Search Results (841)

Nickel coatings were deposited onto the surfaces of red mud, Al₂O₃, and Fe₂O₃ particles via an electroless plating technique. The nickel-coated particles (1.5 wt.%) were subsequently incorporated into a ZL109 aluminum alloy matrix to fabricate three types of composites using a stir-casting process, followed by a T6 heat treatment consisting of solution treatment at 515 °C for 8 h, water-bath quenching at 90–100 °C, and artificial aging at 175 °C for 12 h. The microstructural morphology and phase identification were examined by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Furthermore, the high-temperature tensile properties of the fabricated alloys were evaluated at 350 °C and 400 °C. The results showed that the addition of 1.5 wt.% nickel-coated red mud led to a more uniform distribution of eutectic silicon and an increase in the content of the Al₅Cu₂Mg₈Si₆, Al₇Cu₄Ni, and Al₂Cu strengthening phases. These microstructural changes significantly enhanced the high-temperature tensile performance of the alloy. At 350 °C and 400 °C, the alloy reinforced with 1.5 wt.% nickel-coated red mud achieved tensile strengths of 97.8 MPa and 86.2 MPa, respectively. The combination of an appropriate amount of nickel-coated red mud and a suitable heat treatment process effectively improves the high-temperature stability and tensile properties of the ZL109 aluminum alloy, which could be attributed to the synergistic strengthening effect arising from the precipitation of high-temperature stable phases and the Orowan mechanism. Full article

Nickel release from metallic items is the leading cause of allergic contact dermatitis, and preventive strategies require both reliable detection tools and materials capable of limiting skin exposure. In this work, we propose dual-function bioplastic coatings based on starch, glycerol, and cellulose derivatives incorporating dimethylglyoxime (DMG) and a pH-10 borate buffer to enable colorimetric nickel sensing directly in the solid state. The Ni–DMG assay was first optimized in solution through UV-Vis spectroscopy and a Central Composite Face-Centered Design, identifying reagent concentrations that maximize linearity while minimizing detection limits. These conditions were transferred to bioplastic films prepared using carboxymethyl cellulose (CMC) or quaternized hydroxyethyl cellulose ethoxylate (QHECE). The materials were characterized by FT-IR spectroscopy and Principal Component Analysis, while gravimetric tests assessed hydrophilicity. Both bioplastics showed clear and reproducible colorimetric responses upon nickel exposure, and multivariate models built from RGB values and UV-Vis spectra enabled quantitative prediction of Ni²⁺ content. However, the proof-of-concept experiment revealed insufficient resistance to prolonged moisture, with films softening and partially losing cohesion under conditions mimicking skin perspiration. These results demonstrate that the sensing mechanism is robust, but the current bioplastic formulation requires improved water resistance before practical deployment as protective coatings for jewelry. Full article

Nickel–titanium (NiTi) stents have been widely used for the palliative management of portal vein tumor thrombosis (PVTT) due to their excellent mechanical strength and biocompatibility. However, conventional NiTi implants are therapeutically passive and lack intrinsic antitumor activity, rendering them vulnerable to tumor ingrowth and subsequent restenosis. Electrical stimulation-mediated ablation offers a controllable physical strategy for local tumor clearance; however, the native TiO₂ passivation layer on the NiTi surface restricts its interfacial electroactivity. Electrochemical impedance spectroscopy revealed that the PPy coating significantly reduced the interfacial impedance of the NiTi substrate. After loading with sorafenib, NiTi−PPy−S maintained good electrochemical responsiveness and enabled voltage-dependent drug release characteristics. Under an applied potential of 0.9 V for 24 h, approximately 10.522 ± 0.295 μg/cm² of the loaded sorafenib was released mechanistically, whereas only 0.249 ± 0.171 μg/cm² was released through passive diffusion over the same period. The antitumor effect is closely associated with ES-triggered Ca²⁺ influx, mitochondrial Ca²⁺ overload, loss of mitochondrial membrane potential, and caspase-3-dependent apoptosis. These findings demonstrate that electro-responsive PPy can transform passive NiTi implants into active antitumor therapeutic interfaces, offering a promising strategy for developing multifunctional implants for PVTT treatment. Full article

