Selasa, 25 Oktober 2011


Design of experiments for statistical modeling and multi-response optimization of nickel electroplating process Original Research Article
Chemical Engineering Research and Design, Volume 89, Issue 2, February 2011, Pages 136-147
Maria Poroch-Seritan, Sonia Gutt, Gheorghe Gutt, Igor Cretescu, Corneliu Cojocaru, Traian Severin
The central composite experimental design and response surface methodology have been employed for statistical modeling and analysis of the results dealing with nickel electroplating process. The empirical models developed in terms of design variables (current density J (A/dm2), temperature T (°C) and pH) have been found statistically adequate to describe the process responses, i.e. cathode efficiency Y (%), coating thickness U (μm), brightness V (%) and hardness W (HV). The graphical representations consisted of 2D contour plots and 3D surface plots have been used for exploring and analysis of response surfaces in order to identify the main, quadratic and interaction effects. The multi-response optimization of nickel electroplating process has been carried out by means of desirability function approach. To this end, a genetic algorithm has been used for mathematical optimization of the multi-response problem. The optimization algorithm has conducted to a set of equivalent solutions named Pareto optimal set. The confirmation runs have been employed in order to make a decision about the optimal solution approved by experiment. Thus, the optimum conditions of nickel electroplating has been defined in this work as J* = 5.35 (A/dm2), T* = 33.44 (°C) and pH* = 6.22 and respectively the responses confirmed by experiment were Y = 79.12 ± 0.18 (%), U = 52.77 ± 0.48 (μm), V = 26.12 ± 0.45 (%) and W = 371.6 ± 1.77 (HV). In such conditions the quality of nickel electroplating deposit was the best one in accordance with experimental results.
Keywords: Electroplating; Experimental design; Response surface method; Desirability function; Genetic algorithm

Treatment of nanowaste via fast crystal growth: With recycling of nano-SnO2 from electroplating sludge as a study case Original Research Article
Journal of Hazardous Materials, In Press, Corrected Proof, Available online 16 September 2011
Zanyong Zhuang, Xinjiang Xu, Yongjing Wang, Yandi Wang, Feng Huang, Zhang Lin
The treatment of industrial sludge containing amorphous/nanophase metal oxides or hydroxides is one of the vital issues in hazardous waste disposal. In this work, we developed a strategy to recycle nano-SnO2 from tinplate electroplating sludge. It revealed that the major components of this sludge were acid soluble Sn and Fe amorphous phases. By introducing NaOH as a mineralizer, a fast growth of amorphous Sn compound into acid-insoluble SnO2 nanowires was achieved selectively. Thus, the as-formed nano-SnO2 could be recycled via dissolving other solid compositions in the sludge by using acid. The role of NaOH on accelerating both the Oriented Attachment (OA) and Ostwald Ripening (OR) growth of SnO2 was discussed, which was regarded as a critical factor for treating the sludge. A pilot-scale experiment was conducted to treat 2.3 kg original sludge and the recycling of about 90 g nano-SnO2 was achieved. We anticipate this work can provide a good example for the recycling of valuable metals from industrial sludge containing fine metal oxides or hydroxides.
Keywords: Metals recovery; Tin oxides; Electroplating sludge; Fast crystal growth; Mineralization

Fabrication of metallic microstructure on curved substrate by optical soft lithography and copper electroplating Original Research Article
Sensors and Actuators A: Physical, Volume 168, Issue 1, July 2011, Pages 105-111
Jongho Park, Hiroyuki Fujita, Beomjoon Kim
Microfabrication of copper structures with a high aspect ratio was successfully performed on a curved substrate by optical soft lithography and metal electroplating. This fabrication method comprises mainly of three steps. Firstly, a flexible polymer photomask was fabricated by a direct metal transfer technique via two types of self-assembled monolayer treatments. Next, SU-8 micro patterns were fabricated on a curved glass substrate by optical soft lithography. Here, we utilised a mask with a microslit and a flexible polymer photomask. Lastly, copper electroplating was performed on the curved substrate using the SU-8 patterns as molds to form high-aspect-ratio copper structures. We confirmed that SU-8 microline patterns with an aspect ratio of over 2.5 were formed on the curved substrate. Subsequently, copper structures fabricated on the curved substrate with SU-8 micro patterns were acquired. The unconventional microfabrication technique introduced in this work can be used for the fabrication of 3-D high-aspect-ratio metallic microstructures on curved or nonplanar substrates.
Keywords: Microfabrication; Nonplanar substrate; Curved substrate; SU-8; Copper electroplating

Application of a system dynamics approach for assessment of the impact of regulations on cleaner production in the electroplating industry in China Original Research Article
Journal of Cleaner Production, Volume 20, Issue 1, January 2012, Pages 72-81
Xiaoqing Dong, Chaolin Li, Ji Li, Wantao Huang, Jia Wang, Ruibin Liao
Compared with pollution transfer, cleaner production (CP) is more effective to reduce heavy metal pollution in many less developed countries. However, it’s more difficult to develop an efficient policy to make enterprises to completely invest in CP. This paper analyses the effects of CP policies on investment decisions of firms using a dynamic systems model and by simulating a typical electroplating enterprise in Shenzhen, China. Results show that water price could be effective only when it is increased by a sufficient amount. For instance, only when it is increased directly from 2 to 8 CNY/m3 (0.3–1.2 USD/m3), or from 8 to 16 CNY/m3 (1.2–2.5 USD/m3), will an enterprise gradually increase CP investment from process modification to recovery technology. Increasing the metal utilization rate of CP standard-plating and surface finishing industry from its current value of 75%–85% would encourage an enterprise to add recovery technology. Uniform preferential tax rate and penalties for the three parts of CP do not affect investment decisions on CP. Using the same investment subsidy rate for the three parts of CP could be effective in promoting CP only if it is above 60%. The current emission standard of metal has played a role in promoting CP. A comparison of three possible strategies indicates that a distinct policy for the different parts of CP is the optimal policy combination. An overall investigation of typical enterprises based on the abovementioned framework is suggested to make more practical policies, which than can promote CP instead of pollution transfer.
Keywords: Cleaner production; Electroplating; System dynamics; Investment decisions

The formation of micro/nanoparticles in laser-enhanced electroplating with continuous-wave and pulsed Nd-YAG laser interactions Original Research Article
Optics & Laser Technology, Volume 44, Issue 1, February 2012, Pages 169-176
Shiang-Hung Chen, Jehnming Lin
The copper particles generated by the laser-enhanced electroplating method have been investigated in this study, and the results have been examined at various process conditions. The electrolyte jet of copper sulfate was impinged on a stainless steel electrode and irradiated with a Nd-YAG laser at continuous-wave (CW) and Q-switched output modes, respectively, to generate the particle size distribution from micro- to nano-scale.
According to the electrochemical dynamics theory, the mechanism of the proposed technique for the particles formation is mainly due to the thermal effects from the laser interaction in electroplating. In the experiments, the laser energy absorbed by the electrolyte jet and the temperature rise of the electrode during the laser radiation has been measured. In the numerical simulation, the temperature fields of the impinging jet of the laser nozzle were calculated. It shows that the growth of the particle is significantly corresponding to the laser power and pulse mode of the laser interaction.

