Selasa, 25 Oktober 2011


Attribute based specification, comparison and selection of electroplating system using MADM approach Original Research Article
Expert Systems with Applications, Volume 36, Issue 8, October 2009, Pages 10815-10827
Abhishek Kumar, V.P. Agrawal
The problem of electroplating selection has been of concern to users for many years. The selection process is becoming more and more difficult due to the availability of large variety of electroplating configurations and manufacturing plants/products. The methods proposed so far consider only physical parameters (thickness, hardness, adhesion, etc.). In order to have precise information about the selection process, the performance of electroplating plays a vital role.
The objective of this paper is to propose a methodology by which selection of electroplating product/plant can be made easy. This selection procedure will help the user to select the system most suited for his operational needs. Moreover, the paper discusses how the electroplating suppliers, designers and maintenance personnel will also be benefited.
The identification and codification of attributes based on n-digit alpha numeric code is presented here. The 3 stage selection procedure allows rapid convergence from a very large number of options to manageable shortlist of potentially suitable electroplating option using ‘elimination search’ based on a few pertinent attributes. Then the selection procedure ranks them by employing a multiple attributes decision making (MADM) method using the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) approach. It helps the decision maker(s) to organize the problem to be solved, and carry out analysis, comparisons and ranking of the alternatives. Magnitudes of different attributes are used to generate parameters of the hypothetical ideal electroplating, with all the candidate electroplating compared and ranked. This ranking gives the best available electroplating for particular application. The methodology is presented with the help of illustrated example of gold plating, which shows that it can benefit the designers, users or manufacturers.

Keywords: TOPSIS; Attributes characterization; Electroplating; Normalization; Coefficient of suitability; Ranking

Structural modeling and analysis of an effluent treatment process for electroplating—A graph theoretic approach Original Research Article
Journal of Hazardous Materials, Volume 179, Issues 1-3, 15 July 2010, Pages 748-761
Abhishek Kumar, Shibu Clement, V.P. Agrawal
An attempt is made to address a few ecological and environment issues by developing different structural models for effluent treatment system for electroplating. The effluent treatment system is defined with the help of different subsystems contributing to waste minimization. Hierarchical tree and block diagram showing all possible interactions among subsystems are proposed. These non-mathematical diagrams are converted into mathematical models for design improvement, analysis, comparison, storage retrieval and commercially off-the-shelf purchases of different subsystems. This is achieved by developing graph theoretic model, matrix models and variable permanent function model. Analysis is carried out by permanent function, hierarchical tree and block diagram methods. Storage and retrieval is done using matrix models. The methodology is illustrated with the help of an example. Benefits to the electroplaters/end user are identified.

Keywords: Electroplating effluent treatment system (EETS); System structure; Graph theory; Matrix approach; Variable permanent function (VPF)

Stabilization of chromium-bearing electroplating sludge with MSWI fly ash-based Friedel matrices Original Research Article
Journal of Hazardous Materials, Volume 165, Issues 1-3, 15 June 2009, Pages 955-960
Guangren Qian, Xiaoyan Yang, Shixiang Dong, Jizhi Zhou, Ying Sun, Yunfeng Xu, Qiang Liu
This work investigated the feasibility and effectiveness of MSWI fly ash-based Friedel matrices on stabilizing/solidifying industrial chromium-bearing electroplating sludge using MSWI fly ash as the main raw material with a small addition of active aluminum. The compressive strength, leaching behavior and chemical speciation of heavy metals and hydration phases of matrices were characterized by TCLP, XRD, FTIR and other experimental methods. The results revealed that MSWI fly ash-based Friedel matrices could effectively stabilize chromium-bearing electroplating sludge, the formed ettringite and Friedel phases played a significant role in the fixation of heavy metals in electroplating sludge. The co-disposal of chromium-bearing electroplating sludge and MSWI fly ash-based Friedel matrices with a small addition of active aluminum is promising to be an effective way of stabilizing chromium-bearing electroplating sludge.

Keywords: Chromium-bearing electroplating sludge; MSWI fly ash; Friedel matrix; Stabilization/solidification

Multiple heavy metals extraction and recovery from hazardous electroplating sludge waste via ultrasonically enhanced two-stage acid leaching Original Research Article
Journal of Hazardous Materials, Volume 178, Issues 1-3, 15 June 2010, Pages 823-833
Chuncheng Li, Fengchun Xie, Yang Ma, Tingting Cai, Haiying Li, Zhiyuan Huang, Gaoqing Yuan
An ultrasonically enhanced two-stage acid leaching process on extracting and recovering multiple heavy metals from actual electroplating sludge was studied in lab tests. It provided an effective technique for separation of valuable metals (Cu, Ni and Zn) from less valuable metals (Fe and Cr) in electroplating sludge. The efficiency of the process had been measured with the leaching efficiencies and recovery rates of the metals. Enhanced by ultrasonic power, the first-stage acid leaching demonstrated leaching rates of 96.72%, 97.77%, 98.00%, 53.03%, and 0.44% for Cu, Ni, Zn, Cr, and Fe respectively, effectively separated half of Cr and almost all of Fe from mixed metals. The subsequent second-stage leaching achieved leaching rates of 75.03%, 81.05%, 81.39%, 1.02%, and 0% for Cu, Ni, Zn, Cr, and Fe that further separated Cu, Ni, and Zn from mixed metals. With the stabilized two-stage ultrasonically enhanced leaching, the resulting over all recovery rates of Cu, Ni, Zn, Cr and Fe from electroplating sludge could be achieved at 97.42%, 98.46%, 98.63%, 98.32% and 100% respectively, with Cr and Fe in solids and the rest of the metals in an aqueous solution discharged from the leaching system. The process performance parameters studied were pH, ultrasonic power, and contact time. The results were also confirmed in an industrial pilot-scale test, and same high metal recoveries were performed.

Keywords: Ultrasound; Metal recovery; Leaching separation; Electroplating sludge

Technology-based industrial environmental management: a case study of electroplating in Shenzhen, China Original Research Article
Journal of Cleaner Production, Volume 18, Issues 16-17, November 2010, Pages 1731-1739
Lei Liu, Xiaoming Ma
Severe industrial pollution has largely hindered the sustainable development of China. Taking Shenzhen’s electroplating industry as a case, this article investigates the current status of the industry and proposes a specialized policy framework to push its environmental innovation. There is a relatively complete environmental management system in Shenzhen’s government, but it does not work well when dealing with the electroplating industry, mainly because it lacks regulation aiming at production technology, which is the underlying decisive factor of the environmental performance of the industry. So, we first develop an evaluation criterion, which incorporates a technological index about whether enterprises engage identified obsolete technologies. With this evaluation criterion, enterprises are classified into “advanced” and “obsolete”. Then, we propose specific policy suggestions for different types of enterprises, including command and control mixed with economic tools, voluntary agreements, establishing electroplating parks, and improving current management system. Finally, we assess the impact of the policy proposal and prove it to be conducive to the sustainable development of the industry and conclude it from a more general perspective.

Keywords: Industrial environmental management; Obsolete technology; Electroplating industry; Shenzhen

Recovery of copper by LIX 984N-C from electroplating rinse bath solution Original Research Article
Hydrometallurgy, Volume 98, Issues 1-2, August 2009, Pages 86-91
Mehmet Kul, Ümit Çetinkaya
Development of a complete hydrometallurgical process at the laboratory scale for recovering copper from the copper electroplating second rinse bath solution containing ~ 2.5 g/L copper (CESRBS) by solvent extraction route using LIX 984N-C dissolved in commercial kerosene was investigated. By using LIX 984N-C, an electrolyte from CESRBS with ~ 97 g/L copper content, which was addable to the copper electroplating bath, was generated by 30 vol.% LIX 984N-C in commercial kerosene at the O/A ratio of 1/8 and equilibrium pH value of 2 with two-stage counter-current extraction, and stripping of loaded organic by copper electroplating first rinse bath solution (7.8 g/L Cu) with 550 g/L sulfuric acid addition and with the O/A ratio of 2 at two-stage counter-current stripping process. The copper in stripping solution precipitated as CuSO4 3H2O salt. If the copper sulfate is produced without contaminated with organic phase, it could be recycled to the copper electroplating bath. A complete flow sheet of 30 vol.% LIX 984N-C process for the recovery of copper from CESRBS was demonstrated.

Keywords: Copper electroplating 2nd rinse bath solution; Copper recovery; Solvent extraction

Removal of Zn2+ from aqueous single metal solutions and electroplating wastewater with wood sawdust and sugarcane bagasse modified with EDTA dianhydride (EDTAD) Original Research Article
Journal of Hazardous Materials, Volume 176, Issues 1-3, 15 April 2010, Pages 856-863
Flaviane Vilela Pereira, Leandro Vinícius Alves Gurgel, Laurent Frédéric Gil
This work describes the preparation of a new chelating material derived from wood sawdust, Manilkara sp., and not only the use of a new support, but also a chemically modified sugarcane bagasse synthesized in our previous work to remove Zn2+ from aqueous solutions and electroplating wastewater. The first part describes the chemical modification of wood sawdust and sugarcane bagasse using ethylenediaminetetraacetic dianhydride (EDTAD) as modifying agent in order to introduce carboxylic acid and amine functional groups into these materials. The obtained materials such as the modified sugarcane bagasse, EB, and modified wood sawdust, ES were then characterized by infrared spectroscopy (IR) and CHN. The second part evaluates the adsorption capacity of Zn2+ by EB and ES from aqueous single metal solutions and real electroplating wastewater, which concentration was determined through direct titration with EDTA and inductively coupled plasma (ICP-OES). Adsorption isotherms were developed using Langmuir model. Zn2+ adsorption capacities were found to be 80 mg/g for ES and 105 mg/g for EB whereas for the industrial wastewater these values were found to be 47 mg/g for ES and 45 mg/g for EB. Zn2+ adsorption in the wastewater was found to be lower than in Zn2+ spiked solution due to the competition between other cations and/or interference of other ions, mainly Ca2+ and Cl− that were present in the wastewater.

