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1.
E. G. Vinokurov T. F. Burukhina V. V. Bondar’ 《Theoretical Foundations of Chemical Engineering》2012,46(4):338-347
Based on a statistical analysis of the information on the composition of solutions for the electrodeposition of A-B alloys, a mathematical model is proposed that makes it possible to choose the preferable range of the total concentrations of ligands in solutions for alloy electrodeposition. The prediction by the model is verified by known and new experimental data. 相似文献
2.
提出了混合金属离子定量萃取分离时酸度范围的简便计算方法,并应用于双硫腙-CC l4溶液定量萃取分离Hg2+和Zn2+体系,所得计算结果与实验值一致。 相似文献
3.
The electrodeposition of copper-silver and copper-nickel powders from aqueous ammoniacal solutions at a continuously scraped rotating cylinder cathode is described. Ag-Cu powders can be prepared under these conditions, but the individual particles are inhomogeneous and the extent of this inhomogeneity is examined. Surface areas (from BET) and particle size distributions are reported, and the morphology is considered. Cu-Ni powders deposited under these conditions are heavily contaminated with oxide/ hydroxides and this is attributed to an increase in near-cathode pH. 相似文献
4.
研究了以酒石酸钾钠、柠檬酸三钠作为络合剂的酸性硫酸盐溶液中的Cu-Zn合金镀层。探讨了电流密度、pH、温度对镀液分散能力和镀层组成的影响。在本实验条件下,添加剂的加入可以使镀液具有较好的分散能力和较高的电流效率。实验发现,在所研究的各种添加剂中,糖精、苯酚是加速剂,而硫脲、甘油是阻化剂。采用动电位极化和电化学阻抗谱方法,测定了Cu-Zn合金镀层在NaCl(φ=3.5%)溶液中的耐蚀性能。采用扫描电镜研究了添加剂对控制沉积质量的微妙作用。X-射线衍射分析表明,合金镀层的相结构是正交晶。在上述研究的基础上,提出了Cu-Zn合金电沉积的最佳组成和工艺控制参数。 相似文献
5.
Haiyan Wang 《Electrochimica acta》2008,53(5):2430-2440
The influence of Pb2+ on the initial stages of Sn electrodeposition onto copper from methyl sulphonic acid solutions in the absence of organic additives has been investigated. Particular attention is placed on the effect of Pb2+ at concentrations much lower than previously reported and where no lead is detected in the resulting deposit. Linear sweep scans and i-t transients show that Pb2+ catalyzes Sn plating at Pb2+:Sn2+ molar concentration ratios between about 1:1000 and 20:1000. This effect can be significant, with as much as a 30% increase in the amount of tin deposited over that obtained in the absence of Pb2+ when the concentration ratio is 2:1000 or 5:1000. At concentration ratios above 20:1000, the effect disappears and, in fact, Pb2+ has an inhibitory effect on Sn2+ reduction. Under conditions where Pb2+ enhances Sn electrodeposition, it also begins to affect electrocrystallization by promoting faster nucleation and a more 2-dimensional coating that more rapidly covers the substrate. This trend continues as the Pb2+ concentration is further increased and the catalytic effect disappears. 相似文献
6.
The stability of the process for electrodeposition of CoPt alloys from ammonium citrate electrolytes containing [Pt(NO2)2(NH3)2]0 as the source of Pt was studied. Voltammetric monitoring of the anodic oxidation of the electrolyte and deposition of CoPt
on the cathode showed the effect of the changes of the nature of the Pt complex on the performance of the plating bath. Anodic
oxidation of the Pt complex was shown to involve mainly the oxidation of and to some extent NH3 ligands. The cathodic process is accompanied by reduction of free The reduction of this anion in the bound form is highly inhibited. In contrast, its oxidation at the anode proceeds almost
as readily in the bound form as that in the free form. 相似文献
7.
