Search Results (282)

Hydroxamic acid extractants, such as LIX984, demonstrate high efficiency in extracting nickel from electron-free nickel waste solutions; however, they suffer from a slow extraction rate. This study investigated the effect of adding 2–5 vol.% of three organophosphate extractants (P507, P204, and Cyanex272) to LIX984. The results show that incorporating 2–5 vol.% of P507 or Cyanex272 significantly improves both extraction efficiency and kinetics. The addition of organophosphate extractants increased the extraction rate by 1.5–10 times, indicating a direct correlation between the extractant content and the acceleration of the extraction process, with higher concentrations yielding faster extraction. Compared to the use of LIX984 alone, where nickel extraction efficiency was only 46%, the addition of 5 vol.% P507 increased efficiency to over 99%, with a substantial improvement in extraction rate. Similarly, 2 vol.% P204 achieved a nickel removal efficiency of 99.8%. In non-electroplating waste solutions (pH 4–6), selective removal of iron and zinc impurities was achieved by first adding 2–5 vol.% P204 or P507, followed by adjusting the pH to 6–7 and using a mixture of organophosphate extractants. The spent electroless nickel plating baths were then treated with LIX984 combined with organophosphoric acid extractants, yielding nickel salt solutions of higher purity. Thus, P507, P204, and Cyanex272 serve as effective promoters for the hydroxamic acid extractant LIX984, resulting in both enhanced nickel extraction efficiency and faster extraction kinetics. Full article

In this study, a highly conductive nickel (Ni) layer was deposited onto a P-type (Zr,Ti)Co(Sn,Sb) half-Heusler (HH) thermoelectric (TE) material using a low-cost electro-brush plating technique. Before depositing Ni on the TE material, the plating process was optimised on a stainless steel (SS) substrate. An optimal medium-rate deposition voltage of 6V was identified on the SS substrate, with the desired thickness, superior mechanical performance, reduced sheet resistance and surface roughness, and enhanced electrical conductivity. The optimised deposition condition was then applied to the P-type (Zr,Ti)Co(Sn,Sb) material, resulting in a Ni layer that significantly enhanced its electrical and thermal stability. After thermal exposure at 500 °C for 10 h, the Ni coating effectively protected the TE surface against oxidation and sublimation, suggesting that the interfacial contact properties of P-type (Zr,Ti)Co(Sn,Sb) TE material can be effectively enhanced by depositing a highly conductive, oxidation-resistant Ni layer using the cost-effective, straightforward electro-brush plating technique. Full article

Under harsh conditions involving high temperatures and severe abrasion, the copper plates of continuous casting crystallizers are highly susceptible to wear failure and thermal cracking. In this study, a Ni60AA transition layer is applied onto the copper plate via laser cladding to enhance the interfacial bonding properties. To further reinforce the coating, TiB₂ is incorporated into the nickel-based transition layer, leading to a significant improvement in overall performance. With the addition of 3 wt.% TiB₂ and 0.5% Y₂O₃, the coating microstructure undergoes notable refinement: coarse columnar grains transform into fine equiaxed grains, and the microhardness reaches 1225.3 HV0.1. The coating demonstrates excellent wear resistance, exhibiting a minimal wear depth of 97.09 μm, a low weight loss of 0.0089 g, and a stable friction coefficient of 0.32. By synergistically optimizing the transition layer and incorporating TiB₂, this study successfully enhances the surface strength and wear resistance of the crystallizer copper plate, offering a reliable technical approach for extending the service life of continuous casting crystallizers. Full article

Brass components are widely used in heat dissipation and thermal emission devices due to their high thermal conductivity and ease of processing. However, these applications demand good thermal oxidation resistance, high emissivity, and excellent corrosion resistance. In this study, nickel coatings were deposited on brass substrates by direct current electroplating, and the effects of current density and cathode configuration on the microstructure, emissivity, and corrosion resistance of the coatings were systematically investigated. The results show that the emissivity of the coatings first increased and then decreased with increasing current density. Optimal performance was achieved when the cathode and anode were positioned perpendicular to the horizontal plane at a current density of 3.0 A·dm⁻². Under these conditions, the coatings exhibited a smooth, uniform, and dense microstructure, with evenly distributed metallic grains. Electrochemical polarization and impedance measurements further confirmed the superior corrosion resistance of this coating, with a minimum corrosion current density of 0.259 μA·cm⁻², a maximum polarization resistance of 6381.55 Ω·cm², and a minimum corrosion rate of 0.023 mm/a. These findings demonstrate a simple and effective approach to enhancing both the emissivity and corrosion resistance of brass substrates, offering practical value for thermal management applications. Full article

