Advanced Engineering Materials最新文献

To prepare polymer foams with low-density and high-energy absorption efficiency, this study designs epoxy foaming experiments employing the Box–Behnken method and investigates the impact of process parameters on the microscopic geometric parameters and uniaxial compression response of foam. Finite element analysis models are created to investigate the microscale deformation mechanism. The main results are as follows: 1) The average equivalent cell diameter is significantly affected by foaming temperature and foaming agent content, while cell wall thickness is more influenced by the foaming agent content and the precuring time. 2) The compression response is most significantly affected by foaming temperature, followed by foaming agent content, with precuring time showing less significant influence. The differences in the stress–strain curves during various stages of deformation are due to the buckling of cell walls and the subsequent collapse of cells. 3) Density exhibits a highly positive correlation with strength and modulus while showing a relatively high negative correlation with energy absorption efficiency. Based on these findings, process parameters are optimized using the Hooke–Jeeves algorithm and experimentally validated, demonstrating the reliability of the optimization strategy. The experimental design and process parameter optimization strategy can be applied to other polymer foaming research.

Understanding the impact of the aluminum zinc oxide (AZO) seed layer thickness on zinc oxide nanowires (ZnO NWs) growth is decisive in attaining high-quality NWs with higher transparency and without cracking issues when using flexible substrates, especially for optoelectronic applications. Therefore, herein, ZnO NWs have been grown on various thicknesses of AZO films deposited onto flexible substrates (PET, PET/ITO (60 Ω sq⁻¹) and (200 Ω sq⁻¹)) through a simple, low-temperature hydrothermal growth process. Based on AZO layer thickness, structural, optical, morphological, and topographical properties have been systematically investigated. The results demonstrate that 1) thicker AZO films (≈250 nm) increase the crystallinity of the ZnO NWs than thinner AZO films (≈200 and 100 nm). 2) ZnO NWs on the thicker AZO films with different ITO grades (60 or 200 Ω sq⁻¹) provide an optical bandgap value of 3.24–3.27 eV and offer good transmittance (>80%) in the visible range. 3) The AZO film thickness strongly influences ZnO NWs growth, especially NWs’ average diameter and density. 4) Annealing the samples at 100 °C after NW growth is pointless. Overall, the findings demonstrate efficient tuning of the ZnO NW properties that exhibit promising potentiality for perovskite solar cells, which have also been preliminarily tested.

Magnesium matrix composites reinforced with 5–25 vol% Ti_49.2Ni_50.8 microparticles are produced by uniaxial hot pressing technique. Powder mixtures are hot pressed in cylindrical graphite dies under 50 MPa pressure for 1 h at 600 °C. Density measurements show that specimens reach almost full density and do not contain any pores. Microstructural analyses demonstrate that undesired secondary phases or compounds do not form at matrix/reinforcement interface. As a result of aging heat treatment performed simultaneously with the manufacturing process, martensite phase (B19′) and Ti₃Ni₄ precipitates are also observed in the microstructure of reinforcing materials in addition to the main austenite (B2) phase. The room-temperature yield strength and compressive strength of the composite materials range between 60 and 86 MPa and 232 and 296 MPa, respectively. Although the ductility values decrease with increasing reinforcement content, the decrease is less than those of ceramic and other metallic reinforced composites. The ductility is determined to be 17.6% for the composite with the highest reinforcement content. In contrast to the reference and conventional materials, the yield strengths of the composite samples produced increase significantly with the increasing temperature up to 100 °C. This unusual behavior is attributed to the stress-induced martensitic transformations observed in TiNi alloys.

The hyperpressure solution (HS) is used on Zn-16Ag alloy to break the limit of atmospheric solid solution, and then the precipitation heat treatment is performed for 8 h at 100 °C. The X-ray diffraction pattern of HS Zn-16Ag alloy exhibits no obvious second phase peaks, the dispersive AgZn₃ phases precipitate after precipitation heat treatment. The tensile strength of AS-2 (atmospheric pressure solid solution–precipitation heat treatment–rolling) and HS-2 (HS solid solution–precipitation heat treatment–rolling) Zn-16Ag is 296 and 256 MPa, with elongation of 38% and 59%, respectively. After natural aging, the tensile strength of AS-2 samples decreases by 25.6%, whereas that of HS-2 samples only decreases by 2%. The fine diffusion AgZn₃ precipitated inhibits the growth and dynamic recrystallization of the grains, showing excellent resistance of self-aging. Moreover, HS-2 Zn-16Ag exhibits a more uniform corrosion mode than the AS-2 alloy after immersion tests.

Herein, edible solenoids are introduced, which are realized by coating spaghetti with edible gold leaves, creating fully edible and functional radio frequency (RF) electronic components. As a proof-of-principle of their use in RF circuits, a completely edible passive inductor-capacitor (LC) resonator at ≈200 MHz is demonstrated. The results significantly expand the applications of edible electronics to RF regime, supporting future developments in edible sensing and edible robotic systems, emerging fields with a high grade of sustainability.

