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The conditions for electrodeposition of Fe-Sn alloys from a novel, environmentally friendly, ferrous chloride-based electrolyte were studied. The influence of the pH on the electrolyte stability and deposit stoichiometry was studied and discussed. Anodic stripping voltammetry (ASV), XRD and SEM/EDX were used to characterise the electrodeposited phases. The results from ASVs indicated the possibility to deposit at least two different phases at high overpotentials. Hull cell depositions in an electrolyte with a Sn to Fe ratio 1:1 and a pH value of 2.8 showed regular deposition of Fe-Sn. Fe-rich deposits (54.84 at.-%) were obtained from an electrolyte with Sn to Fe ratio 1:10. The XRD results were compatible with the electrochemical investigations. In all studied samples β-Sn, FeSn2 and Fe5Sn3 were detected. The presence of ferromagnetic Fe5Sn3 was not influenced by the Sn to Fe ions ratio in the electrolyte.

This work compares different electrodeposition procedures to produce nickel black coatings as greener and less toxic alternatives to Cr(VI)-based coatings used in different applications. Nickel and nickel-plated brass served as substrates in studies with a Hull cell and polarization curves. After a set of comparative experiments, the best electrodeposition procedure was further studied and optimized. Optimal conditions were found with a bath consisting of 75 g/L NiCl2·6H2O + 30 g/L NaCl and a current density of 0.143 A dm−2 applied for 5 min at room temperature. Furthermore, a pre-treatment with 18.5 vol.% of hydrochloric acid in water was found to be necessary to warrant good coating adhesion to the substrate. The black color is attributed to the development of a nanostructured surface that absorbs the incident light. Corrosion testing was performed in 0.5 M NaCl aqueous solution using electrochemical impedance spectroscopy (EIS) and polarization tests.

Electrowinning circuits normally use a number of additives in the electrolyte to promote smooth, compact deposits. These cathodes have the best levels of purity. When electrowinning is coupled to a solvent extraction operation, it is important to minimize the amount of surface-active additives used, as their presence tends to increase phase-disengagement times. In the present work the effects of Magnafloc 333 and chloride concentration were studied with the aim of minimizing the amounts currently being added, while producing an acceptable copper cathode morphology. Magnafloc 333 is a non-ionic polyacrylamide that promotes the plating of smooth, dense copper deposits with minimal impurities. Chloride is added to promote the growth of dense, fine-grained, low-impurity copper deposits on the cathode. A Hull cell was used for the test work. Optimum Magnafloc 333 and chloride concentrations for a synthetic plant electrolyte were found to be 0.01 g/L and 0.025 g/L, respectively. These concentrations were then used to plate laboratory-scale copper cathodes from synthetic and plant electrolytes. Scanning electron microscopy was used to analyse the morphology of the cathodes plated. Many polyhedral crystals were deposited from the synthetic electrolytes, but deposits from the plant electrolytes tended to be spherical, with a large degree of porosity at the lower Magnafloc 333 concentration of 0.01 g/L. Polyhedral deposits were associated with high-quality, smooth plated cathodes.

The electro deposition of zinc-nickel alloy was carried out in the presence of Lawsone (2-hydroxy1,4-napthoquinone) isolated from Lawsonia inermis Linn leaf. The bath constituents were optimized through Hull cell experiments. Operating parameters such as pH, temperature and current density were also optimized. The current efficiency and throwing power are measured at different current densities.SEM photomicrographs revealed fine-grained structure of the deposit from the optimum bath. IR spectrum of the scratched deposit showed inclusion of addition agent. XRD and EDAX studies revealed the inclusion of lawsone.

