bath contribute towards higher current efficiency and better deposit in the elecrowinning of cobalt.     

Novel copper immersion coating on magnesium alloy AZ91D in an alkaline bath

Copper immersion coating of magnesium alloys has, to date, been conducted only in acidic baths. This article describes a novel alkaline bath for copper immersion coating on AZ91D magnesium alloy. Prior to the coating process, a chemical etching process of the magnesium substrate was optimized using orthogonal experimental methodology. The copper immersion coating was then investigated with regard to the effect of pH and fluoride content in the deposition bath. It was revealed during the coating process that an increase of pH and fluoride content led to a surface film formation on the magnesium substrate. The surface film formation occurred simultaneously with copper reduction, rendering a controlled magnesium dissolution, thereby a controlled copper deposition. With optimized conditions of chemical etching and immersion coating processes, uniform copper deposits were achieved.     

Electrodeposition of zinc-nickel alloy coatings from a chloride bath containing NH4Cl

Zinc-nickel alloys were electrodeposited on steel from chloride baths containing NH₄Cl using different plating conditions. Current density, temperature and nickel percentage in the baths were found to strongly influence the composition of the deposits and the morphology. At low current densities transition from anomalous to normal codeposition was observed. The changes in potential, current efficiency, composition and morphology which follow the transition were studied. No increase in the partial current of hydrogen reduction was observed at the potential values from which anomalous codeposition begins; this fact, plus the formation of zinc ammonium complexes, seems to exclude the precipitation of zinc hydroxide at the electrode surface. The electrodeposition of zinc-nickel alloys is discussed emphasizing the importance of kinetic parameters and cathodic potentials.     

碱性锌酸盐体系锌-铁合金电镀添加剂的研究

锌基合金电镀层由于具有优良的耐蚀性而受到人们的关注。研制出一种用于碱性锌酸盐体系锌－铁合金电镀的添加剂ZFA,ZFA由一种主光剂DE、三种辅光剂如芳香醛、乙二胺四乙酸和苯甲酸钠以及一种润滑剂十二烷基磺酸钠组成。研究了ZFA中各组分对合金镀层外观的影响,优选出最佳ZFA配方。通过赫尔槽试验和扫描电子显微技术研究了ZFA的加入对合金电镀光亮电流密度范围和支表面、断面形貌的影响。结果表明,ZFA的加入能扩大合金电镀的光亮电流密度范围,所得合金支平滑、光亮、均匀、致密,与基体结合力好。     

Anodic electrodeposition of cobalt oxides from an alkaline bath containing Co-gluconate complexes on glassy carbon. An electroanalytical investigation

In this study an electrodeposition procedure of cobalt oxides operating under anodic condition and directly from 0.5 M NaOH solutions containing 12 mM gluconate and 12 mM CoCl₂ was defined for the modification of glassy carbon surface electrode. Different experimental approaches based on cyclic voltammetry, steady-state potentiostatic technique, chronoamperometry and scanning electron microscopy were used to characterize the deposited cobalt oxide films and to evaluate the kinetics and mechanism of electrodeposition. Some aliphatic aldehydes were tested as compound model in order to evaluate the electroanalytical properties of the electrodeposited cobalt film as active redox material for amperometric applications in strong alkaline aqueous solutions. Interesting results in terms of surface electrode modification “in situ” of glassy carbon substrate with cobalt oxides were obtained and critically discussed.     

碱性锌-钴合金镀液中锌、钴含量的测定

为获得耐蚀性良好的锌 钴合金镀层 ,必须维持镀液中的锌 钴含量在工艺范围内。采用EDTA滴定和分光光度相结合的方法测定碱性锌 钴合金镀液中的锌、钴含量。介绍了该方法的分析步骤 ,探讨了测量波长的确定 ,亚硝酸钠、镀液共存组分、酸度以及铜离子和铁离子等杂质对测量结果的影响。结果表明 ,在 530nm波长下 ,钴浓度在 0 - 3μg/mL范围内所测吸光度与钴浓度间的关系遵守比耳定律 ,该方法准确度高 ,回收率达 97% - 1 0 3 5%。     

Electroplating of a Co–Cu alloy from a citrate bath containing boric acid

The effects of bath composition, current density and temperature on cathodic polarization, cathodic current efficiency of codeposition, composition and structure of Co–Cu alloys electroplated on a steel substrate from citrate baths have been studied. Addition of boric acid to citrate electrolyte increases the percentage of Co in the deposits and improves the quality of these deposits. The cathodic current efficiency of the baths is relatively high and increases with increases in the metal content in the bath and the current density but decreases with temperature. The composition of the deposit is controlled by the applied current density. At low current densities, Cu‐rich alloys were obtained. At higher current densities, the composition of the alloys was controlled by the limiting current density of Cu codeposition. The Co content of the deposits increases with increases in the metal content in the bath and the temperature. The structure of the deposited alloys was characterized by anodic stripping and X‐ray diffraction techniques. The deposited alloys consisted of a single solid solution phase with a face‐centred cubic structure. © 2000 Society of Chemical Industry     

清洁生产型锌铁合金电镀工艺

本文综合十多年发表的系列文章,介绍了锌铁合金电镀工艺、水处理、镀液性能和镀层性能。多年的生产实践表明其具有良好的发展前景。     

Influence of tartaric acid on zinc electrodeposition from sulphate bath

The effect of tartaric acid on zinc electrodeposition from sulphate plating bath was investigated by electrochemical impedance spectroscopy (EIS), stationary polarization curves, X-ray diffraction and SEM imagery. The study shows that it is possible to obtain homogeneous, compact and dendrites-free zinc deposits from sulphate solutions containing tartaric acid. For various hydrodynamic methods (rotating disc electrode and static vertical or horizontal electrode), the results indicate that, the presence of only small quantity of tartaric acid, may induce significant changes on deposition rates and deposit quality.     