Rule of formation of aluminum electroplating layer on Q235 steel Original Research Article
Journal of Environmental Sciences, Volume 23, Supplement, June 2011, Pages S138-S141
Zhimin Ding, Qiuyuan Feng, Changbin Shen, Hong Gao
Aluminum electroplating layer on Q235 steel in AlCl3-NaCl-KCl molten salt was obtained, and the rule of its nucleation and growth were investigated. The results showed that aluminum electroplating layer formed through nucleating and growing of aluminum particles, and thickened by delaminating growth pattern. At low current density, the morphology of aluminum particles took on flake-like, while at high current density they changed to spherical. The thickness of plating layer increases with increasing current density and electroplating time. The relationship between the plating thickness (δ) and electroplating time (t) or current density (i) can be expressed as δ = 0.28f137, and δ = 1.1i1-39.
Key words: molten salt; electroplating aluminum layer; nucleation and growth; formation mechanism

Fabrication and characterization of micro-sized copper bump of multi-layer PCB by pulse-reverse electroplating Original Research Article
Current Applied Physics, Volume 11, Issue 1, Supplement, January 2011, Pages S289-S292
Hyun Seon Hong, Min Hye Seo, Sungkyu Lee, Soon Jik Hong, H.G. Suk, Jae-Hwan Ahn
In this research, micro-sized copper bump for multi-layered printed circuit board (PCB) was successfully developed using pulse-reverse electroplating method. The electroplating parameters of current density, pulse-reverse ratio and brightener content were optimized for fabrication of suitable micro-bumps. The pulse-reverse electroplated micro-bumps were characterized using various analytical tools and techniques such as optical microscopy, scanning electron microscopy, atomic force microscopy and hydraulic bulge testing. Optical microscope and scanning electron microscope analysis results indicated good electroplating uniformity in the current density range of 1.4–3.0 A/dm2, pulse-reverse ratio of 1:1, and brightener concentration of 600 ppm.
Keywords: Copper bump; Multi-layered PCB; Pulse-reverse; Electroplating

Electrochemical impedance spectroscopy and X-ray photoelectron spectroscopy study of the corrosion behaviour of galvanized steel and electroplating steel Original Research Article
Applied Surface Science, Volume 257, Issue 8, 1 February 2011, Pages 3383-3387
M. Lebrini, M. Traisnel, L. Gengembre, G. Fontaine, O. Lerasle, N. Genet
The efficiency of a formula containing 2-{(2-hydroxyethyl)[(4-methyl-1H-1,2,3-benzotriazol-1-yl)methyl]amino}ethanol (tolyltriazole) and decanoic acid as corrosion inhibitor for galvanized steel and electroplating steel in aqueous solution have been determined by electrochemical impedance spectroscopy (EIS) techniques. The experimental data obtained from this method show a frequency distribution and therefore a modelling element with frequency dispersion behaviour, a constant phase element (CPE) has been used. The corrosion behaviour in the presence of different concentration of decanoic acid (DA) in the formula was also investigated by EIS. Results obtained reveal that, the formula is a good inhibitor for galvanized steel and electroplating steel in aqueous solution, the better performance was obtained in the case of galvanized steel. The ability of the inhibitor to be adsorbed on the surface was dependent on the nature of metal. X-ray photoelectron spectroscopy surface analysis with inhibitor shows that it's chemisorbed at the galvanized and electroplating steel/aqueous solution interface.
Keywords: Tolyltriazole; Decanoic acid; Corrosion inhibitors; Galvanized steel; Electroplating steel; Aqueous solution; X-ray photoelectron spectroscopy

Function and mechanism of supercritical carbon dioxide emulsified electrolyte in nickel electroplating reaction Original Research Article
Surface and Coatings Technology, Volume 205, Issues 13-14, 25 March 2011, Pages 3890-3899
Tso-Fu Mark Chang, Masato Sone
Physical properties of supercritical carbon dioxide emulsion (Sc–CO2–E) were controlled to evaluate the effects on properties of nickel film electroplated. Additive-free Watts bath was used to study sole-effect of Sc–CO2–E on nickel electroplating reaction. Experimental pressure, volume fraction of CO2 and surfactant were adjusted to control physical properties of Sc–CO2–E. Influence of current density was also studied. Surface roughness (Ra) was found to decrease with increase in pressure, volume fraction of CO2, volume fraction of surfactant and current density. Reduction in Ra was believed to be caused by improved homogeneity of Sc–CO2–E, enhanced desorption of hydrogen bubbles from surface of cathode, and increased nickel nuclei density. Grain refinement was observed when increasing pressure, volume fraction of CO2 and surfactant, which was believed to be caused by periodic plating characteristic of electroplating with Sc–CO2–E. On the other hand, grain coarsening was observed with increase in current density.
Keywords: Nickel electroplating; Supercritical carbon dioxide emulsion; Additive-free Watts bath; Pressure effect

Micromachined anti-scatter grid fabricated using crystalline wet etching of (1 1 0) silicon and metal electroplating for X-ray imaging Original Research Article
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Volume 652, Issue 1, 1 October 2011, Pages 846-849
Dae-Hun Jeong, Jae Myung Kim, Do Young Noh, Kwang Hyun Kim, Jong-Hyun Lee
Two-dimensional micromachined anti-scatter grids were fabricated using MEMS technology, including crystalline wet etching of (1 1 0) silicon and metal electroplating for X-ray imaging. The core sizes of the square grids were 100, 200, and 300 μm with 2.2 mm height and 50 μm septa thickness. To prepare the etch mask for crystalline wet etching, silicon nitride was deposited using low pressure chemical vapor deposition (LPCVD). The grid patterns, which are aligned parallel to the vertical (1 1 1) plane of the (1 1 0) silicon, were transferred from the photomask onto the photoresist using deep ultraviolet (DUV) photolithography, and consecutively onto the silicon nitride using reactive ion etching (RIE). A (1 1 0) silicon substrate was then etched in a tetramethyl ammonium hydroxide (TMAH) solution to form a skeleton for the septa structure. Chrome was sputtered to provide a seed layer for nickel electroplating, where nickel grows on the sidewalls of the skeleton of the septa structure. Finally, two-dimensional septa with various grid ratios were constructed by cross-stacking several layers of the patterned (1 1 0) silicon wafer. Anti-scattering ability was experimentally characterized in terms of X-ray transmission by one-dimensional scanning of incident angle.
Keywords: X-ray imaging; Micromachined anti-scatter grid; Micromachining; (1 1 0) Silicon; Crystalline wet etching; Electroplating