Keywords: Adsorption; Modified wood; Zinc; Modified sugarcane bagasse; Ethylenediaminetetraacetic dianhydride; Electroplating wastewater

Feasibility study on the recovery of hexavalent chromium from a simulated electroplating effluent using Alamine 336 and refined palm oil Original Research Article
Separation and Purification Technology, Volume 75, Issue 3, 20 November 2010, Pages 303-309
R.T. Bachmann, D. Wiemken, A.B. Tengkiat, M. Wilichowski
Chromium is an element that is widely used in stainless steel manufacturing, leather tanning and electroplating. Its hexavalent species are toxic and cause of considerable damage if released into the environment. Coupled with depleting reserves and stricter environmental laws it becomes necessary to reduce, reuse and recycle this important commodity.
The objective of the study is to test the suitability of Alamine 336 and a renewable and biodegradable diluent, i.e. refined palm oil, in the recovery of hexavalent chromium from synthetic concentrated electroplating effluents using the anionic liquid ion exchange (ALIX) process. The performance of refined palm oil was compared with kerosene, a flammable nonbiodegradable commercial solvent.
Alamine 336:diluent molar ratios of up to 1:1 can be carried out with refined palm oil over a pH range of 1–4 with a single-step extraction efficiency of up to 95%. Speciation modelling with Visual MINTEQ® suggests a high Alamine 336 affinity for hexavalent chromium species CrO3SO42− and HCrO4−. The presence of interfering metal ions like iron and zinc slightly suppressed the chromium uptake capability of Alamine 336. Sulphate anions, as well as the presence of copper and nickel ions have no negative effect on Cr(VI) extraction. Visual MINTEQ® has proven to be a useful tool in solving relatively complex metal speciation and solubility problems encountered in ALIX extraction.
The findings of this study provide a significant step towards a greener and safer chromium recovery process in the electroplating industry but also commercial and academic analytical laboratories.

Keywords: ALIX; Chromium; Palm oil; Solvent extraction; Electroplating effluent

The influence of ultrasonic agitation on copper electroplating of blind-vias for SOI three-dimensional integration Original Research Article
Microelectronic Engineering, Volume 87, Issue 3, March 2010, Pages 527-531
Qianwen Chen, Zheyao Wang, Jian Cai, Litian Liu
Three-dimensional (3D) integration, which employs through-silicon-vias (TSVs) to electrically interconnect multiple-stacked chips, is a promising technology for significant reduction in interconnect delay and for hetero-integration of different technologies. To fabricate void-free TSVs, this paper presents a copper electroplating technique with the assistance of ultrasonic agitation to fill blind-vias, and discusses the influence of ultrasonic agitation on copper electroplating. Blind-vias with an aspect ratio of 3:1 are used for copper electroplating with both direct current (DC) and pulse-reverse current modes, combined with either ultrasonic agitation or mechanical agitation. Experimental results show that blind-vias with small aspect ratio can be completely filled using pulse-reverse current, regardless of the agitation methods. For DC, ultrasonic agitation is superior to mechanical agitation for copper electroplating in filling void-free vias. These results indicate that agitation, though is a secondary control factor to pulse-reverse current, can enhance mass transfer in blind-vias during copper electroplating and can improve the filling capability of copper electroplating.

Keywords: 3D integration; Ultrasonic agitation; Copper electroplating; Through-silicon-vias (TSVs)

Ferrite materials prepared from two industrial wastes: Electroplating sludge and spent pickle liquor Original Research Article
Separation and Purification Technology, Volume 75, Issue 2, 13 October 2010, Pages 210-217
Dan Chen, Jun Hou, Li-hua Yao, Hong-ming Jin, Guang-Ren Qian, Zhi Ping Xu
Simultaneous treatment of two industrial wastes, i.e. the electroplating sludge and the spent pickling liquor, to produce valuable spinel ferrite with high crystallinity and high saturation magnetization through the hydrothermal process has been investigated. After the hydrothermal treatment, the electroplating sludge can only produce poorly crystallized ferrite with high content of impurities. However, co-hydrothermal treatment of the electroplating sludge and the spent pickle liquor in a suitable mixing ratio results in a well crystallized ferrite product, with all heavy metals being fixed into the ferrite lattice. In order for the ferrite product to have a maximum saturation magnetization (41.42 emu g−1 in this research), the response surface methodology (RSM) has been employed to derive the optimal experiment condition, e.g. hydrothermal treatment at 300 °C for 6 h with the initial pH adjusted to 10. This optimal experimental condition has been further proven valid when applied to a different kind of electroplating sludge. In addition, the magnetization of ferrite products can be further enhanced to 58.34 emu g−1 by acid washing to remove the impurity (calcite). This research thus shows an effective way to transfer two common industrial wastes into valuable ferrite materials.

Keywords: Electroplating sludge; Spent pickling liquor; Hydrothermal treatment; Spinel ferrite; Response surface methodology (RSM)

Progress of electroplating and electroless plating on magnesium alloy Original Research Article
Transactions of Nonferrous Metals Society of China, Volume 20, Supplement 2, July 2010, Pages s630-s637
Li-ping WU, Jing-jing ZHAO, Yong-ping XIE, Zhong-dong YANG

The current research processes of electroplating and electroless Ni-P alloy plating on magnesium alloys were reviewed. Theoretically, the reason for difficulties in electroplating and electroless plating on magnesium alloys was given. The zinc immersion, copper immersion, direct electroless Ni-P alloy plating and electroplating and electroless plating on magnesium alloys prepared by chemical conversion coating were presented in detail. Especially, the research development of magnesium alloy AZ91 and AZ31 was discussed briefly. Based on the analysis, the existing problems and future research directions were then given.

Keywords: magnesium alloy; electroplating; electroless Ni-P alloy; chemical conversion coating; zinc immersion/copper; direct electroless Ni-P alloy plating

Influence of Cu electroplating solutions on boron carbon nitride (BCN) film Original Research Article
Applied Surface Science, Volume 255, Issue 6, 1 January 2009, Pages 3719-3722
Hidemitsu Aoki, Makoto Hara, Takuro Masuzumi, Motaharu K. Mazumder, Naoki Ooi, Daisuke Watanabe, Chiharu Kimura, Takashi Sugino
Cu electroplating is required for the fabrication of Cu/low-k interconnections. The permeation of a plating solution into low-k films during Cu electroplating is a serious challenge for 45-nm nodes and more complex devices. We investigated the influence of Cu electroplating solutions on boron carbon nitride (BCN) as a low-k film. After dipping it into a Cu electroplating solution that contained additives, the BCN film's hydrophilic surface changed to a hydrophobic surface, and the incorporation of water into the BCN film was suppressed by surfactant adsorption. Sulfuric residue was detected on the BCN sample by thermal desorption spectroscopy after treatment in the Cu electroplating solution with additives; however, it was found through electrical measurements that this solution did not affect the leakage current or the dielectric constant of the BCN film. We successfully fabricated an electroplating Cu layer on a BCN film with good adhesion, and we believe that this BCN film is a sufficiently useful material for Cu/BCN integration in LSI.

Keywords: BCN; Low-k; Cu; Electroplating; Boron carbon nitride

Process effects of double step DRIE and Ni–Co electroplating for a trench-type cantilever probe for a fine-pitched MEMS probe card Original Research Article
Sensors and Actuators A: Physical, Volume 152, Issue 2, 18 June 2009, Pages 252-260
Bong-Hwan Kim, Bum-Jin Park, Jong Bok Kim
This paper describes the effects of a process of double step deep reactive ion etch (DRIE) using an inductively coupled plasma (ICP) etch system and nickel–cobalt electroplating for a trench-type cantilever probe for a fine-pitched micro-electro mechanical systems (MEMS) probe card. The cantilever probe tip was formed inside silicon after double step DRIE to make a cantilever beam and pyramid type cantilever probe tip and electroplated in a nickel–cobalt solution to produce compliant and wear resistance structures. The advantage of a trench-type cantilever probe tip is that it can be used for a fine-pitch MEMS probe card. For forming the cantilever beam and pyramid probe tip in a trench, DRIE conditions were developed by varying the flow rate of SF6 and C4F8. For electroplating the tip in a deep trench, use of a seed layer was investigated on the bottom of the tip using electron probe microanalyzers (EPMA) and scanning electron microscopy (SEM) for analysis. To reduce tensile stress and to electroplate uniformly over a 6 in. wafer, a cathode mask was employed. Contact force was measured with varying composition of nickel–cobalt. As the percentage of cobalt increased, contact force was improved without depressions. The wafer was exposed to X-rays to investigate the quality of nickel–cobalt electroplating, such as the presence of seams or voids. There were no broken cantilevers or significant degradation after 1,000,000 touchdowns.

Keywords: MEMS probe card; DRIE; Nickel–cobalt electroplating; Seed layer

Removal of iron from Cr-electroplating solution by extraction with di(2-ethylhexyl)phosphoric acid in kerosene Original Research Article
Chemical Engineering and Processing: Process Intensification, Volume 49, Issue 2, February 2010, Pages 159-164
Y.A. El-Nadi, N.E. El-Hefny
The extraction of iron(III) from aqueous sulphate solution was studied using di(2-ethylhexyl)phosphoric acid (HA) mixed with kerosene. Distribution ratios were investigated as a function of the concentration of sulphuric acid, extractant, metal, hydrogen ion as well as the phase ratio and loading capacity of the extractant. The extracted iron species was suggested as [Fe(HA2)3] and the extraction constant was found to equal (9.1 ± 0.5) × 102. The thermodynamic functions calculated from the temperature dependence data referred to the endothermic nature of the extraction process. The method of extraction was successfully applied to remove the iron from the chromium electroplating solution giving purification percent of about 97.5%.

Keywords: Extraction; Iron; DEHPA; Chromium; Electroplating

Composite electroplating of Cu–SiO2 nano particles on carbon fiber reinforced epoxy composites
Applied Surface Science, Volume 256, Issue 5, 15 December 2009, Pages 1614-1616
Hao Li, Yizao Wan, Hui Liang, Xiaolei Li, Yuan Huang, Fang He
The main purpose of this work is to co-deposit nano-SiO2 particles into the copper coatings on carbon fiber reinforced epoxy (C/EP) composite surface by electrodeposition method in order to improve the micro hardness of coatings. C/EP composites are copper plated with sulfuric acid based solution, and the effects of nano-SiO2 and C6H12O6 in the electrolyte contents on the copper coatings are investigated. It is found that crystalline grains of coatings are markedly refined by nano-SiO2 in the acidic sulfate copper plating bath and the ceramic particles cause an increase in hardness of coatings though nano-SiO2 results in a decline of deposition rate and a decrease in electrical conductivity of electroplating layers. Otherwise, C6H12O6 in the plating bath is indispensable to the layer formation even though nano-SiO2 added. These results demonstrate that the hardness of coatings will be increased with appropriate contents of co-deposited SiO2 and C6H12O6 in the plating bath.