The scattering capacity of a complex citrate electrolyte was studied to produce coatings with ternary Fe-Co-Mo alloys with Hull's cell. It is established that the dependence of the scattering capacity on the current density has an extreme character. The optimal values of the electrolysis energy parameter for obtaining uniform and qualitative functional coatings are determined. The inexpediency of using small values of current densities is justified. The dependences of the scattering ability and the content of the alloy components on the current density are established. It is determined that an increase in the current density promotes the enrichment of the coatings with molybdenum. It is shown that the formation of coatings with ternary Fe-Co-Mo alloys leads to a competitive co-precipitation of cobalt and molybdenum with iron. It is established that the variation of the current density has a direct effect on the current output values. This fact is explained by the fact that as the current density increases, the polarizability of the cathode decreases in specific ranges of current density.The deceleration of the combined hydrogen evolution reaction was justified. The difference in the quality and in the thickness of the coating on the near and far cathode plates was substantiated. The complexity of obtaining ternary alloys is associated with a change in the rates of partial reactions of the recovery of individual leaving with a change in polarization., Исследована рассеивающая способность комплексного цитратного электролита для получения покрытий тернарными сплавами Fe-Co-Moс помощью ячейки Хулла. Установлено, что зависимость рассеивающей способности от плотности тока имеет экстремальный характер. Определены оптимальные значения энергетического параметра электролиза для получения равномерных и качественных функциональных покрытий. Обосновано нецелесообразность использования малых значений плотностей тока. Установлены зависимости рассеивающей способности и содержания компонентов сплава от плотности тока. Определено, что увеличение плотности тока способствует обогащению покрытий молибденом. Показано, что при формировании покрытий тернарными сплавами Fe-Co-Мо происходит конкурентное соосаждение кобальта и молибдена с железом. Установлено, что варьирование плотности тока имеет непосредственное влияние на значения выхода по току. Данный факт объясняется тем, что с увеличением плотности тока уменьшается поляризуемость катода в конкретных диапазонах плотности тока., Досліджено розсіювальну здатність комплексного цитратного електроліту для отримання покривів тернарними сплавами Fe-Co-Mo за допомогою комірки Хулла. Встановлено, що залежність розсіювальної здатності від густини струму має екстремальний характер. Визначено оптимальні значення енергетичного параметру електролізу для отримання рівномірних та якісних функціональних покривів. Обґрунтовано недоцільність використання малих значень густини струму. Встановлено залежності розсіювальної здатності та вмісту компонентів сплаву від густини струму. Визначено, що збільшення густини струму сприяє збагаченню покривів молібденом. Показано, що при формуванні покривів тернарними сплавами Fe-Co-Мо відбувається конкурентне відновлення кобальту і молібдену з залізом. Встановлено, що варіювання густини струму має безпосередній вплив на вихід за струмом. Даний факт пояснюється тим, що зі збільшенням густини струму зменшується поляризованість катоду в конкретних діапазонах густини струму.

Досліджено розсіювальну здатність комплексного цитратного електроліту для отримання покривів тернарними сплавами Fe-Co-Mo за допомогою комірки Хулла. Встановлено, що залежність розсіювальної здатності від густини струму має екстремальний характер. Визначено оптимальні значення енергетичного параметру електролізу для отримання рівномірних та якісних функціональних покривів. Обґрунтовано недоцільність використання малих значень густини струму. Встановлено залежності розсіювальної здатності та вмісту компонентів сплаву від густини струму. Визначено, що збільшення густини струму сприяє збагаченню покривів молібденом. Показано, що при формуванні покривів тернарними сплавами Fe-Co-Мо відбувається конкурентне відновлення кобальту і молібдену з залізом. Встановлено, що варіювання густини струму має безпосередній вплив на вихід за струмом. Даний факт пояснюється тим, що зі збільшенням густини струму зменшується поляризованість катоду в конкретних діапазонах густини струму. The scattering capacity of a complex citrate electrolyte was studied to produce coatings with ternary Fe-Co-Mo alloys with Hull's cell. It is established that the dependence of the scattering capacity on the current density has an extreme character. The optimal values of the electrolysis energy parameter for obtaining uniform and qualitative functional coatings are determined. The inexpediency of using small values of current densities is justified. The dependences of the scattering ability and the content of the alloy components on the current density are established. It is determined that an increase in the current density promotes the enrichment of the coatings with molybdenum. It is shown that the formation of coatings with ternary Fe-Co-Mo alloys leads to a competitive co-precipitation of cobalt and molybdenum with iron. It is established that the variation of the current density has a direct effect on the current output values. This fact is explained by the fact that as the current density increases, the polarizability of the cathode decreases in specific ranges of current density. The deceleration of the combined hydrogen evolution reaction was justified. The difference in the quality and in the thickness of the coating on the near and far cathode plates was substantiated. The complexity of obtaining ternary alloys is associated with a change in the rates of partial reactions of the recovery of individual leaving with a change in polarization.