Electrolytic tilt sensor fabricated by using electroplating process Original Research Article
Sensors and Actuators A: Physical, Volume 167, Issue 1, May 2011, Pages 1-7
Jae Hyoung Lee, Seung S. Lee
This paper proposes new electrolytic tilt sensor fabricated by MEMS process especially using electroplating process to form vertical electrodes each of which is connected to planar electrode. Comparing with conventional electrolytic tilt sensors having difficulty in manufacturing in small size, the present tilt sensor can be manufactured in small size, particularly in very small height, having comparable performance, thus resulting in mass production possible, while still having a variety of manufacturing in higher height which is possible using electroplating process. In order to perform the electroplating process, an assembly of SU-8 polymer and PDMS was used as electroplating mold, former not being removed to form outer wall of sensor cavity but latter being removed to make a cavity in which electrolytic solution is contained. The nonzero null output voltage offset has minimum value in the range of 100–800 Hz of the frequency of alternating input voltage source. Analytically derived equation and experiments to examine how the sensor cavity size affects the performances confirmed that smaller the cavity diameter D, the smaller sensitivity but larger angle range. Compared to commercial electrolytic tilt sensor products, the fabricated tilt sensor has comparable performances such as angle range of about ±40°, especially linear range of about ±10°, sensitivity of 4.4 V/° in case of Vin = 1 V (rms), and resolution of 0.5 arc min.
Keywords: Electrolytic tilt sensor; Electroplating; SU-8; PDMS; MEMS

The characteristics of chromized 1020 steel with electrical discharge machining and Ni electroplating pretreatments Original Research Article
Applied Surface Science, Volume 257, Issue 8, 1 February 2011, Pages 3529-3537
Ching-Yuan Bai, Jeou-Long Lee, Tse-Min Wen, Kung-Hsu Hou, Min-Sheng Wu, Ming-Der Ger
A uniform and continuous chromized coating on AISI 1020 steel is produced by low-temperature pack chromization (LTPC) with electrical discharge machining and Ni electroplating pretreatments. The anticorrosive performance of the chromized steels is investigated in a 0.5 M H2SO4 solution at room temperature. The testing results indicate that the chromized specimen with electrical discharge machining and Ni electroplating pretreatments exhibits the lowest corrosion current density, 2.16 × 10−8 A cm−2, among the tested specimens. The corrosion resistance of all tested specimens are in the order of bare 1020 < 1020-Cr(700-2) < 1020-Ni–Cr(700-2) < 1020-EDM-Ni–Cr(700-2). Moreover, the 1020-Ni–Cr(700-2) specimen have the best conductivity as a result of the less amount of oxides in the superficial coating.
Keywords: AISI 1020 steel; Low-temperature pack chromization; Electrical discharge machining; Electroplating; Corrosion current density

Facile synthesis and electromagnetic wave absorption properties of magnetic carbon fiber coated with Fe–Co alloy by electroplating Original Research Article
Journal of Alloys and Compounds, Volume 509, Issue 14, 7 April 2011, Pages 4726-4730
Lei Wang, Fang He, Yizao Wan
Magnetic carbon fiber coated with Fe–Co alloy was prepared by electroplating at 25 °C for 5 min. The obtained magnetic coatings show sheet-like morphology and the crystal structure of the uniform coating is Co3Fe7 with a thickness of about 0.5 μm. The saturation magnetization of the magnetic carbon fiber reaches 31.5 emu/g with a coercivity of 87.1 Oe. The complex permittivity and permeability of magnetic carbon fiber/paraffin (30 wt%) composite were measured in the 2–18 GHz frequency range. The reflection loss below −10 dB covers the whole frequency range while below −20 dB the absorption frequency bandwidth is 6.8 GHz, and the minimum value is −48.2 dB at a coating thickness of 1.7 mm. Magnetic carbon fiber exhibits excellent electromagnetic wave absorption properties.
Keywords: Coating materials; Alloy electroplating; Fe–Co alloy; Carbon fiber; Electromagnetic wave absorption

Room temperature mass production of carbon nanotube field emission micro-cathode arrays using electroplating of a CNT/Ni composite followed by micro-machining Original Research Article
Vacuum, Volume 85, Issue 8, 1 February 2011, Pages 827-832
Min Deng, Guifu Ding, Yan Wang, Xuemei Cui, Hong Wang, Faheng Zang, Huiqing Wu
A room temperature fabrication method for the mass production of carbon nanotube (CNT) field emission micro-cathode arrays is reported. The technique combines electroplating of a CNT/Ni composite and micro-machining. This method combines the advantages of direct growth and screen printing conventionally used to fabricate such structures and avoids their disadvantages. Due to its integration and room temperature processing, the technique is proven to be advantageous in mass production and low cost. Results of field emission testing show that the CNT micro-cathodes have excellent field-emission properties, such as high current density (15.7 mA/cm2), field enhancement factor (2.4 × 106/cm), and good stability (109 h for 10% degradation of current density from 400 μA/cm2).
Keywords: Carbon nanotube; Electroplating; Micro-machining; Micro-cathode; Field emission

A variable hydrophobic surface improves corrosion resistance of electroplating copper coating Original Research Article
Applied Surface Science, Volume 257, Issue 13, 15 April 2011, Pages 5524-5528
Xiuqing Xu, Liqun Zhu, Weiping Li, Huicong Liu
In this paper, Cu/liquid microcapsule composite coating was prepared by electroplating method. And a variable hydrophobic surface was obtained due to the slow release of microcapsules and the rough surface. The hydrophobic property and corrosion resistance of the composite was investigated by means of water contact angle instrument and electrochemical technique, respectively. The results suggest that the contact angle (CA) of composite increases gradually with the increasing storing time, and the stable super-hydrophobic property was exhibited after storing in air for 15 days. Meanwhile, the excellent corrosion resistance was displayed, which could be ascribed to the good stability of hydrophobic film on composite surface.
Keywords: Electroplating; Super-hydrophobic; Copper; Microcapsule; Corrosion resistance

Electroplating formation of Al–C covalent bonds on multiwalled carbon nanotubes Original Research Article
Synthetic Metals, Volume 161, Issues 3-4, February 2011, Pages 208-212
Kang Pyo So, Chandan Biswas, Seong Chu Lim, Kay Hyeok An, Young Hee Lee
We focus on the formation of strong aluminum (Al)–carbon nanotube (CNT) covalent bonds on the CNT walls without deteriorating CNTs for mechanically strong composite. We propose a simple electroplating method to realize Al–CNT covalent bonds on the CNT wall. The CNT electrode was formed on the Cu collector as a cathode and separated from the anode by an organic separator in tetrahydrofuran (THF) under Ar atmosphere. The Al deposition started to increase rapidly at above Al reduction potential. The formation of Al–C covalent bonds was confirmed by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Charge transfer from CNTs to Al and generation of D-bands in Raman spectroscopy further confirmed the formation of Al–C covalent bonds.
Keywords: Carbon nanotube; Aluminum; Covalent bond; Composite; Electroplating

