查看更多>>摘要：The FeCoNi1.5CrCu/2024Al composites fabricated by microwave sintering were hot rolled to investigate the effect of hot rolling reduction on microstructure, mechanical properties and macroscopic crystal structure. The results show that when the rolling reduction is 62.5%, the refining effect of reinforced particle clusters is obvious, and the large-size reinforced particle clusters have basically disappeared. Besides, it distributes homogeneously in the matrix along the rolling direction, and the grain size of matrix is significantly reduced. With the increase of reduction, the relative density and microhardness of the composites increase first and then decrease, reaching the maximum of 96.6% and 172.5HV at 62.5%, respectively. Hot rolling is conducive to improving the interface bonding between HEA particles and 2024Al matrix. And when rolled with 62.5% reduction, the micro-nanohardness and elastic modulus at the interface reach 1715 MPa and 83.93 GPa, respectively. The tensile strength of hot-rolled composites increases rapidly first and then slowly, and the elongation decreases rapidly first and then slowly. When at the optimum rolling reduction 62.5%, the tensile strength and elongation of composites reach 173.54 MPa and 12.93%, respectively. The strengthening mechanisms are mainly grain refinement strengthening, load transfer strengthening and Orowan strengthening.
查看更多>>摘要：3D printing has unique advantages for the preparation of batteries. It is of great significance to 3D print sodium ion full batteries and aqueous zinc ion full batteries in view of the fact that they are very promising among post-lithium-ion batteries. Here, a facile 3D-printing strategy is proposed to fabricate sodium ion full batteries and aqueous zinc ion full batteries via the polymer-based inks with high active material content. The prepared electrode inks can be easily scaled up and have the shear thinning behaviors. Electrochemical analyses confirming that the 3D printed sodium ion full batteries and aqueous zinc ion full batteries both deliver high electrochemical performance. The former composed of sodium vanadium phosphate (Na3V2(PO4)3) cathode and anode delivers the high capacity (21 mAh g?1), high-rate capability (10 C), and long cycle stability (4000 cycles). Meanwhile, the latter constituted by vanadium dioxide (VO2(B)) cathode and zinc powders anode also reveals the high capacity (173 mAh g?1), high-rate capability (73 mAh g?1 at 1600 mA g?1), and long cycle stability. This 3D printing strategy provides a way to construct ultra-micro batteries, large-size batteries, and special-shaped batteries.
查看更多>>摘要：The topological-insulator/superconductor heterostructure is predicted to offer an opportunity to investigate the proximity effect in condensed matter systems. Here, we construct a well-ordered Bi2Te3/FeSe0.5Te0.5 superlattice structure on TiO2-SrTiO3 substrate by pulsed laser deposition, and investigate its superconducting property induced by the proximity effect. Based on the electrical transport measurements, Cooper pairs in superconducting FeSe0.5Te0.5 layers can be introduced into the surface states of Bi2Te3 layers, and so induce superconductivity of the entire Bi2Te3/FeSe0.5Te0.5 superlattice. The superconducting properties in the superlattices such as the superconducting critical temperature Tc, anisotropy γ, critical current density Jc, and flux pinning mechanism depend strongly on the thicknesses of FeSe0.5Te0.5 and Bi2Te3 layers. The thicker FeSe0.5Te0.5 layer and thinner Bi2Te3 layer are beneficial for the performance of superconductivity. Our experimental results provide a pathway to studying the mechanism of proximity effect at the interfaces between superconductor and topological insulator.
查看更多>>摘要：The wire-in-tube structure was often prepared by electrostatic spinning method, and a kind of novel wire-in-tube structure porous C12H12O12S3Tb2 @g-C3N4/ZnO luminescent material was obtained by hydrothermal method in this study in which a wire-like C12H12O12S3Tb2 was wrapped in the inner layer of the porous tube-like g-C3N4/ZnO shell layer, and an obvious g-C3N4 narrow edge layer was distributed on the outer layer of the tube-like structure. Due to the wire-in-tube structure and the stronger UV absorption capacity of g-C3N4/ZnO matrix and organic ligand (SSA), the characteristic emission of Tb was greatly enhanced in the C12H12O12S3Tb2 @g-C3N4/ZnO phosphors which showed a very strong green light emission at 543 nm. On the other hand, the g-C3N4 shows much better absorbing ability to visible light which has been rarely used to optimize the luminescence properties of rare earth materials. In this study, the g-C3N4 showed the absorption to 490 nm emission light which was precisely used to improve the emission at 543 nm.
查看更多>>摘要：The Pt-loaded WO3 materials have been synthesized via simple hydrothermal and chemical reduction methods. The microstructure of prepared Pt-WO3 exhibits as nanorods consisting of bundles of finer nanorods and the Pt nanoparticles with a size of ca. 5 nm loaded on the surface of WO3. The gas sensing measurements of Pt-WO3 material show excellent gas sensing selectivity to H2S compared with many other pollution gases (e.g. NO2, SO2, NH3, CO and CO2). In particular, 0.2 at% Pt-WO3 exhibits extremely high response (1638–10 ppm H2S), short response/recovery time (42 s/37 s) and low detection limit (1.27–5 ppb H2S) at 200 °C. The superior performance of 0.2 at% Pt-WO3 compared with pure WO3 mainly originate from its modulating action to conductive band electrons of WO3 and its catalysis to the chemisorption reaction on the surface.