Hull cell tests were carried out to examine a series of polyethylene amines to evaluate their abilities as brighteners in the electrodeposition of aluminum from a dimethylsulfone (DMSO 2 )-AlCl 3 bath. The tests demonstrated the current density ranges that yielded bright, semi-bright, dull, burnt, and streaked Al deposits from the baths containing each polyethylene amine at a variety of concentrations. Among the amines examined in this study, triethylenetetramine (TETA) was found to be the most effective brightener, providing a bright Al deposit with the highest specular reflectance over a wide range of current densities. No correlation was found between the preferential crystal orientation of the Al and the brightness of the deposit, which along with the acquired scanning electron microscopy images, indicated that surface morphology was primarily responsible for the differences in brightness.

The method of measuring the color of electrodeposit ed gold films on hull cell panels is described. Gui delines are also given for the selection of locations for measurements on a panel as well as for reporting the appropriate L* a* and b* values for use in calculating the color difference in terms of ΔE* ab between the measured locations. By developing the control charts of ΔE* ab range and average, the color tolerances between locations on a gold el ectrodeposited hull cell panel that have a bright a ppearance observed was established. The ΔE* ab for an ‘acceptable’ color match was found to be fr om 2.59 to 5.74. For the purpose of reporting the L *, a* and b* value for an electroplated hull cell panels, the average value of L* a* and b* measured from all lo cations in a panel should be used.

Zn-Fe alloy electrodeposition was carried out in the presence of condensation product 2-{[(1E)-(3,4-dimethoxyphenyl)methylidene]amino}-3-hydroxypropanoic acid formed between veratraldehyde and serine in acid sulphate bath. Hull cell was used for optimizing the operating parameters and bath constituents. During deposition, the potential was shifted towards cathodic direction in the presence of addition agents and brightener. The polarization studies show that deposition taking place in basic bath and optimum bath was 1.08 and 1.15 V, respectively. Current efficiency and throwing power were reached around 85% and 26%, respectively. The SEM images of bright deposit indicated its fine-grained nature and appreciable reduction in the grain size. XRD studies have showed that the grain size of the deposit generated from optimum bath was 16 nm. UV-visible spectroscopic studies confirm the formation of complex between metal ion and brightener.

Interest in NiW coatings has grown in recent years due to its favourable properties such as hardness, and resistance to both wear and corrosion, making it one of the actual alternatives to hard chromium coatings. In this work, we have undertaken a Hull cell study, investigating the influence of the metal concentration, temperature, pH and current density on the composition of the alloy formed and its thickness. We have also studied the most important properties of the NiW deposits, including morphology, hardness, and resistance to abrasion and corrosion.El interés en los recubrimientos de NiW ha aumentado en los últimos años debido a sus buenas propiedades como dureza, resistencia al desgaste y resistencia a la corrosión, situándolos como una de las alternativas a los actuales recubrimientos de cromo duro. En este trabajo se ha estudiado, mediante el empleo de célula Hull, la influencia de la concentración de metales, la temperatura, el pH y la densidad de corriente sobre la composición de la aleación y su espesor. Asimismo se han estudiado las principales propiedades de los depósitos de NiW como morfología, dureza, y resistencia a la abrasión y a la corrosión.

Mestrado em Engenharia Química A corrosão é um problema frequente nos materiais. De modo a evitá-la um dos principais métodos é a aplicação de revestimentos protetores no qual ocorre a eletrodeposi-ção de um metal sobre o metal a proteger, destinando-se a conferir propriedades como durabilidade, resistência, pro-teção e aspeto. Este trabalho teve como objetivo otimizar o rendimento de uma linha de tratamentos eletrolíticos, para revestimentos em zinco alcalino ou zinco-níquel. Para tal foram planeados vários conjuntos de experiências, nos quais os valores dos fatores supostos serem os mais significativos para o resultado final foram escolhidos obe-decendo a um planeamento fatorial, tendo os resultados sido obtidos numa célula de Hull. Realizaram-se quatro fases de ensaios acerca do banho de zinco-níquel e duas sobre o banho de zinco alcalino. Atra-vés das respostas obtidas após a eletrodeposição na célula de Hull, foi possível avaliar a importância de fatores como a temperatura do banho, o tempo de eletrodeposição, a in-tensidade da corrente e as concentrações dos principais reagentes em causa. A principal conclusão é referente ao tempo de eletrodepo-sição, pois este é o fator com um maior impacto perante o processo em estudo. O aumento do tempo de eletrodepo-sição origina um aumento nas espessuras das camadas depositadas de zinco-níquel e de zinco alcalino. Os resultados obtidos permitiram ainda concluir que a di-minuição da concentração de zinco, proporciona um au-mento na percentagem em peso de níquel na liga de Zn-Ni depositada. Corrosion is a common problem that affects most metallic materials. In order to avoid it one of the main methods is the application of protective coatings which can be the electrodeposition of a metal or alloy into the metallic sur-face to be protected. These coatings are designed to im-prove the protection, strength, durability and appearance of the protected item. The propose of this thesis is to optimize the yield of an electrolytic line for alkaline zinc and zinc-nickel coatings. To achieve this goal, several sets of experiences were planned, in which the values of factors that supposed to influence the outcome were chosen according to an ex-perimental design scheme (full factorial), and conducted in a Hull cell. There were two sets for the alkaline zinc bath and four sets for the zinc-nickel bath, and from the results of the Hull cell, it was possible to access the significance of the factors temperature of the bath, time of electrodeposition, intensity of current and concentrations of the main rea-gents used, in the thickness of the zinc-nickel and alkaline zinc layers, and percent weight of nickel in the same layer. The main conclusion is that the deposition time is the most significant factor and when it increases the thickness of the layers deposited increases as expected. It should also be noted that when the zinc concentration decreases the weight percentage of nickel in the depos-ited zinc-nickel alloy increases.

