scholarly journals Preparation and Characterization of Nanocrystalline Hard Chromium Coatings Using Eco-Friendly Trivalent Chromium Bath

2011 ◽  
Vol 8 (4) ◽  
pp. 1925-1929 ◽  
Author(s):  
V. S. Protsenko ◽  
V. O Gordiienko ◽  
F. I. Danilov ◽  
S. C. Kwon
Keyword(s):  
Formic Acid ◽  
Current Density ◽  
Nanocrystalline Structure ◽  
Cathode Current Density ◽  
Trivalent Chromium ◽  
Complexing Agents ◽  
Hard Chromium ◽  
Cathode Current

A new aqueous sulfate trivalent chromium bath is described. The chromium bath contains formic acid and carbamide as complexing agents. Chromium was deposited at a temperature of 30÷40oC and a cathode current density of 10÷25 A dm-2. The bath allows obtaining thick (up to several hundred micrometers) hard chromium coatings with nanocrystalline structure. The electrodeposition rate reaches 0.8÷0.9 µm min-1.

RESTORATION OF MACHINE PARTS WITH GALVANIZED ZINC COATINGS

2020 ◽  
Vol 4 (141) ◽  
pp. 140-147
Author(s):  
MIKHAIL VIKHAREV ◽  
◽  
VLADIMIR YUDIN ◽  
VESELOVSKIY NIKOLAY ◽  
◽  
...  
Keyword(s):  
Current Density ◽  
Cathode Surface ◽  
Zinc Coating ◽  
Cathode Current Density ◽  
Research Purpose ◽  
Cathode Layer ◽  
Properties Of Coatings ◽  
Chemical Polarization ◽  
Cathode Current ◽  
Zinc Coatings

The article shows the role of electroplating in the restoration of parts, indicates the advantages of restoring parts with electroplating over other methods, and gives the characteristics and properties of coatings obtained by electroplating. (Research purpose) The research purpose is in increasing the speed of application of zinc electroplating when restoring parts. (Materials and methods) The cathode current density has a decisive influence on the coating speed. The main reason for limiting the cathode current density during galvanizing from sulfuric acid electrolytes is the chemical polarization of the cathode. The article presents a study on the designed installation for the application of galvanic coatings. When applying coatings to the internal surfaces of parts, there was used a device with activating elements having an electromechanical rotation drive. This device prevents depletion of the near-cathode layer of the electrolyte and reduces the chemical polarization of the cathode. Elements made of moisture-resistant skin were used as activators. (Results and discussion) The article presents the results of experiments as a dependence of the coating speed on the speed of the activator relative to the restoring surface. It also presents the relationship between the size of the abrasive grains of the activating elements, the force of their pressing against the cathode surface, the speed of movement of the activator and the speed of applying the zinc coating, as well as its quality. By activating the cathode surface, it was possible to raise the operating current density to 100-150 amperes per square decimeter. The speed of application of zinc coatings is 16-25 micrometers per minute. (Conclusions) In the course of research, authors determined the conditions of electrolysis during galvanizing, which provide a significant increase in the cathode current density and the rate of application of these coatings during the restoration of parts.

Study on Electroplated Diamond Wire Saw Development and Wire Saw Wear Analysis

2009 ◽  
Vol 416 ◽  
pp. 311-315 ◽  
Author(s):  
Pei Qi Ge ◽  
Yu Fei Gao ◽  
Shao Jie Li ◽  
Zhi Jian Hou
Keyword(s):  
Current Density ◽  
High Performance ◽  
Experimental Studies ◽  
Cathode Current Density ◽  
Diamond Wire ◽  
Wire Saw ◽  
Diamond Wire Saw ◽  
Cathode Current ◽  
The Wire ◽  
Electroplating Process

Development of high performance diamond impregnated wire is the key of application for fixed-abrasive wire sawing technology. In this paper, some experimental studies were done for development of electroplated diamond wire saw by employing the bright nickel bath. The wire saw electroplating process was developed, the effects of cathode current density and time at tack-on stage on diamond grits density and adhesion between saw matrix and plating coating were discussed. The wire saw cutting experiments were carried out for analysis the used wire wear using the scanning electron microscope (SEM). The experimental results show the optimum tack-on current density to obtain the wire saw with good abrasive distribution and adhesion is 1.5~2.0A/dm2, and the time of pre-plating, tack-on and buildup is 6, 8~10 and 18min in turn. Diamond wire saw wear includes coating wear and grain-abrasion, and the primary wear form is grits pulled-out.