Effects of supporting electrolytes on copper electroplating for filling through-hole Original Research Article
Electrochimica Acta, Volume 56, Issue 17, 1 July 2011, Pages 5954-5960
Chien-Hung Chen, Chun-Wei Lu, Su-Mei Huang, Wei-Ping Dow
The filling of micron through-holes (THs) in a printed circuit board (PCB) by copper electroplating was investigated in this study. The role of supporting electrolytes, such as H2SO4, Na2SO4 and K2SO4, was explored using practical TH filling plating and linear-sweep voltammetry (LSV) analysis of plating solutions. The copper could selectively fill THs using one organic additive, namely, tetranitroblue tetrazolium chloride (TNBT), as an inhibitor. The inhibiting strength of TNBT depended on the supporting electrolytes. Although H2SO4 could enhance the inhibiting strength of TNBT, it also decreased the filling capability of the copper plating solution; Na2SO4 and K2SO4 did not enhance the inhibiting strength of TNBT but they increased the filling capability of the copper plating solution. Additionally, the protons could chemically interact with TNBT to form precipitate, whereas sodium and potassium ions did not easily interact with TNBT. The filling capability of the copper plating solution using Na2SO4 and K2SO4 as supporting electrolytes could be greatly improved by adding a small amount of bis(3-sulfopropyl)-disulfide (SPS) and poly(ethylene glycol) (PEG) with a molecular weight of 600.
Keywords: Through-hole filling; Copper electroplating; Supporting electrolyte

Preparation and characterization of Nb2O5–Al2O3 composite oxide formed by cathodic electroplating and anodizing
Materials Science and Engineering: B, Volume 176, Issue 18, 15 November 2011, Pages 1505-1508
Joo-Hee Jang, Tae-Yoo Kim, Nam-Jeong Kim, Chang-Hyoung Lee, Eun-Mi Park, Chan Park, Su-Jeong Suh
Al foil was coated with niobium oxide by cathodic electroplating and anodized in a neutral boric acid solution to achieve high capacitance in a thin film capacitor. X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) revealed the niobium oxide layer on Al to be a hydroxide-rich amorphous phase. The film was crystalline and had stoichiometric stability after annealing at temperatures up to 600 °C followed by anodizing at 500 V, and the specific capacitance of the Nb2O5–Al2O3 composite oxide was approximately 27% higher than that of Al2O3 without a Nb2O5 layer. The capacitance was quite stable to the resonance frequency. Overall, the Nb2O5–Al2O3 composite oxide film is a suitable material for thin film capacitors.
Keywords: Thin film capacitor; Cathodic electroplating; Anodizing; Nb2O5–Al2O3 composite oxide

High aspect ratio nanostructuring by high energy electrons and electroplating Original Research Article
Microelectronic Engineering, Volume 88, Issue 8, August 2011, Pages 2259-2262
Sergey Gorelick, Joan Vila-Comamala, Vitaliy A. Guzenko, Christian David
Due to the ability of 100 keV electrons to penetrate deep into resist with little scattering, we were able to directly write various dense and high aspect ratio nanostructures in up to 1.65 μm thick layers of poly(methyl methacrylate) (PMMA) resist. The PMMA molds produced by electron beam lithography were developed using a high contrast developer. The molds were used to transfer the pattern into metallic nanostructures by filling the developed trenches with Au by electroplating. By exposing lines narrower than the target width, we observed improved process latitude and line width control. The obtained aspect ratios of the dense structures are nearly 17 in 1.1 μm PMMA layers and >13 for structures electroplated into these PMMA molds. The fabrication method was successfully applied to produce Au diffractive X-ray Fresnel zone plates of exceptionally good quality with 70 nm outermost zones using 1.1 μm thick PMMA mold. In addition, we also produced regular arrays of high aspect ratio and dense Au nanorods and high aspect ratio split ring resonators with line widths down to 65 nm and with heights up to 1.5 μm.
Keywords: High aspect ratio; PMMA; Electron beam lithography; X-ray optics; Nanorod; Split-ring resonator; Au electroplating

Fabrication and electromagnetic properties of bio-based helical soft-core particles by way of Ni–Fe alloy electroplating Original Research Article
Journal of Magnetism and Magnetic Materials, Volume 323, Issue 24, December 2011, Pages 3223-3228
Mingming Lan, Deyuan Zhang, Jun Cai, Wenqiang Zhang, Liming Yuan
Ni–Fe alloy electroplating was used as a bio-limited forming process to fabricate bio-based helical soft-core ferromagnetic particles, and a low frequency vibration device was applied to the cathode to avoid microorganism (Spirulina platens) cells adhesion to the copper net during the course of plating. The morphologies and ingredients of the coated Spirulina cells were characterized using scanning electron microscopy and energy dispersive spectrometer. The complex permittivity and permeability of the samples containing the coated Spirulina cells before and after heat treatment were measured and investigated by a vector network analyzer. The results show that the Spirulina cells after plating keep their initial helical shape, and applying low frequency vibration to the copper net cathode in the plating process can effectively prevent agglomeration and intertwinement of the Spirulina cells. The microwave absorbing and electromagnetic properties of the samples containing the coated Spirulina cells particles with heat treatment are superior to those samples containing the coated Spirulina cells particles without heat treatment.
Keywords: Bio-limited forming; Bio-based helical particle; Ni–Fe alloy electroplating; Heat treatment; Electromagnetic property

Modeling of galvanostatic pulse and pulsed reverse electroplating of gold Original Research Article
Electrochimica Acta, Volume 56, Issue 9, 30 March 2011, Pages 3328-3333
Zhengwei Liu, Alan C. West
A mathematical model of galvanostatic pulse and pulsed reverse electroplating of gold on a rotating disk electrode is presented. Using experimental polarization curves, dc current efficiencies, and literature-reported diffusion coefficients, model parameters are estimated. An accurate prediction of current efficiency by the on–off pulse-plating model was confirmed by experimental measurement. The current efficiency of pulse-reverse plating at relatively low waveform frequency is also successfully predicted, with less agreement at higher frequencies, presumably due to the simplified approach that the model employs to treat the complex set of reactions that occur during the anodic portion of the wave. When the reduction of adsorbed gold species produced during the oxidation portion of the pulse is included, improved agreement between experiment and theory is obtained.
Keywords: Electroplating; Simulation; Gold; Pulsed reverse plating; Hydrogen evolution

Copper electroplating into deep microvias for the “SiP” application Original Research Article
Microelectronic Engineering, Volume 88, Issue 5, May 2011, Pages 749-753
Cheng Fang, Alain Le Corre, Dominique Yon
In order to anticipate the further demands of miniaturization and integration of “System-in-Package”, the technology of 3D through-silicon-vias (TSVs) has been developed at NXP Semiconductors. The sputtering and the electroplating have been chosen for realize respectively a copper seed layer and a thick copper deposition inside 75 μm wide and hundreds micrometer deep microvias. The microvias, for an aspect-ratio (AR) up to 2.3, can be successfully covered by a sputtered 3 μm thick copper layer. To achieve a thick microvia filling, the pulsed current is preferred and a perpendicular electrolyte flow is critical. With an 11 μm thick patterned photoresist mask on the field, the 75 μm diameter and 180 μm deep microvias can be more-than-the-half filled using the “superfilling” recipe when the field depositing layer reaches the mask level. Such partially filled microvias exhibit excellent electrical resistances within the range of 4 mΩ.
Keywords: SiP; Copper seed coating; Copper electroplating; Microvias

