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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.

The Rotating Cylinder Hull Cell was used to demonstrate the electrodeposition of nanocomposites. A two-part lecture and demonstration unit is presented here that attempts to motivate students through the development of new materials right in the classroom. Current distribution concepts are introduced as a way to survey electrodeposition conditions for alloy and metal matrix composite materials. NiCu-alumina and ceria composites were successfully fabricated. Particles altered the deposition rate of both Cu and Ni affecting the deposit composition.

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.

Uniform deposits are typically desired in electrodeposition; however, the geometry of the deposited surface often makes a uniform deposit difficult to achieve. The objectives of this thesis are to provide experimental and modeling data for deposit uniformity of several geometries in a copper sulfate solution and to create a model capable of predicting deposit uniformity on any geometry. Bench scale electroplating cells were set up to test deposit distributions of multiple geometries as well as to test deposit uniformity with varying copper concentrations and temperatures ranging from 30 g/L to 50 g/L Cu2+ and 30 °C to 60 °C. The deposit uniformity was determined by cross- sectioning the samples. Models were generated using a finite element analysis-based software package named COMSOL Multiphysics. The model results were compared to experimental results to verify model accuracy. Model results were determined to be accurate as long as the cathode size was not too small. In addition, a numerical model was developed based on cell geometry, current density, and limiting current density. This numerical model was compared with the COMSOL model, and the results show very good agreement between the two models. Results from the electrodeposition experiments, COMSOL model, and numerical model can be used to predict copper electrodeposition profiles and uniformity in a wide range of conditions and geometries.

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.