Ni–W–P electrodeposits were synthesized in a Hull cell in order to simulate the obtainment under industrial conditions. Complete coverage of panels was accomplished by applying total currents of 1.0 and 2.0 A. Panels obtained with a current of 1.0 A appeared brighter. The best compositional uniformities, as determined by Energy Dispersive Spectrometer (EDS) occurred in the current density ranges of 0.6 to 3.0 A dm−2 and 1.6 to 6.0 A dm−2 obtained with 1.0 and 2.0 A, respectively. However, the best morphological characteristics, as determined by Scanning Electro Microscope (SEM), were observed in those obtained with a total current of 1.0 A. Analysis of corrosion resistance by Electrochemical Impedance Spectroscopy (EIS) and Potentiodynamic Linear Polarization (PLP) in NaCl have shown significant variations in the amount of corrosion potential, polarization resistance, and even total impedance. The alloys exhibited amorphous character (XRD) and crystallized above 400 °C to Ni and Ni3P phases, and possibly Ni–W, with a subsequent increase in hardness. The results suggest that under industrial conditions, current density variations due to the large and complex geometric shapes of substrates lead to formation of distinct alloys. Furthermore, these materials are potential substitutes for chromium deposits in many applications.

A new nickel electroplating bath called a “Nickel citrate bath” uses citric acid in place of boric acid. In order to clarify its properties, a Hull cell test and measurements of current efficiency and pH titration curves were performed. The results were compared with those obtained from a Watts bath. The citric acid in a Nickel citrate bath consists of various ratios of citrate ion and nickel-citrate complexes forming complex equilibrium at various pH levels. A Nickel citrate bath with a concentration of citric acid above 0.06M has a good appearance, current efficiency, and pH buffering action for the bath. The results were almost the same as those obtained with a Watts bath under the same conditions. This result is attributed to interaction of nickel-citrate complexes at the electrode surface in the Nickel citrate bath.

Interest in NiW coatings has grown in recent years due to its favourable properties such as hardness, and resistance to both wear and corrosion, making it one of the actual alternatives to hard chromium coatings. In this work, we have undertaken a Hull cell study, investigating the influence of the metal concentration, temperature, pH and current density on the composition of the alloy formed and its thickness. We have also studied the most important properties of the NiW deposits, including morphology, hardness, and resistance to abrasion and corrosion. El interés en los recubrimientos de NiW ha aumentado en los últimos años debido a sus buenas propiedades como dureza, resistencia al desgaste y resistencia a la corrosión, situándolos como una de las alternativas a los actuales recubrimientos de cromo duro. En este trabajo se ha estudiado, mediante el empleo de célula Hull, la influencia de la concentración de metales, la temperatura, el pH y la densidad de corriente sobre la composición de la aleación y su espesor. Asimismo se han estudiado las principales propiedades de los depósitos de NiW como morfología, dureza, y resistencia a la abrasión y a la corrosión.

La distribution de la densite de courant peut etre predite grâce a la methode de l'element fini

International audience; 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.

