Plating Bath Research Articles

The effect of fluoride on the formation of an electroless Ni–P plating film on MAO-coated AZ31B magnesium alloy

This study adds fluoride to the electroless nickel-phosphorus (Ni–P) plating solution to prevent the deterioration of MAO-coated AZ31B Magnesium alloy after contact with an electroless plating bath. During the electroless Ni–P plating process, fluoride reacts with Ni2+ ions and the MAO coating to form interphases (NaMgF3), which exhibit good bonding and corrosion resistance. NaMgF3 buffers H+ ions formed from the initiation of Ni–P deposition, preventing the interface of materials from damaging the MAO coating with H+ ions. As immersion time increases, nickel is scattered over the coating.The fundamental data for MAO/Ni–P coated AZ31B Mg alloy determines whether there is fluoride in the electroless Ni–P plating solution. The results show that the coating for a fluoride-containing solution is more resistant to corrosion than those in fluoride-free solution. The compositions, structure and morphology of the MAO/Ni–P coatings that formed for different working parameters are determined using energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The corrosion resistance of the MAO/Ni–P coatings is calculated in a 3.5 wt.% NaCl solution using a potentiodynamic polarization test, electrochemical impedance spectroscopy (EIS) and a salt spray test (SST).

Effects of Electroless NiSnP Plating Bath Composition with High Sn Containing Deposited Film

Many studies have investigated Ni-Sn alloy because it has good luster and excellent corrosion resistance. Electroplating methods have already reached a practical level of applicability, but electroless plating methods have not reached such a degree of utility because they present difficulties such as insufficient film thickness and low Sn content in the deposited film. Therefore, we fixed the bath temperature and stirring under the operating conditions and studied details of the plating bath composition to deposit a film with a high Sn content of 50 wt% or more using electroless plating.

Indirect electrodeposition of a NiMo@Ni(OH)2MoOx composite catalyst for superior hydrogen production in acidic and alkaline electrolytes

Hydrogen production from renewable energy urgently needs application-oriented catalysts. In this work, a coupled procedure of indirect electrodeposition and in situ electrochemical activation is presented to synthesize a NiMo@Ni(OH)2MoOx composite coating on a graphite substrate. A mixed oxide coating of Ni(OH)2 and MoO3 is indirectly electrodeposited from a weak acidic citrate plating bath by means of local pH increase at the electrode interface caused by the hydrogen evolution reaction (HER). Without the need of special treatment, low valence of Ni0, Mo0 and MoO2 are naturally formed and dispersed in the oxide matrix at the initial stage of the HER process in 1.0 M H2SO4 or 1.0 M KOH, leading to a significant activation of the catalyst coating. The final catalyst can achieve a HER activity comparable or even superior to Pt-based electrocatalysts in both acidic and alkaline solutions. Density functional theory calculations support a bimetallic catalytic mechanism involving NiMo active centers, which need a Gibbs free energy of atomic hydrogen absorption smaller than that on the Pt (111) surface. This work provides a facile and unique procedure for preparing highly active and industrially attractive electrocatalysts.

Graphene Nanoplatelets Modified Chemlok® Adhesive System for Natural Rubber – Aluminium Bonded Component in Engine Mount

Generally, the engine mount is made from rubber and mild steel bonded with a Chemlok® adhesive system. It could be modified to provide sufficient bonding between natural rubber and aluminum. Therefore, this work aims to study a nano-manipulated adhesive system by modifying the existing Chemlok® adhesive system at different weight percentages of graphene nanoplatelets (GNPs) loading via two steps ultrasonic-assisted stirring process by ultrasonic bath and hot plate. The natural rubber (NR)-aluminum (Al) substrates were bonded using a hot press machine under the pressure of 100 kgf/cm2 for 20 minutes at 140 °C temperature. The samples were subjected to a 90-degree peel test based on ASTM D429 by the UTM machine, and the peel-fractured surfaces were evaluated both physically and under SEM. The adhesive strength increased with the increment of GNPs in the modified Chemlok® 205/220 system. The GNPs modified Chemlok® system achieved 30% improvement than the existing adhesive. The analyses proved the modification was successful. The modified system with GNPs dispersed at certain intercalation levels showed active functional groups, reinforcing effects, and thermal stability.