The design and production of goods have been completely transformed by additive manufacturing (AM), which makes it possible to create components with intricate and complex geometries that were previously impossible or impractical to produce. However, current technologies continue to produce coarse-surfaced metal components that typically exhibit fatigue properties, resulting in component failure and unfavorable friction coefficients on the printed part. Therefore, to improve the surface quality of the fabricated parts, post-processing of AM-created components is required. With emphasis on electroless nickel plating, ChemPolishing (CP), and ElectroPolishing (EP), this study investigates post-processing methods for stainless steel that is additively manufactured (AM). The rough surfaces created by additive manufacturing (AM) restrict direct use. While ElectroPolishing (EP) achieves high material removal rates but may not be consistent, ChemPolishing (CP) offers uniform smoothening. Nickel plating enhances additive manufacturing (AM) products’ resistance to wear and scratches and corrosion protection. To optimize nickel deposition, medium (6%–9%) and high (10%–13%) phosphorus nickel was tested using the L9 Taguchi design of experiments (DOE). Mechanical properties, including scratch resistance and adhesion, were evaluated using the TABER 5900 reciprocating (Taber Industries, North Tonawanda, NY, USA) abraser apparatus, a 5 N scratch test, and ASTM B-733 thermal shock method. Surface analysis was performed with the KEYENCE VHX-7000 microscope (Keyence Corporation, Itasca, IL, USA), and chemical composition before and after nickel deposition was assessed via the ThermoFisher Phenom XL scanning electron microscope (SEM, Thermo Fisher Scientific, Waltham, MA, USA) Optimal processing conditions, determined using Qualitek-4 software, Version 20.1.0 revealed improvements in both surface finish and mechanical robustness. This comprehensive analysis underscores the potential of nickel-coated additive manufacturing (AM) parts for enhanced performance, offering a pathway to more durable and efficient additive manufacturing (AM) applications. Full article

A novel process for the synthesis of binder-free, porous nickel/polythiophene-functionalized sulfur (Ni/S-PTh) composite cathodes for lithium–sulfur (Li–S) batteries is introduced in this paper. Initially, a polyvinyl butyl polymer scaffold is 3D printed, then coated with a graphite-based conducting layer, and, finally, it is pulse-plated for nickel deposition to produce a high-surface-area, mechanically stable current collector. S-PTh particles are afterwards co-deposited into the Ni matrix through composite electrodeposition. After the dissolution of the polymer template, the resulting self-standing electrodes still maintain porous structure with uniform sulfur distribution and a distinct transition between the dense Ni layer and the Ni/S-PTh composite layer. Electrochemical characterization of the Ni/S-PTh composite cathodes by galvanostatic cycling at C/10 rate results in an initial specific discharge capacity of ~1120 mAh·g⁻¹ and a specific capacity of ~910 mAh·g⁻¹ after 200 cycles, resulting in a high capacity retention of ~81 %. For our novel approach, no steps at high temperatures or toxic solvents are involved and the need for polymer binders and conductive additives is avoided. These results demonstrate the potential of composite electrodeposition in combination with 3D printing for producing sustainable, high-performance sulfur cathodes with tunable architecture. Full article

Traditional natural gas transportation pipeline steels, such as API 5L X42 grade and the higher grades, are currently receiving a lot of attention in terms of their potential implementation in hydrogen transmission infrastructure. However, the microstructural constitution of steels with a ferrite phase and the presence of welds, with their non-polyhedral “sharp” microstructures acting as structural notches, make these steels prone to hydrogen embrittlement (HE). In this work, the notch tensile properties of copper- or nickel–phosphorus-coated API 5L X42 grade pipeline steel were studied in both the non-hydrogenated and electrochemically hydrogen-charged conditions in order to estimate anticipated protective effects of the coatings against HE. Both the Cu and Ni–P coatings were produced using conventional coating solutions for electroless plating. To study the material systems’ HE sensitivity, electrochemical hydrogenation of cylindrical, circumferentially V-notched tensile specimens was performed in a solution of hydrochloric acid with the addition of hydrazine sulfate. Notch tensile tests were carried out for the uncoated steel, Cu-coated steel, and Ni–P-coated steel at room temperature. The HE resistance was evaluated by determination of the hydrogen embrittlement index (HEI) in terms of relative changes in notch tensile properties related to the non-hydrogenated and hydrogen-charged material conditions. The results showed that pure electroless deposition of both coatings induced some degree of HE, likely due to the presence of hydrogen ions in the coating solutions used and the lower surface quality of the coatings. However, after the electrochemical hydrogen charging, the coated systems showed improved HE resistance (lower HEI_RA values) compared with the uncoated material. This behavior was accompanied by the hydrogen-induced coatings’ deterioration, including the occurrence of superficial defects, such as bubbling, flocks, and spallation. Thus, further continuing research is needed to improve the coatings’ surface quality and long-term durability, including examination of their performance under pressurized hydrogen gas charging conditions. Full article

