共查询到20条相似文献,搜索用时 31 毫秒
1.
José Luis Ortiz-Aparicio Yunny Meas Gabriel Trejo Raúl Ortega Thomas W. Chapman Eric Chainet Patrick Ozil 《Journal of Applied Electrochemistry》2011,41(6):669-679
The effects of vanillin and anisaldehyde on electrodeposition of zinc–cobalt alloys onto AISI 1018 carbon steel were studied
in an alkaline gluconate zincate electrolyte. The influence of an additive on the metal discharge depends on the structure
of the added molecule and on the nature of the substrate. The composition of the deposit varies during the electrodeposition
process. Maximum cobalt content is observed close to the steel–ZnCo interface for ZnCo formed with or without vanillin, but
the composition profile becomes more uniform when anisaldehyde is added to the bath. The morphology of Zn-rich Co-alloy coatings
was evaluated: Cobalt ions produce porous ZnCo alloys; vanillin induces slightly porous deposits, whereas uniform and more
compact deposits were observed with anisaldehyde. Furthermore, a crystallographic study showed that the orientation of the
lattice planes changes, with highly oriented deposits produced in the presence of anisaldehyde. 相似文献
2.
以铜片为基体,分别在酸性或碱性镀液中电沉积得到掺铋的金属锌电极。采用X射线衍射(XRD)、电感耦合等离子光谱(ICP)和扫描电子显微镜(SEM)等测试手段对制备的材料进行了表征。结果表明,在碱性镀液中添加Bi离子并不能从根本上改变金属锌疏松的树枝状沉积形态,随着镀液中Bi含量的增加,沉积层中的金属铋含量几乎不发生变化;而在酸性镀液中添加Bi离子后,金属锌由致密的树枝状沉积改变为颗粒状沉积,且随着镀液中Bi含量的增加,金属铋在锌沉积层中的含量线性增加。后者能够在一定程度上提高二次锌负极在1 mol·L-1ZnSO4溶液中的放电容量并改善其循环性能,这可能得益于金属锌结晶形态的改变。 相似文献
3.
R. FRATESI G. ROVENTI G. GIULIANI C. R. TOMACHUK 《Journal of Applied Electrochemistry》1997,27(9):1088-1094
Electrodeposition of Zn–Co alloys on iron substrate from chloride baths under galvanostatic and potentiostatic conditions were carried out. Current density, temperature and cobalt percentage in the bath were found to strongly influence the composition of the deposits and their morphology. Changes in potentials, current efficiency and partial current densities were studied. The results show that the shift in potential and in the cobalt percentage of the deposits, for a particular current density during galvanostatic electrodeposition, does not always correspond to the transition from normal to anomalous codeposition. This shift is attributed to zinc ion discharge, which passes from underpotential to thermodynamic conditions. In the range of potentials for the underpotential deposition of zinc, the electrodeposition of zinc–cobalt alloys is discussed, emphasizing the influence of the electrode potential on the composition and microstructure of the deposits. 相似文献
4.
The influence of sorbitol or glycerol polyalcohols on the electrodeposition of zinc and on morphology of the zinc film is
discussed. The deposition current efficiency, in the potential range −1.30 V to −2.50 V, was ∼90% in all baths. Increasing
the sorbitol concentration in the bath shifted the deposition to more negative potentials, ∼50 mV, and decreased the current
density (j
p
) of the zinc deposition significantly. On the other hand, adding glycerol did not significantly affect either j or the deposition potential of zinc. Scanning electron microscopy (SEM) showed that either sorbitol or glycerol lead to the
formation of granular deposits. The best zinc morphology was obtained with 0.52 M sorbitol or glycerol in the plating bath.
The presence of sorbitol or glycerol in the plating bath was beneficial, since the resulting zinc deposits were compact and
without holes. 相似文献
5.
G. Roventi 《Electrochimica acta》2006,51(13):2691-2697
Zn-Co alloy electrodeposition from chloride baths containing different Zn2+/Co2+ ratios was investigated by cyclic voltammetry and anodic linear sweep voltammetry using a Pt electrode. The peaks were attributed by means of EDX analysis, SEM and TEM observations performed on some alloys potentiostatically deposited. In the range of potential where zinc deposits underpotential, cyclic voltammetry showed a complex cathodic peak with one maximum and two shoulders, correlated with the deposition of different cobalt rich alloys. Up to four anodic peaks, two correlated with zinc oxidation from η and γ phases and two correlated with oxidation of solid solutions of zinc in cobalt, were observed. ALSV and TEM indicated that the remarkable increase in Zn content of the alloy, which occurs with a strong inhibition of the process at potentials more negative than that of the cathodic peak and more positive than the bulk deposition potential of zinc, is due to the deposition of γ phase. No inhibition of the alloy deposition process was observed with very low concentrations of zinc (<0.015 M) in the bath containing 0.19 M Co2+. 相似文献
6.