Preparation of High-Purity Titanium by Molten-Salt Electrolysis Process

2011 ◽  
Vol 284-286 ◽  
pp. 1477-1482 ◽  
Author(s):  
Tie Chui Yuan ◽  
Qi Gang Weng ◽  
Zhi Hui Zhou ◽  
Jian Li ◽  
Yue Hui He
Keyword(s):  
Molten Salt ◽  
Current Density ◽  
High Purity ◽  
Titanium Sponge ◽  
Cathode Current Density ◽  
Titanium Concentration ◽  
Titanium Plate ◽  
Molten Salt Electrolysis ◽  
Cathode Current ◽  
Purity Titanium

Titanium sponge is used as anode, titanium plate as cathode and NaCl-KCl-TiClx molten salt as electrolyte, to prepare high purity titanium by molten-salt electrolysis at 900~980°C. The effects of feeding TiCl4 temperature, electrolytic temperature, soluble titanium concentration and cathode current density on the content of impurities of cathode products have been studied. The results show that the impurities in product can be controlled when the temperature of feeding and electrolyte is higher. The final product with different morphology and degree of purity can be prepared by controlling the soluble titanium concentration and cathode current density.

Study of Properties of Ni-Base Nano-ZrO2 Composite Plating Coatings

2011 ◽  
Vol 239-242 ◽  
pp. 1452-1456
Author(s):  
Lei Zhang ◽  
Ben Liang Sun ◽  
Lin Wang ◽  
Yang Xu ◽  
Yang Li ◽  
...  
Keyword(s):  
Current Density ◽  
Base Alloy ◽  
Bath Temperature ◽  
Cathode Current Density ◽  
Copper Plate ◽  
Optimum Process ◽  
Optimum Process Parameter ◽  
Composite Plating ◽  
Cathode Current ◽  
Plating Layer

The surface of copper plate of the mold need to be reinforced to obtain the plating coatings with high hardness and corrosion resistant properties. Nowadays, Ni-base alloy coatings is used widely in the industrial production. In order to raise the service life of mold, the experiments on the property of Ni-base nano ZrO2 composite plating coatings was done in this paper. The experiments were planned with the orthogonal test design method. The effective factors on the property of coatings, bath temperature, cathode current density, the distance between two electrodes and the magnitude of Nano-ZrO2,were experimentally studied. The optimum process parameter were obtained. The results show that the composite plating layer of Ni-base Nano ZrO2 with good properties can be obtained.The optimal conditions are as follows: the bath temperature is 40 °C, cathode current density is 3A/dm2, the distance between two electrodes is 12 cm, the magnitude of Nano-ZrO2 is 12g/L. In addition binding strength of the coatings were measured quantitatively, and the structure of the plating layer were observed with SEM. The layer with good properties can be obtained in this method.

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.

Nickel-Based Composition Coating with Titanium Nanoboride

2015 ◽  
Vol 788 ◽  
pp. 75-81 ◽  
Author(s):  
Ksenia A. Efimova ◽  
Gennady V. Galevskii ◽  
Victoria V. Rudneva ◽  
N.A. Kozyrev ◽  
Eugenia G. Orshanskaya
Keyword(s):  
Mechanical Properties ◽  
Current Density ◽  
Titanium Boride ◽  
Cathode Current Density ◽  
Internal Stresses ◽  
Nickel Matrix ◽  
Upper Limit ◽  
Cathode Current ◽  
Low Porosity

Conditions of electrodeposition, the structure and physical-mechanical properties (microhardness, base cohesion, internal stresses, corrosion currents) of nickel-based galvanic composition coatings with nano and micropowders of titanium boride are investigated. It is determined that electrocrystallization of nickel in the presence of boride nanoparticles leads to the formation of coatings with small-sized structural fragments, low porosity and increased physical-mechanical properties. Titanium nanoboride is simultaneously a component of the composition coating and an effective modifier of the nickel matrix. The presence of nanoboride in the electrolyte improves its performance by increasing the allowable upper limit of the cathode current density.

Optimization of Process Parameters of Ni-TiN-CeO2 Binary Nanocomposite Coatings by Ultrasound-Pulse Electrodeposition

2012 ◽  
Vol 217-219 ◽  
pp. 1331-1335
Author(s):  
Na Na Liu ◽  
Meng Hua Wu ◽  
Zhi Li
Keyword(s):  
Process Parameters ◽  
Current Density ◽  
Duty Cycle ◽  
Steel Substrate ◽  
Cathode Current Density ◽  
Pulse Electrodeposition ◽  
Nanocomposite Coatings ◽  
Ultrasonic Power ◽  
Cathode Current ◽  
Ultrasound Pulse

Ni-TiN-CeO2 nanocomposite coatings on 45 steel substrate were prepared by ultrasound-pulse electrodeposition. The effects of process parameters, such as CeO2 and TiN nanoparticles addition, cathode current density, positive pulse duty cycle and ultrasonic power on the Ni-TiN-CeO2 nanocomposite electrodeposition process were studied by orthogonal experiments. The nanoparticles contents in the coating were determined, and the surface morphology of the coating was analyzed. The results show that the optimized process parameters are: the CeO2 particles addition of 40g/l, the TiN particles addition of 15g/l, cathode current density of 4A/dm2, positive duty cycle of 20%, and the ultrasonic power of 180W. Under the optimum condition, the desirable Ni-TiN-CeO2 nanocomposite coatings are prepared with higher particle content and better surface quality.

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