Search Results (265)

Transition-metal phosphides are promising non-noble-metal electrocatalysts for alkaline hydrogen evolution, yet further improving their performance remains challenging. In this work, a Co-doped nanoporous Fe₃P self-supported electrode was fabricated by vacuum high-frequency induction and melt spinning of Fe₇₅Co₅P₂₀ precursor alloys, followed by electrochemical dealloying. Nanoporous Fe₃P prepared from Fe₈₀P₂₀ was used as the reference. Structural analyses show that dealloying selectively removes the α-Fe phase while preserving the Fe₃P framework, resulting in a three-dimensional nanoporous architecture. XPS results further confirm successful Co incorporation and reveal that Co doping modifies the local chemical environment of Fe and P. Benefiting from the combined effects of Co incorporation and the nanoporous structure, np-Co-Fe₃P exhibits significantly improved HER performance in 1.0 M KOH, requiring only 70 mV to reach 10 mA cm⁻², much lower than that of np-Fe₃P (199 mV). In addition, np-Co-Fe₃P shows a smaller Tafel slope of 94 mV dec⁻¹, lower charge-transfer resistance, and a larger double-layer capacitance of 109.4 mF cm⁻². This work demonstrates an effective strategy for enhancing the alkaline HER performance of Fe-based phosphides through the combination of Co incorporation and dealloying-derived nanoporous architecture. Full article

To address the uneven deposition of zirconium conversion coatings on multiphase 55AlZnMg under short pretreatment cycles, this study investigated the time-dependent formation behavior of ZrCC in a selected H₂ZrF₆ bath. By precisely controlling the immersion time (20–90 s) and utilizing SEM-EDS and AFM characterization techniques, this study systematically revealed the growth kinetics and film-forming mechanisms of ZrCC on complex alloy surfaces. The results indicate that the Zn-rich phase on the surface of the 55AlZnMg coating, due to its relatively positive potential, preferentially induces the deposition of the film-forming material. Subsequently, dealloying occurs in the Al-rich phase and the Mg/Zn enriched regions, forming Zn-enriched regions that promote the continuous deposition of the film-forming material, ultimately achieving complete surface coverage; the film morphology evolves from an initial needle-like structure to a network structure, eventually forming a nanosheet structure. The film-forming process of ZrCC on the 55AlZnMg substrate surface is primarily driven by selective growth, with electrochemical properties of the alloy phases, significantly enhancing adhesion between the aluminum-zinc-magnesium coating and the overcoat and providing practical guidance for improving surface uniformity and interfacial adhesion of Al-Zn-Mg-coated steel. Full article

Porous bilayer Ni–Co and sandwiched Ni–Co–Ni electrodes were fabricated by combining aqueous electrodeposition with high-temperature molten-salt Al deposition and subsequent electrochemical dissolution in NaCl–KCl–AlF₃ melt at 750 °C. The study aimed to determine how the initial layer architecture controls phase evolution, porous structure formation, and hydrogen evolution performance in alkaline media. SEM/EDS and XRD analyses showed that the two electrode designs followed different reaction pathways during molten-salt treatment. In the Ni–Co system, Al reacted predominantly with Co, leading mainly to Co–Al intermetallic formation and, after dissolution, to a highly open coral-like porous network. In contrast, the Ni–Co–Ni architecture promoted mainly Ni–Al phase formation and produced a more compact porous surface with a Ni-rich outer layer. Despite these morphological differences, both layered porous electrodes outperformed untreated Ni and porous Ni in 1 M NaOH. At −0.6 V vs. RHE, porous Ni–Co and NiCo–Ni reached current densities of −162 and −141 mA·cm⁻², respectively, compared with −87 mA·cm for porous Ni and −45 mA·cm for flat Ni. The Ni–Co–Ni sandwiched electrode showed the most favourable HER kinetics and benchmark performance, with the lowest Tafel slope (111 mV·dec) and the lowest potentials at −10 and −100 mA·cm (−0.132 and −0.556 V, respectively). These results demonstrate that the electrocatalytic response of molten-salt-derived porous Ni-based electrodes is governed not only by porosity development but also by the spatial arrangement of metallic layers prior to Al infiltration and dealloying. Full article

