Modeling of electrochemical machining with the use of a curvilinear electrode and a stepwise dependence of the current efficiency on the current density

2016 ◽  
Vol 57 (1) ◽  
pp. 127-135 ◽  
Author(s):  
L. M. Kotlyar ◽  
N. M. Minazetdinov
Keyword(s):  
Current Efficiency ◽  
Current Density ◽  
Electrochemical Machining

A theoretical analysis of electrochemical arc machining

1990 ◽  
Vol 429 (1877) ◽  
pp. 429-447 ◽  
Keyword(s):  
Current Efficiency ◽  
Current Density ◽  
Electrochemical Machining ◽  
Approximate Solutions ◽  
Hole Drilling ◽  
Metal Loss ◽  
Interelectrode Gap ◽  
Surface Irregularities ◽  
Gap Width ◽  
Lower Loss

Electrochemical arc machining (ECAM) involves the removal of metal from an anodically polarized workpiece by both erosion arising from discharges produced in an aqueous electrolyte and electrolytic dissolution. A theoretical model is derived for the process and analysed for two specific applications, fine-hole drilling and the finishing of components by smoothing of their initially rough surfaces. In the second of these examples, a perturbation procedure for obtaining approximate solutions is used; the model so developed encorporates the effects of current density on current efficiency which are known from experimental electrochemical machining (ECM) studies to influence the rate and mode of smoothing. For fine-hole drilling by ECAM, the analysis predicts that the interelectrode gap width increases with the applied voltage and inversely with the square root of the mechanically driven anode. In the case of smoothing, ECAM is found to remove the surface irregularities at a much faster rate and with lower loss of stock metal than ECM alone, when electrolytes such as sodium chloride solution yielding 100% current efficiency are used for the latter process. The analysis shows that an electrolyte solution with a current density-dependent current efficiency is needed if parent metal loss by ECM is to approach that of ECAM, and even then, machining by the latter is still much faster. Attention is drawn to experimental evidence in support of these predictions of ECAM behaviour. Finally, results from the model are used to verify the practical use of ECM for rapid finishing of the surfaces of components left rough by electrodischarge machining.

Optimization for white organic light-emitting diode based on DCJTB as color conversion layer

2018 ◽  
Vol 32 (27) ◽  
pp. 1850299
Author(s):  
Pei Wang ◽  
Zhen Wang ◽  
Ai Chen ◽  
Jia-Feng Xie ◽  
Xin Zheng
Keyword(s):  
Current Efficiency ◽  
Current Density ◽  
White Light ◽  
Power Efficiency ◽  
Light Emitting Diode ◽  
Light Emitting ◽  
Organic Light Emitting Diode ◽  
Organic Light ◽  
High Efficient ◽  
Color Conversion

In this paper, combining phosphorescence and fluorescence to form white light was realized based on DCJTB:PMMA/ITO/NPB/TCTA/FIrpic:TCTA/TPBi/Ir(ppy)3:TPBi/TPBi/Cs2CO3/Al. The effects of red fluorescence on this white light device was studied by adjusting the concentration of DCJTB. The study shows that the device with a DCJTB concentration of 0.7% in the color conversion layer (CCL) generates a peak current efficiency and power efficiency of 23.4 cd ⋅ A[Formula: see text] and 7.5 lm ⋅ W[Formula: see text], respectively. And it is closest to the equal-energy white point of (0.33, 0.33) which shows a CIE (Commission Internationale de L’Eclairage) coordinate of (0.35, 0.43) and a color rendering index (CRI) of 70 at current density of 10 mA ⋅ cm[Formula: see text]. In order to improve the efficiency, we design and fabricate both high efficient and pure white organic light-emitting diode (WOLED) by replacing the single blue emission layer (EML) with double EMLs of FIrpic:TCTA and FIrpic:TPBi. The further study shows that, when the layers of EML is three and the concentration of DCJTB at 0.7%, the device exhibits good performance specifically, at current density of 10 mA ⋅ cm[Formula: see text], the current efficiency of 28.2 cd ⋅ A[Formula: see text] (power efficiency of 10.3 lm ⋅ W[Formula: see text]), and the CIE coordinate of (0.33, 0.31) (CRI of 80.38).