The effect of a cationic surfactant, dodecyltrimethylammonium chloride (DTAC) on CoNi electrodeposition process has been analysed. CoNi electrodeposition is greatly modified by the presence of the cationic surfactant in the bath. The DTAC modifies the initial stages of the deposition process and enhances the cobalt percentage in the deposits. Structure and morphology of the deposits are also modified, as the manner that magnetic properties of the electrodeposited films were affected as a consequence of the structural change. The presence of the surfactant in the bath causes changes on the CoNi structure from face-centred cubic (fcc) to close-packed hexagonal (hcp). DTAC incorporation into the deposits is a function of its concentration in the bath. Thus, it is important to be careful with the effects caused by the surfactant on deposits when it assists the particles insertion. 相似文献
7.
M. Heydari Gharahcheshmeh M. Heydarzadeh Sohi 《Journal of Applied Electrochemistry》2010,40(8):1563-1570
Co-deposition of Zn–Co alloy coatings that were electrodeposited from weakly alkaline glycine solutions has been studied by
cyclic voltammetry. Scanning electron microscopy (SEM), energy depressive spectroscopy (EDS), and X-ray diffraction (XRD)
analyses were used to study surface morphology, chemical composition, and phase structure of the coatings. Corrosion behavior
of the coatings was also studied using potentiodynamic polarization tests in 3.5 wt% NaCl solution. Cyclic voltammetry results
showed that in Zn–Co deposition from an alkaline bath in the presence of glycine, cobalt deposited at a potential near to
that of zinc together with successful co-deposition of Co and Zn. It was also shown that reduction–oxidation (redox) reactions
of Zn–Co alloy deposits were quasi-reversible and resulted in deviation of electrodeposited alloys from the equilibrium phase
diagrams. The corrosion resistance of the deposits was also highly influenced by the composition and morphology of the coatings.
Overall, Zn–Co deposit containing 0.89 wt% Co showed that the highest corrosion resistance among the coatings that was due
to its single phase structure and fine morphology. 相似文献
8.
9.
Some aspects of the electrodeposition of copper and cobalt from aqueous sulphate solutions containing low concentrations of their ions were studied with a view to heavy metal removal via an electrochemical process. Both metals were deposited on a vitreous carbon rotating disc electrode. Deposits formed under different conditions were studied employing linear sweep voltammetry, scanning electron microscopy and EDAX surface analysis. Constant potential electrolysis was used to simulate recovery in a laboratory batch reactor. Copper can be deposited without cobalt interference at potentials as cathodic as –1.0 V despite high Co concentrations. At more negative potentials, both metals are deposited simultaneously, although the copper proportion in the binary mixture is greater than that corresponding to the solution concentration ratio. Voltammetry studies effected under conditions in which codeposition occurs show only minor changes in copper behaviour. On the other hand, cobalt behaviour exhibits significant modifications. Even though formation of an intermetallic compound is possible, ASVL and microscopy tests indicate cobalt deposition in different crystalline forms as the more probable cause. In turn, cobalt deposition depends on the polarization conditions of the electrode and on the cobalt and copper concentrations. 相似文献
10.
A. C. M. de Moraes J. L. P. Siqueira L. L. Barbosa I. A. Carlos 《Journal of Applied Electrochemistry》2009,39(3):369-375
Copper electrodeposition on to a platinum substrate from an acid sulphate plating bath was investigated with and without the
additive benzotriazole (BTAH). In voltammetric experiments, the deposition process is shifted to more negative potentials
in the presence of BTAH than in its absence from the bath. Moreover, the current density of the deposition process was higher
in the presence of this additive than in its absence. With or without the additive, copper deposition showed features of nucleation
in the voltammetric curves. Scanning electronic microscopy (SEM) images showed that copper deposits laid down in the presence
of BTAH, for any potential and charge density studied, were smoother than in the absence of this additive. X-ray spectra indicated
that the electrodeposits produced in the absence or presence of BTAH were composed of a mixture of copper, copper oxide and
platinum oxide and also indicated that in the presence of BTAH, the deposit was less crystalline than in its absence. 相似文献
11.
12.
E. Gómez E. Guaus J. Torrent X. Alcobe E. Vallés 《Journal of Applied Electrochemistry》2001,31(3):349-354
The electrodeposition of tin + cobalt alloys from a slightly acidic sulfate–gluconate bath on both vitreous carbon and copper substrates has been studied for different [Sn(II)]/[Co(II)] ratios in the bath, varying between 1/10 and 1/2. A relationship between the electrochemical stripping analysis and the morphology of the deposits has been found. Two different types of deposit were obtained. At low [Sn(II)]/[Co(II)] ratios and relatively high deposition rates a nodular, cobalt-rich, nanocrystalline coating was obtained, while at high [Sn(II)]/[Co(II)] ratios and low deposition rates a new, well-defined tetragonal SnCo phase was obtained, with cell parameters of a = 3.087 Å and c = 5.849 Å. This structure favours hydrogen evolution. 相似文献
13.
