查看更多>>摘要：? 2022 Elsevier B.V.To develop high-performance magnesium alloy sheets for sheet applications in the automotive industry, we investigated the effects of the Al content on the tensile properties, stretch formability, and corrosion resistances of Mg-xAl-0.5Ca-0.4Mn-0.8Zn (mass%, x = 2, 5, 8, AXMZx101) alloy sheets. The addition of 5% Al led to the highest limiting dome height of 6.4 mm. The AXMZ5101 alloy sheet also exhibited a good combination of in-plane isotropic strength and ductility. The 0.2% proof stress and elongation to failure were 193 MPa and 24.2% for the rolling direction and 188 MPa and 23.1% for the transverse direction, respectively. Such moderate Al addition resulted in a significantly improved corrosion resistance with a corrosion rate of 0.18 mm/y after immersion in a 3.5% NaCl solution for 7 days, which was approximately 1/4 lower than that of a commercial Mg-Al-Zn alloy sheet. An in-depth characterization revealed that such a good combination of tensile properties and stretch formability is associated with the small grain size, weak basal texture, high work hardenability, and activation of nonbasal slips and that a high corrosion resistance should be achieved by the formation of a dense oxide-rich layer.
查看更多>>摘要：? 2022 The AuthorsThe electrocatalysts are critical to the electrocatalytic nitrogen reduction reaction (e-NRR) technique and its development. Herein, through morphological structure modulation, three-dimensional (3D) fibrous silica nanospheres (KCC-1) are firstly fabricated as the supporting scaffold, followed by the coating of nitrogen-doped carbon and interspersing of copper nanoparticles. The resulting carbon spheres (KNC) has very uniform interspersion of copper nanoparticles (Cu-NPs) in the 3D fibrous structure ensuring high accessible active sites for nitrogen molecules; the thin surface carbon layer offering a rich channel for electron transport; and nitrogen dopant allowing efficient electron transfer of copper atoms throng metal-nitrogen covalent bonds. When used as electrocatalysts to e-NRR, KNC exhibits good electrochemical activity, selectivity, and good stability, and can obtain an ammonia yield of approximately 6.67 μg h?1 mgcat?1 and an excellent Faraday efficiency (FE) of 8.1% in 0.1 M sodium sulfate solution at ? 0.4 V (vs. RHE).
查看更多>>摘要：? 2022 The Author(s)Demand for new Ti alloys for AM is immense. Ti–5Al–5Mo–5V–3Cr (wt%), a β type Ti alloy is chosen for this study as it possesses excellent properties. Samples are manufactured using SLM technique. Relative density, surface morphologies and hardness of samples produced by varying laser processing parameters, e.g., laser scan speed and laser power, are thoroughly investigated. Top surface of the as-built samples shows adhered powder particles and discontinuous ripple patterns. A change in scan speed from 1200 to 1400 mm.s-1 drastically deteriorates top surface quality in terms of ripples patterns and adhered powders. Surface roughness (Sa/Ra) of the side surface of the produced samples shows a value of below 20 μm. Side surfaces show adhered powder particles, open surface pores, microcrack and interlayer crack. Substantial increase in adhered powder particles is evident when both laser power and laser scan speed are increased distinctively. These results are discussed with the help of the thermodynamic and metallurgical phenomena involved in the SLM processing. Hardness of the as-built samples is measured, the value is in agreement with conventional processing. This fundamental study will be useful for producing Ti-5553 alloy AM parts with optimum surface.
查看更多>>摘要：? 2022 Elsevier B.V.Sodium metal is a promising alternative anode for high-energy Na-based batteries due to its natural abundance, favorable redox voltage and remarkable theoretical capacity. However, unstable solid electrolyte interface (SEI) film, huge volume variation and uncontrolled Na dendrite growth, resulting in low Coulombic efficiency and limited span-life, have dragged the Na metal anode out of practical application. Herein, 3D hierarchical porous nickel foam matrix decorated by Fe2O3 nanosheets (Fe2O3 @Ni) is synthesized and served as a sodiophilic scaffold to reduce Na nucleation overpotential and achieve uniform Na deposition without dendrite growth. Consequently, the composite Na/Fe2O3 @Ni anode shows smaller hysteresis voltage at a high current density of 5 mA cm?2 and exhibits satisfactory cycling stability with a Coulombic efficiency of ~ 99.77% (up to 1000 cycles). When in couple with Na3V2(PO4)3 cathode, the full cell shows higher capacity and better cycling stability than the one with bare Na anode. The 3D porous nickel modified by Fe2O3 presents a new perspective for the anode design of sodium metal battery.
查看更多>>摘要：? 2022 Elsevier B.V.Semiconductor metal oxide nanostructures with large specific surface areas and high porosity will enhance their gas-sensing performance. Here, cross-linked porous tin dioxide nanosheets were obtained using three-dimensional reduced graphene oxide as a template followed by an annealing process. The as-synthesized porous SnO2 nanosheets were composed of nanocrystals with a mean diameter of ca. 7.6 nm. The products were characterized using a range of techniques. The sensing property of the cross-linked porous SnO2 nanosheets for toxic organic vapors, such as ethanol, acetone, isopropanol, benzene, methylbenzene, methanol, and formaldehyde, were studied. The sensor showed a high response of 37.9 for 100 ppm acetone, making it a promising candidate as a practical detector of volatile organic compounds.