Metallic sandwich panels featuring cellular metal cores are widely utilized across various sectors due to their exceptional load-bearing efficiency and design versatility. However, their application is often limited by the challenge of shaping complex geometries. This study introduces a novel thin sandwich panel incorporating stainless steel wire mesh (SSWM) core, designed to offer both lightweight properties and enhanced flexibility. Mechanical properties and forming limit diagrams of the sandwich sheet are assessed through tensile tests and Nakajima forming tests. The study investigates how the SSWM stacking angle and strain paths influence the panel's failure behavior and formability. Comparative analyses with monolithic stainless steel sheets of identical dimensions are also conducted. The findings reveal that the sandwich sheet exhibits comparable formability to the monolithic sheet in the tension-compression stain zone, with about 32% higher average specific tensile strength compared to the monolithic counterpart. Importantly, the formability and failure characteristics of the sandwich panel are significantly influenced by in-plane shear deformation of the SSWM core, which is primarily dictated by the SSWM stacking angle and strain paths. Notably, the sandwich sheet with 45° stacking angle demonstrates superior plasticity and formability.

NaV₂O₅ is a promising cathode material for ion batteries with high capacity and good cycle performance. The high concentration of vanadium and low impurity in vanadium-rich solution makes it possible to be used as raw material for vanadium product preparation. Vanadium solution containing impurity was prepared to investigate its influence mechanism on NaV₂O₅ crystal precipitation. The influence of four major impurity elements on the precipitation of NaV₂O₅ following the order of P > Al > Si > Fe. With the increase of impurity concentrations, vanadium conversion rate and V content of the precipitates decreased to varying degrees, while impurity content increased. When concentrations of Fe, Al and Si were high, the resulting precipitate was still NaV₂O₅, but the crystal structure changed. The AlOH and SiOH hider the condensation between VOH and broke the rod into irregular flakes and blocks. As P concentration gradually increased, the precipitates changed from NaV₂O₅ to VO₂(H₂O) 0.5 and then to Na₃.053((V₅O₉)(PO₄)2(OH)0.1(H₂O)8, meanwhile, the morphologies changed from rod to plate, then to cross-like, and finally to cube. Revealing the influence of impurity in vanadium-rich solution on the growth of NaV₂O₅ crystal is conducive to the popularization of the process.

Effective wastewater treatment is essential for mitigating organic pollutants, such as dyes and antibiotics. In this study, the enhancement of niobium pentoxide (Nb₂O₅) nanostructures via molybdenum (Mo) doping to improve adsorption efficiency, selectivity, and reusability is investigated. Mo doping, successfully confirmed by X-ray diffraction, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy, demonstrates effective integration into the Nb₂O₅ lattice, inducing lattice expansion and modifying its structural and surface properties. Mo-doped Nb₂O₅ exhibits increased adsorption capacities for methylene blue (MB) and crystal violet (CV), improving from 26.9 and 17.0 (undoped) to 35.4 and 44.8 mg g⁻¹, respectively. In contrast, the capacities for Congo red and tetracycline decrease from 31.6 and 36.8 to 16.7 and 32.0 mg g⁻¹, respectively. Isotherm modeling shows Langmuir-type adsorption with maximum capacities of 48.6 mg g⁻¹ for MB and 52.4 mg g⁻¹ for CV. Point of zero charge analysis indicates improved cationic dye selectivity, while recyclability tests demonstrate that Mo-doped Nb₂O₅ can retain over 96% of its capacity after five cycles. In thermodynamic studies, an exothermic and spontaneous process is revealed, with pseudo-second-order kinetics confirming chemisorption as the dominant mechanism. In these findings, Mo-doped Nb₂O₅ is established as a highly effective material for treatment applications.

Monitoring the structural health of composites during manufacturing and in-service is desirable to alert against damage or deterioration of conditions beyond an acceptable level. Wireless sensors embedded into materials that can endure the forming and curing of carbon fiber-reinforced polymer laminates will open the door to automated near-field detection of key metrics such as temperature, strain, and manufacturing defects. Current sensing technologies are generally too intrusive and fragile to be reliably embedded into laminates or too expensive to be applied commercially. The development of embedded, low-weight, small-footprint sensors is reported here, and how these sensors can be used to monitor ply movement during the manufacturing process is demonstrated. These screen-printed sensors consist of closed-loop spiral coils excited externally with an AC magnetic field to generate a secondary field, which alerts on the change of relative position of each ply. This proof-of-concept work demonstrates how printed coil sensors can be fabricated to generate a high electromagnetic response, while minimizing their footprint in the laminate. It is determined that stacked silver coils, which are subsequently plated with copper to increase the conductance, are capable of producing signals that can be detected through over 3 mm of composite material.

To investigate whether high-W-content (Nb,W) co-alloying TiAl-based alloys have better high-temperature tensile property at different tensile rates, the Ti-44Al-4Nb-1W-0.1B alloy (high W) is designed and prepared. Meanwhile, the Ti-44Al-7.2Nb-0.2W-0.1B alloy (low W) and the Ti-44Al-8Nb-0.1B alloy (pure Nb) are also prepared for comparative analysis. The tensile property is tested at 800 °C. The microstructure evolution and fracture surface are studied. Finally, the two (Nb,W) co-alloying alloys exhibit higher ultimate tensile strength than the pure Nb alloying alloy at different tensile rates. The Ti-44Al-4Nb-1W-0.1B alloy shows higher ultimate tensile strength than the Ti-44Al-7.2Nb-0.2W-0.1B alloy at low tensile rate, but demonstrates lower ultimate tensile strength at high tensile rate. As W content increases, the alloy's grain size decreases, enhancing the fine-grain effect. Combined Nb and W elements also contribute to solid solution strengthening, while the B2 phase improves stress coordination. These factors lead to better dislocation strengthening, so that the ultimate tensile strength of the two (Nb,W) co-alloying alloys is higher than that of the pure Nb alloying alloy. Under different tensile rates, the three alloys exhibit a combination of trans-lamella fracture and trans-granular cleavage fracture modes.