High-speed laser cladding shows significant potential for application in the field of high-performance surface hardening due to its low heat input and high cladding efficiency. However, the pool solidification time is significantly reduced at high scanning speeds, resulting in a narrower process window and making it more difficult to ensure coating formation stability and control performance. Therefore, this study employed high-speed laser cladding technology to prepare FeCrNiB alloy coatings, and systematically conducted research on process parameter optimization and friction properties. Firstly, the response surface method (RSM) was used to establish quantitative relationship models between laser power, scanning speed, and powder feed rate and the dilution ratio, forming coefficient, and microhardness. Then, the hybrid differential evolution and NSGA-II algorithm (DE-NSGA-II) was employed for multi-objective optimization. Finally, a systematic analysis was conducted on the friction and wear properties of the coatings produced under the optimal process parameters. The results indicate that the interaction between laser power and scanning speed has a significant impact on the dilution behavior of the coating, while the coupling between scanning speed and powder feed rate governs the formation characteristics and microhardness evolution of the coating. The experiment verified that the prediction error for the optimal parameters is controlled within 5%, demonstrating good engineering applicability. Further analysis indicates that grain refinement and the formation of strengthening phases in the optimal coating are the key mechanisms behind the significant improvement in hardness and wear resistance, and the coating primarily exhibits a mild abrasive wear mechanism. This work realizes the multi-objective optimization of the high-speed laser cladding process via RSM and DE-NSGA-II algorithm, which provides a novel and efficient method for parameter optimization and engineering application of high-speed laser cladding. Full article

Efficient and durable non-noble catalysts are crucial for alkaline hydrogen evolution (HER), and high-entropy alloys (HEAs) offer a promising platform due to their multicomponent synergy and tunable surface chemistry. Herein, self-supported nanoporous high-entropy alloy electrodes, Fe₃₅Co₂₅Ni₃₀Mo₁₀ and Fe₃₅Co₂₅Ni₃₀Mo₇W₃, were prepared by arc melting followed by electrochemical dealloying in 1 M HCl. XRD results show that both alloys retain an FCC framework after dealloying, whereas SEM reveals that W promotes a more continuous sponge-like nanoporous structure. In 1 M KOH, dealloyed Fe₃₅Co₂₅Ni₃₀Mo₇W₃ shows enhanced HER activity, requiring an overpotential of 178 mV at 10 mA cm⁻², which is lower than that of dealloyed Fe₃₅Co₂₅Ni₃₀Mo₁₀ and the precursors. Dealloyed Fe₃₅Co₂₅Ni₃₀Mo₇W₃ also exhibits faster kinetics (Tafel slope 98.5 mV dec⁻¹; Rct 3.33 Ω) and a larger C_dl (19.2 mF cm⁻²) than dealloyed Fe₃₅Co₂₅Ni₃₀Mo₁₀. These results highlight W-enabled dealloying-induced reconstruction as an effective route to robust nanoporous HEA electrodes for alkaline HER. Full article

Duplex stainless steel (DSS) blends impressive mechanical and chemical characteristics to withstand aggressive environments. Its fabrication by Gas Metal Arc Welding-Additive Manufacturing is an emerging research topic. However, its sensitive grain structure and alloy composition are prone to deterioration by repeated thermal shocks. Whether optimal weld parameters can resolve these challenges without additional costs from special fillers, gases, or mechanisms is a valid question. In this study, how different wire feed speeds, travel speeds, and weld voltages, chosen from a set of preliminary beads, translate into wall dimensions, phase formation and distribution, morphological transformation, and elemental segregation is investigated. The unique DSS microstructures were characterised using scanning electron microscopy and energy-dispersive spectroscopy to reveal differences in microstructural evolution and ferrite-austenite (α-γ) structure. The deposited walls exhibited satisfactory geometric quality with negligible distortions. However, the height suppression was noticeable at the deposition energy (DE) of 755 J/mm. Metallographic analysis revealed low γ phase formation (<30%) at low DE (230 J/mm) and excessive γ formation (>70%) in the high DE wall (755 J/mm). The parameters WFS:TS = 15, TS = 35 cm/min, WFS = 525 cm/min, and V = 20.804 volts suppressed the elemental segregation while maintaining a suitable phase balance without post-processing. Full article