Keywords: Epoxy resin; Composites; Nano-particles; Electroplating; Composite coatings

The influence of heavy metals on the polymorphs of dicalcium silicate in the belite-rich clinkers produced from electroplating sludge Original Research Article
Journal of Hazardous Materials, Volume 170, Issue 1, 15 October 2009, Pages 443-448
Ying-Liang Chen, Pai-Haung Shih, Li-Choung Chiang, Yi-Kuo Chang, Hsing-Cheng Lu, Juu-En Chang
The purpose of this study is to utilize an electroplating sludge for belite-rich clinker production and to observe the influence of heavy metals on the polymorphs of dicalcium silicate (C2S). Belite-rich clinkers prepared with 0.5–2% of NiO, ZnO, CuO, and Cr2O3 were used to investigate the individual effects of the heavy metals in question. The Reference Intensity Ratio (RIR) method was employed to determine the weight fractions of γ-C2S and β-C2S in the clinkers, and their microstructures were examined by the transmission electron microscopy (TEM). The results showed that nickel, zinc, and chromium have positive effects on β-C2S stabilization (Cr3+ > Ni2+ > Zn2+), whereas copper has a negative effect. The addition of up to 10% electroplating sludge did not have any negative influence on the formation of C2S. It was observed that γ-C2S decreased while β-C2S increased with a rise in the addition of the electroplating sludge. Moreover, nickel and chromium mainly contributed to stabilizing β-C2S in the belite-rich clinkers produced from the electroplating sludge.

Keywords: Belite-rich clinker; Heavy metal; X-ray diffraction; Transmission electron microscopy; Electroplating sludge

Creating low-impedance tetrodes by electroplating with additives Original Research Article
Sensors and Actuators A: Physical, Volume 156, Issue 2, December 2009, Pages 388-393
John E. Ferguson, Chris Boldt, A. David Redish
A tetrode is a bundle of four microwires that can record from multiple neurons simultaneously in the brain of a freely moving animal. Tetrodes are usually electroplated to reduce impedances from 2–3 MΩ to 200–500 kΩ (measured at 1 kHz), which increases the signal-to-noise ratio and allows for the recording of small-amplitude signals. Tetrodes with even lower impedances could improve neural recordings but cannot be made using standard electroplating methods without shorting. We were able to electroplate tetrodes to 30–70 kΩ by adding polyethylene glycol (PEG) or multi-walled carbon nanotube (MWCNT) solutions to a commercial gold-plating solution. The MWCNTs and PEG acted as inhibitors in the electroplating process and created large surface area, low-impedance coatings on the tetrode tips.

Keywords: Tetrodes; Electroplating; Carbon nanotubes; Impedance; Extracellular recording

Frequency-controlled wireless shape-memory-alloy microactuators integrated using an electroplating bonding process Original Research Article
Sensors and Actuators A: Physical, Volume 163, Issue 1, September 2010, Pages 363-372
M.S. Mohamed Ali, K. Takahata
This paper reports the wireless control of bulk-micromachined shape-memory-alloy actuators using external radiofrequency magnetic fields and its application to microgrippers. The frequency-sensitive wireless resonant heater to which the gripper actuator is bonded is activated only when the field frequency is tuned to the resonant frequency of the heater. A batch-compatible bonding technique based on photo-defined copper electroplating is developed to mechanically and thermally couple the gripper with the planar heater circuit fabricated using copper-clad polyimide film. The actuation range of 600 μm as the tip opening distance is obtained with normally closed 5-mm long grippers at a device temperature of 92 °C. The field frequency range to which the devices with 140-MHz resonant frequency respond is measured to be ∼13 MHz about the resonant frequency. The manipulation of vertically aligned carbon-nanotube forests is experimentally demonstrated. Mechanical stress tests for the bond formed by the developed electroplating bonding method show a shear strength greater than 40 MPa.

Keywords: Shape-memory-alloys; Micro-electro-mechanical systems; Actuators; Grippers; Wireless; Electroplating; Bonding

Concentration and purification of chromate from electroplating wastewater by two-stage electrodialysis processes Original Research Article
Journal of Hazardous Materials, Volume 161, Issues 2-3, 30 January 2009, Pages 1075-1080
Shiao-Shing Chen, Chi-Wang Li, Hong-Der Hsu, Po-Ching Lee, Yu-Min Chang, Chia-Hao Yang
A designed two-stage electrodialysis system is proposed to concentrate and purify chromate from a low pH electroplating wastewater using monovalent selective electrodialysis membranes. With low pH of the raw water (pH 2.2) in the first stage, chromate was presented as HCrO4− and monovalent ions (HCrO4−, NH2SO3−, Na+ and Cl−) were able to pass through the membrane thus chromate was concentrated up to 191%. Higher current density, flowrate and more membrane area all increased the chromium recovery. When pH was adjusted to 8.5 before entering the second stage, the chromate species was presented as divalent CrO42− and retained in the concentrated stream, and the rest monovalent ions (NH2SO3−, Na+ and Cl−) were separated by passing through the membrane. For example, 45% of the chlorides were separated in this study. The separation efficiencies in the second stage were also increased when the current density, flowrate and membrane area were increased. Electron Spectroscopy for Chemical Analysis was used to examine the surface chromate species for stage 1, and anion exchange membrane showed more chromate fouling comparing to cation exchange membrane due to more adsorption and concentration polarization effects for the anion exchange membrane.

Keywords: Chromate; Concentration; Purification; Two-stage electrodialysis; Electroplating wastewater

Seedless copper electroplating on Ta from a “single” electrolytic bath Original Research Article
Electrochimica Acta, Volume 55, Issue 5, 1 February 2010, Pages 1656-1663
David Starosvetsky, Nina Sezin, Yair Ein-Eli
An alternative approach for copper electroplating on Ta surface from a “single” injected bath is being described in this work. Copper electrodeposition over a thin TaN/Ta barrier was performed in a two-step process: (1) activation conducted by electrochemically reduction of Ta oxide from the TaN/Ta barrier at a negative potential of −2 V for a short period (“removal” step) and (2) copper electroplating performed in the invariable electrochemical bath by injecting a solution containing Cu-ions. Supplementary Cu plating is continued by shifting the applied potential to −1.2 V in the same electrolytic bath. It was also established that addition of low content (up to 10 ppm) dimercaptothiadiazole (DMcT) improves Cu nucleation and growth on Ta surface and allows a conformal features fillings. Copper layer deposited is characterized with an excellent adhesion to the Ta surface.

Keywords: Electroplating; Seedless copper; Ta barrier; Single bath; Oxide removal

Fabrication and characterization of Cu–Ni–YSZ SOFC anodes for direct use of methane via Cu-electroplating Original Research Article
International Journal of Hydrogen Energy, Volume 34, Issue 13, July 2009, Pages 5537-5545
Eon Woo Park, Hwan Moon, Moon-soo Park, Sang Hoon Hyun
The Cu–Ni–YSZ cermet anodes for direct use of methane in solid oxide fuel cells have been fabricated by electroplating Cu into a porous Ni–YSZ cermet anode. The uniform distribution of Cu in the Ni–YSZ anode was obtained by electroplating in an aqueous solution mixture of CuSO4•5H2O and H2SO4 for 30 min with 0.1 A of applied current. When the Cu–Ni–YSZ anode was exposed to methane at 700 °C, the amount of carbon deposited on the anode decreased as the amount of Cu in the Cu–Ni solid solution increased. The power density (0.24 W/cm2) of a single cell with a Cu–Ni–YSZ anode was slightly lower in methane at 700 °C than the power density (0.28 W/cm2) of a single cell with a Ni–YSZ anode. However, the performance of the Ni–YSZ anode-supported single cell degraded steeply over 21 h because of carbon deposition, whereas the Cu–Ni–YSZ anode-supported single cell showed enhanced durability up to 200 h.

Keywords: Solid oxide fuel cell; Methane fuel; Carbon deposition; Direct oxidation; Cu-electroplating

Evaluation of a low-cost adsorbent for removal of toxic metal ions from wastewater of an electroplating factory Original Research Article
Journal of Environmental Management, Volume 90, Issue 11, August 2009, Pages 3340-3344
Francisco W. Sousa, Marcelo James Sousa, Isadora R.N. Oliveira, André G. Oliveira, Rivelino M. Cavalcante, Pierre B.A. Fechine, Vicente O.S. Neto, Denis de Keukeleire, Ronaldo F. Nascimento
In this study, sugar cane residue or bagasse was used for removal of toxic metal ions from wastewater of an electroplating factory located in northeast Brazil. Prior acid treatment increased the adsorption efficacies in batch wise experiments. The microstructure of the material before and after the treatment was investigated by X-ray diffraction, infrared spectroscopy and scanning electron microscopy. Column operations showed that removals of Cu2+, Ni2+ and Zn2+ from wastewater (in the absence of cyanide) were 95.5%, 96.3.0%, and 97.1%, respectively. Regeneration of the adsorbent obtained in acid indicated that the efficiencies decreased only after the fourth cycle of re-use. Acid-treated sugar cane bagasse can be considered a viable alternative to common methods to remove toxic metal ions from aqueous effluents of electroplating industries.

Keywords: Electroplating wastewater; Toxic metal ions; Adsorption; Sugar cane bagasse

Preparation, characterization and performance of nanofiltration membranes for the treatment of electroplating industry effluent Original Research Article
Separation and Purification Technology, Volume 65, Issue 3, 12 March 2009, Pages 282-289
Alka G. Boricha, Z.V.P. Murthy
Two new nanofiltration (NF) membranes were prepared by coating (cast and spray) of strong chelating agent diethylene triamine pentaacetic acid (DTPA), using polyether sulfone (PES) ultrafiltration (UF) membrane as substrate and their performance were studied to treat actual electroplating industry wastewater. The resulting membranes, observed to be nanofiltration membranes, were characterized with the help of scanning electron microscopy (SEM) and swelling behavior. The structure of sprayed membranes was observed to be more porous than that of cast membranes and hence, the sprayed membranes gave higher permeation rate than that of cast membranes. Effects of pressure, feed flow rate, feed pH, and concentration of DTPA on the rejection of zinc and iron were investigated. The rejection was higher for cast membrane when compared to spray membrane. The maximum observed rejection for cast and spray membranes was found to be 94% and 89% for zinc and 93% and 88% for iron, respectively. The rejection of SS and TDS was over 99.4%. From the experimental results it was evident that as pressure, and feed flow increased, the observed rejection of both the metal ions increased. Also, it was observed that the feed pH had great effect on permeate flux but marginal influence on observed rejection for both ions.

