Effect Of Electrolysis Parameters Research Articles

Effect of Electrolysis Parameters on the Fractal Structure of Electrodeposited Copper

<p>Models based on diffusion-limited aggregation (DLA) have been extensively used to explore the mechanisms of dendritic particle aggregation phenomena. The physical and chemical properties of systems in which DLA aggregates emerge are given in their fractal. In this paper, we present a comprehensive study of the growth of electrodeposited copper dendrites in flat plate electrochemical cells from a fractal perspective. The effects of growth time, applied voltage, copper ion concentration, and electrolyte acidity on the morphology and fractal dimension of deposited copper were examined. ‘Phase diagram’ set out the variety of electrodeposited copper fractal morphology analysed by metallographic microscopy. The box counting method confirms that the electrodeposited dendritic structures manifestly exhibit fractal character. It was found that with the increase of the voltage and copper ion concentration. The fractal copper size becomes larger and its morphology shifts towards a dendritic structure, with the fractal dimension fluctuating around 1.60–1.70. In addition, the morphology of the deposited copper is significantly affected by the acidity of the electrolyte. The increase in acidity from 0.01 to 1.00 mol/L intensifies the hydrogen precipitation side reactions and the overflow path of hydrogen bubbles affects the fractal growth of copper dendrites.</p>

STRUCTURE AND PHYSICAL-MECHANICAL PROPERTIES OF ELECTROCRYSTALLISED COATINGS OF Ni−P ALLOY

The purpose of the research. Ni−P electrolytic alloy coated products are of great interest in many industries such as electronics (magnetic recording devices), oil and gas industry, medical equipment manufacturing, catalyst manufacturing. In this connection, the task of determining rational deposition modes of electrocrystallized coatings based on Ni−P alloy with increased technological and operational properties and researching their structure arises. In addition, there is a need to replace chrome electrocoatings, which, along with very high indicators of mechanical, protective and decorative properties, are obtained from toxic electrolytes that are dangerous of human life and health. Materials and methodology. In this work, electroplating of Ni−P alloy, obtained from a new electrolyte developed by us, was proposed as a replacement for chromium. Modes of obtaining high-quality electrocoating with Ni−P alloy have been identified, in which the best deposition characteristics, mechanical and decorative properties have been determined. Results. The effect of electrolysis parameters on current output, deposition rate, microhardness, surface morphology and reflectivity of electrocrystallized coatings was investigated. It was also found that the addition of phosphorus ions to the nickel plating electrolyte leads to amorphization of Ni−P alloy deposits. Scientific novelty. The influence of the deposition regime on the formation of the internal structure and surface morphology of Ni−P electrolytic coatings obtained from the electrolyte developed by the authors was studied. Conclusions. The patterns of electrodeposition of Ni−P alloy coatings were studied, and the factors influencing the formation of structure and properties were identified. It was established that the addition of phosphorus ions to the nickel plating electrolyte leads to amorphization of coatings, an increase in microhardness and reflectivity. On the basis of the analysis of the received data, the optimal conditions of electrocrystallization, under which it is possible to obtain a coating with specified physical and mechanical properties, are determined.

СВОЙСТВА ЭЛЕКТРОЛИТИЧЕСКИХ ЦИНК-НИКЕЛЕВЫХ СПЛАВОВ, ОСАЖДЕННЫХ ИЗ СЛАБОКИСЛЫХ ХЛОРИДНЫХ ЭЛЕКТРОЛИТОВ

The effect of electrolysis parameters on the composition and structure of zinc–nickel coatings during their electrodeposition on a copper substrate from a weakly acidic chloride electrolyte with a Zn(II)/Ni(II) ratio of 1 was studied in this work. The chemical composition of the electrolytes was controlled by complexometric titration. The phase composition was studied using a Rigaku Ultima IV X-ray diffractometer. The gross composition was determined using a JEOL JSM-6460LV scanning electron microscope with computer control. It has been established that an increase in the current density increases the deposition rate of the alloy. It is shown that an increase in temperature leads to an increase in the proportion of nickel in the alloy and an increase in the rate of nickel deposition. An increase in temperature does not affect the rate of zinc deposition. At the same time, at temperatures below 60 °C, the deposition of the alloy is anomalous; at higher temperatures, the deposition becomes normal. The open and total porosity of the coating was determined, it was found that there is no open porosity, the total porosity is about 50%.