This study focuses on the deposition of nickel thin-films onto glass fiber fabric via DC magnetron sputtering and explores their potential for broadband microwave absorption applications. A total of twelve laminate samples were prepared by integrating the coated fabrics with epoxy resin, with sputtering powers ranging from 0.5 to 2 kW and deposition times ranging from 10 to 90 min. The microstructure, surface resistance, electromagnetic parameters, and microwave absorption performance were systematically characterized using SEM, XRD, four-point probe measurements, and vector network analysis, supplemented by the Lorentz model fitting and simulation validation. The results indicate that the nickel coatings exhibit a non-uniform arc-like morphology, with preferential growth along the (111) crystallographic plane, while the (200) and (220) planes form under specific conditions. The surface resistance reaches up to 10⁸ Ω·m, suggesting the absence of a continuous conductive network. Electromagnetic parameter analysis reveals that the laminates display dielectric-loss-dominated microwave absorption, and the Lorentz fitting identifies double resonance peaks under prolonged or high-power sputtering. The addition of a dielectric matching layer further enhances the absorption performance. All samples achieve wideband absorption within the Ku-band. Notably, the samples prepared at 1 kW for 30 min and at 1 kW for 90 min both exhibit a reflectivity of ≤−10 dB across the entire 8–18 GHz frequency range. The experimental results are in good agreement with simulations. The bulk density of the laminates is approximately 1.8 g/cm³. These findings confirm that magnetron-sputtered nickel-coated continuous glass fiber fabrics hold considerable promise for wideband microwave absorption applications. Full article

Engine blade maintenance can extend engine service life, with coating removal being the initial step in the regeneration process. Silicon-modified diffusion aluminum-silicon coating (AlSi coating) is well-established as a protective coating for nickel-based superalloys due to its excellent oxidation and corrosion resistance, and is widely used in applications such as aero-engines and gas turbines. This study proposes a synergistic strategy combining oxidation and coordination to remove AlSi coating from nickel-based superalloy surfaces. The results demonstrate that this formulation effectively removes the coating while controlling substrate corrosion, avoiding detrimental effects such as intergranular corrosion and over-etching that compromise product quality. Mechanism analysis based on Density Functional Theory Simulations indicates that oxidizing elements such as Ni and Al into nickel oxide and aluminum oxide, followed by electronic structure modulation via a chelating agent, promotes efficient and uniform removal of the post-service AlSi coating by the acid solution. Full article

Steel is the most fundamental material used in structural system elements in the construction industry. It needs to be coated with materials that provide resistance to high temperatures, wear, and corrosion. Ni-Al powder is preferred in coatings because nickel increases corrosion resistance and aluminium forms an oxide layer to reduce oxidation. In the long term, the protective effect of coatings decreases, and corrosion resistance declines. In this study, a random forest model was evaluated using experimental data on the corrosion performance of A36 steel coated with Ni-Al powder for corrosion prevention, after exposure to a 3.5% NaCl solution for 1 h and 30 days for short- and long-term electrochemical response prediction. The impedance and phase angle characteristics, which represent the electrochemical response of coated and uncoated steel, have been predicted. In addition, the model’s reproducibility was investigated using the multi-seed (30 seeds) method to analyse the stability and consistency of the random forest model. The aim of this study was to develop a machine learning model that learns the frequency-dependent electrochemical impedance (Bode) response of graphene oxide-enriched Ni–Al coatings on steel, which reflects the corrosion-related electrochemical behaviour of the coating system, and to evaluate the model for predicting the impedance magnitude and phase angle of reference coatings over the investigated frequency range. The developed artificial intelligence model predicted the Bode response (impedance magnitude and phase angle) of coated and uncoated steel to NaCl solution after 1 h and 30 days as a function of frequency and coating type. The predicted impedance spectra reflected the deterioration of the corrosion protection performance of the Ni–Al coatings with increasing exposure time. The predicted EIS responses were subsequently used to assess changes in the corrosion-related electrochemical behaviour of the coatings over short- and long-term exposure. According to the findings, the random forest models can predict the frequency-dependent electrochemical response (impedance magnitude and phase angle) with high accuracy. Full article