Keywords: Nanofiltration; Cast coating; Spray coating; Electroplating wastewater; Rejection

3D metallo-dielectric structures combining electrochemical and electroplating techniques Original Research Article
Microelectronic Engineering, Volume 87, Issues 5-8, May-August 2010, Pages 1458-1462
D. Hernández, D. Lange, T. Trifonov, M. Garín, M. García, A. Rodríguez, R. Alcubilla
Three-dimensional (3D) periodic nickel micro-structures with a periodicity of 4 μm and high number of structural periods were fabricated by electrodeposition. Macroporous silicon, consisting of periodic arrays of sine-wave modulated pores, was used as a deposition template. It was prepared by electrochemical etching of silicon and subsequent pore widening by multiple oxidation/oxide-removal steps. The pore widening allows to open windows between adjacent pores obtaining a 3D network of interconnected voids embedded in silicon. This structure is then void-free filled with nickel in the electroplating process. The combination of electrochemical etching and electroplating techniques opens a route for the fabrication of large-scale 3D-periodic metallic micro-structures.

Keywords: Macroporous silicon; Three-dimensional structures; Electrochemical etching; Electroplating; Photonic crystals

Corrosion protection of galvanized steel and electroplating steel by decanoïc acid in aqueous solution: Electrochemical impedance spectroscopy, XPS and ATR-FTIR Review Article
Corrosion Science, Volume 51, Issue 6, June 2009, Pages 1201-1206
M. Lebrini, G. Fontaine, L. Gengembre, M. Traisnel, O. Lerasle, N. Genet
The inhibiting action of decanoïc acid towards the corrosion behaviour of galvanized steel and electroplating steel in aqueous solution has been studied using electrochemical impedance spectroscopy (EIS) techniques. Data obtained from EIS show a frequency distribution and therefore a modelling element with frequency dispersion behaviour, a constant phase element (CPE) has been used. Results obtained revealed that decanoïc acid is an effective inhibitor. The better performance was obtained in the case of electroplating steel. X-ray photoelectron spectroscopy surface analysis shows that, decanoïc acid is chemisorbed on surface of galvanized steel and electroplating steel. These studies have shown that the active site for binding the film on metal surface is the anionic carboxylate head. Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) spectroscopy was used to identify the nature of the deposits on the metal surface.
Keywords: Decanoïc acid; Corrosion inhibitors; Galvanized steel; Electroplating steel; Aqueous solution

Extractive separation and determination of chromium in tannery effluents and electroplating waste water using tribenzylamine as the extractant Original Research Article
Journal of Hazardous Materials, Volume 165, Issues 1-3, 15 June 2009, Pages 886-892
S. Kalidhasan, M. Ganesh, S. Sricharan, N. Rajesh
A simple extractive separation method has been developed for the determination of chromium based on the extraction of Cr (VI) as its ion-pair with tribenzylamine (TBA). The ion-pair is extracted at acidic pH using toluene as the diluent. The concentration of chromium in the organic phase was measured spectrophotometrically at 309 nm. The influence of experimental variables such as pH, sample volume, equilibration time, diverse ions etc. has been studied in detail. The extracted chromium (VI) could be stripped to the aqueous phase using NaOH as the stripping agent. The extracts were characterized using FT-IR spectroscopy. A detection limit of 0.08 μg mL−1 could be achieved and the validity of the method was checked in real tannery effluent, electroplating waste water and spiked water samples.

Keywords: Chromium (VI); Tribenzylamine; Toluene; Tannery effluent; Electroplating waste water

A new capillary electrophoresis buffer for determining organic and inorganic anions in electroplating bath with surfactant additives Original Research Article
Journal of Chromatography A, Volume 1217, Issue 19, 7 May 2010, Pages 3244-3250
H. Sun, K.M. Lau, Y.S. Fung
Monitoring of trace impurities in electroplating bath is needed to meet EU requirements for WEEE and RoHS and for quality control of electrodeposits. Methods using IC and 100% aqueous CE buffer were found producing non-repeatable results attributed to interference of surfactants and major methanesulphonate anion. A new CE buffer containing 1.5 mM tetraethylenepentaamine, 3 mM 1,3,5-benzenetricarboxylic acid and 15 mM Tris in 20% (v/v) methanol at pH = 8.4 was shown to enhance the separation window, reduce interaction between buffer and bath constituents, and give satisfactory repeatability with baseline separation for 14 organic and inorganic anions within 14 min, good repeatability for migration time (0.32–0.57% RSD), satisfactory peak area and peak height (2.9–4.5 and 3–4.7% respectively), low detection limit (S/N = 2, 20–150 ppb), and wide working ranges (0.1–100 ppm). The CE buffer with 20% (v/v) methanol has demonstrated its capability for identifying anion impurities causing problem in aged tin bath and the use of only 10-fold dilution to produce reliable results for quality assessment in plating bath containing high surfactant additives.

Keywords: Capillary zone electrophoresis; Ion chromatography; High methanol buffer; Surfactant interference; Electroplating bath

Studies on influence of zinc immersion and fluoride on nickel electroplating on magnesium alloy AZ91D Original Research Article
Applied Surface Science, Volume 255, Issue 17, 15 June 2009, Pages 7773-7779
Ziping Zhang, Gang Yu, Yuejun Ouyang, Xiaomei He, Bonian Hu, Jun Zhang, Zhenjun Wu

The effect of zinc immersion and the role of fluoride in nickel plating bath were mainly investigated in nickel electroplating on magnesium alloy AZ91D. The state of zinc immersion, the composition of zinc film and the role of fluoride in nickel plating bath were explored from the curves of open circuit potential (OCP) and potentiodynamic polarization, the images of scanning electron microscopy (SEM) and the patterns of energy dispersive X-ray (EDX). Results show that the optimum zinc film mixing small amount of Mg(OH)2 and MgF2 is obtained by zinc immersion for 30–90 s. The corrosion potential of magnesium alloy substrate attached zinc film will be increased in nickel plating bath and the quantity of MgF2 sandwiched between magnesium alloy substrate and nickel coating will be reduced, which contributed to produce nickel coating with good performance. Fluoride in nickel plating bath serves as an activator of nickel anodic dissolution and corrosion inhibitor of magnesium alloy substrate. 1.0–1.5 mol dm−3 of F− is the optimum concentration range for dissolving nickel anode and protecting magnesium alloy substrate from over-corrosion in nickel plating bath. The nickel coating with good adhesion and high corrosion resistance on magnesium alloy AZ91D is obtained by the developed process of nickel electroplating. This nickel layer can be used as the rendering coating for further plating on magnesium alloys.

Keywords: Magnesium alloy; Electroplating nickel; Zinc immersion; Fluoride; Adhesion; Corrosion resistance

A game-theoretic analysis of implementation of cleaner production policies in the Chinese electroplating industry Original Research Article
Resources, Conservation and Recycling, Volume 54, Issue 12, October 2010, Pages 1442-1448
Xiaoqing Dong, Chaolin Li, Ji Li, Jia Wang, Wantao Huang
Cleaner production plays an important role in minimizing the consumption of water, raw materials, energy, and the generation of waste during industrial processes. Tax breaks, equipment subsidies and penalties are often considered the main policy tools for promoting enterprises to adopt cleaner production technologies, especially in Chinese electroplating industry. However, the results of these policies implementation are confronting with some uncertainty because of the conflicts of the interest between players involved. This paper presents a framework for analyzing the conflicts between a local government and a potentially polluting firm by using game theory. We enriched the model by adding policy variables, such as psychological costs (m), environmental benefit evaluation (E), and reward local government for its implementation (R), to change the payoffs, which can improve the current policies. Using theoretical and numerical analysis, the effects of subsidies, penalties and other policy variables on implementation of cleaner production were obtained.

Keywords: Game theory; Electroplating industry; Cleaner production; Policy

The preparation of lotus-like super-hydrophobic copper surfaces by electroplating Original Research Article
Applied Surface Science, Volume 255, Issue 9, 15 February 2009, Pages 4836-4839
Wenjun Xi, Zhenmei Qiao, Chunlei Zhu, Ao Jia, Ming Li
The preparation of super-hydrophobic metal surfaces had to combine rough structures and the surface modifications with low surface energy materials. Although there were different views on it, no experiment was done to prove it yet. In this paper, the structure of natural lotus leaf was observed and the lotus-like surfaces on hydrophilic copper substrates were fabricated via electroplating in large current density. These surfaces were super-hydrophobic without any chemical modification. The hydrophobic mechanism was analyzed. It is believed that this was a meta-stable state in Cassie model. As long as the surface structure was suitable, hydrophobic surface, even super-hydrophobic surface, could be got on hydrophilic substrate.

Keywords: Super-hydrophobic; Electroplating; Rough surface; Lotus leaves structure; Hydrophilic materials

Sol-enhanced electroplating of nanostructured Ni–TiO2 composite coatings—The effects of sol concentration on the mechanical and corrosion properties Original Research Article
Electrochimica Acta, Volume 55, Issue 22, 1 September 2010, Pages 6865-6871
Weiwei Chen, Wei Gao
Novel sol-enhanced Ni–TiO2 nano-composite coatings were electroplated by adding a transparent TiO2 sol into the traditional electroplating Ni solution. It was found that the structure, mechanical properties and corrosion resistance of the nano-composite coatings were largely determined by the sol concentration. The higher sol concentration in the plating electrolyte led to a higher content of TiO2 nano-particles in the coating matrix. The coating prepared at the sol concentration of 12.5 mL/L had the best microhardness, wear resistance and corrosion resistance. Adding excessive sol to the electrolyte changed the surface microstructure, caused cracking on the coating surface and deteriorated the properties. It was demonstrated that the corrosion resistance of the composite coatings is determined by two factors: surface microstructure and incorporation of TiO2 nano-particles.

Keywords: Sol-enhanced electroplating; Ni–TiO2 composite coatings; Microhardness; Wear resistance; Corrosion resistance

Micro-scale modification of diamond-like carbon and copper electroplating by scanning probe field emission current method Original Research Article
Superlattices and Microstructures, Volume 45, Issues 4-5, April-May 2009, Pages 326-331
Shigehiro Hayashi, Yuki Antoku, Younggun Han, Woon Choi, Hajime Tomokage
Micro-scale modification of nitrogen-doped diamond-like carbon (DLC) is performed by applying an electric field between a tungsten tip and DLC film surface in vacuum using the scanning probe field emission current (SPFEC) method. The dc voltage ranging from −700 V to −3000 V is applied to the tip. Then, electroplating of Cu is performed on the DLC film surface in CuCl2 solution by a three electrode-cell. The cathodic polarization curves indicate that the start potential of Cu on modified DLC film is shifted to a lower value than that of Cu on an as-grown DLC film. Cu deposits selectively on the DLC surface modified by an electric field. With this technique, the micro-scale patterning of Cu can be achieved by electroplating without a lithographic process.