The Performance of Zn-Ni Alloy Coating Electrodeposited from Stabilized Bath

A metallic part corrodes when it undergoes electrochemical reactions which cause the surface and structural deterioration of the metal. Through electroplating, metallic components can be protected from corrosion by coating them with Zn-Ni alloys. This study examined the electrodeposition of a Zn-Ni alloy film on a steel substrate from a chloride bath containing ethylene-diamine-tetraacetic acid (EDTA). A Pourbaix diagram using the OLI software was used to determine the stability of the Zn-Ni plating bath and the suppression of hydrogen evolution reaction (HER). Comparing the composition of Zn-Ni coating deposited in the EDTA bath with the pure Zn-Ni coating, the EDTA bath yielded higher deposition thickness and an average crystallite size reduction. The Zn-Ni coating deposited from the EDTA bath has a lower dissolution rate and better corrosion resistance properties than the non-EDTA bath. Polarization tests exhibited that the Zn-Ni alloy deposited from 0.119 mol/l EDTA bath at 20 mA/cm2 current density showed lower corrosion current (Icorr) and more positive corrosion potential (Ecorr). Atomic force microscopy (AFM) and Vickers microhardness testing were used to characterize the morphological properties, topographic structures, and microhardness of Zn-Ni coatings.

Effects of Carrier, Leveller, and Booster Concentrations on Zinc Plating from Alkaline Zincate Baths

Organic additives are required for alkaline zincate plating baths to obtain an acceptable coating on steel for corrosion protection. The effects and possible interactions of three commercial additives (Eldiem Carrier, Eldiem Booster, and Bright Enhancer 2× on zinc electrodeposition from a high-concentration alkaline zincate bath were investigated. Visually acceptable deposits were produced within the current density range of 130 to 430 A m−2 for most additive conditions examined. Over concentration ranges examined, decreasing the booster concentration led to brighter zinc deposits, and an interaction between the carrier and the booster was detected. The additives fostered the formation of compact and adherent coatings as illustrated by scanning electron microscopy. Throwing power and current efficiency were not impacted by the additives over the concentration ranges examined. Linear sweep voltammetry proved that the additives increased the overpotential for zinc deposition. The additive combination that produced the brightest deposit also demonstrated the strongest adsorption of additives in linear sweep voltammetry.

A study of dielectrics generated by electro-less electrochemical method for semiconductor devices

The aim of this work is to the basic concepts of the varies chemical and electrochemical procedures used m the fabrication of semiconductor devices seems to be useful to provide a suitable background for the present work, a brief review of the same as also the results obtained by earlier workers has been undertaken at the outset. A careful scrutiny of the results obtained by different workers reveals that although the aforesaid methods have a few limitations, they may be satisfice borily used as an alternative to sputter and evaporation techniques for device fabrication. The author carried out experimental investigations on the formation and properties of ohmic contact to silicon using two electroless plating baths - one operated at room temperature and the other at 95°C. In particular, the variation of contact resistance of ohmic contacts formed by electroless Ni-P process on silicon was studied as a function of sintering temperatures with operating point temperatures and pH of the baths as parameters. ^rom these studies it has been shown that both the baths yielded an adherent and dense deposit of nickel-phosphorous alloy on n-Si, which when sintered at very high temperatures give a less value of contact resistance due to the formation of metal-n -n contact. The phosphorous component of the Ni-P deposit diffuses into n-Si during heat treatment and forms the metal-n+ --n contact which behaves as an ohmic contact. As expected, the value of contact resistance was found to decrease with the increase of phosphorous materials in the deposit. The most favourable temperature range of heat treatment was found to be between 600°-700°C. Heats studying above 700°C slightly less increase the contact resistance probably due to the out diffusion of phosphorous from the Ni-P deposit. The barrier height and ideality factor are two important parameters for m-s contacts. The values of these two parameters of electrochemically fabricated Schottky diodes as obtained from the capacitance and current voltage characteristics were found to be in fairly close agreement with those of vacuumevaporated diodes. It is therefore, concluded that the electrochemical method of metal deposition is a valid and convenient technique for the fabrication and study of metalsemiconductor contacts