Germanium (Ge) is a promising high-capacity anode material for lithium-ion batteries; however, its practical application remains limited by substantial volume variation, unstable interfacial reactions, and rapid capacity degradation during repeated lithiation/delithiation. In this work, a binder-free Ge/C/MXene@NF hybrid electrode was developed through a sequential fabrication process, where Ge nanoparticles were immobilized within a PVP-derived carbon matrix supported on a three-dimensional nickel-foam scaffold and subsequently integrated with a Ti₃C₂T_x MXene conductive network to construct a hierarchical Ge/C/MXene hybrid architecture. The nickel foam provides a continuous current-collecting framework and mechanical support, while the MXene network improves electrical connectivity, electrolyte accessibility, and interfacial charge-transfer kinetics. Structural and compositional analyses further indicate the presence of PVP-derived carbon and a possible minor NiGe interfacial phase formed during annealing. Comparison with Ge@NF and the individual component electrodes provides insight into the respective contributions of MXene, Ge, and the PVP-derived carbon framework to the electrochemical behaviour of the composite electrode. Using the total deposited active-material mass as the normalisation basis, the MXene@Ge@NF electrode retains a reversible specific capacity of 789.8 mAh g⁻¹ after 100 cycles at an effective current density of 76.2 mA g⁻¹. The observed electrochemical behaviour originates from the integrated contributions of Ge nanoparticles, the PVP-derived carbon matrix, the conductive Ti₃C₂T_x MXene network, the three-dimensional nickel-foam scaffold, and possible Ni–Ge interfacial interactions. Rather than representing a Ge-dominated electrode, this architecture demonstrates the advantages of integrating multiple functional components within a binder-free Ge/C/MXene hybrid architecture. Full article

In recent years, multifunctional composite nanoparticles have garnered substantial attention across multiple fields, from medicine to environmental science and the food industry, owing to their superior physicochemical properties. The synching of Ni nanoparticles by chemical reduction with nickel chloride as the source, and Fe₃O₄ nanoparticles by the co-precipitation method, with Fe²⁺ and Fe³⁺ as salts, is the focus of this study. Silane was used for the surface modification of Fe₃O₄ nanoparticles, while sulfuric acid was used to modify the SMCNT. A composite in PVDF based on the blend of Ni and modified Fe₃O₄/single-walled carbon tube (SWCNT) was used as an additive. Moreover, thermoplastic polyurethane (TPU) was hot-pressed over the film to improve flexibility. To examine and characterize the nanoparticles and composite films, we used X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), and scanning electron microscopy with energy-dispersive spectroscopy (EDS). The results verified that the films and nanoparticles were well formed. For a deeper characterization, UV-visible spectroscopy and EMI shielding experiments were conducted for the composite films. The composite films exhibited excellent UV-blocking performance (99.9%) and a total shielding effectiveness (SET) of 13.78 dB in the Ku-band (12–18 GHz) for a thickness of 1 mm. The reflection and absorption mechanisms yield shielding performance through the synergy between conducting (Ni, SWCNT) and magnetic (Fe₃O₄) components. These results reveal that the TPU-coated composite film is a promising candidate for multifunctional UV and electromagnetic shielding. Full article

Porous nickel (Ni) coatings were fabricated by wet powder metallurgy using urea and ammonium bicarbonate (NH₄HCO₃) as low-temperature pore-forming additives. Ni powder was mixed with 3 wt.% carboxymethyl cellulose (CMC), coated onto Ni mesh substrates, and sintered in a hydrogen atmosphere at temperatures of 550–900 °C for 30–120 min. The microstructural evolution, phase composition, elemental distribution, and pore characteristics were systematically characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and Brunauer–Emmett–Teller (BET) analyses. The results demonstrate that sintering temperature governs the evolution of the porous structure more strongly than the investigated space holders. With increasing temperature, progressive neck growth, grain coarsening, and densification were observed, consistent with the transition from initial particle contact to the intermediate stage of solid-state sintering. An interconnected porous framework formed at 700 °C, identified as the selected condition due to its balance between interparticle bonding and pore preservation. XRD confirmed a single face-centered cubic (FCC) Ni phase after sintering, while BET analysis showed minor differences in specific surface area but noticeable variations in pore volume and pore-size characteristics. The limited influence of urea and NH₄HCO₃ is attributed to their decomposition at temperatures well below the effective sintering range of Ni. Consequently, the generated gases are likely to escape before a continuous metallic framework is established, resulting in only modest changes in the final pore architecture. These findings indicate that the porous structure is governed predominantly by diffusion-controlled solid-state sintering rather than by the direct pore-forming action of the investigated additives. This study highlights the importance of thermal compatibility between space holders and the sintering window of the metal matrix, providing new insight into the rational design of porous Ni materials prepared by wet powder metallurgy. Full article