A new, simple, and accurate assay was developed for the colorimetric determination of nickel ions in 96-well plates. The proposed method utilized the color change immediately visible even to the naked eye during the reaction of Ni(II) ions with dithiothreitol molecules (DTT). The intensity of the color produced by the formation of the complex between nickel and dithiothreitol is linearly proportional to the concentration of the metal ions in an alkaline environment, at room temperature, and the detection was performed using a mobile phone as the detector. The proposed method had a good linear response between 0.05 and 0.75 mmol L⁻¹ and a detection limit of 0.13 mmol L⁻¹ and was successfully applied for the determination of Ni(II) in bottled and surface water samples. Full article

The Jinchuan Cu–Ni sulfide deposit, one of only two ultra-large magmatic Ni–Cu–PGE deposits in Eurasia, is hosted in a small ultramafic intrusion at the southwestern margin of the Alxa block, North China Craton, and contains over five million tonnes of nickel. Previous studies suggest that its formation is linked to large-scale deep magmatic processes, but direct evidence from the mantle source region has been limited. Using P-wave seismic tomography, we imaged the crust and mantle beneath the Qilian–Longshoushan area, revealing a deep low-velocity anomaly at ~400 km depth, interpreted as residual mantle plume material. This anomaly spatially corresponds to the Jinchuan deposit, representing a long-term material and heat supply pathway for ore formation. A high-velocity anomaly at ~200 km depth, likely related to Indian plate subduction, influenced the Cenozoic tectonic evolution of the Longshoushan region. These results integrate geophysical, geochemical, and geological evidence, highlighting how deep mantle dynamics and associated magmatic activity controlled the supply of material to the Jinchuan Cu–Ni deposit and contributed to its formation. Full article

Corrosion failure of oil well tubing in the ocean can lead to significant economic losses. Surface treatment is often used to enhance the corrosion resistance of tubing, while corrosion acceleration will occur in a certain environment. This work combined onset failure analysis and corrosion simulation measurements to understand the failure procedure and corrosion mechanism of nickel plating materials in calcium chloride water-type weak corrosion environment. The microscopic analysis results of the failed part show CO₂ corrosion products co-deposit with SRB bacterial sulfide products and Ca compounds. The damage of nickel plating is accompanied by S-containing products, which was confirmed by simulated immersion experiments at 50 °C, 0.28 MPa CO₂ partial pressure, and a speed of 3 m/s. The aggressive solution penetrates through the micro-damage pores, followed by the degradation of the Ni plating layer into NiS, leading to the localized loss of protection and triggering under-deposit corrosion. Concurrently, the SRB’s anaerobic environment generates CO₂ corrosion byproducts and SRB-derived FeS. Full article

Hydrogen is emerging as a key energy vector for the transition toward renewable and sustainable energy sources. However, its safe and efficient storage remains a significant technical challenge in terms of cost, safety, and performance. In this study, we aimed to address the kinetic limitations of Mg by synthesizing catalyzed Mg@Ni systems using commercially available micrometric magnesium particles (~26 µm), which were decorated via electroless nickel plating under both aqueous and anhydrous conditions. Morphological and compositional characterization was carried out using SEM, EDS, and XRD. The resulting materials were evaluated through Temperature-Programmed Desorption (TPD), DSC, and isothermal hydrogen absorption/desorption kinetics. Reversibility over multiple absorption–desorption cycles was also investigated. The synthesized Mg@NiB system shows a reduction of 37 °C in the hydrogen release activation temperature at atmospheric pressure and a decrease of 167.3 °C under high vacuum conditions (4.5 × 10⁻⁷ MPa), in addition to a reversible hydrogen absorption/desorption capacity of 3.5 ± 0.09 wt.%. Additionally, the apparent activation energy for hydrogen desorption was lower (161.7 ± 21.7 kJ/mol) than that of hydrogenated commercial pure magnesium and was comparable to that of milling MgH₂ systems. This research is expected to contribute to the development of efficient and low-cost processing routes for large-scale Mg catalysis. Full article