Keywords: Diamond-like carbon; Copper electroplating; Maskless patterning

Microvia filling by copper electroplating using diazine black as a leveler Original Research Article
Electrochimica Acta, Volume 54, Issue 24, 1 October 2009, Pages 5894-5901
Wei-Ping Dow, Chih-Chan Li, Yong-Chih Su, Shao-Ping Shen, Chen-Chia Huang, Cliff Lee, Bob Hsu, Shar Hsu
An organic additive, Diazine Black (DB), was employed as a leveler for microvia filling using copper electroplating. DB is a derivative of Janus Green B (JGB), which is a common leveler used for copper fill of submicron or micron circuit metallization in electronic products. This study determined the optimal DB concentration for achieving the best filling performance. The electrochemical behavior of DB and its interaction with other additives, such as a suppressor and an accelerator were characterized using galvanostatic measurements. These electrochemical analyses helped explaining the filling mechanism of the plating formula containing the DB. Various surface morphologies and the crystalline orientation of the plated copper films caused by different DB concentrations were characterized by a scanning electron microscope (SEM) and X-ray diffraction (XRD), respectively. The corresponding chemical activity of the surface atoms of the plated copper films caused by different DB concentrations was characterized using a test of etching rate.

Keywords: Copper electroplating; Leveler; Microvia filling

Proton beam written hydrogen silsesquioxane (HSQ) nanostructures for Nickel electroplating Original Research Article
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 267, Issues 12-13, 15 June 2009, Pages 2309-2311
S. Gorelick, F. Zhang, P.G. Shao, J.A. van Kan, Harry J. Whitlow, F. Watt
Hydrogen silsesquioxane (HSQ) behaves as a negative resist under MeV proton beam exposure. HSQ is a high-resolution resist suitable for production of tall high-aspect-ratio nanostructures with dimensions down to 22 nm. High-aspect-ratio HSQ structures are required in many applications, e.g. nanofluidics, biomedical research, etc. Since P-beam writing is a direct and hence slow process, it is beneficiary to fabricate a reverse image of the patterns in a metallic stamp, e.g. by Ni electroplating. The Ni stamp can then be used to produce multiple copies of the same pattern. In this study we investigate the possibility to produce Ni stamps from p-beam written HSQ samples. HSQ high aspect ratio nanostructures, however, tend to detach from Au/Si substrates (typically used in electroplating) during the development process due to the weak adhesive forces between the resist and the substrate material. To determine an optimal substrate material and the proton irradiation doses for HSQ structures, a series of m long and 60–600 nm wide free-standing lines were written with varying doses of 2 MeV protons in 1.2μm thick HSQ resist spun on Ti/Si, Cr/Si and Au/Cr/Si substrates. The results indicate that both Ti/Si and Cr/Si substrates are superior in terms of adhesion. The adhesion of high aspect ratio HSQ nanostructures to Au/Cr/Si is poor with a maximum aspect ratio of the adhering structures not exceeding two. Cr/Si is not suitable as a substrate for HSQ resist as debris is formed around the structures, presumably due to a chemical reaction between the resist and Cr.
PACS: 29.20.Ba; 42.82.Cr; 47.55.dr; 68.35.Np; 68.35.Fx; 81.07.−b

Keywords: Proton beam writing; Hydrogen silsesquioxane; High aspect ratio; Ni electroplating; Ti; Cr

Electroplating using high-aspect-ratio microstructures fabricated by proton beam writing Original Research Article
Microelectronic Engineering, Volume 86, Issues 4-6, April-June 2009, Pages 945-948
Y. Seki, Y. Furuta, H. Nishikawa, T. Watanabe, T. Nakata, T. Satoh, Y. Ishii, T. Kamiya
Proton beam writing (PBW) is one of the direct write techniques for the purpose of deep micromachining. Together with the flexibility of the direct write feature, micromachining of high-aspect-ratio structures is possible due to the straight trajectory of the MeV energy protons. However, direct writing is a low throughput process, when compared with a mask process such as UV lithography. For better productivity, coupled use of PBW with electroplating has been proposed as a method to fabricate metal microstructures for molds of imprint lithography. We demonstrate the electroplating of high-aspect-ratio Ni microstructures on PMMA micromachined by PBW.

Keywords: Proton beam writing; Electroplating; Microstructures; PMMA

On the structure of micrometer copper features fabricated by intermittent micro-anode guided electroplating Original Research Article
Electrochimica Acta, Volume 54, Issue 24, 1 October 2009, Pages 5703-5708
J.C. Lin, J.H. Yang, T.K. Chang, S.B. Jiang
Micrometer copper features were fabricated by an intermittent micro-anode guided electroplating (MAGE) process and revealed different structures depending upon the experimental conditions. A hollow microtube was developed at 4.0 V with an initial distance of 2 μm/step. By decreasing the voltage from 4.0 to 3.2 V while increasing the initial distance from 2 to 25 μm/step, a dense copper column with a smooth surface was formed instead of a rough-surfaced tube. The dense column was prepared on a base with larger area compared to that used for the hollow tube. The observation of different structures by electrochemical deposition could be explained using a quantitative model based on finite element analysis. According to this model, the structure is determined by the ratio of field strength at the periphery to that in the center (i.e., Ee/Et) of the location. Using a ratio higher than 1.5 results in hollow tubes, whereas a ratio less than 1.0 produces dense pillars.

Keywords: Micro-hollow tube; Dense microcolumn; Micrometer feature; Micro-anode guided electroplating; Electric-field strength

Failure behavior of ITO diffusion barrier between electroplating Cu and Si substrate annealed in a low vacuum Original Research Article
Applied Surface Science, Volume 255, Issue 16, 30 May 2009, Pages 7357-7360
S.H. Hsieh, C.M. Chien, W.L. Liu, W.J. Chen
A structure of Cu/ITO(10 nm)/Si was first formed and then annealed at various temperatures for 5 min in a rapid thermal annealing furnace under 10−2 Torr pressure. In Cu/ITO(10 nm)/Si structure, the ITO(10 nm) film was coated on Si substrate by sputtering process and the Cu film was deposited on ITO film by electroplating technique. The various Cu/ITO(10 nm)/Si samples were characterized by a four-point probe, a scanning electron microscope, an X-ray diffractometer, and a transmission electron microscope. The results showed that when the annealing temperature increases near 600 °C the interface between Cu and ITO becomes unstable, and the Cu3Si particles begin to form; and when the annealing temperature increases to 650 °C, a good many of Cu3Si particles about 1 μm in size form and the sheet resistance of Cu/ITO(10 nm)/Si structure largely increases.
Keywords: Diffusion barrier; Indium Tin Oxide (ITO); Electroplating Cu; Cu metallization; Si substrate

Effect of Electroplating Parameters on Microstructure of Nanocrystalline Nickel Coatings Original Research Article
Journal of Materials Science & Technology, Volume 26, Issue 1, January 2010, Pages 82-86
A.M. Rashidi, A. Amadeh
In order to achieve the optimum conditions for electroplating nanocrystalline nickel coating from Watts-type bath, the effect of some process parameters namely, bath temperature, current density, and saccharin addition on grain size and texture coefficient (TC= I(200)/I(111)) of the deposits were investigated by X-ray diffraction (XRD). The results showed that in a bath containing 5 g/L saccharin, by increasing the bath temperature from 45°C to 55°C, the grain size decreased, whereas further increase of bath temperature resulted in a contrary effect. By increasing the current density from 10 to 75 mA/cm2, both the grain size and TC decreased, while further increase in current density had no significant effect on the grain size. At a given current density, the grain size and TC decreased rapidly by increasing the saccharin content before leveling off at 3 g/L of saccharin. Finally, based on the grain refining the optimum conditions for producing nanocrystalline nickel coating from Watts-type bath have been proposed.

Key Words: Electroplating; Grain size; Nanocrystalline; Coating

Synthesis of silver nanowires via electroplating technology and its surface enhanced Raman scattering effect Original Research Article
Applied Surface Science, Volume 255, Issue 20, 30 July 2009, Pages 8571-8574
Zhiwei Li, Huabin Song, Zhimei Yang, Yong Jin, Zhifeng Jiao, Yunsen Zhang, Yanli Gao, Zhou Yu, Wenyu Li, Min Gong, Xiaosong Sun
This very paper is focusing on the preparation of silver nanostructures and the surface enhanced Raman scattering effect of the silver nanostructures produced. Via electroplating technology, silver nanowires and nanoparticles were prepared on silicon wafers. Characterization was performed by X-ray diffraction, scanning electron microscope, transmission electron microscope equipped with X-ray energy dispersion spectroscope and selected area electron diffraction, which reveals that the formation of silver nanostructures depends on the over-potential. The produced silver nanowires are of crystalline FCC structure and grow in 〈0 1 1〉 direction. The growth mechanism has been further discussed. The surface enhanced Raman scattering effect is achieved with the silver nanostructures produced.

Keywords: Silver; Nanomaterials; Electroplating; Surface enhanced Raman scattering

Proton beam writing and electroplating for the fabrication of high aspect ratio Au microstructures Original Research Article
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 267, Issue 14, 1 July 2009, Pages 2376-2380
Weisheng Yue, Yaping Ren, Jeroen Anton van Kan, Sher-Yi Chiam, Linke Jian, Herbert O. Moser, Thomas Osipowicz, Frank Watt

We present an approach to fabricate tall high aspect ratio Au microstructures by means of proton beam direct writing. Combining proton beam direct writing and electroplating, we successfully produced gold structures with sub-micrometer lateral dimensions, structure heights in excess of 11 μm, and aspect ratios over 28. Sidewall quality of the Au structures was improved by lowering the process temperature to 20 °C when developing PMMA patterns with GG developer. The application of such structures as X-ray masks for deep X-ray lithography with synchrotron radiation was demonstrated.

Keywords: Proton beam writing; High aspect ratio; Electroplating; Au microstructure

Electroplating to visualize defects in Al2O3 thin films grown using atomic layer deposition
Thin Solid Films, Volume 517, Issue 11, 2 April 2009, Pages 3269-3272
Yadong Zhang, Jacob A. Bertrand, Ronggui Yang, Steven M. George, Y.C. Lee
Thin films grown using atomic layer deposition (ALD) are known for being continuous and nearly pinhole-free. These characteristics enable ALD films to be important in many applications such as gas or copper diffusion barriers, gate dielectrics, surface modification and functionalization layers. Few methods have been demonstrated to characterize defects in ALD films. In this study, a method to render the defects visible in Al2O3 ALD thin films on conductive substrates has been developed by growing copper bumps locally at the defect sites using electroplating. The electroplated copper can be easily observed or inspected using conventional optical- or electron-microscopy. Using this approach, the defect density in Al2O3 ALD thin films grown on nickel substrates has been shown to be as low as 38 /cm2.