This study investigates the synthesis, phase evolution, and high-temperature oxidation behavior of multi-component aluminide coatings on EP670 (Fe-Ni base), EP718 (Ni-Fe base), and EP648 (Ni-base) superalloys. The coatings were produced using an economical hot-dip aluminizing method, followed by diffusion heat treatment at 1100 °C. In the as-deposited state, the coatings exhibit a heterogeneous structure consisting of an aluminum matrix with various Al-rich intermetallic inclusions. Subsequent heat treatment promotes the redistribution of chemical elements, leading to the elimination of free aluminum and the stabilization of a protective β-phase matrix. Long-term oxidation tests were performed at 900 °C, 1100 °C, and 1300 °C for up to 1000 h. At 1100 °C, the coatings on EP670 and EP648 demonstrated high stability, following a near-parabolic oxidation law and significantly reducing mass gain compared to uncoated substrates. However, at 1100 °C, the EP718 alloy underwent catastrophic failure within 200 h due to pest oxidation, disintegrating into an oxide powder—a phenomenon quantitatively confirmed by the kinetic exponent dropping below 1.0. At 1300 °C, the thermal limit for all coatings was established, with protective properties failing after 50 h. Based on the aluminum depletion kinetics, the service life at 1100 °C was estimated at 1300 h for EP670 and 2200 h for EP648. Scratch testing confirmed a complete absence of interfacial adhesive cracks across all systems. Contact loading triggered only cohesive cracks localized within the near-surface zone of the coatings. The results highlight the superior thermodynamic compatibility of the EP670 and EP648 systems with aluminide coatings, making them the most suitable candidates for extreme high-temperature applications. Full article

Fixed orthodontic appliances promote biofilm-mediated enamel demineralization and release metallic ions, motivating surface strategies that are intrinsic to the device rather than dependent on patient compliance. Chitosan, a biodegradable polycationic biopolymer, has been proposed as a multifunctional coating. This narrative review critically appraises the evidence for chitosan-based coatings on orthodontic appliances across three pillars—antimicrobial performance, ion-release/corrosion mitigation, and clinical translation—with explicit calibration of evidentiary strength. The evidence base is heterogeneous and of markedly uneven quality across the three pillars, and the conclusions below are weighted accordingly. Consistent with its narrative design, the literature was surveyed for critical synthesis rather than exhaustively, without formal eligibility screening, risk-of-bias appraisal, or quantitative pooling. Antimicrobial efficacy is the best-supported pillar, consistent in vitro and now extended by two short in vivo randomized trials, although all endpoints are microbiological surrogates rather than white spot lesion outcomes. Ion-release mitigation remains a plausible but insufficiently demonstrated effect: it is supported only indirectly, through electrochemical corrosion proxies on predominantly implant substrates, and no study quantifies ion-release reduction from a coated appliance. Coating durability under combined enzymatic and mechanical load—and its effect on friction—remains largely uncharacterized. Chitosan coatings are promising but translationally immature; durability, not antimicrobial potency, is the rate-limiting barrier. Defined clinical-endpoint and appliance-level ion-release studies are required. Full article

The evolution of electronic technology has intensified the demand for lithium-ion batteries to achieve elevated energy density, prolonged cycling longevity, and enhanced safety. Traditional graphite anodes are inadequate in meeting these requirements. α-Fe₂O₃ possesses a high theoretical capacity and is abundantly available; however, its poor conductivity and significant volume expansion during charge–discharge cycles restrict its practical applicability. This study addresses these issues by developing a three-layer cooperative structural anode material composed of foam nickel (NF), α-Fe₂O₃, and polypyrrole (PPY). Employing a hydrothermal method, α-Fe₂O₃ nanowires were in-situ grown on the 3D framework of foam nickel, followed by electro-polymerization to achieve a dense PPY coating. The foam nickel offers a highly conductive scaffold and mechanical support, while PPY enhances conductivity, provides structural buffering, and facilitates in-situ nitrogen doping. Collectively, these components synergistically improve conductivity, mitigate volume expansion, and optimize the solid electrolyte interphase. This composite material demonstrates comprehensive enhancements in conductivity, structural stability, and interface compatibility, as evidenced by the well-preserved structural integrity after prolonged cycling, thereby overcoming the performance limitations associated with singular α-Fe₂O₃ and simplistic composite systems, and presenting novel insights and technical support for the advancement of high-energy-density lithium-ion battery anodes. Full article

