Optimization of the Preparation Parameters of High-Strength Nickel Layers by Electrodeposition on Mild Steel Substrates

The electrodeposition process parameters were optimized for the acquisition of high-strength monolithic nickel layers on Q235A substrates based on the Watts nickel plating solution using the DC electrodeposition method. Based on the study of the electrochemical polarization behavior of nickel ions in Watts’ plating solution, 16 experimental protocols were selected according to the orthogonal test method. The residual stress, microhardness, modulus of elasticity, and surface roughness of the nickel plating were tested by X-ray diffractometer, nano-mechanical test system, and surface profilometer, respectively, to investigate the influence of current density, temperature, and PH on the mechanical properties of nickel plating, so as to determine the best process solution for the preparation of high-strength nickel plating. The results of the study show that the mechanical properties of the nickel deposits electrodeposited onto Q235A are optimized when plating at a current density of 3 A/dm2, a bath temperature of 45 °C, and a pH of 3.5. The nickel-plated layer has a minimum grain size of 34.8 nm, a microhardness of 3.86 GPa, a modulus of elasticity of 238 GPa, and a surface roughness Ra of 0.182 μm.

Influence of Double-Pulse Electrodeposition Parameters on the Performance of Nickel/Nanodiamond Composite Coatings

In this study, using 45# carbon steel as the substrate, a first experimental analysis was carried out on the polarisation behaviour of different component wattage plating solutions in order to determine the reasonable content of nanodiamond particles in a nickel/nanodiamond composite plating solution. Secondly, the effect of double-pulse forward and reverse duty cycle and reverse working time on the performance of nickel/nanodiamond composite plating was then investigated by testing the thickness, hardness and surface roughness of the composite plating and observing the surface micromorphology. The experimental results show that, when the content of nanodiamond particles in the plating solution is 5 g/L, the anti-pulse working time, forward and reverse pulse duty cycle of the double-pulse plating parameters are 20, 0.3 and 0.2 ms, respectively, and the composite plating layer prepared by double pulse has good comprehensive performance. This research work provides technical support for the optimisation of process parameters for the preparation of nickel/nanodiamond composite coatings by double-pulse electrodeposition.

One-step CZT electroplating from alkaline solution on flexible Mo foil for CZTS absorber

In this work, Cu-Zn-Sn (CZT) is co-electrodeposited onto a flexible Mo substrate exploiting an alkaline bath (pH 10). The plating solution is studied by cyclic voltammetry, highlighting the effects of potassium pyrophosphate (K4P2O7) and EDTA-Na2 on the electrochemical behavior and stability of the metallic ionic species. The optimized synthesis results in a homogeneous precursor layer, with composition Cu 44 ± 2 at. %, Zn 28 ± 1 at. %, and Sn 28 ± 2 at. %. Soft and reactive annealing are employed respectively to promote intermetallic phase formation and sulfurization of the precursor to obtain CZTS. Microstructural (XRD, Raman), morphological (SEM), and compositional (EDX, XRF) characterization is carried out on CZT and CZTS films, showing a minor presence of secondary phases. Finally, photo-assisted water splitting tests are performed considering a CZTS/CdS/Pt photoelectrode, showing a photocurrent density of 1.01 mA cm−2 at 0 V vs. RHE under 1 sun illumination. Graphical abstract

Morphological and elemental analyses of supported palladium (Pd)/silver (Ag) composite membranes

Supported palladium (Pd)/silver (Ag) composite membranes have been investigated for hydrogen separation mainly in order to avoid hydrogen embrittlement, improve hydrogen permeance and reduce membrane cost. The electroless method is recommended for the co-plating of Pd and Ag on a substrate surface. However, Ag precursor has a higher redox potential than Pd and, thus, Ag is preferentially deposited, which compromises the membrane selectivity to hydrogen. Here we investigated the morphology and elemental composition of supported palladium (Pd)/silver (Ag) composite membranes produced by different methods. The first membrane was produced from a plating solution of 80 wt% of Pd and 20 wt% of Ag. The membrane surface presented several large dendritic crystals that not grown in a direction to form a dense metallic film. According to EDS results, the membrane surface presented similar Pd and Ag composition, which confirms the preferential Ag deposition. At room temperature, this membrane presented a nitrogen flux of 0.35 mol m-2 s-1 at 200 kPa of transmembrane pressure. Thus, the formed membrane is not suitable for hydrogen separation. The second membrane was formed by adding small amounts of Ag to the plating solution during the electroless process. The final plating solution contained 75 wt% of Pd and 25 w% of Ag. The membrane thickness was 2 µm, but the membrane morphology was not totally dense. According to EDS results, the Ag composition was greater than the Pd composition, especially at the membrane top surface. This membrane also presented high nitrogen permeance probably due to the holes formed on the membrane surface. Thus, although the controlled addition of Ag is recommended to form dense membranes, the Ag was preferentially deposited over the Pd when starting with the highest rate of Ag addition. Adding lower Ag rates at the beginning could be helpful to avoid the preferential Ag deposition.