Properties of Al2O3 nano-particle reinforced copper matrix composite coatings prepared by pulse and direct current electroplating Original Research Article
Materials & Design, Volume 32, Issues 8-9, September 2011, Pages 4478-4484
Saeed Reza Allahkaram, Setareh Golroh, Morteza Mohammadalipour
Cu–Al2O3 nano-composite coatings have high potential for use in applications in which high mechanical properties together with high corrosion resistance are required. In the present study it is intended to produce copper nano-alumina composite coatings with various nano-alumina contents in order to investigate the effect of alumina reinforcement particles on corrosion resistance and mechanical properties such as hardness and wear resistance. The composite coatings were deposited using direct current (DC) and pulse current (PC) plating. The microstructures of the coatings produced from both methods were examined via scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques. The wear behaviors, micro hardness, coating thickness, corrosion rate and coating porosity were examined using appropriate methods. Compared to DC deposition, PC plating facilitated higher amounts of particle incorporation with more uniform distribution. The results indicated that the mechanical properties of the applied coatings with incorporated nano-alumina reinforcement were far more superior as compared to its own matrix as well as non-composite copper coatings. It was also found out that increasing the amount of nano-alumina content in the coating, led to enhanced general properties of the coatings.
Keywords: A. Metal matrix composite; C. Electroplating; E. Mechanical properties

Biosorption of Ni(II) from electroplating wastewater by modified (Eriobotrya japonica) loquat bark Original Research Article
Journal of Saudi Chemical Society, In Press, Corrected Proof, Available online 18 July 2011
Nidá M. Salem, Akl M. Awwad
Biosorption of nickel ions from aqueous solutions by modified loquat bark waste (MLB) has been investigated in a batch biosorption process. The biosorbent MLB was characterized by FTIR analysis. The extent of biosorption of Ni(II) ions was found to be dependent on solution pH, initial nickel ions concentration, biosorbent dose, contact time, and temperature. The experimental equilibrium biosorption data were analyzed by three widely used two-parameters Langmuir, Temkin and Freundlich isotherm models. Langmuir and Temkin isotherm models provided a better fit with the experimental data than Freundlich isotherm model by high correlation coefficients R2. The maximum adsorption capacity was 27.548 mg/g of Ni(II) ions onto MLB. The thermodynamic analysis indicated that the biosorption behavior of nickel ions onto MLB biosorbent was an endothermic process, resulting in higher biosorption capacities at higher temperatures. The negative values of ΔG° (−5.84 kJ/mol) and positive values of ΔH° (13.33 kJ/mol) revealed that the biosorption process was spontaneous and endothermic. Kinetic studies showed that pseudo-second order described well the biosorption experimental data. The modified loquat bark (MLB) was successfully used for the biosorption of nickel ions from synthetic and industrial electroplating effluents.
Keywords: Biosorption; Nickel; Modified loquat bark; Adsorption isotherms; Adsorption kinetic

Integration of electroplating process design and operation for simultaneous productivity maximization, energy saving, and freshwater minimization Original Research Article
Chemical Engineering Science, In Press, Corrected Proof, Available online 24 September 2011
Chaowei Liu, Chuanyu Zhao, Qiang Xu
Electroplating industry annually produces numerous plated workpieces for U.S. pillar industries. However, it is also a major environment polluter in forms of wastewater, sludge, and spent solution. Thus, waste source reduction for the electroplating industry is a must. In practice, when productivity and energy use efficiency are also taken into account, the design and operation of an electroplating process become very complicated and need an in-depth study. In this paper, productivity maximization, energy saving, and freshwater/wastewater minimization are simultaneously addressed for the optimal design and operation of electroplating processes, which generates a triple-objective mixed-integer dynamic optimization (MIDO) model. The MIDO model is iteratively solved by a developed methodology to obtain the 3D Pareto frontier of the optimization problem, which provides important technical supports for the design and operation of electroplating processes. The efficacy has been demonstrated with a case study on an electroplating process.
Keywords: Hoist scheduling; Water network synthesis; Energy saving; Optimization; MINLP; Pareto frontier

Simultaneous mixed-integer dynamic optimization for environmentally benign electroplating Original Research Article
Computers & Chemical Engineering, Volume 35, Issue 11, 15 November 2011, Pages 2411-2425
Chaowei Liu, Jie Fu, Qiang Xu
Hoist scheduling, especially cyclic hoist scheduling (CHS), is used to maximize the manufacturing productivity of electroplating processes. Water-reuse network design (WRND) for the electroplating rinsing system targets the optimal water allocation, such that fresh water consumption and wastewater generation are minimized. Currently, there is still a lack of studies on integrating CHS and WRND technologies for electroplating manufacturing. In this paper, a multi-objective mixed-integer dynamic optimization (MIDO) model has been developed to integrate CHS and WRND technologies for simultaneous consideration of productivity and water use efficiency for environmentally benign electroplating. The orthogonal collocation method on finite elements is employed to convert the MIDO problem into a mixed-integer nonlinear programming (MINLP) problem. The efficacy of the methodology is demonstrated by solving a real electroplating example. It demonstrates that the computational methods of production scheduling, process design, and dynamic optimization can be effectively integrated to create economic and environmental win–win situations for the electroplating industry.
Keywords: Hoist scheduling; Water-reuse network design; Environmentally benign manufacturing

Hydration and leaching characteristics of cement pastes made from electroplating sludge Original Research Article
Waste Management, Volume 31, Issue 6, June 2011, Pages 1357-1363
Ying-Liang Chen, Ming-Sheng Ko, Yi-Chieh Lai, Juu-En Chang
The purpose of this study was to investigate the hydration and leaching characteristics of the pastes of belite-rich cements made from electroplating sludge. The compressive strength of the pastes cured for 1, 3, 7, 28, and 90 days was determined, and the condensation of silicate anions in hydrates was examined with the 29Si nuclear magnetic resonance (NMR) technology. The leachabilities of the electroplating sludge and the hardened pastes were studied with the multiple toxicity characteristic leaching procedure (MTCLP) and the tank leaching test (NEN 7345), respectively. The results showed that the electroplating sludge continued to leach heavy metals, including nickel, copper, and zinc, and posed a serious threat to the environment. The belite-rich cement made from the electroplating sludge was abundant in hydraulic β-dicalcium silicate, and it performed well with regard to compressive-strength development when properly blended with ordinary Portland cements. The blended cement containing up to 40% the belite-rich cement can still satisfy the compressive-strength requirements of ASTM standards, and the pastes cured for 90 days had comparable compressive strength to an ordinary Portland cement paste. It was also found that the later hydration reaction of the blended cements was relatively more active, and high fractions of belite-rich cement increased the chain length of silicate hydrates. In addition, by converting the sludge into belite-rich cements, the heavy metals became stable in the hardened cement pastes. This study thus indicates a viable alternative approach to dealing with heavy metal bearing wastes, and the resulting products show good compressive strength and heavy-metal stability.

