scholarly journals Efficiency definition of the deposition process of electrochromic Ni(OH)2-PVA films formed on a metal substrate from concentrated solutions

2021 ◽  
Vol 6 (12 (114)) ◽  
Author(s):  
Valerii Kotok ◽  
Vadym Kovalenko ◽  
Rovil Nafeev ◽  
Volodymyr Verbitskiy ◽  
Olena Melnyk ◽  
...  
Keyword(s):  
Polyvinyl Alcohol ◽  
Current Efficiency ◽  
Nickel Hydroxide ◽  
Deposition Process ◽  
Amorphous Structure ◽  
Cathode Current Density ◽  
Nickel Nitrate ◽  
Cathodic Current ◽  
Smart Windows ◽  
Lack Of Information

Electrochemical devices based on nickel hydroxide electrodes are used in different areas. The main ones are chemical current sources, variable transparency “smart” windows, devices for carrying out electrocatalytic reactions, sensors for determining various substances. In this regard, methods of nickel hydroxide synthesis are of great interest, especially those that allow forming nickel hydroxide directly on the surface of electrodes. One of these methods is electrochemical deposition with cathodic current polarization. The available information on nickel hydroxide synthesis from nickel solutions was considered. It was shown that the available data mainly covered information on dilute solutions from 0.01 to 0.25 mol/L Ni(NO3)2. In addition, no comparison was found in the literature for the efficiency of the cathodic formation of Ni(OH)2 at different concentrations of nickel nitrate. To eliminate the lack of information, the dependence of the current efficiency on the concentration of nickel nitrate in the electrodeposition solution was determined at a constant cathode current density of 0.625 mA/cm2. The resulting dependence decreased nonlinearly with increasing concentration. The nickel hydroxide deposit formed in this case had an X-ray amorphous structure, and it depended little on the Ni(NO3)2 concentration. In addition, the current efficiency reached zero at concentrations of 1.5 mol/L Ni(NO3)2 and higher. However, with polyvinyl alcohol in the solution and at Ni(NO3)2 concentrations of 1.5 and 2 mol/L, electrochemically and electrochromically active Ni(OH)2 films were deposited. The current efficiency calculated indirectly for 1.5 and 2 mol/L Ni(NO3)2 solutions was 3.2 and 2.3 %, respectively. Thus, it was concluded that polyvinyl alcohol affected the mechanism of nickel hydroxide electrodeposition from aqueous solutions of nickel nitrate.

scholarly journals ELECTROCHEMICAL DEPOSITION OF TIN–ZINC ALLOY FROM CITRATE–AMMONIA ELECTROLYTE

2021 ◽  
pp. 61-67
Author(s):  
Svitlana Hermanivna Deribo ◽  
Serhii Anatoliiovych Leshchenko ◽  
Valrii Pavlovych Gomozov ◽  
Yuliia Ivanivna Kovalenko
Keyword(s):  
Current Efficiency ◽  
Electrochemical Deposition ◽  
Current Density ◽  
Zinc Content ◽  
Cathode Current Density ◽  
Cathodic Current Density ◽  
Zinc Alloy ◽  
Cathodic Current ◽  
Corrosion Properties ◽  
Fine Grained Structure

The cathodic processes of electrochemical deposition of a tin–zinc alloy in citrate–ammonia electrolytes have been investigated. The content of the main components of the investigated electrolyte (g/dm3): SnCl2·2H2O – 44, ZnO – 4, NH4Cl – 100, Na3C6H5O7 – 100. Wood glue (1.5 g/dm3) and neonol (4 ml/dm3) were added to the electrolyte as surfactants. It was found that high–quality coatings are deposited without heating and stirring only in the pH range from 6,0 to 7,0. The addition of these substances to the electrolyte is predicted to lead to inhibition of the reduction of metals, an improvement in the crystal structure of the deposit, but decreases the cathodic current efficiency. Hull cell studies showed that an electrolyte containing neonol as a surfactant showed better throwing power compared to other solutions. The dependence of the current efficiency of the alloy on the cathode current density showed that in the range of current densities from 0.5 A/dm2 to 4 A/dm2, the current efficiency decreases nonlinearly from 82 % to 52 %. The experimentally obtained dependence of the zinc content in the alloy on the cathodic current density showed the possibility of obtaining alloys with a zinc content of 8 % to 33 %. The obtained results allowed us to determine that for the deposition of an alloy with a zinc content of 20–25 %, which provides the best anti–corrosion properties of the coating, it is necessary to carry out the process at a cathodic current density of 1,5–2,0 A/dm2, while the current efficiency is about 70 %, and the deposition rate alloy is 0,44–0,54 μm/min. The received coatings have a semi–bright appearance, a fine–grained structure, light gray color, they are strongly adhered to the substrate.