Keywords: Defect Visualization; Atomic Layer Deposition (ALD); Electroplating; Thin Films; Diffusion Barriers

Bottom-up copper electroplating using transfer wafers for fabrication of high aspect-ratio through-silicon-vias Original Research Article
Microelectronic Engineering, Volume 87, Issue 3, March 2010, Pages 510-513
Chongshen Song, Zheyao Wang, Litian Liu
Three-dimensional (3D) integration is emerging as an attractive technology to continue Moore’s law through the integration of multi-stacked chips interconnected with through-silicon-vias (TSVs). To address the challenge in filling high aspect-ratio TSVs with copper, this paper reports an improved bottom-up copper electroplating (BCE) technique by introducing a glass transfer wafer, which is temporarily bonded with the device wafer to provide a copper seed layer. As the copper seed layer on the transfer wafer covers the through-holes, copper is electroplated from the bottom seed layer to the top opening of the through-holes without forming any voids or seams. This avoids the time consuming sealing process in conventional BCE, which normally takes 3–5 h. Thanks to the mechanical support of the transfer wafer, the device wafer can be thinned to several tens of micrometers. Using this technique, TSVs with diameter of 5 μm and aspect-ratio of 13:1 have been achieved. Based on the improved BCE technique, a through-via type 3D integration strategy is developed.

Keywords: 3D integration; Bottom-up copper electroplating (BCE); Through-silicon-vias (TSVs); Transfer wafer

Influence of carbonation on the acid neutralization capacity of cements and cement-solidified/stabilized electroplating sludge Original Research Article
Chemosphere, Volume 74, Issue 6, February 2009, Pages 758-764
Quanyuan Chen, Lina Zhang, Yujuan Ke, Colin Hills, Yanming Kang
Portland cement (PC) and blended cements containing pulverized fuel ash (PFA) or granulated blast-furnace slag (GGBS) were used to solidify/stabilize an electroplating sludge in this work. The acid neutralization capacity (ANC) of the hydrated pastes increased in the order of PC > PC/GGBS > PC/PFA. The GGBS or PFA replacement (80 wt%) reduced the ANC of the hydrated pastes by 30–50%. The ANC of the blended cement-solidified electroplating sludge (cement/sludge 1:2) was 20–30% higher than that of the hydrated blended cement pastes. Upon carbonation, there was little difference in the ANC of the three cement pastes, but the presence of electroplating sludge (cement/sludge 1:2) increased the ANC by 20%. Blended cements were more effective binders for immobilization of Ni, Cr and Cu, compared with PC, whereas Zn was encapsulated more effectively in the latter. Accelerated carbonation improved the immobilization of Cr, Cu and Zn, but not Ni. The geochemical code PHREEQC, with the edited database from EQ3/6 and HATCHES, was used to calculate the saturation index and solubility of likely heavy metal precipitates in cement-based solidification/stabilization systems. The release of heavy metals could be related to the disruption of cement matrices and the remarkable variation of solubility of heavy metal precipitates at different pH values.

Keywords: Solidification/stabilization; Heavy metals; Blended cement; Accelerated carbonation; Thermodynamic modeling

New environmentally friendly noncyanide alkaline electrolyte for copper electroplating Original Research Article
Surface and Coatings Technology, Volume 203, Issues 10-11, 25 February 2009, Pages 1360-1365
Z. Abdel Hamid, A. Abdel Aal
This article presents a novel noncyanide alkaline bath for electroplating thin copper films on stainless steel substrate. A detailed study was made about the effect of the operating parameters (current density and temperature), concentration of complexing agent on cathodic current efficiency (CCE %) and the characteristics of the deposited layers. The addition of sorbitol as complexing agent to the plating bath assists in the formation of fine-grained and highly adherent copper film. The phase structure and surface morphology of the deposited films were examined by using X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The analysis of XRD patterns showed that the crystallographic orientation of copper deposits is independent on the current density while the bath efficiency is function of the applied current density, operating bath temperature and sorbitol concentration. The corrosion rate of copper films depends on the current density and the films deposited at 2 A dm− 2 exhibited the best corrosion performance.

Keywords: Copper electrodeposition; Environmental coatings; Complexing agent; Free cyanide bath; Cathodic current efficiency

Feasibility of a two-stage biological aerated filter for depth processing of electroplating-wastewater Original Research Article
Bioresource Technology, Volume 100, Issue 17, September 2009, Pages 3891-3896
Bo Liu, Dongdong Yan, Qi Wang, Song Li, Shaogui Yang, Wenfei Wu
A “two-stage biological aerated filter” (T-SBAF) consisting of two columns in series was developed to treat electroplating-wastewater. Due to the low BOD/CODcr values of electroplating-wastewater, “twice start-up” was employed to reduce the time for adaptation of microorganisms, a process that takes up of 20 days. Under steady-state conditions, the removal of CODcr and increased first and then decreased while the hydraulic loadings increased from 0.75 to 1.5 m3 m−2 h−1. The air/water ratio had the same influence on the removal of CODcr and when increasing from 3:1 to 6:1. When the hydraulic loadings and air/water ratio were 1.20 m3 m−2 h−1 and 4:1, the optimal removal of CODcr, and total-nitrogen (T-N) were 90.13%, 92.51% and 55.46%, respectively. The effluent steadily reached the wastewater reuse standard. Compared to the traditional BAF, the period before backwashing of the T-SBAF could be extended to 10 days, and the recovery time was considerably shortened.

Keywords: Hydraulic loading; Air/water ratio; Backwashing; B/C value; T-N

Using electrode electrolytes to enhance electrokinetic removal of heavy metals from electroplating sludge Review Article
Chemical Engineering Journal, Volume 165, Issue 2, 1 December 2010, Pages 388-394
Guiqun Peng, Guangming Tian
An enhanced EK (electrokinetic) process for the removal of heavy metals from an electroplating sludge was performed by adding electrolytes in electrode chambers. The EK experiments were conducted under a constant cell potential (32 V) for 5 days using tap water (TW) and aqueous solution containing sodium dodecylsulfate (SDS) and citric acid (CA) as electrolytes. The results indicated the removal efficiency of heavy metals using TW and aqueous solution containing SDS and CA as electrolytes were 20–51%, 26–65% and 34–69%, respectively, the highest metal removal performance was found using CA as electrolyte. And the removal efficiency of the five metals from sludge in all the EK experiments was Cr > Zn > Ni > Cu > Pb. And sequential extraction analysis revealed that the binding forms of heavy metals with sludge highly depended on the electrolytes, changed from the most difficult extraction type (residual form) to the easier extraction types (soluble, exchangeable, sorbed, sulfate and carbonate forms) after electrokinetic process.

Keywords: Citric acid; Surfactant; Electrokinetic remediation; Heavy metal; Sludge

Selective recovery of copper, nickel and zinc from ashes produced from Saccharomyces cerevisiae contaminated biomass used in the treatment of real electroplating effluents Original Research Article
Journal of Hazardous Materials, Volume 184, Issues 1-3, 15 December 2010, Pages 357-363
Manuela D. Machado, Eduardo V. Soares, Helena M.V.M. Soares
The aim of this work was to seek an environmentally friendly process for recycling metals from biomass-sludges generated in the treatment of industrial wastewaters. This work proposes a hybrid process for selective recovery of copper, nickel and zinc from contaminated biomass of Saccharomyces cerevisiae, used in the bioremediation of electroplating effluents. The developed separation scheme comprised five consecutive steps: (1) incineration of the contaminated biomass; (2) microwave acid (HCl) digestion of the ashes; (3) recovery of copper from the acid solution by electrolysis at controlled potential; (4) recycle of nickel, as nickel hydroxide, by alcalinization of the previous solution at pH 14; (5) recovery of zinc, as zinc hydroxide, by adjusting the pH of the previous solution at 10. This integrated approach allowed recovering each metal with high yielder (>99% for all metals) and purity (99.9%, 92% and 99.4% for copper, nickel and zinc, respectively). The purity of the metals recovered allows selling them in the market or being recycled in the electroplating process without waste generation.

Key words: Chemical precipitation; Chemical speciation; Electrolysis; Heavy metals recovery; Incineration

Iron isotope electroplating: Diffusion-limited fractionation Original Research Article
Chemical Geology, Volume 267, Issues 3-4, 30 September 2009, Pages 131-138
A. Kavner, A. Shahar, J. Black, E.D. Young
Electron-transfer related isotope fractionation may produce large stable isotope geochemical signatures as a result of a variety of Earth processes, including biology, chemical weathering, fluid–rock interactions, and deep Earth redox reactions. In the laboratory, isotope fractionation at a charged electrode has been observed for electroplating of Fe and Zn; however these can arise from a variety of effects besides the electron transfer process. Here, we examine the effect of mass transport on observed isotope fractionation during potentiostatic electroplating of iron. We examine the observed isotope fractionation as a function of the ratio of the observed plating current to the mass-transport limited current (the Cottrell current). When the electroplating experiments are run at currents greater than the Cottrell current, the observed fractionation is ~− 1.15(± 0.40) ‰, and the extent of fractionation shows a tendency to decrease with increasing plating rate. When electroplating experiments are run at currents below the Cottrell current, observed fractionations are strongly dependent on the plating rate, with a maximum value of δ56Fe = − 4.8. The data set demonstrates that mass transport to the electrode tends to attenuate a large fractionation factor associated with other, non-mass transport, processes at the electrode.

Keywords: Electrochemistry; Redox; Diffusion; Stable isotope fractionation; Fe stable isotopes

Removal of heavy metals using a brewer's yeast strain of Saccharomyces cerevisiae: Chemical speciation as a tool in the prediction and improving of treatment efficiency of real electroplating effluents Original Research Article
Journal of Hazardous Materials, Volume 180, Issues 1-3, 15 August 2010, Pages 347-353
Manuela D. Machado, Eduardo V. Soares, Helena M.V.M. Soares
In the present work, the influence of the competitive effect of inorganic ligands (carbonates, chlorides, fluorides, phosphates, nitrates and sulphates), which can be present in real multi-metal electroplating effluents, on the biosorption of chromium, copper, nickel and zinc ions by yeast cells of Saccharomyces cerevisiae was rationally examined. Additionally, chemical speciation studies allowed optimizing the amount of yeast biomass to be used in the treatment of effluents contaminated with nickel.
The applicability of chemical simulation studies was tested using two simulated effluents and validated using one real electroplating effluent, all containing high concentrations of nickel (about 303 μmol l−1). For nickel removal, heat-killed biomass of a brewing flocculent strain of S. cerevisiae was used, in a batch mode. After the implementation of the bioremediation process (12 g dry weight l−1 of yeast cells), the concentration of nickel in the real effluent (34 μmol l−1) reached the quality criteria for industrial effluents discharge, after the second or third batch according to the U.S.-Environmental Protection Agency and Portuguese law, respectively. This corresponded to a removal of nickel of 89%.