One-step metal electroplating and patterning on a plastic substrate using an electrically-conductive layer of few-layer graphene Original Research Article
Carbon, In Press, Corrected Proof, Available online 17 September 2011
Taeseon Hwang, Joon Suk Oh, Jung-Pyo Hong, Gi-Yong Nam, Ah-Hyun Bae, Sang-Ik Son, Geun-Ho Lee, Hak-Kyung Sung, Youngkwan Lee, Jae-Do Nam
Few-layer graphene (FLG) was investigated as an electrically-conductive interleaf layer for one-step electroplating and patterning of metal on nonconductive polymer substrates without using multiple and toxic pretreatment processes in traditional electroplating. An individual FLG (5–10 nm of thickness with 6.4% of oxygen content) was obtained by expanding graphite with microwave followed by exfoliating the expanded graphite with sonication in N-methyl-pyrrolidone. Stacking FLG in the in-plane direction, a robust FLG film was obtained by the vacuum-assisted filtering and drying methods, and transferred to a polyethylene terephthalate (PET) substrate via an intermediate transfer to the water surface. The sheet resistance of the FLG film on the PET substrate was 0.9 kΩ/sq with a thickness of 80 nm and the root-mean-square roughness of 29 nm. In the electroplating of nickel on the FLG film, hemisphere-shape metal seeds appeared in the early stage of electroplating and they subsequently grew up to 200–480 nm, which became connected to form a continuous nickel layer. The thickness of the continuous nickel layer increased linearly with electroplating time. The developed electroplating method demonstrated its capability of selective patterning on nonconductive substrates using a simple masking technique.

Microelectrode arrays for electroanalytical sensing: Comparison of electroplating and electron-beam metallisation
Electrochemistry Communications, Volume 13, Issue 5, May 2011, Pages 414-417
Alice Delcourt Lançon, Ritu Kataky, David Wood, Andrew J. Gallant
This paper demonstrates the differences in electrochemical response obtained by two distinct methods of gold microelectrode array fabrication. An array of 306 gold recessed microelectrodes (45 μm in diameter) was fabricated using lithography, metallisation and oxygen plasma treatment processes. The microelectrodes characterised using cyclic voltammetry and AFM showed a marked change in surface roughness from 0.88 nm to 9.76 nm by using electroplating metallisation. This increase resulted in a substantial improvement in the MEA activity while maintaining the behaviour of the microelectrode array; a finding that indicates the cheaper electroplating technique is preferable for producing sensitive and reproducible MEAs.
Keywords: Microelectrode; Array; Metallisation; Roughness; Atomic Force Microscopy

Sorption studies of Cu(II) on gooseberry fruit (emblica officinalis) and its removal from electroplating wastewater Original Research Article
Desalination, Volume 277, Issues 1-3, 15 August 2011, Pages 390-398
Rifaqat Ali Khan Rao, Shaista Ikram
The sorption of Cu(II) onto waste residue left after extraction of juice from Indian gooseberry (Amla) fruit (Emblica officinalis) was studied. Equilibrium isotherms, kinetic data and thermodynamic parameters have been evaluated. Equilibrium data agreed well with Langmuir, Freundlich, Temkin and Dubinin–Radushkevich (D–R) isotherm models. The kinetic data followed pseudo-second-order model and it was found that intra-particle diffusion was not the sole rate-controlling factor. Gibbs free energy showed spontaneous process for all interactions. The breakthrough and exhaustive capacities were found to be 4.0 and 24.0 mg/g respectively. Emblica officinalis was shown to be a promising sorbent for Cu(II) removal from aqueous solutions. The practical utility of the sorbent has been demonstrated by achieving 97.60% removal of Cu(II) from electroplating wastewater by column process.

Sorption of heavy metals from electroplating effluent using immobilized biomass Trichoderma viride in a continuous packed-bed column Original Research Article
International Biodeterioration & Biodegradation, Volume 65, Issue 8, December 2011, Pages 1133-1139
Rajender Kumar, Divya Bhatia, Rajesh Singh, Suman Rani, Narsi R. Bishnoi
The sorption of heavy metals ions by immobilized Trichoderma viride biomass in a packed-bed column was studied. Fungal biomass T. viride was immobilized to Ca-alginate used for removal of Cr(VI), Ni(II) and Zn(II) ions from synthetic solutions and electroplating effluent. The experiments were conducted to study the effect of important design parameters such as bed height, flow rate and initial concentration of metal ions. The maximum sorption capacity was observed at flow rate 5 ml/min, bed height 20 cm and metal ions concentration 50 mg/L with immobilized biomass. Whereas, breakthrough time and saturation time decreased with increase flow rate and metal ions concentration and an inverse condition was found in bed height. The bed depth service time (BDST) Adams–Bohart model was used to analyze the experimental data. The regeneration efficiency was observed 40.1%, 75% and 53% for Cr(VI), Ni(II) and Zn(II) without any significant alteration in sorption capacity after 5th sorption–desorption cycles.
Keywords: Immobilized biosorbent; Packed-bed column; Breakthrough time; Sorption capacity; Bohart–Adams (BDST) model

Photoelectrochemical hydrogen production on Cu2ZnSnS4/Mo-mesh thin-film electrodes prepared by electroplating Original Research Article
Chemical Physics Letters, Volume 501, Issues 4-6, 7 January 2011, Pages 619-622
Guijun Ma, Tsutomu Minegishi, Daisuke Yokoyama, Jun Kubota, Kazunari Domen
P-type Cu2ZnSnS4 (CZTS) thin film was deposited on Mo-mesh substrate by sulfurization of electroplated Zn/Sn/Cu/Mo-mesh precursor. A photoelectrochemical water splitting reaction was investigated using a three-electrode reaction system composed of a Pt/CdS/CZTS/Mo-mesh, Pt wire, and Ag/AgCl as the working, counter, and reference electrodes, respectively, in an electrolyte solution containing Na2SO4 and NaOH. Scanning electron microscopy results indicated that the surface morphology of the CZTS could be changed by changing the pH of the Zn electroplating solution. At a pH of 9, an irregular hollow-column-type CZTS was formed, resulting in the highest CZTS electrode photocurrent observed in this study.