Bituminous Insulations Durability of Underground Metallic Pipelines I Field investigations

2017 ◽  
Vol 68 (3) ◽  
pp. 581-585 ◽  
Author(s):  
Gabriela Oprina ◽  
Ladislau Radermacher ◽  
Daniel Lingvay ◽  
Dorian Marin ◽  
Andreea Voina ◽  
...  
Keyword(s):  
Cathode Current Density ◽  
Induced Voltage ◽  
Cathodic Current ◽  
Field Investigations ◽  
Operation Period ◽  
Cathode Current ◽  
Protection Potential ◽  
Cathodic Protection System ◽  
Corrosion State ◽  
Good Agreement

The corrosion state of an underground metallic pipeline of �161 mm and 565 m length was assessed by specific electrical and electrochemical measurements. The investigated pipe, buried in 1997, was protected against corrosion by successive layers of bituminous material with a total thickness of 1 to 1.2 mm. The pipeline crosses three electrified railway lines (50 Hz - 28 kV), and then its route is approximately parallel to these lines; thus, the induced AC voltages between line and ground were calculated obtaining values between 4.05 and 7.1 Vrms, in good agreement with the values measured in the accessible points. The measurements regarding the insulation capacity against corrosion of the bituminous insulation, performed at one month and after 19 years of burial, showed an increase of the average cathode current density needed for obtaining the protection potential in the range �1.00 � �1.28 VCu/CuSO4 of approx. three times (from 6.65 up to 19.96 mA/m2), in good agreement with the evolution of the insulation resistance measured between the steel pipe (having a contact area with the ground of 270.5 m2) and a ground socket of 4 W, which decreased from 995 to 315 kW. Following the analysis and processing of the field collected data, it is considered that, by implementing a cheap cathodic protection system (without cathodic current power supply), based on the rectification of the AC induced voltage, the safe operation period of the investigated pipeline may be extended by at least 50 years.

scholarly journals The study of Zn–Co alloy coatings electrochemically deposited by pulse current

2012 ◽  
Vol 66 (5) ◽  
pp. 749-757 ◽  
Author(s):  
Jelena Bajat ◽  
Miodrag Maksimovic ◽  
Milorad Tomic ◽  
Miomir Pavlovic
Keyword(s):  
Surface Roughness ◽  
Current Efficiency ◽  
Direct Current ◽  
Current Density ◽  
Pulse Current ◽  
Pulse Plating ◽  
Cathodic Current ◽  
Average Current Density ◽  
Corrosion Stability ◽  
Average Current

The electrochemical deposition by pulse current of Zn-Co alloy coatings on steel was examined, with the aim to find out whether pulse plating could produce alloys that could offer a better corrosion protection. The influence of on-time and the average current density on the cathodic current efficiency, coating morphology, surface roughness and corrosion stability in 3% NaCl was examined. At the same Ton/Toff ratio the current efficiency was insignificantly smaller for deposition at higher average current density. It was shown that, depending on the on-time, pulse plating could produce more homogenous alloy coatings with finer morphology, as compared to deposits obtained by direct current. The surface roughness was the greatest for Zn-Co alloy coatings deposited with direct current, as compared with alloy coatings deposited with pulse current, for both examined average current densities. It was also shown that Zn-Co alloy coatings deposited by pulse current could increase the corrosion stability of Zn-Co alloy coatings on steel. Namely, alloy coatings deposited with pulse current showed higher corrosion stability, as compared with alloy coatings deposited with direct current, for almost all examined cathodic times, Ton. Alloy coatings deposited at higher average current density showed greater corrosion stability as compared with coatings deposited by pulse current at smaller average current density. It was shown that deposits obtained with pulse current and cathodic time of 10 ms had the poorest corrosion stability, for both investigated average deposition current density. Among all investigated alloy coatings the highest corrosion stability was obtained for Zn-Co alloy coatings deposited with pulsed current at higher average current density (jav = 4 A dm-2).