Morphological and Elemental Analyses of Supported Palladium (Pd)/Silver (Ag) Composite Membranes

Supported palladium (Pd)/silver (Ag) composite membranes have been investigated for hydrogen separation mainly in order to avoid hydrogen embrittlement, improve hydrogen permeance and reduce membrane cost. The electroless method is recommended for the co-plating of Pd and Ag on a substrate surface. However, Ag precursor has a higher redox potential than Pd and, thus, Ag is preferentially deposited, which compromises the membrane selectivity to hydrogen. Here we investigated the morphology and elemental composition of supported palladium (Pd)/silver (Ag) composite membranes produced by different methods. The first membrane was produced from a plating solution of 80 wt% of Pd and 20 wt% of Ag. The membrane surface presented several large dendritic crystals that not grown in a direction to form a dense metallic film. According to EDS results, the membrane surface presented similar Pd and Ag composition, which confirms the preferential Ag deposition. At room temperature, this membrane presented a nitrogen flux of 0.35 mol m-2 s-1 at 200 kPa of transmembrane pressure. Thus, the formed membrane is not suitable for hydrogen separation. The second membrane was formed by adding small amounts of Ag to the plating solution during the electroless process. The final plating solution contained 75 wt% of Pd and 25 w% of Ag. The membrane thickness was 2 µm, but the membrane morphology was not totally dense. According to EDS results, the Ag composition was greater than the Pd composition, especially at the membrane top surface. This membrane also presented high nitrogen permeance probably due to the holes formed on the membrane surface. Thus, although the controlled addition of Ag is recommended to form dense membranes, the Ag was preferentially deposited over the Pd when starting with the highest rate of Ag addition. Adding lower Ag rates at the beginning could be helpful to avoid the preferential Ag deposition.

Electroless Platinum Deposition Using Co3+/Co2+ Redox Couple as a Reducing Agent

In the present work, the kinetics of electroless deposition of Pt, using a cobalt ion redox system (Co3+/Co2+) as a reducing agent, has been investigated. The deposition rate of Pt depends on the pH, concentration of reactants, and temperature. The deaeration and bubbling of the plating solution with argon play an essential role. It was found that 0.11 mg cm−2 of Pt films could be deposited on the surface of a roughed glass sheet in one hour without replenishing the solution. Additional data have been obtained on the grounds of electrochemical quartz crystal microbalance experiments. The bubbling (agitation) of the electroless Pt plating solution with argon during the deposition of Pt results in a higher deposition rate and is ca. 3 µg cm−2 min−1. The Pt deposition rate is far less, and is as low as 0.14 µg cm−2 min−1 when the electroless Pt plating solution is not bubbled with argon during the deposition of Pt.

Fabrication of Three-Dimensional Microstructure Film by Ni-Cu Alloy Electrodeposition for Joining Dissimilar Materials

Metals with a three-dimensional microstructure film can be joined to plastics by the anchor effect. The three-dimensional microstructure films can be electrodeposited by a Ni-Cu alloy. In this study, the effects of the ratio of the concentration of Ni amidosulfate and Cu sulfate in the plating solution and plating current density on the shapes and microstructures of electrodeposited films were investigated. When the ratio of the concentration of the Ni amidosulfate and the Cu sulfate is 0.47-1.4:0.06 (M/L), a dendritic-type electrodeposited structure was generated at plating current density of 10 mA/cm2. When the ratio of the concentration of the Ni amidosulfate and the Cu sulfate is 0.47:0.6-1.2 (M/L), a feathery-type and needle-type electrodeposited structure was generated.

Preparation and electrochemical properties of a novel porous Ti/Sn–Sb-RuOx/β-PbO2/MnO2 anode for zinc electrowinning

PbO2 electrodes exhibit symmetry on the CV curve in MnSO4 bath (oxidation peak occurs at 1.00–1.40 V) and asymmetry in Mn(NO3)2 plating solution (negative current value at 1.00–1.18 V). The current rapidly rises to a large peak current at 1.25 V.

Recovery of Phosphorus from Waste Solution of Electroless Nickel-Phosphorus Plating

We attempted to recover phosphorus species from a waste plating solution of electroless nickel-phosphorus plating. With the aim of increasing the recovery yield by oxidizing phosphite to phosphate efficiently, we examined ozonation of a model plating solution by supplying ozonecontaining oxygen gas to the solution employing an aerated mixing vessel. As a result of the measurements of the transient changes in the concentrations of the phosphorus species and dissolved ozone in the solution, we confirmed the effect of the organic additives contained in the plating solution on the ozonation efficiency. Calcium chloride was subsequently added to the ozone-treated solution to precipitate the phosphate as calcium hydrogen phosphate, which was poorly soluble to water. At this moment, the recovery yield of the phosphorus from the model waste plating solution was greater than 86%.