Increasing the structural and compositional diversity of ion-track templated 1D nanostructures through multistep etching, plastic deformation, and deposition

Ion-track etching represents a highly versatile way of introducing artificial pores with diameters down into the nm-regime into polymers, which offers considerable synthetic flexibility in template-assisted nanofabrication schemes. While the mechanistic foundations of ion-track technology are well understood, its potential for creating structurally and compositionally complex nano-architectures is far from being fully tapped. In this study, we showcase different strategies to expand the synthetic repertoire of ion-track membrane templating by creating several new 1D nanostructures, namely metal nanotubes of elliptical cross-section, funnel-shaped nanotubes optionally overcoated with titania or nickel nanospike layers, and concentrical as well as stacked metal nanotube-nanowire heterostructures. These nano-architectures are obtained solely by applying different wet-chemical deposition methods (electroless plating, electrodeposition, and chemical bath deposition) to ion-track etched polycarbonate templates, whose pore geometry is modified through plastic deformation, consecutive etching steps under differing conditions, and etching steps intermitted by spatially confined deposition, providing new motifs for nanoscale replication.

HBM4EU Chromates Study: Determinants of Exposure to Hexavalent Chromium in Plating, Welding and Other Occupational Settings.

Work-related exposures in industrial processing of chromate (chrome plating, surface treatment and welding) raise concern regarding the health risk of hexavalent chromium (Cr(VI)). In this study, performed under the HBM4EU project, we focused on better understanding the determinants of exposure and recognising how risk management measures (RMMs) contribute to a reduction in exposure. HBM and occupational hygiene data were collected from 399 workers and 203 controls recruited in nine European countries. Urinary total chromium (U-Cr), personal inhalable and respirable dust of Cr and Cr(VI) and Cr from hand wipes were collected. Data on the RMMs were collected by questionnaires. We studied the association between different exposure parameters and the use of RMMs. The relationship between exposure by inhalation and U-Cr in different worker groups was analysed using regression analysis and found a strong association. Automatisation of Cr electroplating dipping explained lower exposure levels in platers. The use of personal protective equipment resulted in lower U-Cr levels in welding, bath plating and painting. An effect of wearing gloves was observed in machining. An effect of local exhaust ventilation and training was observed in welding. Regression analyses showed that in platers, exposure to air level of 5 µg/m3 corresponds to U-Cr level of 7 µg/g creatinine. In welders, the same inhalation exposure resulted in lower U-Cr levels reflecting toxicokinetic differences of different chromium species.

Effect of Plating Variables on Oxygen Evolution Reaction of Ni–Zn–Fe Electrodes for Alkaline Water Electrolysis

In this study, we investigated the oxygen evolution reaction (OER) characteristics of Ni–Zn–Fe electrodes by varying plating current density and Ni:Fe ratio in a plating bath. The activity of the OER increased up to the plating current density of 160 mA/cm2, as the Fe content of the deposited electrode increased and electrochemical surface area (ECSA) increased after Zn dealloying. However, for the plated electrode with higher than 160 mA/cm2 of current density, the change in composition caused by underpotential deposition led to decreased activity due to decreasing Fe content and diminishing Zn dealloying. Moreover, when the Ni:Fe ratio in the plating bath was varied, outstanding OER activity was observed at Ni:Fe = 2:1. When the Fe content of the bath increased beyond this ratio, Fe could not restrain Ni oxidation and formed Fe oxides in OER reaction, and oxygen vacancy decreased. These caused a degradation of the OER activity.