Electroless nickel deposition (ELD) is an autocatalytic technique extensively used to impart conductive, protective, and mechanical functionalities to inherently non-conductive synthetic substrates. This review systematically explores the fundamental mechanisms of electroless nickel deposition, emphasising recent advancements in surface activation methods, solvent systems, and microstructural control. Critical analysis reveals that bio-inspired activation methods, such as polydopamine (PDA) and tannic acid (TA), significantly enhance coating adhesion and durability compared to traditional chemical etching and plasma treatments. Additionally, solvent engineering, particularly using polar aprotic solvents like dimethyl sulfoxide (DMSO) and ethanol-based systems, emerges as a key strategy for achieving uniform, dense, and flexible coatings, overcoming limitations associated with traditional aqueous baths. The review also highlights that microstructural tailoring, specifically the development of amorphous-nanocrystalline hybrid nickel coatings, effectively balances mechanical robustness (hardness exceeding 800 HV), flexibility, and corrosion resistance, making these coatings particularly suitable for wearable electronic textiles and smart materials. Furthermore, commercial examples demonstrate the real-world applicability and market readiness of nickel-coated synthetic fibres. Despite significant progress, persistent challenges remain, including reliable long-term adhesion, internal stress management, and environmental sustainability. Future research should prioritise environmentally benign plating baths, standardised surface activation protocols, and scalable deposition processes to fully realise the industrial potential of electroless nickel coatings. Full article

This paper reviews the fundamental principles and techniques of nickel electrodeposition, with a particular focus on metallizing polymeric substrates. It outlines the electrochemical mechanisms involved in depositing nickel from an acidic Watts bath, detailing the roles of key electrolyte components—i.e., nickel sulfate, nickel chloride, and boric acid—and the influence of process parameters, such as current density, temperature, and pH, on deposit quality (density and surface condition) and mechanical properties. In addressing the unique challenges posed by non-conductive polymers, this review compares emerging methods like silver conductive paint, highlighting differences in deposition time, surface resistivity, and environmental impact. Additionally, this paper examines how process parameters affect the as-deposited microstructure, adhesion, and overall mechanical properties (such as hardness, ductility, and tensile strength), while identifying critical issues such as low deposition density and substrate degradation. These insights provide a structured background for optimizing electroplating processes for applications in electronics, automotive, aerospace, and biomedical sectors, and suggest future research directions to enhance deposition uniformity, sustainability, and process control. Full article

The laser heterogeneous lap welding of nickel-plated steel and Cu sheets has been investigated in this study. The YAG (Yttrium-Aluminum-Garnet) laser beam only penetrates the upper Ni-plated steel sheet and cannot weld the bottom Cu sheet due to the low absorption coefficient of the YAG laser beam. Incorporating a blue-light and fiber laser into the coaxial laser beam significantly improves the quality of the weld fusion zone. The fiber laser beam can penetrate the upper nickel-plated steel sheet, and the blue-light laser beam can melt the bottom copper sheet. Introducing the blue-light laser to the coaxial laser beams overcomes the low reflectivity of the bottom copper sheet. The fiber/blue-light coaxial laser continuous welding can achieve the best integrity and defect-free welding. It shows potential in the mass production of the next generation of lithium batteries. Full article

Resistance spot welding was performed to join a 2 mm thick TA2 titanium plate and Q235 steel plate using nickel foil with thicknesses of 0.02 mm, 0.04 mm, and 0.06 mm as interlayers. The microstructure of the nugget zone and the interface region of the joint were systematically observed and analyzed, and the tensile shear-bearing capacity of the joint was evaluated. As the welding current increased, the tensile shear load of the joint exhibited a trend of initially increasing and subsequently decreasing. When the welding current was 8 kA, the tensile shear load of the joints with an interlayer of 0.04 mm thickness reached a maximum value of 8.02 kN. The results indicate that employing a reduced welding current can effectively prevent the mixing of nuggets on both sides of the titanium and steel interface. This ensures that the intermetallic compounds formed in the interface region are confined to the Ti-Ni series, which is crucial for enhancing the tensile shear load of the joint. Full article