The corrosion behavior of inhomogeneous Zn-Ni alloy films electroplated on iron substrates specimens has been studied. Zn-Ni alloy was electroplated in a Hull cell, and immersion tests were carried out in 3% NaCl solutions and in pH6 buffer solutions. In both solutions corrosion took place heterogenously and caused grooves. In the 3% NaCl solutions, both red rust and white rust were formed, the red rust appearing only in a thick layer region, while in the buffer solutions, rust formation was not observed. Corrosion potential and pH at various positions on the specimen were measured. In the 3% NaCl solutions, pH changed markedly depending on position, while in the buffer solutions, the corrosion potential changed. This indicates that a macroscopic corrosion cell is formed along the specimen, and that the buffer capacity of the solutions affects the corrosion behavior.

The current density and throwing power of electrogold plating to acrylic resin were determined by the use of the Hull cell test, and the abrasiveness by denture brush and the discoloration by denture cleanser were examined. The gold plating to acrylic resin will be available in dental practice.

The covering powers of chromium platings from both of the plating baths of low and high concentrations were studied.The following results were obtained:(1) The covering power by the Hull Cell Test was much higher in the bath of low concentration than in that of high concentration.(2) On the contrary, the covering power by the parallel or bend cathode process was lower in the bath of low concentration than in that of high concentration.(3) The above two contradictory phenomena were due to the fact that the current was likely to be concentrated along the edges of the specimen so that the current density in the center was lowered; and the lowering degree of the current density was greater in the bath of low concentration than in that of high concentration.

The throwing power of various nickel plating baths were measured by the Hull cell method, in which throwing powers were expressed in terms of thickness of deposits measured at various points across the cathode, and of primary current distributions derived from the conventional Hull cell current density formula.The effects of current density and of bath compositions on the throwing power of nickel were studied. Among the nickel plating baths, studied, the highest throwing powers were given by dull nickel, all-chloride, NaCl, and high-sulfate nickel solutions. However, Watts, sulfamate, high-sulfamate, and KCl nickel plating baths gave moderate throwing powers, and fluoborate and citrate baths gave low throwing powers.The effects of sulfates on the throwing power and electrolytic conductivity were studied in the Watts bath. It was found that the throwing power and conductivity were improved by raising the concentration of sulfate such as K2SO4, Na2SO4, (NH4)2SO4 and MgSO4.

Electrodeposition of lead is performed to deposit an acid-resistant coating for containers directly onto steel or cast iron. It is commonly done in fluoborate, fluosilicate and sulfamate baths.In this study, the alkaline lead gluconate was used as a new electrolyte in lead depositing bath.The following results were obtained.(1) The most suitable composition of electrolyte for the best results were as follows:2PbCo3·Pb(OH)2 200g/l, (C6H11O7)Na 100g/l, NaOH 100g/l, glue 0.2g/l, red-oil 1 drop/l(2) The cathode current efficiency was 99% up under current density of 5A/dm2 and at bath temperature of 70°C.(3) It was shown by Hull cell method that alkaline lead gluconate bath gave higher throwing power, as compared with fluoborate or fluosilicate bath; the power was more increased when its temperature rise to 70°C or a small amount of additives such as glue and red-oil was added.

Usually the covering power value of the chromium plating bath deviates markedly when measured by Hull cell test. Experiments were carried out in order to investigate the cause of the deviation, and to find the better pre-treating method of the cathode which gives better reproducibility in the test result. Results are as follows:(1) Cyanide bath dipping and chemical polishing of the cathode (copper), especially the latter, increase covering power value remarkably.(2) In chemical polishing the brighter the surface of cathode, the less was the deviation.(3) The least deviation was obtained by using the cathode uniformly electro-plated about 10 microns thick.

By measureing the current efficiencies and by the Hull cell test, the unfavorable effect and the permissible amount of anionic impurities such as Cl-, NO3-, and PO43- were studied on the Sargent bath (CrO3 250 and H2SO4 2.5g/l) and the bath contining sodium fluorosilicate (CrO3 250, H2SO4 1.5, and Na2SiF6 5.0g/l).Each impurity decreases the current efficiency and brightness range. The permissible amount of each impurity is as follows:Cl- is 1g/l (as NaCl) for the both baths, NO3- 1g/l (as NaNO3) for the Sargent bath and 2g/l for the sodium fluorosilicate bath, and PO43- 4g/l (as Na2HPO4⋅12H2O) for the both baths.At the range of so low current density as not to deposit Cr, the base metal of copper, nickel, or iron dissolves into the both baths containing Cl-.

This study deals with the production and the characterization of Ni-P electrodeposits obtained by different electrolytic solutions. Structural, fractographic, mechanical and magnetic property tests are evaluated. Depending on the electrolytic solution used, several types of structures may be obtained by varying the current density.