Effect of W Concentration on Hardness and Wear Properties of Ni-BW Coatings

In this study, coatings were produced at different tungsten (W) sources concentrations in plating baths by the electrodeposition method. The concentration of sodium tungstate was 10, 20, 40 g/L, and the pulse current (PC) method was preferred for prepared of the coatings. The surface morphology, coating thickness, phase analysis of the coatings were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD) methods. The hardness of coatings were measured by the microhardness (Vickers) method. Finally, the coatings were subject to wear tests to determine the coefficient of friction and wear rate. As a result of the studies, it was seen that the coating obtained from the sodium tungstate concentration of 20 g/L had the highest hardness with 859 HV. Wear tests also showed that the lowest friction coefficient and wear rate were seen for coating produced at this concentration.

Effect of Heat Treatment and Applied Load on Mechanical and Tribological Properties of Ni-B-CeO2 Composite Electroless Coating

Cerium oxide (CeO2) particle reinforced Ni-B composite coating was produced by electroless coating method from a Ni-B coating bath containing CeO2 particles. In the electroless plating bath, nickel sulfate hexahydrate ((NiSO4.6H2O) was used as nickel source, dimethylamine borane ((CH3)2NHBH3) as reducing agent, thiourea (CH4N2S) as stabilizer and sodium acetate (CH3COONa) as complexing agent. The aim of the study is to investigate the structural characterization of CeO2 particle reinforced coating and the effects of wear test conditions on its tribological properties. The surface morphology of the coating was performed by scanning electron microscope (SEM), and phase structure analysis was performed by X-ray diffraction (XRD). Nanohardness measurements were carried out with a nanoindenter device, and wear tests were done with a ball-on-disk test device. Worn surface analyzes were made using a 3D profilometer. Experimental results showed that the hardness of the coating increased with heat treatment; however, its tribological behavior changed depending on different loads

Electrodeposition of lead and lead-tin alloy on copper using an eco-friendly methanesulfonate plating bath

Lead coatings were deposited from an electroplating bath contained mainly a lead salt and free methane sulfonic acid (MSA). Electroplating copper samples with a lead-tin alloy was carried out from a plating bath contained a lead salt, a tin salt and free MSA. An organic additive was added to enhance the surface morphology and therefore the appearance of the coated samples. The parameters affected the coating quality like the plating time, current density, temperature and bath composition are optimized. Surface characterization (FE-SEM & EDX) of the formed coating shows a compact dense layer of Pb or Pb–Sn alloy. XRD of Pb–Sn coating shows clear peaks of each lead and tin. The electrochemical properties of the coated samples was investigated using the electrochemical impedance spectroscopy (EIS). The obtained coatings were compared with those obtained using the fluoroborate bath. It is worthy to mention that the presence of the organic additives markedly improved the quality of the lead coating obtained from the methanesulfonate bath so as to have the same quality of the coating obtained from the fluoroborate bath.

A novel approach for quantifying hydrogen embrittlement using side-grooved CT samples

Aerospace parts made of high strength steels, such as landing gears and helicopter transmissions, are often electroplated to satisfy various engineering specifications. However, plated parts are occasionally rejected because of hydrogen embrittlement, and the industry has few means of evaluating quantitatively the actual damage caused by hydrogen. In the present article, we developed a novel method to measure the stress intensity threshold for hydrogen embrittlement (Kth) in industrial plating conditions. The method consists in plating side-grooved CT samples in industrial plating baths, and measuring Kth with an incremental step loading methodology. We validated the method with a benchmark case known to produce embrittlement (omitted post-plating bake) and we used the method on a test case for which the level of embrittlement was unknown (delayed bake). For the benchmark case, we measured a Kth of 49.0MPam0.5 for non-baked samples. This value is significantly lower than the fracture toughness of the unplated material, which is 63.8MPam0.5. We conclude that this novel combination of geometry and test method is efficient in quantifying hydrogen embrittlement of samples plated in industrial conditions. For the test case, the Kth are respectively 57.9MPam0.5 and 58.8MPam0.5 for samples baked 100 h and 4 h after plating. We conclude that delaying the post-plating bake does not cause hydrogen embrittlement in the studied conditions. Using a finite element hydrogen diffusion analysis, we argue that the side grooves on CT samples increase the sensitivity to hydrogen embrittlement in comparison to smooth samples. In smooth samples, a zone of plane stress at the surface of the specimen shields hydrogen from penetrating to the center of the specimen, a phenomenon which is alleviated with machining side grooves.