scholarly journals Electrodeposition of Zn-Fe Alloy from Non-Cyanide Alkaline Sulphate Bath Containing Tartarate

2020 ◽  
Vol 6 (1) ◽  
pp. 180-183 ◽  
Author(s):  
V. Narasimhamurthy ◽  
L.H. Shivashankarappa
Keyword(s):  
Surface Morphology ◽  
Current Efficiency ◽  
Iron Content ◽  
Operating Conditions ◽  
Cathodic Current ◽  
Cyclic Voltammetric ◽  
Cathodic Current Efficiency ◽  
Voltammetric Studies ◽  
Sulphate Bath ◽  
Cyclic Voltammetric Studies

Electrodeposition of Zn-Fe alloy from an alkaline sulphate bath containing tartarate has been carried out. The effect of plating variables on the composition of alloy and on cathodic current efficiency was studied. The cyclic voltammetric studies carried out to know the mutual co-deposition of zinc and iron. Hardness and the surface morphology of the alloy deposits were found to be dependent on the iron content in the alloy. An alloy containing 20% wt. Fe showed smooth, uniform and finer grained deposits. Under the optimum composition and operating conditions, Zn-Fe alloy deposition from alkaline sulphate bath containing tartarate followed anomalous depositing process.

scholarly journals Definition of the influence of pulsed deposition modes on the electrochromic properties of Ni(OH)2-polyvinyl alcohol films

2021 ◽  
Vol 3 (6 (111)) ◽  
pp. 53-58
Author(s):  
Valerii Kotok ◽  
Vadym Kovalenko
Keyword(s):  
Thin Film ◽  
Polyvinyl Alcohol ◽  
Current Density ◽  
Specific Capacity ◽  
Cathode Current Density ◽  
Cathode Current ◽  
Average Current ◽  
Thin Film Electrodes ◽  
Definition Of ◽  
Pulsed Deposition

In this work, the influence of some types of the pulsed deposition mode of electrochromic films from aqueous solutions of nickel nitrate with the addition of polyvinyl alcohol was investigated. Glass coated with a fluorine-doped tin oxide film was used as the basis for deposition. The deposition of nickel (II) hydroxide – polyvinyl alcohol electrochromic films was carried out in three pulsed modes: –0.2 mA/cm2×5 s, 0 mA/cm2×5 s (10 minutes); –0.5 mA/cm2×2 s, 0 mA/cm2×8 s (10 minutes); –1 mA/cm2×1 s, 0 mA/cm2×9 s. In this case, the amount of electricity used for the formation of thin-film electrodes was the same for all samples. The resulting films showed dramatic differences in electrochemical, optical, and quality characteristics. The sample obtained in the mode of the highest cathode current density and the duration of the no-current condition (1 mA/cm2×1 s, 0 mA/cm2×9 s) had the worst specific capacity and optical characteristics. This sample was characterized by the highest number of coating defects and color non-uniformity as well. The sample, which was obtained at average current densities (–0.5 mA/cm2×2 s, 0 mA/cm2×8 s), had the highest specific characteristics among the electrodes in the series. The coating was uniform and solid. Also, this sample had the greatest stability of the coloration depth value, which varied from 79.1 to 78.1 % (first to fifth cycles). The sample obtained in the mode –0.2 mA/cm2×5 s, 0 mA/cm2×5 s showed moderate specific indicators, however, there were some coating defects. According to the results obtained, a mechanism was proposed that explained the differences in the characteristics of thin-film electrodes formed in different modes. This mechanism consists of changing the time of non-stationary processes and the distribution of the current density with a change in the value of the deposition current density, the duration of the cathode period, and the no-current condition.

scholarly journals Methods to Determine the Current Efficiency in AC Electrolysis