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).

Crystal Orientation and Surface Morphology of Sono-Electroplated Zinc Film from Alkali Zincate Bath

2009 ◽  
Vol 79-82 ◽  
pp. 1743-1746
Author(s):  
Atsushi Chiba
Keyword(s):  
Surface Morphology ◽  
Current Efficiency ◽  
Compressive Stress ◽  
Diffusion Layer ◽  
Current Density ◽  
Crystal Orientation ◽  
Shearing Stress ◽  
Thickness Of Diffusion Layer ◽  
Zincate Solution

Zn plated on Cu plate from 0.65 mol/dm3 alkali zincate solution in 8 mol/dm3 KOH bath Electrolysis was carried out as current density of 10 - 100 mA/cm2. The sonication was prepared 40 kHz. The current efficiency was 76.1 % at 10 mA/cm2 in 0.10 mol/dm3 zincate and 100 % in 0.15 mol/dm3 zincate at 50 mA/cm2. The current efficiency and thickness of diffusion layer affected with the agitation of micro-jet. Surface of film was smooth and dense as particle crushed down with the shockwave pressure. (112) plane moved horizontally to <113> direction under the compressive stress or shearing stress.

Comparison of the electrochemical machinability of electron beam melted and casted gamma titanium aluminide TNB-V5

2017 ◽  
Vol 232 (4) ◽  
pp. 586-592 ◽  
Author(s):  
Fritz Klocke ◽  
Tim Herrig ◽  
Markus Zeis ◽  
Andreas Klink
Keyword(s):  
Surface Roughness ◽  
Electron Beam ◽  
Current Density ◽  
Titanium Aluminide ◽  
Titanium Aluminides ◽  
Electrochemical Machining ◽  
Dissolution Behavior ◽  
Removal Rates ◽  
Gamma Titanium Aluminide ◽  
Gamma Titanium

Additive manufacturing technologies are becoming more and more important for the implementation of efficient process chains. Due to the possibility of a near net shape, manufacturing time for finish-machining can significantly be reduced. Especially for conventionally hard to machine materials like gamma titanium aluminides (γ-TiAl), this manufacturing process is very attractive. Nevertheless, for most applications, a rework of these generative components is necessary. Independently of the mechanical material properties, electrochemical machining is one promising technology of machining these materials. Major advantages of electrochemical machining are its process-specific characteristics of high material removal rates in combination with almost no tool wear. But electrochemical machining results are highly dependent on the microstructure of the material regarding the surface roughness. Therefore, this article deals with research on electrochemical machining of electron beam melted γ-TiAl TNB-V5 compared to a casted form of this alloy. The difference between the specific removal rates as a function of current density is investigated using electrolytes based on sodium nitrate and sodium chloride. Moreover, the dissolving behavior of the electron beam melted and casted structure is analyzed by potentiostatic polarization curves. The surface roughness is heavily dependent on a homogeneous dissolution behavior of the microstructure. Thus, the mean roughness as a function of current density is investigated as well as rim zone analyses of the different structures.

Electrodeposition process and composition of Zn-Cr alloy coatings

2018 ◽  
Vol 23 (2) ◽  
pp. 3-10
Author(s):  
Ewa Osuchowska ◽  
Zofia Buczko ◽  
Klaudia Olkowicz
Keyword(s):  
Surface Morphology ◽  
Current Efficiency ◽  
Direct Current ◽  
Current Density ◽  
Pulse Current ◽  
Electrodeposition Process ◽  
Cr Content ◽  
Zinc Coatings ◽  
Deposition Current Density

In the present work, the electrodeposition process of Zn-Cr alloy coatings under the conditions of direct and pulse current was discussed. Changes in the Cr content in the obtained alloy coatings, current efficiency of the process, surface morphology, structure and microhardness as a function of chromium(III) concentration in the bath to deposition, current density (direct and pulse) and solution mixing were determined. Surface morphology, structure and hardness of the obtained coatings were investigated. The Zn-Cr alloy coatings of good quality contained up to 0.25 %Cr (for direct current) and up to 9% Cr (for pulse current). The tested Zn-Cr alloy coatings obtained under pulse current conditions showed higher microhardness than the Zn-Cr coatings obtained under direct current conditions and than zinc coatings.