Enhancement of corrosion resistance and lubricating performance of electrodeposited Ni-Co coating composited with mesoporous silica nanoparticles and silicone oil impregnation

In the present study, we have developed a new type of nanocomposite Ni-Co coating including mesoporous silica nanoparticles (MSNs) by electrodeposition for the corrosion protection of steel fasteners. The effects of the nanoparticles content in the bath on the microstructure, mechanical properties, and corrosion resistance of Ni-Co-MSNs nanocomposite coatings with and without silicone oil impregnation have been investigated comprehensively. It is found a significant improvement in corrosion resistance of the Ni-Co coating after adding 4 g/L of MSNs into the plating bath. The optimized Ni-Co-MSNs composite coating has MSNs both incorporated in the Ni-Co alloy matrix and dispersed on the coating surface. This nanocomposite coating infused with silicone oil decreases the surface wettability, friction coefficient, electrochemical activity at the scratch due to the dispersed mesoporous nanoparticles as oil reservoirs, showing a remarkable enhancement in corrosion resistance and lubricating performance of the composite coating system.

Surface-enhanced Raman scattering (SERS) active substrate from gold nanoparticle-coated porous silicon for sensitive detection of horseradish peroxidase enzyme

The sensitive detection of horseradish peroxidase (HRP) enzyme using a gold nanoparticle/porous silicon (AuNPs/PSi) active substrate via surface-enhanced Raman scattering (SERS) is demonstrated. Electrochemical porosification via galvanostatic anodization in hydrofluoric acid (HF) mixed with ethanol was used to fabricate mesopore-size PSi layers onto a p-type Si (100) wafer. The AuNPs were reduced onto the meso-PSi surface through a spontaneous galvanic displacement reaction by dipping the substrates in a simple plating bath. The structural features and morphology of the designed frameworks were elucidated by X-ray diffraction (XRD) analysis, field-emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDX), and X-ray photoelectron spectroscopy (XPS). The SERS performance of the AuNPs/PSi substrate was firstly examined and evaluated using crystal violet dye as the target analyte, where it exhibited enhanced SERS response. Moreover, the active substrate displayed an extremely sensitive and reproducible SERS response toward the HRP enzyme as a reactive analyte. The active substrate exhibited excellent detectable performance with a very low concentration of 10−8 M HRP and an enhancement factor (EF) of approximately 4.8 × 105. The analytical enhancement of Raman signals in response to Au plasmonic nanoparticles signifies the combination of the charge-transfer mechanism and electromagnetic amplification because of the formed density of hotspot regions. Therefore, the current newly fabricated AuNPs/PSi substrates have optimistic prospects in biophysical, biochemical, and biomedical applications as highly active SERS substrates.

Optimization of Electrodeposited Ni-Cr Composite Coatings by using Taguchi Design and Grey Relational Method

In this investigation, the Nickel (Ni) – Chromium (Cr) composite deposits was developed from conductive type nickel plating bath through electrodeposition technique. The Cr particles concentration in bath were taken in three different proportions such as 10 g/l,20 g/l and 30 g/l and got deposited on the Ni plate. The design of experiment technique, L27 orthogonal array of Taguchi method was employed for conducting experiments with different combination of parameters and its level. The parameters taken into consideration were current density level, pH range, bath temperature, Cr concentration in bath and stirrer speed. The experiment includes the measurement of micro hardness, area fraction of Cr, mass of deposit and coating thickness of coated samples with variable input parameters. The main effects of process parameters and their influences on the responses were analyzed. The outcomes shows that Cr concentration in bath and pH range are the most significant parameters for better enhanced responses measured. Microstructure examinations were conducted to analyze Cr deposition in prepared Ni plates using optical metallurgical microscope, scanning electron microscope (SEM) micro images and Energy Dispersive X-Ray (EDX) spectroscopy studies. Furthermore, the decision-making procedure was carried out for maximization of multi-performance measured responses using grey relational analysis (GRA). The optimized plating parameters levels are found to be 4 A/dm2 for Current density, 2.5 for pH, 45˚C for bath temperature, 30 g/l for bath concentration and 300 rpm for agitation speed to have the maximum micro hardness of 1037 HV, 370 mg of mass of deposit, 42% of Cr particle area fractions and 112 µm of coating thickness. Subsequently the obtained optimal combination of process parameters was validated through confirmation experiment. The results shows that the confirmation test responses are well associated with predicted response values on the Ni-Cr coatings.