查看更多>>摘要：? 2022 Elsevier B.V.We studied the auto-combustion synthesis and fabrication of an oxygen-deficient perovskite-type barium iron oxide and polydimethylsiloxane (BaFeO3-δ/PDMS) composite and tested its feasibility as a magnetic composite. The perovskite was found to exhibit a polycrystalline nature with polymorphic structural distributions, an altered chemistry, and a completely unusual ferro-to-diamagnetic transitional property, as demonstrated by X-ray diffraction, Raman spectroscopy, and vibrating sample magnetometer studies, respectively. Field emission scanning electron microscopy results revealed that the PDMS completely encapsulated the BaFeO3-δ powder.
查看更多>>摘要：? 2022 Elsevier B.V.The influence of T6 heat treatment process and Cu and Ag alloy elements as variables on the microstructure, mechanical properties and intergranular corrosion (IGC) performance of Al-Mg-Zn-Cu-Ag alloy was systematically studied. The results show that there is a small improvement in the mechanical properties and IGC resistance of the 0.50Cu (wt%) alloy compared to the 0.25Cu (wt%) alloy when the peak ageing temperature is reached at 180 °C. At a constant value of Cu element content, with the addition of Ag element and its increasing content, a large number of nanoscale dispersive phases precipitated in the alloy crystals, and their number density also increased. This resulted in a substantial improvement in the mechanical properties (including strength and hardness) of the alloy. Both the 0.50Cu-0.72Ag (wt%) alloy and the 0.50Cu (wt%) alloy reached peak aging at 36 h at 180 °C. At this time, the 0.50Cu-0.72Ag (wt%) alloy showed an increase in hardness of 46.4 MPa, YS of 148.3 MPa, and UTS of 103.6 MPa compared to the 0.50Cu (wt%) alloy. The intergranular corrosion performance (IGC) of the alloy is related to the different aging states, with the solid solution state having the best IGC resistance, the under-aged and over-aged states being the next best, and the peak aging state having the worst IGC resistance. The addition of Ag improves the IGC resistance of the alloy to a small extent, and the weight loss of alloy 5 containing 0.72Ag (wt%) is reduced by 27.2 mg/cm2 compared to alloy 3 containing 0.18Ag (wt%) at T-36 peak aging.
查看更多>>摘要：? 2022 Elsevier B.V.A green chemistry synthesis of a sodium-ion battery (SIB) anode is described. The anode comprises nanometric Sphalerite (ZnS) film, coated uniformly on reduced graphene oxide. Compliance of an energy storage component with sustainability goals requires the following attributes: i) exclusive use of abundant and non-toxic raw materials; ii) energy-minimized processing that uses cheap materials of construction, and involves a minimal waste generation, and no hazardous wastes, and iii) high energy efficiency without compromising power performance. Only low-cost, abundant raw materials are used in this synthesis: zinc acetate, 1 wt% hydrogen peroxide solution, and in-situ generated hydrogen sulfide. The synthesis protocol is based on hydrogen peroxide sol-gel (HPSG) processing, i.e. synthesis of zinc peroxide sol followed by a delicate pH change to deposit the zinc peroxide on dispersed graphene oxide. HPSG is a wet-chemistry process that does not rely on energy-rich hydrothermal/solvothermal steps, water or solvent evaporation, or the use of dispersing organic solvents, and the zinc precursor is fully converted to ZnS. We show film deposition from as low as 1 wt% aqueous hydrogen peroxide solution. The anode exhibits excellent electrochemical characteristics: 550 mAh g?1 at 0.1 A g?1 after 150 cycles between 0 and 2.5 V vs. Na reference, and a high-rate capability of 420 mAh g?1 at 2 A g?1 (ca 5 C rate). Despite being a conversion type anode, ZnS exhibits similar voltage hysteresis (and energy efficiency) to tin sulfide - graphene-oxide composite, a conversion-alloying anode. Despite being a SIB anode, it compares favorably with the Fe3O4 and MnO LIB conversion anodes, commended for their high energy efficiency.
查看更多>>摘要：? 2022 Elsevier B.V.The effect of high pressure on the composition and grain size of the Mg-xAl alloy was studied, and the mechanism of structure refinement from the viewpoint of solute redistribution was discussed. The results show that the amount of Al in the solid solution in the α-Mg matrix increased due to the higher solute distribution coefficient caused by high pressure. The Al content of the original alloy required for the initial eutectic transformation was increased from 5 wt% at atmospheric pressure to 9 wt% at 4 GPa, and the Al content at the eutectic point increased from 32.3 wt% at atmospheric pressure to 38.3 wt% at 4 GPa. Under high pressure, the large increase in the number of α-Mg crystals is related not only to the increase in nucleation rate and the inhibition of crystal growth caused by high pressure but also to the higher Al content, which enhances constitutional supercooling, further increasing the nucleation rate and inhibiting crystal growth.
查看更多>>摘要：? 2022Scintillators play a vital role in high-energy physics, medical imaging, security inspection, etc. Here, we designed and prepared a highly efficient scintillator of Ce,Tb-codoped LiLuF4, which was synthesized by a hydrothermal method using low-cost raw materials. The microcrystalline scintillator exhibits the strong luminescence of rare earth ion, which has a characteristic green fluorescence emission with a quantum yield of 71.59%. This material has a strong X-ray response, superior light output (16,509 ph/MeV), excellent ray cut-off capability and absolute stability. Based on micron-level powdered compounds, we used direct coating to manufacture a scintillation film with a size of 5.5 cm × 8.0 cm for X-ray imaging testing. The imaging test shows that the highly stable scintillation film not only has a spatial resolution capability of more than 10.0 LP/mm but also has great potential to be prepared as a flexible scintillator, which exhibited excellent performance as an potential scintillation detection material.
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