M. Bouanani F. Cherkaoui M. Cherkaoui S. Belcadi R. Fratesi G. Roventi 《Journal of Applied Electrochemistry》1999,29(10):1171-1176
Electroless Ni–Zn–P alloy deposition from a sulphate bath, containing sodium hypophosphite as reducer, was investigated. To increase the plating rate, the deposition parameters were optimized. The effect of process parameters (T, pH and [Zn2+]) on the plating rate and deposit composition was examined and it was found that the presence of zinc in the bath has an inhibitory effect on the alloy deposition. As a consequence, the percentage of zinc in the electroless Ni–Zn–P alloys never reaches high values. Using cyclic voltammetry the electrodeposition mechanism of Ni–Zn–P alloys was investigated. It was observed that the zinc deposition inhibits the nickel discharge and, as a consequence, its catalytic activity on hypophosphite oxidation. It was also found that increase in temperature or pH leads to the deposition of nickel rich alloys. 相似文献
14.
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. 相似文献
15.
16.
P. Guillaume N. Leclerc C. Boulanger J. M. Lecuire François Lapicque 《Journal of Applied Electrochemistry》2007,37(11):1237-1243
Results are reported of an experimental investigation of the effects of aqueous zinc(II) and sulfuric acid concentrations
on current efficiencies and deposit morphologies of metallic zinc, aimed at designing a process for zinc recovery from solid
industrial wastes by leaching and electrodeposition. Voltammetry and chronopotentiometry of additive-free solutions of zinc(II)
sulfate and sulfuric acid were used to determine the zinc(II) reduction kinetics, prior to investigating the deposition in
a Hull cell to observe the effects of the current density and the bath composition on current efficiencies and deposit morphologies.
For a current density of 45 mA cm−2, best performance was obtained with zinc(II) concentrations of the same order of magnitude as the H+ concentration; too acidic solutions resulted in lower current yields and pronounced 3-D growth of the deposit. 相似文献
17.
18.
José Luis Ortiz-Aparicio Yunny Meas Gabriel Trejo Raúl Ortega Thomas W. Chapman Eric Chainet 《Journal of Applied Electrochemistry》2013,43(3):289-300
This work reports the effects of four organic compounds (referred to as levelers) on the electrodeposition of Zn on steel from alkaline free-cyanide electrolytes. The additives tested included polyvinylalcohol (PVA) and the condensation products of epichlorhydrin with amines, called polyamines (PAs), that were synthesized using an aliphatic amine (PA-I, from diethylamine and PA-II from diethylamine-triethylamine), and a heterocyclic quaternary imidazolium molecule (PA-Imid, from imidazole). These compounds were evaluated in the absence and in addition to a quaternary ammonium brightener, N-benzyl-3-carboxylpyridinium chloride (3NCP). The imidazole derivative-based polyamine (PA-Imid) causes greater inhibition of the zinc reduction process than the aliphatic polyamine, and more cathodic overpotential is necessary to promote massive metal deposition. The morphology of the deposits is modified when polyamines are added to the bath; more compact and smaller crystals are obtained with PVA as well as with polyamine PA-I. The addition of PA-II as well as PA-Imid yields crystals growing perpendicular to the substrate. The addition of 3NCP with PVA, PA, or PA-Imid increased the deposition overpotential and modified the morphology by diminishing the grain size. In the absence of additives, crystallographic orientation favored the basal Zn(002) with high atomic packing. The addition of the levelers favored the high-angle pyramidal Zn(101) with low atomic packing. The combination of the levelers with (3NCP) favored the prismatic Zn(100) crystallographic orientation. Additives decrease the size of zinc crystals and tend to increase the energy of lattice favoring the growth of pyramidal and prismatic planes. 相似文献
19.
Renáta Oriňáková Andrea Turoňová Daniela Kladeková Miriam Gálová Roger M. Smith 《Journal of Applied Electrochemistry》2006,36(9):957-972
The numerous theoretical and practical studies of the electrodeposition of nickel and its binary and selected ternary alloys with copper and cobalt over the last 10–15 years are reviewed. The reported mechanisms of the electrodeposition processes and accompanying evolution of hydrogen are considered. The complex influence of different bath compositions, pHs, current densities or potential ranges and temperature on the formation of single or multiple deposition layers are compared. The determination of the structure and morphology of the deposits on different substrates, including solid surfaces and particulate materials, using a range of analytical techniques are reported. 相似文献