Photocatalytic Recovery of Gold from a Non-Cyanide Gold Plating Solution as Au Nanoparticle-Decorated Semiconductors.

In this work, a photocatalytic process was carried out to recover gold (Au) from the simulated non-cyanide plating bath solution. Effects of semiconductor types (TiO2, WO3, Nb2O3, CeO2, and Bi2O3), initial pH of the solution (3–10), and type of complexing agents (Na2S2O3 and Na2SO3) and their concentrations (1–4 mM each) on Au recovery were explored. Among all employed semiconductors, TiO2 exhibited the highest photocatalytic activity to recover Au from the simulated spent plating bath solution both in the absence and presence of complexing agents, in which Au was completely recovered within 15 min at a pH of 6.5. The presence of complexing agents remarkably affected the size of deposited Au on the TiO2 surface, the localized surface plasmon effect (LSPR) behavior, and the valence band (VB) edge position of the obtained Au/TiO2, without a significant change in the textural properties or the band gap energy. The photocatalytic activity of the obtained Au/TiO2 tested via two photocatalytic processes depended on the common reduction mechanism rather than the textural or optical properties. As a result, the Au/TiO2 NPs obtained from the proposed recovery process are recommended for use as a photocatalyst for the reactions occurring at the conduction band rather than at the valence band. Notably, they exhibited good stability after the fifth photocatalytic cycle for Au recovery from the actual cyanide plating bath solution.

Electrochemical Characteristics of Nickel Hydroxide Fabricated from a Spent Electroless Plating Bath

Electrochemical Characteristics of Nickel Hydroxide Fabricated from a Spent Electroless Plating Bath

Tyrosine as a novel potential stabilizer in an electroless Ni-P bath exempt of trisodium citrate as complexing agent: Chemical baths optimization and comparative study

• New formulation of Ni-P alloy electroless plating baths using hypophosphite as reducing agent. • Abundance of trisodium citrate as the main component acting as a complexing agent in Ni-P electroless plating baths. • Addition of tyrosine as a complexing-stabilizing agent led to a significant improvement in bath stability accompanied by a deposition rate of 18 µm h −1 . • Optimization of the tyrosine-containing bath led to a gain of 67% NiSO4,6H2O and 85% CH 3 COONH 4 . The effect of tyrosine (C 9 H 11 NO 3 ) as a new stabilizing agent on the composition and conditions of the electroless plating bath of the Ni-P alloy was studied. A comparative study with trisodium citrate, which is commonly used, as a stabilizing complexing agent revealed the effect of tyrosine in this study. Scanning electron microscopy (SEM) and X-Ray Energy Dispersion (EDX) are used to study the properties of the Ni-P coating deposit developed in the presence of tyrosine and trisodium citrate. The result of this optimization showed that the use of tyrosine causes the concentration of NiSO 4 and CH 3 COONH 4 in the bath to decrease to 67% and 85%, respectively. In contrast, the use of trisodium citrate had no effect neither on the composition nor on the effect of the bath conditions of the deposit. In addition, the use of C 9 H 11 NO 3 as a stabilizing agent in the bath promotes the increase of the phosphorus content more than trisodium citrate when optimizing the accelerating agent in the bath and therefore changes the structure of the Ni-P deposits developed.