Zinc-nickel alloy electrodeposition from uncomplexed acid bath

Zinc-nickel alloys, as protective coatings, are well known and a new citrate bath has been investigated. It was observed that boric acid favoured nickel deposition playing the dual role of specific adsorption and catalysis. The voltammetric behaviour of the alloy deposition in the presence of boric acid is described. The effect of Ni/Zn ratio, and potential scan range on the cathodic and anodic portions of the voltammograms are discussed. The presence of two cathodic peaks at high Ni/Zn ratios, which disappeared at lower ratios was identified.     

氨基磺酸盐-硫酸盐混合溶液中锌-锰合金的电沉积

本文研究了氨基磺酸盐-硫酸盐混合溶液中锌-锰合金的电沉积机理。实验结果显示,在低电流密度区获得哑光镀层,锰离子的催化析氢作用降低了合金沉积效率．玻璃化炭黑上的伏安试验显示锌沉积过程中的第一个电子转移较慢,阳极溶出伏安试验显示锌合金的异常共沉积导致富锌中间相的产生。     

The influence of sorbitol on zinc film deposition, zinc dissolution process and morphology of deposits obtained from alkaline bath

A novel cyanide-free zinc deposition bath was developed in which sorbitol was added at various concentrations. Voltammetric studies indicated that the reduction process is influenced thermodynamically and kinetically by the sorbitol concentration. Also, two cathodic processes were observed, one (wave) associated with the hydrogen evolution reaction (HER) on 1010 steel, the other (peak) with zinc bulk reduction, simultaneous to the HER. Furthermore, the plating-process kinetics was controlled by mass transport. The presence of sorbitol in the bath led to formation of light-grey zinc films, even during the HER, without cracks and dendrites. Plating current efficiency decreased from ∼ ∼62% to 43% on increasing the sorbitol concentration in the plating bath. In the presence of 0.1 M and/or sorbitol concentrations higher than 0.2 M, Zn electrode dissolution was inhibited. However, a small dissolution of zinc electrode was observed with 0.05 M sorbitol in alkaline solution without zincate. SEM micrographs showed that the 1010 steel substrate was fully covered by Zn film and that the sorbitol affected the morphology of zinc films, acting as a grain refiner.     

Study of the influence of the polyalcohol mannitol on zinc electrodeposition from an alkaline bath

In this paper, the effects of adding mannitol to an alkaline plating bath on the electrodeposition of zinc onto AISI 1010 steel are described and assessed. From cyclic voltammograms with various lower-limit potentials, it is concluded that an initial zinc bulk deposition (region of wave c ₀) occurs from −1.45 V in the negative sweep. When the sweep is reversed at −1.60 V, an anodic peak a ₁ is seen in the positive sweep both in the absence and in presence of mannitol, which was assigned to zinc dissolution. This peak indicates that the primary nucleation and growth of zinc in region c ₀ is followed by zinc secondary nucleation and growth (region of peak c ₁). Scanning electron micrographs show that zinc electrodeposits obtained at mannitol concentrations ≥0.10 M were more refined than at lower concentrations. Energy-dispersive X-ray spectroscopy of these electrodeposits show oxygen contents that are generally low or below detection limit.     

添加剂对无氰电镀铜-锡合金(低锡)镀层性能的影响

通过赫尔槽试验与直流电解试验,研究了添加剂在焦磷酸盐溶液体系无氰电镀铜-锡合金(低锡)工艺中的作用.该体系镀液组成与工艺条件为:Cu2P2O7·3H2O 25 g/L,Sn2P2O7 1.0 g/L,K4P2O7·3H2O 250 g/L,K2HPO4·3H2O 60 g/L,温度25℃,pH 8.5,电流密度1.0 A/dm2.采用扫描电镜(SEM)、X射线衍射(XRD)、能谱(EDS)、中性盐雾试验等方法研究了添加剂对镀层组成结构、外观、耐腐蚀性能及微观形貌的影响.结果表明,焦磷酸盐溶液体系无氰电镀铜-锡合金(低锡)时使用有机胺类添加剂可抑制Sn的析出,使合金镀层致密均匀,耐蚀性能好.镀层结晶主要为Cu13.7Sn结构,镀层中Sn含量为9％～11％.镀液中添加剂的使用量增加,则合金镀层中的Sn含量降低.     

ZnNi alloy electrodeposition from acid baths containing sorbitol or glycerol and characterization of ZnNi deposits

The influence of sorbitol or glycerol on the electrodeposition of ZnNi alloys and on the morphology, composition and structure of the ZnNi deposits was investigated. The highest current efficiency (CE), around 90%, was obtained in the presence of glycerol in the potential range from approximately −1.30 V to −1.40 V, while in the presence of sorbitol or absence of either polyalcohol the CE was 82–85%, for the same potential range. Scanning electron microscopy (SEM) analysis showed that ZnNi deposition at −1.26 V or −1.40 V from a bath with sorbitol led to the formation of more compact deposits than with glycerol. Energy dispersive X-ray spectroscopy (EDS) analysis showed that the Ni content in the deposit obtained in the presence of sorbitol remained in the range of 7–9.5 wt% Ni, over a large range of deposition conditions. On the other hand, ZnNi deposits with variable Ni content (5.5–19.5 wt% Ni) were obtained from baths with glycerol or without either polyalcohol, by shifting the deposition potential. All ZnNi deposits showed uniform distribution of the elements Zn and Ni. X-ray analysis of ZnNi deposits obtained from plating baths with and without polyalcohol’s at −1.26 and −1.40 V presented the γ, γ¹ and Pt₃–Zn phases.