Keywords: Bioremediation; Biosorption; Chemical speciation; Heavy metals; Metals bioavailability

An overview of the recovery of acid from spent acidic solutions from steel and electroplating industries Review Article
Journal of Hazardous Materials, Volume 171, Issues 1-3, 15 November 2009, Pages 61-75
Archana Agrawal, K.K. Sahu
Every metal and metallurgical industry is associated with the generation of waste, which may be a solid, liquid or gaseous in nature. Their impacts on the ecological bodies are noticeable due to their complex and hazardous nature affecting the living and non-living environment which is an alarming issue to the environmentalist. The increasingly stringent regulations regarding the discharge of acid and metal into the environment, and the increasing stress upon the recycling/reuse of these effluents after proper treatment have focused the interest of the research community on the development of new approaches for the recovery of acid and metals from industrial wastes. This paper is a critical review on the acidic waste streams generated from steel and electroplating industries particularly from waste pickle liquor and spent bleed streams. Various aspects on the generation of these streams and the methods used for their treatment either for the recovery of acid for reuse or disposal are being dealt with. Major stress is laid upon the hydrometallurgical methods such as solvent extraction.

Keywords: Acid extraction; Solvent extraction; Precipitation; Bleed stream; Waste pickle liquor

Electroplating of Cu(Ag) thin films for interconnect applications Original Research Article
Microelectronic Engineering, Volume 87, Issue 2, February 2010, Pages 180-186
S. Strehle, S. Menzel, J.W. Bartha, K. Wetzig
Electromigration effects in interconnect metallizations cause a need for materials with superior resistance against electromigration failure but with adequate electrical properties. In principle, Cu(Ag) alloys are potential candidates to become an interconnect material of the next generation of microelectronic devices. Therefore, in the following paper the electroplating of such Cu(Ag) alloys from a sulfuric acid electrolyte solution with varying silver content in a home built deposition tool is presented. Besides the general deposition characteristics, the growth mode of the films and the deposition into trenches will be discussed. The investigations show that Cu(Ag) alloys can be deposited with adequate homogeneity of the film thickness by electroplating. Furthermore, the electrical resistivity is low enough to assure a use of these films for interconnect applications. However, distinct island growth and insufficient trench filling capabilities lead to the fact that the additive composition needs to be optimized for Cu(Ag) thin film electroplating.

Keywords: Electrochemical deposition; Copper-silver alloy thin film; Interconnect material

Characteristics and accumulation of heavy metals in sediments originated from an electroplating plant Original Research Article
Journal of Hazardous Materials, Volume 163, Issues 2-3, 30 April 2009, Pages 922-930
Xiaoshuai Hang, Huoyan Wang, Jianmin Zhou, Changwen Du, Xiaoqin Chen
Heavy metals in river water and sediments originated from an electroplating plant in Jiangsu Province of China were studied and analyzed for their environmental impact. The results indicated that the wastewater from the plant degraded the quality of the aquatic environment downstream from the plant. In surface water, considerable concentrations of Cu, Ni, Zn, Mn and Cr were present at the sites near the plant. Unsafe levels of Cu were observed at all sites, and unsafe levels of Ni, Zn, and Cr were present at some sites. Significant accumulation of Ni, Cu, Zn and Cr was identified, and heavy metal longitudinal distribution in sediments was similar to that in water. The contents of Ni, Cu and Cr at all sites and Zn at some sites were likely to result in harmful effects on the environment. The risks posed by Ni, Cu, Zn and Cr in water and sediments decreased with increasing downstream distance. Moreover, a modified sequential extraction procedure was employed to determine exchangeable, carbonate-bound, iron–manganese oxide bound, organic matter bound and residual fractions of metals in sediments. The results showed that Ni was distributed in every fraction except for iron–manganese oxide bound, significant Mn exhibited in exchangeable fractions, and high percentage of Cu was in the organic matter and residual fractions. Residual fraction was the dominant fractions for Pb and Zn. According to RACs, Ni and Mn posed a high risk to the environment, Zn exhibited medium to high risk, Cu had low to high risk, and Pb possessed a low to medium risk.

Keywords: Distribution; Fraction; Metal; Risk assessment; Water

Biosorption of chromium from aqueous solution and electroplating wastewater using mixture of Candida lipolytica and dewatered sewage sludge Original Research Article
Bioresource Technology, Volume 101, Issue 11, June 2010, Pages 3893-3902
Jinshao Ye, Hua Yin, Bixian Mai, Hui Peng, Huaming Qin, Baoyan He, Na Zhang
In this study, the objective was to investigate Cr removal from aqueous solutions, as well as Cr, Cu, Ni and Zn from electroplating wastewaters by the mixture of Candida lipolytica and sewage sludge. The bioreduction ratios of Cr(VI) and the removal ratios of total Cr showed that initial pH, biosorbent dosage and contact time were the important parameters for Cr biosorption. The range of optimal pH for the mixture (1–5) was wider than C. lipolytica (1–4) and sewage sludge (2–4), respectively. Biosorption and bioreduction potentials of living C. lipolytica were better than those of cell wall and cytoplasm. Bonded hydroxyl group, CH2 asymmetric stretch, amide I, amide II, amide III, secondary amide, pyridine(I)β(C–H) and pyridine(II)β(C–H) were detected in the biosorbent and they were the functional groups for binding Cr. The effect of Cu and Zn in combination was significant on the removal of total Cr and the bioreduction of Cr(VI).

Keywords: Candida lipolytica; Chromium; Sewage sludge; Biosorption; Heavy metal

Fabrication of Ni-matrix carbon nanotube field emitters using composite electroplating and micromachining Original Research Article
Carbon, Volume 47, Issue 15, December 2009, Pages 3466-3471
Min Deng, Guifu Ding, Yan Wang, Huiqing Wu, Yuanjin Yao, Lida Zhu
Ni-matrix carbon nanotube (CNT) field emitters have been fabricated by composite electroplating and micromachining (CEMM) at room temperature. Pretreated multi-walled CNT and Ni are deposited onto a Cr/Cu conducting layer by composite electroplating and protruding tips of CNTs are obtained as emitters by etching away a layer of Ni, followed by emitter pixels which are formed by micromachining. Through the process of CEMM, CNTs are vertically embedded in the flat Ni substrate. No further treatment is needed to initiate or augment field emission and the field emitters exhibit good field-emission properties such as high current density (13 mA cm−2 at an applied electric field of 3.4 V μm−1), low turn-on field (0.53 V μm−1), and good stability (110 h for 10% degradation of current density from 400 μA cm−2).

Humic acid-immobilized polymer/bentonite composite as an adsorbent for the removal of copper(II) ions from aqueous solutions and electroplating industry wastewater Original Research Article
Journal of Industrial and Engineering Chemistry, Volume 16, Issue 1, 25 January 2010, Pages 130-139
T.S. Anirudhan, P.S. Suchithra
In this study, humic acid (HA) was immobilized onto amine-modified polyacrylamide/bentonite composite (Am-PAA-B) which was prepared by direct intercalation polymerization technique and the product (HA-Am-PAA-B) was used as an adsorbent for the removal of copper(II) ions from aqueous solutions. The surface characteristics of bentonite, Am-PAA-B and HA-Am-PAA-B were investigated. The adsorbent behaved like a cation exchanger and more than 99.0% Cu(II) ions’ removal was observed at the pH range 5.0–6.0. Kinetic and isotherm experiments showed that amount of Cu(II) ions adsorbed increases with increase of the initial concentration and temperature. The adsorption kinetic data were interpreted by pseudo-first-order and pseudo-second-order rate equations. The suitability of Langmuir, Freundlich and Dubinin–Radushkevich (D-R) adsorption models to the equilibrium data was investigated. The Langmuir isotherm was found to provide the best theoretical correlation of the experimental equilibrium data. The thermodynamic and kinetic activation parameters were derived to predict the nature of adsorption process and discussed in detail. The isosteric heat of adsorption was constant even after increase in surface loading. The removal efficiency of HA-Am-PAA-B was tested using electroplating industry wastewater. The desorption of adsorbed Cu(II) ions was achieved by 0.1 M HCl and four adsorption/desorption cycles were performed without significant decrease in the adsorption capacity.

Keywords: Humic acid; Polymer/clay composite; Copper(II) adsorption; Isotherm; Thermodynamics

New technology in electroplating power supplies: Built for long life, reliability and simplicity of operation
Metal Finishing, Volume 107, Issue 1, January 2009, Page 59
No Abstract

Design for electroplating: OEM automotive parts industry stands to benefit from computer-aided plating simulation Original Research Article
Metal Finishing, Volume 107, Issue 4, 2009, Pages 47-50
Alan Rose. No Abstract
Testing methods for electroplating baths: Part III: Interpretation of test results
Metal Finishing, Volume 107, Issues 7-8, July-August 2009, Pages 20-22
Joe Fox
No Abstract

Testing methods for electroplating baths: Part II: Using and understanding the jiggle cell
Metal Finishing, Volume 107, Issue 5, May 2009, Pages 25-26
Joe Fox
No Abstract

Reducing the operating costs and environmental impact of electroplating equipment
Metal Finishing, Volume 108, Issue 10, October 2010, Pages 27-29
Tony Evans
No abstract

Effect of temperature and mass transport on transition metal isotope fractionation during electroplating Original Research Article
Geochimica et Cosmochimica Acta, Volume 74, Issue 18, 15 September 2010, Pages 5187-5201
Jay R. Black, Seth John, Edward D. Young, Abby Kavner
Transition metal stable isotope signatures can be useful for tracing both natural and anthropogenic signals in the environment, but only if the mechanisms responsible for fractionation are understood. To investigate isotope fractionations due to electrochemistry (or redox processes), we examine the stable isotope behavior of iron and zinc during the reduction reaction + 2e− = Mmetal as a function of electrochemical driving force, temperature, and time. In all cases light isotopes are preferentially electroplated, following a mass-dependent law. Generally, the extent of fractionation is larger for higher temperatures and lower driving forces, and is roughly insensitive to amount of charge delivered. The maximum fractionations are δ56/54Fe = −4.0‰ and δ66/64Zn = −5.5‰, larger than observed fractionations in the natural environment and larger than those predicted due to changes in speciation. All the observed fractionation trends are interpreted in terms of three distinct processes that occur during an electrochemical reaction: mass transport to the electrode, chemical speciation changes adjacent to the electrode, and electron transfer at the electrode. We show that a large isotope effect adjacent the electrode surface arises from the charge-transfer kinetics, but this effect is attenuated in cases where diffusion of ions to the electrode surface becomes the rate-limiting step. Thus while a general increase in fractionation is observed with increasing temperature, this appears to be a result of thermally enhanced mass transport to the reacting interface rather than an isotope effect associated with the charge-transfer kinetics. This study demonstrates that laboratory experiments can successfully distinguish isotopic signatures arising from mass transport, chemical speciation, and electron transfer. Understanding how these processes fractionate metal isotopes under laboratory conditions is the first step towards discovering what role these processes play in fractionating metal isotopes in natural systems.