Effect of electrolysis parameters on corrosion resistance of extra-low carbon high silicon iron-based alloy

PurposeHigh silicon iron-based alloys possess excellent corrosion resistance in certain specific media, but the effects of electrolysis parameters on corrosion resistance remain unknown. This study aims to guide the development and application of an extra-low carbon high silicon iron-based alloy (ECHSIA) in electrode plates.Design/methodology/approachThe corrosion resistance of ECHSIA and a conventional high-silicon cast iron (CHSCI) was analyzed through experimental characterizations. The morphology was observed by scanning electron microscopy. The influence of electrolysis parameters on the corrosion resistance of ECHSIA was investigated through corrosion experiments. The relationship between the electrolysis parameters and the corrosion resistance of ECHSIA was statistically investigated using the grey correlation analysis method.FindingsThe corrosion resistance of the ECHSIA is better than that of the CHSCI. The corrosion rate showed an increasing tendency with the increase in the nitric acid concentration (CHNO3), electrolyte temperature and current density. The grey correlation analysis results showed that the CHNO3 was the main factor affecting the corrosion rate of the ECHSIA.Originality/valueAn ECHSIA with a single ferrite microstructure was prepared. This study provides a guideline for the future development and application of ECHSIAs as electrode plates.

Изучение влияния параметров процесса электролиза на основные технико-экономические показатели работы ванн ОА-300М

Изучение влияния параметров процесса электролиза на основные технико-экономические показатели работы ванн ОА-300М

An electrochemical quartz crystal microbalance study of 5,10,15,20-tetrakis(4-hydroxyphenyl)porphyrin electropolymerization process

The process of 5,10,15,20-tetrakis(4-hydroxyphenyl)porphyrin electropolymerization has been studied by the quartz crystal microbalance method in different electrodeposition conditions. The films were deposited in two modes: in potentiostatic conditions (at the potential of [Formula: see text]2 V) and in potentiodynamic conditions (CV with the potential scan rate of 20 mV/s). The effect of electrolysis parameters on 5,10,15,20-tetrakis(4-hydroxyphenyl)porphyrin electropolymerization has been studied by obtaining films in two modes and using two supporting electrolytes: tetrabutylammonium perchlorate or tetrabutylammonium hexafluorophosphate. The biggest film mass gain was observed on a clean electrode surface. At further film deposition on the polyporphyrin-coated electrode, the film mass growth stopped. The electrodeposition effectiveness was somewhat higher in the potentiodynamic conditions, with the formation of a looser film. The nature of the supporting electrolyte did not have a significant effect on the electrodeposition process. A significant contribution to the deposition was made by the electrode material. The film thickness was 25–80 nm. The films possessed [Formula: see text]-type conductivity; and the flat-band potential for poly-H[Formula: see text]T(4-OHPh)P obtained in potentiodynamic conditions was 0.33 V, for poly-H[Formula: see text]T(4-OHPh)P obtained in potentiostatic conditions it was 0.16 V.

Electrochemical formation of oxide films on Ti6Al4V alloy

The results of the study of the process of electrochemical oxidation of Ti6Al4V titanium alloy in solutions of tartaric, citric and oxalic acids are presented. It is shown that the nature of the forming dependencies of the alloy depends on the magnitude of the current density. When ja<0,5 A∙dm–2, a continuous oxide film does not form on the alloy surface and the specified voltage value is not reached. At ja>0,5 A∙dm–2, a continuous oxide film forms on the surface of the alloy and linear dependences are observed. Films produced under these conditions are interference colored. The maximum thickness of the film is determined by the specified value of the forming voltage U and does not depend on other parameters of electrolysis. For a number of identical values of U, the dependence of the limiting film thickness has a linear form. The color of the oxide film is determined by the voltage value and does not depend on the current density and electrolyte concentration. It is established that the color of the film corresponds to the magnitude of the forming voltage in the range of 10–100 V. The effect is due to the fact that film formation during anodic polarization occurs under the presence of a potential gradient, the magnitude of which is constant for titanium. An increase in a given value of U leads to a proportional increase in the limiting thickness of the oxide, which determines the color of its color. The research results to determine the effect of electrolysis parameters on the characteristics of oxide films make it possible to substantiate the regime for producing TiO2 films on the surface of the Ti6Al4V alloy. The obtained data are the basis for the development of technology for the electrochemical oxidation of titanium alloys to give their surface functional properties

Increasing the Surface Hardness of Cast Iron by Electrodeposition of Borides in Molten Salts

AbstractIn this paper the electrodeposition of boron on the surface of cast iron as a coating is applied to increase the hardness and protect the substrate against abrasive wear. The boron containing coating was synthesized by electrodeposition process from a NaCl-KCl (1:1 mol)-10 w%NaF-10w% KBF4molten salt. The effect of electrolysis parameters (temperature and time) on the hardness is presented; the current density varied in the range −37 – −4.5 mA/cm2, allowing perfect coverage of and respect for dimensions. The electrochemical process was carried out at different temperatures (750°C-900°C) and for different periods of time (5-10 hours). Depending on the current density and duration of electrolysis, the deposits consist of FeB or Fe2B. Microhardness measurements across the boride layer indicated very high hardness values (between 1600 and 2100 HV0.05). The structure of the boride layer is linked to its boron content and thermal history: as-deposited coatings present very small grain sizes and can be considered as nearly amorphous.