Nanotechnology currently offers two approaches to tumor therapy. The first involves coating the surface of nanoparticles with high-affinity molecules for targeted delivery. The second involves directing the nanoparticles to the desired area of the body using an external magnetic field. Such nanoparticles are often made of magnetic metals (iron, nickel, cobalt, etc.), but in living systems, the main problem with such nanoparticles is their toxicity. To address the toxicity issue, various barriers and coatings are primarily used. In this work, a laser technology for producing multifunctional nanocomposites based on graphene-coated iron nanoparticles decorated with gold nanoparticles was developed. Graphene-coated iron nanoparticles (200 nm) were synthesized using laser ablation in isopropanol. The presence of a graphene coating on the surface of the iron nanoparticles was confirmed by TEM, Raman spectroscopy, and luminescence analysis. A technology for depositing gold nanoparticles approximately 10 nm in size onto the graphene shell of the resulting iron nanoparticles was invented. The essence of the technology lies in creating critical conditions in a nanoparticle colloid, leading to intense aggregation with each other. Multifunctional nanocomposites based on graphene-coated iron nanoparticles decorated with gold nanoparticles did not exhibit acute toxicity to cell cultures under normal conditions. Moreover, under the combined influence of an alternating magnetic field and laser radiation, nanocomposites damaged 96% of neuroblastoma cells in culture. Full article

To improve the surface service durability and heat-transfer performance of brass heat-dissipation components, Ni–graphene (Ni–Gr) composite coatings were prepared on brass substrates by electro-brush plating, and the effects of working voltage on the coating microstructure and overall performance were investigated. The coating thickness ranged from 6.667 to 19.334 μm. The results show that the coating prepared at 7 V had a thickness of 8.524 μm, a dense microstructure, relatively uniform graphene dispersion, and the lowest Raman I_D/I_G ratio of 1.2146, thereby exhibiting the best overall performance. The microhardness of this coating reached 395 HV, which was approximately 190% and 127% higher than those of the brass substrate and pure Ni coating, respectively. Its corrosion current density in 3.5 wt.% NaCl solution decreased to 1.0143 × 10⁻⁵ A/cm², corresponding to a 90.4% reduction relative to the pure Ni coating. The room-temperature thermal conductivity of the coating/brass composite specimen reached 145 W/(m·K), which was 29.5% higher than that of the brass substrate. When the working voltage increased to 9–11 V, although the coatings became thicker, surface nodules coarsened, pores/pinholes increased, and graphene agglomeration intensified, leading to declines in mechanical properties, corrosion resistance, and thermal conductivity. These results demonstrate that an appropriate working voltage is beneficial for coordinating Ni nucleation/growth and graphene co-deposition, and is a key processing parameter for obtaining high-performance Ni–Gr composite coatings for brass heat-dissipation components. Full article

Cu-Ni co-deposit electrodes were prepared and tested in an undivided cell for the electrochemical removal of nitrate from aqueous solutions. Pulsed electrodeposition (PED) under a dynamic hydrogen bubble template and direct electrodeposition (DE) techniques were used for synthetizing porous nickel- and copper-based cathodes. Scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) analyses showed dendritic and cauliflower-like deposits with a uniform distribution of nickel and copper on the electrode surface, both using flat and foam nickel supports. The PED technique on nickel foam generated highly porous Cu-Ni coatings, with the largest electrochemical active surface area (ECSA) among all the investigated electrodes. Electrolysis in alkaline solutions containing nitrates was performed in an undivided cell in potentiostatic mode. The selectivity towards N₂ was strongly dependent on both copper loading and applied potential; in particular, the foam electrode containing about 23% Cu showed very low ammonia production even at the highest cathodic overpotential, evidencing its marked preference for nitrogen formation. The process performed in the undivided cell using foam-supported Cu-Ni cathodes enabled 100% of conversion of nitrate to molecular nitrogen within approximately 7 h, allowing the complete denitrification of the water. Full article