Effect of electrodeposition parameters on the hydrogen permeation during Cu-Sn alloy electrodeposition 总被引:1,自引:0,他引:1
The Cu-Sn alloy coatings were synthesized on 27SiMn steel by direct current (DC), pulse current (PC) and pulse reverse current (PRC) electrodeposition techniques from pyrophosphate-based electrolyte. The hydrogen permeation behaviors during the electrodeposition by different techniques were investigated using Devanathan-Stachurski method. The results demonstrated that the hydrogen permeation amount of different electrodeposition techniques decreased in the order: DC > PC > PRC. Frequency and duty cycle have great effect on the sub-surface concentration Co of atomic hydrogen and hydrogen permeation amount. The minimum of hydrogen permeation amount was observed at the frequency of 1000 Hz or 2500 Hz and the duty cycle of 40%. It indicates that the amount of permeated hydrogen in the steel during deposition can be reduced due to the decrease of Co by PC and PRC methods. 相似文献
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The adequacy of a stochastic model for choosing ligands which makes it possible to determine the regions of allowable values of the stability constants of complexes, the reduction of which occurs with the formation of an alloy, and choose ligands on the basis of these data is verified. Experimental data for alloy electrodeposition from solutions with complexes of different ligands and complexes of multivalent ions that are in published data show a good agreement with predictions by this model, which made it possible to formulate an important-for-practice condition of choosing ligands for joint reduction of complexes and the formation of an alloy. 相似文献
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12.
采用双阳极动态阴极电解槽以电沉积的方式制备铁铜合金Fe70Cu30,通过工艺试验、添加试验测定铁铜合金的性能及应用性能研究。研究结果表明:Fe70Cu30本身即具有良好的热压烧结性能和很好的冷压性能;研究表明电沉积铁铜合金能够降低烧结温度,硬度没有大的变化,抗弯强度普遍有不同程度提高。根据应用试验结果,我们认为电沉积铁铜合金在某些方面具有无法替代的作用。 相似文献
13.
The effect of the addition of metal ions to dye solutions in promoting dye aggregation and in changing dye association in solution has been studied. Experimental findings indicate that the promoting effects of calcium and magnesium ions are greater than that of sodium ions. It is expected that any change in dye hydrophobicity would have a direct influence on the extent of dye aggregation. Under acid conditions, a higher concentration of metal ions would result in an increase in dye aggregation with a reduction in dye hydrophobicity. On the other hand, while the dye aggregation is increased under alkaline conditions under the influence of metal ions, hydrophobicity was shown to increase. These changes in dye hydrophobicity could be used to explain the dyeing behaviour of reactive dyes in the dyeing of silk. 相似文献
14.
The kinetics of the induced codischarge of Mo with Ni in citrate-ammonia electrolytes was investigated by means of polarization and a.c. impedance measurements. Three potential ranges were considered. At low polarization, hydrogen evolution resulting from citrate reduction is the main reaction. The impedance plots exhibit a large capacitive loop with a small high frequency inflection characteristic of the development of a porous layer and a low frequency inductive feature. At intermediate polarization, the partial currents for Ni and Mo discharge increase in the same proportion; the hydrogen evolution is first constant and then rapidly decreases. Then a large low-frequency capacitive feature is observed on the impedance plots, whose size decreases with increasing polarization. At still higher polarization, the Mo discharge becomes increasingly controlled by diffusion which generates an additional capacitive loop. A reaction scheme is proposed which accounts for the polarization data and the major impedance features. 相似文献
15.
New sorbent hydrogels for removal of acidic dyes and metal ions from aqueous solutions 总被引:1,自引:0,他引:1
Hasine Kaşgöz 《Polymer Bulletin》2006,56(6):517-528
Summary Poly(N-hydroxymethylacrylamide), PHMA, hydrogels were prepared by using N-hydroxymethylacrylamide, HMA, monomer and polyethyleneglycol(400)diacrylate
as a crosslinking agent in aqueous medium and then amine groups were incorporated onto PHMA hydrogels by amination reaction
with different diamines. The obtained hydrogels were characterized by determination of amine value, hydroxymethyl group content
and FTIR spectra. The amine value of hydrogels changed from 2.23 to 4.64 mmol/g by depending on the amine compounds used in
amination reaction. Their swelling degree increased at acidic pH values and they showed pH dependent swelling behaviour. They
were used as sorbent for removal of indigo carmine and Cu(II) ion, as a model dye molecule and metal ion, respectively, from
aqueous solutions. The adsorption properties of the hydrogels were investigated by depending on pH, time and initial indigo
carmine or Cu(II) ion concentration. It was seen that the amine group incorporated hydrogels have quite high adsorption rate
and adsorption capacity, and their adsorption capacities changed with pH of the solution. Langmuir isotherm model was the
best fit for adsorption of both indigo carmine and Cu (II) ion. 相似文献
16.