Preparation and characterization of tungsten nanopowders from WC scrap in molten salts

Tungsten carbide (WC) scrap was used as a consumable anode to prepare tungsten powder in NaCl–KCl melt at 1023K for the first time. The electrolysis process was investigated. Results showed that the tungsten component in WC anode was dissolved as W2+ into the NaCl–KCl melt. The cathode reaction was controlled by the diffusion of tungsten ions. The effect of electrolysis parameters, including the anode–cathode distance, cathode current density and different electrolysis ways (galvanostatic and potentiostatic electrolysis), on the purity and grain size of the cathode deposits was studied. It showed that a large anode–cathode distance was beneficial to the formation of pure tungsten powder at the cathode. With increasing the cathode current density, the tungsten grain size first decreased and then increased. When the cathode current density was 0.125Acm−2, tungsten powder with a diameter of smaller than 100nm was obtained. Deposits prepared through galvanostatic and potentiostatic electrolysis was compared in the end.

Study on Present Situation and New Trends of the Electrodeposition of Nickel-Cobalt Alloy

Nickel-cobalt alloys have broad application prospect for their excellent properties (i.e. high microhardness, strength, abrasion, corrosion resistance and magnetic properties.etc). Present situation and new trends on mechanism of the anomalous codeposition and technology of electrodepostion of nickel-cobalt were studied. Effects of electrolysis parameters (e.g. concentration of co2+in the electrolyte, cathodic current density, pH value, temperature.etc) on the alloy composition, morphology and mechanical properties were analyzed. The formation of the monovalent intermediate (hydroxides or colloid) may cause the cobalt preferential deposition or the faster charge-transfer of Co2+ reduction compared to that of Ni2+ reduction is the main factor that causes the anomalous codeposition behavior of the nickel-cobalt alloy.

Effect of electrolysis parameters on the morphologies of copper powder obtained at high current densities

The effects of copper ion concentrations and electrolyte temperature on the morphologies and on the apparent densities of electrolytic copper powders at high current densities under galvanostatic regime were examined. These parameters were evaluated by the current efficiency of hydrogen evolution. In addition, scanning electron microscopy was used for analyzing the morphology of the copper powders. It was found that the morphology was dependent over the copper ion concentration and electrolyte temperature under same current density (CD) conditions. At 150 mA cm-2 and the potential of 1000?20 mV (vs. SCE), porous and disperse copper powders were obtained at low concentrations of Cu ions (0.120 M Cu2+ in 0.50 M H2SO4). Under this condition, high rate of hydrogen evolution reaction took place parallel to copper electrodeposition. The morphology was changed from porous, disperse and cauliflower-like to coral-like, shrub-like and stalk-stock like morphology with the increasing of Cu ion concentrations towards 0.120 M, 0.155 M, 0.315 M, 0.475 M and 0.630 M Cu2+ in 0.5 M H2SO4 respectively at the same CD. Similarly, as the temperature was increased, powder morphology and apparent density were observed to be changed. The apparent density values of copper powders were found to be suitable for many of the powder metallurgy applications.

Effect of electrolysis parameters on the morphologies of copper powder obtained in a rotating cylinder electrode cell

Abstract In this paper, electrolysis method was used to produce copper powder particulates. The effects of parametric values, such as current density, concentration of copper ions, electrolyte temperature and rotation speed of cathode, on the morphologies and on the apparent densities of copper powders were examined. These parameters were evaluated by the current efficiency of hydrogen evolution. In addition, scanning electron microscopy (SEM) was used for analyzing the morphology of the copper powders. It was found that the increasing of the current density or the electrolyte temperature decreased the size of the powder particles promoting their morphology into dendritic structure. In contrast, the increase of copper ion concentration or rotation speed of cathode also increased the size of the particles resulting in a cauliflower-like morphology. All powder particles obtained were consisted of agglomerated copper grains. The most important difference was the size and the shape of the copper grains which were notably influenced by the electrolysis parameters. The apparent density values of copper powders were found to be suitable for many powder metallurgical applications. Attempts were also made in the later part of the paper to determine optimum process parameters for the production of electrolytic copper powders.