Icing poses significant operational and safety risks in aviation, especially for engine components such as cowls and baffles. This study explores the potential of a chemically exfoliated graphene-rich carbon platelet epoxy coating to improve the anti-icing and de-icing performance of 3003-H14 aluminum alloy, which is widely used in such applications. Chemically exfoliated graphite was incorporated into an epoxy resin, then applied to aluminum substrates. Characterization of the coated samples revealed ~30% improvement in surface Vickers hardness (HV) (HV 75.6 ± 1.15 vs. HV average of 98.3 ± 1.5) and enhanced thermal dissipation, with coated surfaces cooling from 104 °C to 22 °C in 530 s compared to 870 s for uncoated samples. While anti-icing performance was not directly evaluated, the observed improvements in thermal dissipation and surface hardness suggest that chemically exfoliated graphene-rich carbon platelet coatings could be promising for passive anti-icing applications. The literature suggests that graphene coating improves hydrophobicity, reducing ice adhesion and delaying nucleation due to its low surface energy and nanoscale roughness, thereby supporting potential passive anti-icing functionality for aircraft engine components. SEM analysis confirmed a uniform, compact coating layer. These preliminary findings indicate that chemically exfoliated graphene-rich carbon platelet coatings can deliver multifunctional performance—mechanical, thermal, and surface—making them promising candidates for passive anti-icing/de-icing solutions in engine components where conventional systems are ineffective. Full article

High-entropy alloys (HEAs) exhibit excellent catalytic activity owing to their unique structure and chemical properties. The construction of hierarchical porous HEA catalysts via laser powder bed fusion (LPBF, a typical 3D printing technology) and dealloying techniques opens new avenues for boosting catalytic performance. This study reports the fabrication of a hierarchical porous FeCoNiCuAl HEA catalyst through a two-step strategy: LPBF and subsequent dealloying. The macroscopic triply periodic minimal surface (TPMS) structure of the HEA catalyst was constructed through LPBF, followed by dealloying to create a nanoporous structure on the catalyst surface. The hierarchical porous FeCoNiCuAl HEA catalyst exhibited a catalytic activity 4.33 times higher than that of the pristine, non-porous FeCoNiCuAl HEA (HEA-0). Furthermore, the catalyst maintained nearly 100% degradation efficiency for Acid Red G (ARG) after 20 consecutive catalytic cycles, demonstrating exceptional stability. This stepwise strategy for constructing hierarchical porous structures not only accelerates mass transfer via the macroporous framework but also significantly increases the density of accessible active sites through the nanoporous surface, thereby synergistically enhancing the catalytic activity of HEAs. This work provides a novel and scalable approach for developing high-performance porous HEA catalysts for wastewater treatment. Full article

The structural design of unstiffened cylindrical shells under external hydrostatic pressure is critical for the safety of marine structures, such as submarine hulls and pressure vessels. Accurately assessing nonlinear buckling and collapse failure modes traditionally requires computationally intensive Finite Element Analysis (FEA), which creates a bottleneck in iterative design optimization. To address this, our research leverages a robust Deep Neural Network (DNN) model specifically trained and validated for AL-6061 aluminum alloy cylinders. This predictive model, focusing on unstiffened cylindrical shells within a valid domain ($2\le L/D\le 15$ and $20\le D/t\le 150$), integrates a high-speed surrogate model with a Differential Evolution (DE) algorithm. This predictive model was trained on a large-scale dataset of 46,060 points generated through FEA simulations and rigorously validated against 28 physical experimental data points. Building upon this foundation, the present study implements a novel optimization framework that integrates the pre-trained DNN as a high-speed surrogate model with a Differential Evolution (DE) algorithm for global optimization. The primary objective is to minimize structural weight while strictly satisfying collapse strength requirements. Additionally, a grid search component is incorporated to provide designers with multiple feasible design candidates almost instantaneously. Validation against independent FEA results confirms high fidelity, with error rates of less than 2%. This methodology transforms the design cycle from days to mere minutes, establishing a reusable digital asset that significantly enhances efficiency and structural safety in marine engineering. Full article