DC and pulse plating of copper in acidic sulphate solutions containing benzotriazole (BTA) has been studied. When BTA is the
only additive present, it generally has a stronger effect than the plating mode and significantly enhances deposit morphology
and surface brightness over that produced in additive-free solutions. XPS and voltammetry analyses indicate that BTA is present
at the surface of the deposit, but not through the entire coating, and does not become depleted within the solution over the
course of plating. This may help explain why the initial surface smoothness and brightness is maintained as the coating grows
beyond 5 μm thick. Plating mode does have a strong effect on deposit morphology under specific conditions. Pulse current plating
at low frequency (50 Hz) and low duty cycle (20%) produces deposits with poorer quality than that obtained by DC plating.
Pulse reverse plating yields very coarse and dull coatings when the frequency is low enough for metal dissolution to occur
during the reverse time. Regardless of the plating mode, the addition of Cl− eliminates most of the beneficial effects of BTA and leads to very rough and dull deposits. The observed effects are discussed
in light of previous research on the electrodeposition and corrosion of the Cu–BTA and Cu–BTA–Cl systems. 相似文献
17.
D. R. Gabe 《Journal of Applied Electrochemistry》1997,27(8):908-915
The incidence of codeposition of hydrogen during electrodeposition, described as a cathodic inefficiency in plating processes, is reviewed and the effects of hydrogen on the deposits produced discussed. Characteristic electrode features leading to hydrogen evolution and hydrogen absorption are discussed and the causes of hydrogen embrittlement, which may be regarded as essentially electrochemical in origin, are defined. 相似文献
18.
非晶态镍磷合金电沉积机理的研究 总被引:10,自引:0,他引:10
通过镍磷合金电沉积阴极极化曲线,循环估安曲线,旋转圆盘电极极化曲线以及电位阶跃电流-时间曲线的测量和分析,并根据数学,物理,物理化学,流体力学和电化学动力学等原理,在假设的基础出镍磷合金电沉积的理论模型,镍磷合金电沉积为液相扩散和电化学放电混合控制,与实验结果相一致。 相似文献
19.
Transition metal electrocatalysts for hydrogen evolution were prepared by thermal decomposition of solutions containing nickel or cobalt and molybdenum, tungsten or vanadium on a metallic substrate and curing the oxide coated substrate under an atmosphere of hydrogen at elevated temperatures.The most active and stable hydrogen evolving cathode, based on a nickel and molybdenum combination, exhibited overvoltages of about 60 mV for over 11,000 h of continuous electrolysis in 30 w/o KOH at 500 mA cm?2 and 70°C. The cathode was prepared by high temperature (ca. 400°C) treatment of a nickel substrate, coated with an aqueous solution containing nickel and molybdenum salts in the atomic ratio 60:40 followed by reduction of the resulting oxides at about 500°C in atmosphere of hydrogen.X-ray diffraction, and thermogravimetric and ESCA measurements, were employed to identify the active component of the nickel-molybdenum system responsible for its electrocatalytic activity. The results indicated that the electrocatalyst is a face centred cubic nickel-molybdenum alloy in which the molybdenum is randomly substituted at the nickel lattice.The electrochemical properties of a number of nickel-molybdenum electrocatalysts (NiMo = 60:40) were determined in the temperature range 20–80°C. Steady state measurements at different temperatures in 30 w/o KOH showed that the electrodes had low apparent activation energies (ca. 5 kcal mol?1) and revealed the presence of two Tafel regions with transfer coefficients of 1.13 and 0.63. The corresponding exchange current densities at 70°C, based on the electrodes geometric areas, were 52 and 150 mA cm?2 respectively. Results of potentiodynamic measurements and preliminary work on hydrogen oxidation are also presented. 相似文献
20.
The adsorption of Cu(II), Ni(II), Zn(II), and Pb(II) from aqueous solutions on acrylonitrile copolymer sorbents was studied. We prepared five types of sorbents from polyacrylonitrile by varying its concentration in the initial polymer solution and the composition of the coagulation bath, aiming to achieve a different porous structure. The specific area, pore volume, and pore radius of the sorbents were determined on a porosimeter. The porous structure was studied by scanning electron microscopy. Modification of sorbents with sodium hydroxide and hydroxylamine was carried out to form amidooxyme and carboxylic groups with proven complex‐forming properties toward heavy metal ions. The optimal pH of the sorption of metal ions was found. The adsorption kinetics were investigated. The order of polymer sorbents toward the sorption of Pb(II), Cu(II), Ni(II), and Zn(II) ions, and the order of heavy metal uptake were determined for all types of sorbents. The effectiveness of heavy metal desorption and the coefficient of recovery of sorption ability were determined. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 3036–3044, 2002; DOI 10.1002/app.2334 相似文献