2020 ◽  
Vol 46 (1) ◽  
pp. 343-352
Author(s):  
S. Yu. Kireev ◽  
Yu. P. Perelygin ◽  
S. N. Kireeva ◽  
M. J. Jaskula
Keyword(s):  
Current Efficiency ◽  
Double Layer ◽  
Pulse Current ◽  
Metal Deposition ◽  
Cathodic Current ◽  
Cathodic Current Efficiency ◽  
Deposition Processes ◽  
Methods Analytical ◽  
Experimental Researches

AbstractThe paper presents several methods (analytical, electromechanical and electronic) for determining the cathodic current efficiency of the metal deposition processes carried out by AC or pulse current. Based on the results of own experimental researches (for indium, cadmium, nickel, tin and zinc), the appropriate equations are given and the distribution of both faradaic and non-faradaic parts of charge (charging of the electrode double layer) is calculated.

Sn Negative Electrode Consists of Amorphous Structures for Sodium ion Secondary Batteries

MRS Advances ◽  
2016 ◽  
Vol 1 (6) ◽  
pp. 409-414
Author(s):  
Koki Morita ◽  
Naoki Okamoto ◽  
Takatomo Fujiyama ◽  
Takeyasu Saito ◽  
Kazuo Kondo
Keyword(s):  
Discharge Capacity ◽  
Electrode Materials ◽  
Negative Electrode ◽  
Deposition Process ◽  
Amorphous Structure ◽  
Sodium Ion ◽  
Cycle Performance ◽  
Amorphous Structures ◽  
High Theoretical Capacity ◽  
Number Of Cycles

ABSTRACTTin(Sn) and its alloys have been attracting attentions as a negative electrode material for sodium-ion secondary batteries with high theoretical capacity (Na15Sn4, ca. 847 mAh/g) and high electromotiveforce. There still remains the issue as regards the discharge capacity decrease with increasing the number of cycles. In order to improve cycle performance, there are many studies such as using Sn-Ni alloy, however, using Sn based alloy as negative electrode materials and it suffer from the disadvantage of lowering of discharge capacity. In this study, a deposition process for making Sn film which consists of amorphous structure for negative electrode of sodium ion secondary batteries utilizing electordeposition from aqueous bath was developed. The effect of additives on the surface morphology and microstructure of Sn film was investigated. Furthermore, we evaluated the effect of amorphous structure in the Sn film on cycle performance of the Sn negative electrode. Sn film has a good cycle characteristic (>50 cycles) and discharge capacity (> 400 mAh/g). Amorphous structure in the Sn film showed a microscopic effect on the volume change by sodiation and desodiation.

scholarly journals Influence of Current Density on the Microstructure of Carbon-Based Cathode Materials during Aluminum Electrolysis

2020 ◽  
Vol 10 (7) ◽  
pp. 2228
Author(s):  
Wei Wang ◽  
Kai Sun
Keyword(s):  
Current Density ◽  
Aluminum Electrolysis ◽  
Cathode Current Density ◽  
Cathodic Current Density ◽  
Cathodic Current ◽  
Aluminum Reduction ◽  
Electrostatic Charging ◽  
Cathode Current ◽  
Current Densities ◽  
Sodium Expansion

Sodium expansion plays an important role in cathode deterioration during aluminum electrolysis. In this work, the sodium expansion of semigraphitic cathode material has been measured at various cathodic current densities using a modified Rapoport apparatus. We have studied the microstructural changes of carbon cathodes after aluminum electrolysis using high-resolution transmission electron microscopy (HRTEM). Because of an increasing trend toward higher amperage in retrofitted aluminum reduction cells, an investigation is conducted both at a representative cathode current density (0.45 A/cm2) and at a high cathodic current density (0.7 A/cm2). The results indicate that the microstructures of carbon cathodes can be modified by Joule heating and electrostatic charging with higher current densities during aluminum electrolysis. With the penetration of the sodium and melt, zigzag and armchair edges, disordered carbon, and exfoliation of the surface layers may appear in the interior of the carbon cathode. The penetration of the sodium and melt causes remarkable stresses and strains in the carbon cathodes, that gradually result in performance degradation. This shows that increasing the amperage in aluminum reduction cells may exacerbate the material deterioration of the cathodes.

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