In the present work, we selected an amorphous Nd₆₀Ni₄₀ alloy as a basic alloy and added Er with a higher effective magnetic moment and de Gennes factor to replace Nd for the purpose of improving the magnetocaloric performance of the Nd₆₀Ni₄₀ amorphous alloy. The formability, magnetization, and magnetocaloric behaviors of the Nd_60-xEr_xNi₄₀ (x = 5, 10, 15, 20) amorphous alloys were studied. It was found that Er substitution generally improved the glass formability, but simultaneously decreased the Curie temperature, coercivity, and magnetic entropy change peak of the basic alloy. The mechanism for these unexpected results was investigated, and it was supposed that the decreased Curie temperature and the deteriorated magnetocaloric properties may have resulted from the antiferromagnetic coupling between the Nd and Er atoms. Full article

p-Nitrophenol (PNP), a highly toxic and recalcitrant organic pollutant prevalent in industrial wastewater, poses severe challenges to traditional Fenton treatment technologies. In this study, a novel nanoporous catalyst is synthesized via a combined annealing–dealloying strategy. Annealing at 550 °C and 600 °C induces partial crystallization, generating α-Fe and Fe₂B phases that serve as preferential corrosion sites during chemical dealloying. This process results in a three-dimensionally interconnected nanoporous structure, which significantly increases the specific surface area of the catalyst to 2.642 m²/g. The optimized nanoporous catalyst exhibits excellent degradation performance, achieving complete removal of PNP within 30 min under room temperature reaction conditions. Notably, kinetic analysis reveals a degradation mechanism involving adsorption and Fenton-like catalysis. The high specific surface area provides abundant active sites for PNP adsorption, while the enhanced Fe²⁺ dissolution synergistically accelerates the degradation. The adsorption kinetic follows a pseudo-second-order model, and the degradation kinetic conforms to a first-order model, with activation energy analysis further confirming a surface-reaction-controlled process. This work provides a feasible approach and technical reference for designing efficient porous catalysts based on amorphous alloys for advanced treatment of refractory organic wastewater. Full article

Fe-Ni-based alloys have attracted attention due to their potential for applications such as transmission line de-icing, where the core requirements include a Curie temperature near the freezing point and sufficient saturation magnetization. Accordingly, this study designed an Fe-29Ni-2Cr-1.5Mn (at.%) alloy with a Curie temperature around the freezing point, aiming to investigate the correlation between microstructural evolution and magnetic properties after cold rolling and annealing. The alloy was cold-rolled by 65% and subsequently annealed at 873 K for 0 to 60 min. The study reveals systematic evolutions in the alloy’s microstructure and magnetic properties. During the initial annealing stage, recovery substructures predominantly formed within the deformed grains, accompanied by a reduction in dislocation density and lattice constant. In the later annealing stage, the recrystallized fraction increased, although complete recrystallization was not achieved. Texture analysis indicates that the intensity of the Cube texture strengthened from 0.48 to 1.13. Correspondingly, the saturation magnetization and Curie temperature increased by approximately 9.76% and 10.25%, respectively, in the early annealing period, and then stabilized thereafter. The early-stage improvement in properties is likely related to stress relief and lattice distortion relaxation during the recovery stage. The calculated magnetocrystalline anisotropy constant of this alloy at 273 K is K₁ = 126 ± 18 J/m³, indicating that the <100> direction is its easy magnetization axis. This study provides insights into optimizing the magnetic properties of this alloy through controlled annealing. Full article