Electrolytic Preparation, Structure Characterization and Electrochemical Performance of NiOOH

NiOOH was prepared by one-step electrolysis of spherical Ni(OH) 2 and the effects of electrolysis parameters were examined. The highly pure NiOOH was obtained after electrolysis at a current density of 60mA.g -1 and 30°C with anodic potential controlled in the range of 1.73–1.85V ( vs. Zn/ZnO) for 360min. The NiOOH samples were characterized by X-ray powder diffraction (XRD) and scanning electron microscope (SEM) analysis. Results indicate that the electrolysis product is spherical NiOOH doped with graphite. Charge and discharge tests show that the prepared NiOOH offers a discharge capacity of over 270mAh.g -1 at current density of 30mA.g -1 and can be directly used as cathode material of alkaline Zn/NiOOH batteries. Galvanostatic charge/discharge and cyclic voltammetry (CV) tests reveal good cycling reversibility of the NiOOH electrode.

電析法によるＰｔ‐Ｍｏ合金

Pt-Mo alloy films were obtained by electrodeposition from a plating bath containing H2PtCl6 and Na2MoO4, using ammonia alkaline baths, and the effects of electrolysis parameters on Pt and Mo content, the total current efficiency and the structure and thermal stability of Pt-Mo alloy films were investigated under varying conditions of electrolysis.Electrodeposited Pt-Mo alloy films were then studied by X-ray diffraction, DSC analysis and ESCA, and information on the structure of the alloy films was obtained. X-ray diffraction patterns showed that films containing about 10∼15 wt% Mo consisted of a mixture of amorphous and crystalline alloys. ESCA spectra of Mo 3d levels for the alloy films showed that these elements existed in a metallic state.

Dimensionless correlation between conditions of electrolysis and particle size distribution

Particle shape and size are the two most important characteristics of a powder that affect its apparent density. It is necessary for copper powder producers to understand the relationship between these physical properties and the production parameters in order to obtain a specified product quality. In this paper, an experimental study of the effect of electrolysis parameters (copper concentration, acid content, current density, temperature, electrode spacing, and brush-down interval) on the copper powder deposition (particle size) is described, and a correlation is established by dimensional analysis. Information on the electrolytic production of copper powder and the characteristics of the deposit can be found in the literature.1,2

Electrosynthesis in systems of two immiscible liquids and a phase transfer catalyst. I. The anodic cyanation of naphthalene

The anodic cyanation of naphthalene in a methylene chloride/water emulsion using a phase transfer catalyst to supply cyanide ions to the organic medium has been re-examined. The effect of electrolysis parameters (e.g., current density, electrode material, concentration of cyanide, naphthalene and phase transfer catalyst) on the current and organic yields of products is reported. It is shown that by correct selection of conditions it is possible to improve substantially on the yields reported in the literature; the organic and current yields of 1-cyanonaphthalene can exceed 80% and 65%, respectively.

Manufacture of coarse copper powder from sulfamate electrolytes

1. A study was made of the effects of electrolysis parameters (copper concentration in electrolyte, electrolyte temperature, and cathode current density) upon the properties of copper powder deposits. The optimum process parameters resulting in the formation of coarse copper powder of good ductility were determined. 2. The effects of various cathode materials upon the properties of loose copper deposits were investigated. It was established that powder deposits forming on a copper cathode exhibit the highest ductility, but are comparatively difficult to strip from the cathode.

Electrolytic method of continuous production of multicomponent metal powders

1. A process has been developed for the continuous electrolytic preparation of iron-nickel powders of any desired component ratio. The process is based on the use for electrolysis of composite anodes and an auxiliary iron-gauze electrode with independent regulation of the currents passing through each electrode. 2. An investigation was conducted into the effects of electrolysis parameters (cathodic current density, solution composition, concentration and acidity, temperature, etc.) on the current yield, chemical composition, and particle size of the powder. By varying the cathodic current density, the Ni/Fe ratio of the solution, and, accordingly, the ratio of the anodic currents, it is possible to obtain iron-nickel powders of various particle sizes and any required composition. 3. The optimum electrolysis parameters for the preparation of iron-nickel powders of various compositions and particle sizes have been established. 4. The resulting powders were subjected to metallographic and x-ray diffraction examinations and sieve analysis, and their hydrogen and oxygen contents were determined. It was found that, structurally, the powders are solid solutions of one of the components in the other. 5. The new process for the electrolytic preparation of iron-nickel powders was tested and found to be effective at the Leningrad Coke and Gas Plant.