Removal of nickel from electroplating rinse waters using electrostatic shielding electrodialysis/electrodeionization Original Research Article
Journal of Hazardous Materials, Volume 173, Issues 1-3, 15 January 2010, Pages 647-652
Konstantinos Dermentzis
Electrostatic shielding zones made of electrode graphite powder were used as a new type of ionic and electronic current sinks. Because of the local elimination of the applied electric field, voltage and current within the zones, ions are led inside them and accumulate there. The current sinks were implemented in electrostatic shielding electrodialysis of a simulated nickel plating rinse water containing 100 mg L−1 nickel and electrodeionization of a 0.001 M NiSO4 solution with simultaneous electrochemical regeneration of the ion exchange resin beds. Pure water was obtained with a Ni2+ ion concentration of less than 0.1 mg L−1 at a flow rate of 2.02 × 10−4 dm3 s−1 diluate stream and a current density of 30 A m−2.

Keywords: Membrane-less electrodialysis; Porous bipolar electrode; Ionic current sink–source; Faraday cage; Continuous capacitive deionization

Low-ammonia, high-speed palladium—nickel electroplating process for connector applications: One-year industrial practice results for Pallamet 600 support claims regarding the process' suitability as a hard gold replacement Original Research Article
Metal Finishing, Volume 107, Issue 3, March 2009, Pages 22-26
Wan Zhang, Margit Clauss, Jonas Guebey, Felix Schwager
The Pallamet 600 process presents the advantages of both conventional ammoniacal and ammonia-free processes. The on-line ammonia odor in a production environment is dramatically reduced due to the extremely low free ammonia in the electrolyte. In addition, Pallamet 600 does not require any addition of ammonia for pH adjustment during use.
The beneficial characteristics of the plating process and the Pd−Ni deposit of the conventional ammonia-based processes are retained with Pallamet 600. Production trials have shown that the Pallamet 600 process is suitable for various reel-to-reel selective plating techniques, and the plating bath is chemically stable, in spite of the low ammonia content. The quality of the Pd−Ni deposits produced by Pallamet 600 has been well accepted by end users as a viable hard gold replacement at a substantially lower cost.

Synthesis of polymeric and hybrid nanoparticles for electroplating applications Original Research Article
Electrochimica Acta, Volume 54, Issue 9, 30 March 2009, Pages 2450-2457
O. Kammona, K. Kotti, C. Kiparissides, J.P. Celis, J. Fransaer
Monodisperse polymeric particles with diameters in the range of 60–1400 nm were prepared by (emulsifier-free) emulsion polymerization and incorporated into electrolytic zinc coatings aiming to improve the corrosion resistance of electrogalvanized steel. Various types of polymeric nanoparticles were thus synthesized in order to assess the effect of the emulsifier, initiator and comonomer type on the particle morphology, stability and codeposition behavior. The polymerization experiments were carried out in laboratory-scale glass reactors and the most promising recipes were successfully scaled-up in a fully automated pilot-scale reactor. Replicates of some representative experiments, which were run both in lab and pilot-scale reactors, indicated excellent reproducibility of the polymerization process. Uniform, polymer-containing zinc coatings were produced by electrolytic codeposition of the nanoparticles from an acid zinc plating bath using a rotating disk electrode (RDE). Hybrid polystyrene/silica nanoparticles with increased silica content were also prepared via emulsifier-free emulsion polymerization, in the presence of an ultrafine aqueous silica sol, to be used in electrocoating applications. The effect of key process parameters, such as initial monomers molar ratio and pH on the size, morphology and silica content of the produced hybrid nanoparticles was investigated.

Keywords: Monodisperse polymeric nanoparticles; Hybrid nanoparticles; Silica; Electrolytic codeposition; Zinc coatings

Effect of magnetic field on electroplating Ni/nano-Al2O3 composite coating Original Research Article
Journal of Electroanalytical Chemistry, Volume 630, Issues 1-2, 15 May 2009, Pages 42-48
Chao Wang, Yun-Bo Zhong, Jiang Wang, Zhi-qiang Wang, Wei-Li Ren, Zuo-Sheng Lei, Zhong-Ming Ren
The influence of static horizontal magnetic field on the electrocodeposition process of Ni/nano-Al2O3 composite coating has been studied in a modified Watts electrolyte through stationary and dynamic electrochemical investigations. The results showed that the mass transport process and charge transfer process were enhanced by applying magnetic field. The results of SEM and XRD showed that the nickel grains were refined by adding nano-particles and (2 2 0) crystal orientation was strengthened by increasing magnetic flux density (MFD). Alumina particles content and deposit rate increased with increasing MFD due to the magneto hydrodynamic effect (MHD effect). However, the current efficiency decreased with particle content increased.

Keywords: Magnetic Field; Composite coating; Nickel; Nano-alumina; Electrochemical analysis

Recovery and reuse of Ni(II) from rinsewater of electroplating industries Original Research Article
Journal of Hazardous Materials, Volume 163, Issues 2-3, 30 April 2009, Pages 899-909
P. Gomathi Priya, C. Ahmed Basha, V. Ramamurthi, S. Nathira Begum
Discharge of nickel compounds, which may occur in both liquid and solid phases, can cause severe environmental problems. In this work, ‘point of source’ treatment strategy is followed and reduced the nickel content of rinsewater to about less than 1 mg L−1 by ion-exchange method using a packed column involving batch recirculation mode of operation and to recovered Ni(II) content by desorption. The treated water could be recycled for rinsing operation.
The nickel from resin is first precipitated as nickel hydroxide to synthesize positive active material and that was used in Nickel/Metal hydride cell. The performances in terms of electrochemical utilization of nickel hydroxide, specific capacity as a function of discharge current density and cycle life were examined and the nickel hydroxide electrode with 5% CaCO3 addition, having 200 mAh g−1 specific capacity, could be subjected to charge/discharge cycles at C/5 rate for more than 200 cycles without the capacity fading.

Keywords: Rinsewater; Ni recovery; Water reuse; Ion exchange; Adsorption

Si3N4/Ni nanocomposite formed by electroplating: Effect of average size of nanoparticulates Original Research Article
Transactions of Nonferrous Metals Society of China, Volume 20, Issue 6, June 2010, Pages 1017-1023
Properties of Si3N4/Ni electroplated nanocomposite such as corrosion current density after long time immersion, roughness of obtained layer and distribution of nanometric particulates were studied. Other effective factors for fabrication of nanocomposite coatings were fixed for better studying the effect of the average size of nanoparticulates. The effects of the different average size of nanometric particulates (ASNP) from submicron scale (less than 1 μm) to nanometric scale (less than 10 nm) were studied. The nanostructures of surfaces were examined by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and atomic force microscopy (AFM). Corrosion rates of the coatings were determined using the Tafel polarization test. It is seen that decreasing the ASNP will lead to lower corrosion current densities; however, in some cases, pitting phenomena are observed. The roughness illustrates a minimum level while the distribution of nanometric particulates is more uniform by decreasing the ASNP. The effects of pulsed current on electrodeposition (frequency, duty cycle) and concentration of nanoparticulates in electrodeposition bath on trend of obtained curves have been discussed. Response surface methodology was applied for optimizing the effective operating conditions of coatings. The levels studied were frequency range between 1 000 and 9 000 Hz, duty cycle between 10% and 90% and concentration of nanoparticulates of 10–90 g/L.

Keywords: corrosion; electrodeposition; nanocomposite; nanostructure; nano diamond

Modeling of grain size and hardness for pulse current electroplating Original Research Article
Electrochimica Acta, Volume 54, Issue 6, 15 February 2009, Pages 1784-1790
Jarol Molina, Bibian A. Hoyos
A mathematical model was developed to describe the effect of the current shape waveform on the grain size, formation, growth rate, and deposits hardness for progressive nucleation (simultaneous nucleation and growth) when four pulse current waveforms are applied: rectangular, ramp up, ramp down, and triangular waveforms. In the model, it is considered that species diffusion across the limit layer is the rate determinant step. The Hall-Petch expression was used to relate the grain size in the metal to its hardness. The model results are compared with the experimental data for nickel electrodeposit hardness, which were presented by Wong et al. (K.P. Wong, K.C. Chan, T.M. Yue, J. Appl. Electrochem. 31 (2001) 25). The model predictions are consistent with the experimental results for the four current waveforms, with an average hardness deviation of about 10% for currents between 1 and 6 kA/m2.

Keywords: Electrochemical nucleation; Grain size; Hardness; Pulse current; Mathematical model

Electroplating and characterization of Zn–Ni, Zn–Co and Zn–Ni–Co alloys Original Research Article
Surface and Coatings Technology, Volume 205, Issue 7, 25 December 2010, Pages 1969-1978
N. Eliaz, K. Venkatakrishna, A. Chitharanjan Hegde
Zn–Ni, Zn–Co and Zn–Ni–Co coatings were electrodeposited on mild steel from an acidic chloride bath containing p-aminobenzenesulphonic acid (SA) and gelatin. These additives changed the phase content in the coatings, most likely as a result of their adsorption at the surface of the cathode. The effect of gelatin was more pronounced than that of SA. The Faradaic efficiency was higher than 90%. As the current density was increased or the bath temperature was decreased, the concentration of the nobler metal in the coating increased. Both concentrations of Ni and Co in the ternary alloy increased as the applied current density was increased. Nickel and cobalt were found to have a synergistic catalytic effect. The thickness of all coatings increased as the applied current density was increased. The hardness increased with current density to a peak value, and then decreased. The rate of Zn deposition was heavily influenced by mass-transport limitation at high applied current densities, while the rates of Ni and Co deposition were not. The anomalous codeposition was explained by the great difference between the exchange current densities of Zn and the iron-group metal. Potentiodynamic polarization scans and electrochemical impedance spectroscopy showed that the corrosion resistance of the ternary Zn–Ni–Co alloy coatings was approximately 10 times higher than that of Zn–Ni and 7 times higher than that of Zn–Co. The improved corrosion resistance of the ternary alloy was attributed to its surface chemistry, phase content, texture, and surface morphology. The ternary Zn–Ni–Co coating may thus replace the conventional Zn–Ni and Zn–Co coatings in a variety of applications.

Keywords: Zn-based alloys; Electrodeposition; Anomalous codeposition (ACD); Corrosion resistance

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