We demonstrate the enhancement of antibacterial and cytocompatibility characteristics of femtosecond laser-treated pure titanium and Ti-6Al-4V titanium alloy samples suitable for orthopedic implant applications. We controlled the wettability of the titanium samples by tailoring the surface geometry using a femtosecond laser. To increase the hydrophobicity, laser-assisted micro-grids patterning was performed on the titanium samples, where we achieved a highest contact angle of 144.6° for a 1 µL de-ionized water droplet. In contrast, the hydrophobic Ti-6Al-4V titanium alloy surfaces were converted to hydrophilic surfaces by fabricating periodic micro-gratings on the samples’ surface, where a lowest contact angle of 19.84° was achieved. Furthermore, we assessed the biocompatibility of the micro-patterned titanium samples by investigating the antibacterial activity against Staphylococcus Aureus bacteria. Moreover, the cytocompatibility of the micro-patterned titanium samples was examined using NCTC Clone 929 (L-929) mouse fibroblasts. The laser-treated titanium samples exhibited enhanced antibacterial performance while maintaining excellent cell compatibility. The experimental results confirmed excellent correlation with the wettability of the laser-patterned samples and their antibacterial characteristics and cytocompatibility. Overall, the findings highlight femtosecond laser surface structuring as a highly effective strategy to simultaneously improve antibacterial behavior and the biocompatibility of implant materials, offering a promising way for the advanced functionalization of orthopedic implants. Full article

Deep eutectic solvents (DES) have emerged as a versatile and sustainable medium for the green synthesis of nanomaterials, offering a viable alternative to conventional organic solvents and ionic liquids. Nanomaterials can be synthesised in DESs via multiple routes, including chemical reduction, solvothermal, and electrochemical methods. Among the different pathways, this review focuses on the electrochemical synthesis of nanomaterials in DESs, as it offers several advantages: low cost, scalability for large-scale production, and low-temperature processing. The size, shape, and morphology (e.g., nanoparticles, nanoflowers, nanowires) of the resulting nanostructures can be tuned by adjusting the concentration of the electroactive species, the applied potential, the current density, mechanical agitation, and the electrolyte temperature. The use of DES as an electrolytic medium represents an environmentally friendly alternative. From an electrochemical perspective, it exhibits high electrochemical stability, good solubility for a wide range of precursors, and a broad electrochemical window. Furthermore, their low surface tensions promote high nucleation rates, and their high ionic strengths induce structural effects such as templating, capping and stabilisation, that play a crucial role in controlling particle morphology, size distribution and aggregation. Despite significant progress, key challenges persist, including incomplete mechanistic understanding, limited recyclability, and difficulties in scaling up synthesis while maintaining structural precision. This review highlights recent advances in the development of metal, alloy, oxide, and carbon-based composite nanomaterials obtained by electrochemical routes from DESs, along with their applications. Full article

The present study assesses the effectiveness of the indole-type alkaloid Yohimbine (YHB) as a green corrosion inhibitor for OLC52 carbon steel and Al in 0.25/0.25 mol L⁻¹ acetic acid/potassium acetate solutions relevant for de-icing applications. Electrochemical techniques, including cyclic and linear sweep voltammetry, chronoamperometry, and electrochemical impedance spectroscopy have been combined with the evaluation of adsorption isotherms and molecular modeling calculations. YHB significantly decreases the corrosion rate for both metals, attaining inhibitory efficiencies of up to 95% for OLC52 and 91% for Al at 298 K, while maintaining high protection efficiency even at higher temperatures. The Langmuir adsorption model and the values of $∆G_{ads}^o$ between −31 and −41 kJ mol⁻¹ indicate a spontaneous adsorption process defined by a mixed physicochemical mechanism, resulting in the formation of a compact protective film. Quantum molecular descriptors support the ability of YHB molecules to interact with metal surfaces via donor–acceptor interactions and electrostatic interactions. The findings demonstrate the potential of YHB as an environmentally friendly inhibitor for the protection of ferrous and non-ferrous alloys in mildly acidic acetic/acetate media used in de-icing solutions. Full article