Application of polarization measurements for current efficiency calculation

2019 ◽  
pp. 32-39
Author(s):  
V. M. Rudoy ◽  
N. I. Ostanin ◽  
T. N. Ostanina ◽  
A. B. Darintseva ◽  
V. S. Nikitin ◽  
...  
Keyword(s):  
Current Efficiency ◽  
Kinetic Parameters ◽  
Hydrogen Evolution ◽  
Current Density ◽  
Hydrogen Reduction ◽  
Background Electrolyte ◽  
Gravimetric Method ◽  
Nickel Sulfate ◽  
Polarization Measurements ◽  
Partial Current

The paper considers a method used to determine Faraday current efficiency (CeF) based on the ratio of partial currents of metal and hydrogen reduction. To calculate the Faraday current efficiency based on polarization measurements, it is necessary to know the working current density and potential (Ei) at which the metal is deposited in the corresponding solution, as well as kinetic parameters of hydrogen evolution for determining the partial current density of hydrogen (iН2 ) at this potential. The proposed method was used to calculate current efficiency for the processes of nickel extraction and nickel coating application from solutions containing nickel sulfate at current density of 300 A/m2. The study allowed to determine kinetic parameters of hydrogen evolution by the polarization curve obtained in the background electrolyte solution containing 120 g/l of magnesium sulfate and 18 g/l of boric acid at pH = 3.9. An equation was obtained to calculate the partial current density of hydrogen evolution at any potential by kinetic parameters. The use of kinetic regularities made it possible to calculate nickel CeF in sulphate solutions of different composition and with different pH values (3.0 and 4.1). The calculated CeF values within the margin of error coincide with the current efficiency value determined by the gravimetric method using a copper coulometer. It is shown that the division of the «total current efficiency» (CeΣ), which is a commercial indicator, into Faraday (CeF) and apparatus (Ceap) indicators in combination with the method using partial polarization provide additional information about the degree of process perfection.

Current efficiency during the electrochemical machining of iron and nickel

1975 ◽  
Vol 15 (6-12) ◽  
pp. 435-440 ◽  
Author(s):  
James P. Hoare ◽  
Charles R. Wiese
Keyword(s):  
Current Efficiency ◽  
Electrochemical Machining

Study on Electrodeposition Recovery of Cupric and Zinc in Complexation Ultrafiltration Process

2013 ◽  
Vol 777 ◽  
pp. 52-55
Author(s):  
You Xin Zhou ◽  
Ke Jun Yan
Keyword(s):  
Heavy Metals ◽  
Wastewater Treatment ◽  
Current Efficiency ◽  
Optimal Condition ◽  
Current Density ◽  
Mass Concentration ◽  
Zinc Recovery ◽  
Cell Reactor ◽  
Concentrated Solution ◽  
Ultrafiltration Process

Electrodeposition recovery of heavy metals in concentrated solution of wastewater treatment by complexation ultrafiltration was studied. In the study, cheap plategraphite electrode was applied in the traditional electric cell reactor. Current density and mass concentration of the electrodeposition for cupric and zinc recovery were discussed, and the optimal condition were determined. The results showed that the current efficiency of cupric and zinc recovery were more than 60%, and corresponding power consumptions were 11.5 kW·h/kg and 14.0 kW·h/kg, respectively.

Electrochemical Treatment of Oilfield Produced Wastewater on Ni-Sb- SnO2/Ti Electrodes

2013 ◽  
Vol 16 (2) ◽  
Author(s):  
Wang Yun-Hai ◽  
Kuang Jun-Yao
Keyword(s):  
Energy Efficiency ◽  
Current Efficiency ◽  
Current Density ◽  
Tin Dioxide ◽  
Electrochemical Treatment ◽  
Cod Removal ◽  
Electrolysis Time ◽  
Removal Ratio ◽  
Electrode Distance

AbstractNickel and antimony doped tin dioxide (NATO) coated titanium electrodes were used for electrochemical treatment of oilfield produced wastewater. The effects of electrode distance, current density and electrolysis time on COD removal ratio, current efficiency, energy efficiency and BOD to COD ratio were investigated. The optimized electrode distance of 5 mm and current density of 6 mA cm

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