查看更多>>摘要：Determination of intermediate temperature phase diagrams is a challenging task due to sluggish transformation kinetics, metastable phases and low diffusion coefficients encountered under these conditions. The development of Ti-Al-Nb alloys has been hampered by scarcity of intermediate temperature phase diagrams. Through guidance from diffusion simulation results, we designed the composition of the diffusion components in a diffusion multiple capable of efficiently and accurately testing the Ti-Al-Nb ternary phase diagrams at intermediate temperatures, which is the service temperature of Ti-Al-Nb alloys. We systematically characterized the diffusion multiples using scanning electron microscopy (SEM), electron probe microanalysis (EPMA), electron backscatter diffraction (EBSD), transmission kikuchi diffraction (TKD) and transmission electron microscope (TEM), and constructed the whole composition range of the 900 °C isothermal section. The constructed range includes ten stable phases, nineteen two-phase regions and ten three-phase regions. Two ternary phases (O-Ti2AlNb and ωo-Ti4Al3Nb phases) were determined and the ωo phase was defined on the experimental phase diagram for the first time. The previous thermodynamic database at 900 °C is unreliable, based on the present work. The present experimental results will bridge the existing research gap by providing the missing thermodynamic data. The present diffusion multiple is expected to construct more isothermal sections of Ti-Al-Nb ternary system at intermediate temperatures in the future. The constructed phase diagrams are also invaluable tools to researchers and industry for development of Ti-Al-Nb alloys.
查看更多>>摘要：A 2D-Bi4NbO8Cl nanosheet (BNOCF) photocatalyst was fabricated using molten salt or flux method and was employed to degrade tetracycline (TCH) under visible light irradiation. The as-synthesized photocatalyst was characterized by a wide range of studies and compared with bulk-Bi4NbO8Cl (BNOCS). The BNOCF photocatalyst displayed 2.2 times higher degradation efficiency as compared to BNOCS. The enhanced efficiency could be attributed to the 2D architecture, with increased surface area and reduced charge recombination rate. The effect of various parameters was studied, and the optimal photocatalytic efficiency (96.5%) of BNOCF was obtained at a dosage of 1 g L?1, TCH concentration of 10 mg L?1, pH 4.4, and the light intensity of 10 mW cm?2. The effects of coexisting inorganic salts and real wastewater sources were also studied. A detailed study showed that a complex between BNOCF and TCH led to TCH degradation by inducing strong visible-light absorption. The radical trapping experiments showed that ?O2? was primarily responsible for the degradation of TCH. Based on these findings, the photocatalytic mechanism was proposed. The inorganic ions like CO32-, Cl- and SO42- were found to hinder the degradation efficiency of BNOCF slightly. Excellent degradation efficiency (95.9%) was achieved towards TCH present in a real wastewater sample. The catalyst efficiently mineralized 34.6% TCH in 1 h, and after four recycling tests, was found quite stable. The intermediate products of TCH degradation over BNOCF were detected, and plausible degradation pathways were proposed. This study proves that BNOCF possesses tremendous potential as a visible-light-reactive photocatalyst in prospective wastewater treatment applications.
查看更多>>摘要：Graphene Nanoplatelets(GNPs) dispersed aluminium composites with excellent mechanical and thermal properties offer great potentials for heat exchanger applications. Graphene Nanoplatelets reinforced aluminium composites are prepared using powder metallurgy and a hot extrusion process, with the GNPs content ranging from zero to 2 wt. percentage in increments of 0.5 wt%. In this work, the thermal conductivity of aluminium composites with 0.5 wt%, 1 wt%, 1.5% and 2 wt% GNPs are predicted using finite element analysis, experimental and theoretical models. The unit cell approach method is used to find the thermal conductivity of GNPs dispersed aluminium composites numerically. The thermal conductivity of GNPs dispersed aluminium composites are predicted with different models. The thermal conductivity of the GNPs dispersed aluminium composites increases with increasing the wt% of GNPs. After comparisons with the theoretical model and experimental results for thermal conductivity of GNPs dispersed aluminium composites, it can be seen that our finite element analysis result can reach a good agreement with experimental values.
查看更多>>摘要：In this study, we proposed a novel method for in-situ additive manufacturing of TiC reinforced Ti6Al4V-matrix functionally graded composite materials (FGMs) based on gas–liquid reaction. Laser-induced pyrolysis of methane gas (CH4) near the surface of the Ti6Al4V melt pool provides carbon atoms/ions which react with titanium atoms to in-situ synthesize TiC reinforcements. Clean interface and excellent dispersion between the TiC reinforcement and Ti matrix were achieved owing to in-situ gas–liquid reaction, good diffusivity and dispersibility of the gaseous carbon source. As anticipated, spatially varying volume fraction and grain size of the TiC reinforcement, continuously varying microhardness and wear resistance were attained in the TiC/Ti6Al4V FGM by controlling continuous variation of CH4 concentration.
查看更多>>摘要：One of the effective strategies to enhance the activity and stability of the Pt-based catalysts in low-temperature solid oxide fuel cells (LT-SOFCs) is modifying the electronic structure and reducing the surface energy of Pt by transition metal alloying. Herein, co-sputtered Pt/Ti alloy cathodes for LT-SOFC with varying Pt/Ti compositional ratios (Ti 0–26 at%) are fabricated and tested. The cell constructed with the optimal (6–11 at% Ti) Pt/Ti alloy cathode shows five times lower degradation rate in activation resistance compared to a pure Pt cathode at 450 °C, resulting in a 33% enhancement in the maximum power density after 2 h of operation. We show that the performance enhancement of the Pt/Ti alloy cathode at elevated temperature is due to the formation of a catalytically active and thermally stable Pt3Ti alloy phase, in which coarsening is effectively prevented as opposed to its pure Pt counterpart. Moreover, we demonstrate that Pt/Ti alloy cathodes with excessive Ti content (≥ 19 at%) suffer from the formation of a nonreactive TiO2 surface upon oxygen exposure at elevated temperature, which causes higher activation resistance.
NSTL
Elsevier