DSSC with a novel Pt counter electrodes using pulsed electroplating techniques Original Research Article
Current Applied Physics, Volume 11, Issue 1, Supplement, January 2011, Pages S147-S153
Chun-Chen Yang, Huan Qing Zhang, Yu Rong Zheng
The thin Pt electrode on transparent conductive oxide (TCO) substrate, i.e., FTO/glass, for the dye-sensitized solar cell was prepared by a pulsed electrodeposition method. The characteristic properties of the pulse-plated Pt film were prepared and compared with the conventional sputtered Pt film. The composition and surface morphology of the Pt thin film were examined by scanning electron microscope with energy dispersive X-ray spectroscopy (SEM/EDX), atomic force microscope (AFM). The AFM results indicated that the surface roughness of the pulsed plated Pt film is much higher than that of the sputtered Pt film. The catalytic activities of the as-prepared Pt films were examined by cyclic voltammetry (CV). It was found that the catalytic activities of the pulsed plated Pt films were much higher than those of the sputtered Pt film and the DC-plated Pt film. The highest energy conversion efficiency of ca. 6.0% on the DSSC with the pulse-plated Pt electrode was obtained. The result demonstrated that the pulse-plated thin Pt film can be a good candidate for dye-sensitized solar cell (DSSC) application.
Keywords: Thin Pt film; Pulse-plated Pt; Sputtered Pt; Counter electrode; Dye-sensitized solar cell (DSSC); Energy conversion efficiency

Image analysis for maintenance of coating quality in nickel electroplating baths – Real time control Original Research Article
Analytica Chimica Acta, Volume 706, Issue 1, 7 November 2011, Pages 1-7
M. Vidal, J.M. Amigo, R. Bro, F. van den Berg, M. Ostra, C. Ubide
The aim of this paper is to show how it is possible to extract analytical information from images acquired with a flatbed scanner and make use of this information for real time control of a nickel plating process. Digital images of plated steel sheets in a nickel bath are used to follow the process under degradation of specific additives. Dedicated software has been developed for making the obtained results accessible to process operators. This includes obtaining the RGB image, to select the red channel data exclusively, to calculate the histogram of the red channel data and to calculate the mean colour value (MCV) and the standard deviation of the red channel data. MCV is then used by the software to determine the concentration of the additives Supreme Plus Brightner (SPB) and SA-1 (for confidentiality reasons, the chemical contents cannot be further detailed) present in the bath (these two additives degrade and their concentration changes during the process). Finally, the software informs the operator when the bath is generating unsuitable quality plating and suggests the amount of SPB and SA-1 to be added in order to recover the original plating quality.
Keywords: Flatbed scanner; Image analysis; Nickel electrodeposition; Additives determination; “Real control” software; Process analysis

Nanofabrication of hard X-ray optics by metal electroplating in a dry etched mechanically stable inorganic template Original Research Article
Microelectronic Engineering, Volume 88, Issue 8, August 2011, Pages 2552-2555
Gianluca Grenci, Alessandro Pozzato, Alessandro Carpentiero, Enrico Sovernigo, Massimo Tormen
A nanofabrication process for high resolution X-ray optics and X-ray lithography masks was developed. The process is based on the plasma etching of a sacrificial hard inorganic interlayer (Si, Si3N4, SiOx or HSQ) used for pattern transfer and aspect ratio amplification. The structures are first defined on a top thin metal film by electron beam lithography and lift-off; a thin nickel layer at the bottom of the hard interlayer is used as etch stop. A base plating (Cr/Au) under the nickel serves as seed layer for the electroplating of an X-ray absorber or phase shifting material. The fabrication is completed by the stripping of the hard template by wet or dry etching. Compared to methods based on analogous process schemes, in which the aspect ratio of nanostructures is instead amplified by pattern transfer into a sacrificial polymer interlayer by oxygen plasma, the investigated method is advantageous for the higher mechanical stability of the nanostructured hard templates with respect to the polymer ones, thus enabling the realization of higher aspect ratio features.
Keywords: X-ray optics; X-ray microscopy; X-ray lithography; HSQ; EBL; Dry etching

Nanoparticle–electrode collision processes: The electroplating of bulk cadmium on impacting silver nanoparticles Original Research Article
Chemical Physics Letters, Volume 511, Issues 4-6, 5 August 2011, Pages 183-186
Yi-Ge Zhou, Neil V. Rees, Richard G. Compton
We report, for the first time, the bulk deposition (electroplating) of a metal onto nanoparticles during collisions with an inert electrode surface. Experiments show that for silver nanoparticles, multiple layers of Cd atoms can be electroplated onto the AgNPs from aqueous Cd2+ during collisions with a glassy carbon electrode held at a suitably reducing potential, and an average of 19 atomic layers of cadmium are found to be deposited in the few milliseconds that the NP is in contact with the electrode. For comparison, results are also presented for the underpotential deposition of Cd onto AgNPs under similar conditions.

Effect of copper pretreatment on the zincate process and subsequent electroplating of a protective copper/nickel deposit on the AZ91D magnesium alloy Original Research Article
Electrochimica Acta, Volume 56, Issue 24, 1 October 2011, Pages 8776-8782
Jinwei Tang, Kazuhisa Azumi
To obtain a durable Ni coating with excellent adhesion strength on an AZ91D Mg alloy, a pretreatment was performed with a small amount of Cu2+ ions added to the activation bath used in the pretreatment prior to the plating process. In the pretreatment activation process, a high density Cu layer was deposited on both the α-phase and β-phase areas of the substrate accompanied with Mg dissolution. The Cu deposit acted as nucleation seeds for the Zn deposition in the following zincate process which provided a uniform and dense Zn layer almost completely covering the substrate. Then a thin Cu layer was electroplated on this zincated substrate as an undercoating for the succeeding electroplating with Ni. Cross-sectional scanning electron microscopy observations showed that the Cu deposited by the pretreatment enabled the deposition of a protective Ni layer with few defects. This structure also contributed to the improvement of adhesion strength and corrosion resistance as compared with the non-Cu added sample.
Keywords: AZ91D Mg alloy; Cu pretreatment; Nickel electrodeposition; Corrosion protection; Adhesion strength

Assessment of heavy metal tolerance in native plant species from soils contaminated with electroplating effluent Original Research Article
Ecotoxicology and Environmental Safety, In Press, Corrected Proof, Available online 5 August 2011
Poonam Ahlawat Sainger, Rajesh Dhankhar, Manish Sainger, Anubha Kaushik, Rana Pratap Singh
Heavy metals concentrations of (Cr, Zn, Fe, Cu and Ni) were determined in plants and soils contaminated with electroplating industrial effluent. The ranges of total soil Cr, Zn, Fe, Cu and Ni concentrations were found to be 1443–3240, 1376–3112, 683–2228, 263–374 and 234–335 mg kg−1, respectively. Metal accumulation, along with hyperaccumulative characteristics of the screened plants was investigated. Present study highlighted that metal accumulation in different plants varied with species, tissues and metals. Only one plant (Amaranthus viridis) accumulated Fe concentrations over 1000 mg kg−1. On the basis of TF, eight plant species for Zn and Fe, three plant species for Cu and two plant species for Ni, could be used in phytoextraction technology. Although BAF of all plant species was lesser than one, these species exhibited high metal adaptability and could be considered as potential hyperaccumulators. Phytoremediation potential of these plants can be used to remediate metal contaminated soils, though further investigation is still needed.
Keywords: Industrial effluent; Heavy metals; India; Phytoremediation; Hyperaccumulators

Recovery of copper and water from copper-electroplating wastewater by the combination process of electrolysis and electrodialysis Original Research Article
Journal of Hazardous Materials, Volume 189, Issue 3, 30 May 2011, Pages 814-820
Changsheng Peng, Yanyan Liu, Jingjing Bi, Huizhen Xu, Abou-Shady Ahmed
In this paper, a laboratory-scale process which combined electrolysis (EL) and electrodialysis (ED) was developed to treat copper-containing wastewater. The feasibility of such process for copper recovery as well as water reuse was determined. Effects of three operating parameters, voltage, initial Cu2+ concentration and water flux on the recovery of copper and water were investigated and optimized. The results showed that about 82% of copper could be recovered from high concentration wastewater (HCW, >400 mg/L) by EL, at the optimal conditions of voltage 2.5 V/cm and water flux 4 L/h; while 50% of diluted water could be recycled from low concentration wastewater (LCW, <200 100="" 40="" 4="" 97.9="" 99.5="" according="" almost="" analysis="" and="" as="" at="" be="" because="" before="" both="" br="" by="" combination="" concentrated="" conditions="" consumption="" copper="" could="" developed="" discharged.="" ed="" edx="" effectively="" effluent="" el="" energy="" flux="" for="" from="" further="" h.="" h="" hcw="" high="" however="" kg="" kw="" l="" lcw.="" lcw="" limitation="" m3.="" mg="" not="" of="" optimal="" process="" purity="" realize="" recovered="" recovery="" results="" sem="" should="" showed="" simultaneously="" that="" the="" therefore="" to="" treated="" v="" voltage="" was="" water="" with="">Keywords: Electrolysis; Electrodialysis; Copper recovery; Water reuse; Combination process

Removal of chromium in electroplating wastewater by nanoscale zero-valent metal with synergistic effect of reduction and immobilization Original Research Article
Desalination, Volume 280, Issues 1-3, 3 October 2011, Pages 224-231
Zhanqiang Fang, Xiuqi Qiu, Ruixiong Huang, Xinhong Qiu, Mingyu Li
Reductive immobilization of chromium in wastewater by nanoscale zero-valent metal (nZVM) prepared from steel pickling waste liquor was investigated. A series of characterization techniques were conducted to characterize the properties of the synthesized nanoparticles. Effects of pH, buffer substances, natural organic matter (NOM) and hardness were evaluated to probe the impact of environmental factors. Removal of Cr(VI) benefited from a decrease in pH value and the presences of buffer substances and Ca2+. NOM was found to be suppressive on the activity of ZVM, and coupled effect of Ca2+ and NOM was additive effect due to their non-interference when operating under acidic condition. The nZVM was proved to be more effective (up to 40.6-fold) than zero-valent iron and nanoscale zero-valent iron for Cr(VI) removal, and its removal capacity in wastewater was 182 ± 2 mg g−1. The removal mechanism included mass transfer on solid–liquid interface, reduction of Cr(VI) and simultaneous co-precipitation as Cr–Fe (oxy)hydroxide on the surface of nanoparticles. The results presented herein indicated nZVM was promising for in-situ remediation of Cr(VI).

Flatbed scanners as a source of imaging. Brightness assessment and additives determination in a nickel electroplating bath Original Research Article
Analytica Chimica Acta, Volume 694, Issues 1-2, 23 May 2011, Pages 38-45
M. Vidal, J.M. Amigo, R. Bro, M. Ostra, C. Ubide, J. Zuriarrain
Desktop flatbed scanners are very well-known devices that can provide digitized information of flat surfaces. They are practically present in most laboratories as a part of the computer support. Several quality levels can be found in the market, but all of them can be considered as tools with a high performance and low cost. The present paper shows how the information obtained with a scanner, from a flat surface, can be used with fine results for exploratory and quantitative purposes through image analysis. It provides cheap analytical measurements for assessment of quality parameters of coated metallic surfaces and monitoring of electrochemical coating bath lives. The samples used were steel sheets nickel-plated in an electrodeposition bath. The quality of the final deposit depends on the bath conditions and, especially, on the concentration of the additives in the bath. Some additives become degraded with the bath life and so is the quality of the plate finish. Analysis of the scanner images can be used to follow the evolution of the metal deposit and the concentration of additives in the bath. Principal component analysis (PCA) is applied to find significant differences in the coating of sheets, to find directions of maximum variability and to identify odd samples. The results found are favorably compared with those obtained by means of specular reflectance (SR), which is here used as a reference technique. Also the concentration of additives SPB and SA-1 along a nickel bath life can be followed using image data handled with algorithms such as partial least squares (PLS) regression and support vector regression (SVR). The quantitative results obtained with these and other algorithms are compared. All this opens new qualitative and quantitative possibilities to flatbed scanners.
Keywords: Image analysis; Flatbed scanner; Principal component analysis; Partial least squares regression; Support vector regression; Nickel electrodeposition; Coating quality

Void-free micro-pattern of nickel fabricated by electroplating with supercritical carbon dioxide emulsion Original Research Article
Microelectronic Engineering, Volume 88, Issue 8, August 2011, Pages 2225-2228
Tso-Fu Mark Chang, Toshikazu Tasaki, Chiemi Ishiyama, Masato Sone
Void-free micro-pattern of nickel was fabricated electrochemically by applying supercritical carbon dioxide emulsion (Sc-CO2-E). Evolution of hydrogen gas bubbles is usually the cause of defect and pinholes for microstructures fabricated electrochemically using aqueous electrolyte. Defect and pinholes formed dramatically limit application of the micro-sized metallic pattern in fine and complex mechanical systems. Micro-pattern of nickel pillars with diameters from ca. 50 to 125 μm was fabricated by using film-type SU-8 as the template and brightener-contained Watts bath as the electrolyte. Height of the nickel pillars is limited by thickness of SU-8 film and controlled by current applied and deposition time. Defect was found for micro-pattern of nickel prepared by conventional method; that is without application of Sc-CO2-E. Void-free micro-pattern of nickel was obtained when Sc-CO2-E was applied with experimental pressure and temperature at 15 MPa and 323 K, respectively. In addition, the SU-8 film could be simply peeled off using tweezers when electroplated with Sc-CO2-E using 15-μm-thick SU-8 film.
Keywords: Supercritical carbon dioxide emulsion; Void-free; Micro-pattern; Microstructure; Nickel

Influence of zincate pretreatment on adhesion strength of a copper electroplating layer on AZ91 D magnesium alloy Original Research Article
Surface and Coatings Technology, Volume 205, Issues 8-9, 25 January 2011, Pages 3050-3057
Jinwei Tang, Kazuhisa Azumi
Cu was electrodeposited on AZ91 D Mg alloy with zincate pretreatment in an alkaline plating bath, and the effect of zincate pretreatment on adhesion strength of the Cu layer was investigated. Scanning electron microscopy results showed that Zn was mainly deposited on the α-phase surface, and ultrasonic agitation at the initial stage of the zincate pretreatment improved the coverage of the Zn layer even on the β-phase surface, resulting in enhancement of the adhesion strength of the Zn layer and the successive Cu layer to the substrate. Adhesion tests revealed that the plating layer peeled off at the mixed layer of Zn and Cu deposits formed at the interface between the zincated layer and the electrodeposited Cu layer. A smooth Cu surface was obtained in the plating bath containing H3BO3.
Keywords: AZ91 D Mg alloy; Zincate pretreatment; Copper electrodeposition; Adhesion strength

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