查看更多>>摘要：? 2022 Elsevier B.V.High-temperature oxidation and elemental diffusion significantly affect the microstructure and mechanical properties of Cr-coated zircaloys under accident conditions, leading to cracking modes different from those of samples with fresh coatings. To clarify the intrinsic mechanisms, in situ three-point bending tests were performed and finite element models were built for the Cr-coated Zr-4 alloys oxidized and vacuum-annealed at 1000 °C. In the case of vacuum-annealed Cr coatings, although numerous microcracks were initiated in the brittle ZrCr2 diffusion layer under external loading, they could hardly propagate through the Cr coating. Recrystallization and grain growth under the annealing conditions led to significant improvement in the ductility of the Cr coating and its deformation compatibility with the substrate, resulting in the best crack resistance of the coating. In the case of oxidized Cr coatings, oxygen penetrated the Cr coating on the substrate, causing a β-Zr to α-Zr(O) phase transformation beneath the interface at the high annealing temperature. Under external loading, driven by large stresses, the brittle layers of Cr2O3, ZrCr2, and α-Zr(O) were susceptible to microcracking, and some cracks penetrated the Cr coating. However, the crack resistance of the oxidized Cr coating was better than that of the as-deposited coating.
查看更多>>摘要：? 2022The work presented in this paper focused on the effects of laser remelting with varied laser energy densities from 800 J/mm to 1400 J/mm on the phase transformation and microstructural characteristics in the tungsten carbide nickel-based matrix composite (Ni-WC) tracks obtained by laser hot wire cladding. The microstructures of the as-deposited tracks fabricated by laser hot-wire deposition were mainly composed of spherical residual carbons, eutectic Ni/Ni3B, retained WC/W2C particles and the granular in situ W2C particles formed in the interdendritic regions of primary (Ni,Fe) dendrites. When the low laser energy densities of 800 J/mm and 1000 J/mm were applied, the dispersive W2C particles in the as-deposited tracks were dissolved, and the WC particles were successfully in situ synthesized and uniformly distributed in the remelted tracks. When the laser energy density was increased to 1200 J/mm, the feather-like M6C(Ni2W4C) carbides homogeneously precipitated in the remelted tracks. When the laser energy density was further increased to 1400 J/mm, the dissolution degree of the ex-situ WC/W2C particles was significantly increased, resulting in a remelted track with a relative low volume fraction of retained ceramic particles and a high dilution ratio of the base metal. In addition, the dendritic M6C(Fe3W3C) carbides were precipitated around the retained particles, and the eutectic M6C(Fe3W3C) carbides in the herringbone morphology were uniformly distributed in the matrix of the track remelted by a high laser energy density of 1400 J/mm. These experimental results confirmed that the homogenization of the in situ synthesized reinforcements in the tracks could be well realized by laser hot wire cladding and the subsequent laser remelting. The coatings remelted by the low energy densities (800 J/mm and 1000 J/mm) possessed higher wear resistance than that of the as-deposited coating, but the wear performance of the remelted coatings was decreased when the laser energy densities were increased to 1200 J/mm and 1400 J/mm.
查看更多>>摘要：? 2022NiAlY alloys with the addition of Zr, Ti, Ta and Mo were prepared by arc melting. The oxidation and NaCl-induced hot corrosion behavior of the alloys were investigated at 650 ℃, with the focus on the effect of element-doping and phase. With the addition of Ti, Ta and Mo, the oxidation resistance of the tested alloys was effectively enhanced compared to the undoped NiAlY alloy. However, the NiZrAlY alloy showed very poor oxidation resistance. Under the NaCl-induced hot corrosion test, the NiTaAlY and NiMoAlY alloys exhibited an improved hot corrosion resistance, while the NiZrAlY and NiTiAlY alloys showed very poor hot corrosion resistance. Moreover, the NiAl and Ni5Y phases exhibited different behavior during the oxidation and NaCl-induced hot corrosion tests.
查看更多>>摘要：? 2022 Elsevier B.V.Recently, thin film metallic glasses (TFMGs) gained renewed attention as they can circumvent the brittleness problem of bulk metallic glasses. When sputtered from a multicomponent cast target, the composition control of TFMG is always challenging. Here, we demonstrate the tight composition control of sputtered Ti-Zr-Cu-Ni-Al TFMG by a spark plasma sintered multicomponent target and investigate their structural and nanoscratch properties. The radio frequency (RF) power and Ar pressure were tuned to optimize nanoscratch properties. The highest hardness (~16.2 GPa) and thus best nanoscratch resistance was obtained at an RF power of 160 W and Ar pressure of 7 Pa. The best nanoscratch properties originated from the dense, fine column morphology of the TFMG. Moreover, it was found that the scratch mechanism changed from plowing to a combination of plowing and stick-slip under a ramping scratching load of 10 mN. The transition happened progressively at lower loads when the hardness of the TFMG decreased. This study provides a useful guideline for developing TFMG as a scratch-resistant protective coating.
查看更多>>摘要：? 2022 Elsevier B.V.Textile-based supercapacitors are ideal energy supply equipment for intelligent wearable products. Apart from the further enhanced energy storage property, the poor bending resistance and air permeability also compromise their electrochemical performance in practical use. Based on traditional textile technology, the supercapacitors woven by fibrous electrodes promise to combine both electrochemical and wearable performances. Herein, the carbon fiber-based Ni-Fe double hydroxide electrode (NiFe@NiFeDH/CF) with uniform morphology has been obtained through a facile route of palladium-free electroless plating coupled electrooxidation. By controlling Fe2+ content in the plating baths, the interwoven nanosheets with small intervals and large crystal spacing could be designed, which provided low diffusion resistance for electrolyte ions and adequate active sites for energy storage. Subsequently, the all-solid-state asymmetric textile supercapacitors (wSC-NF//CY) were fabricated by weaving techniques with NiFe@NiFeDH/CF as positive electrode and carbon yarns as the negative electrode. Benefit from the better electrochemical property of NiFe@NiFeDH/CF, the wSC-NF//CY owned unexpected excellent energy storage performance that at the power density of 9.0 W cm?2 the energy density could reach 26.8 mW h cm?2. Additionally, with the help of fabric structure, the wSC-NF//CY could be integrated into different materials to accommodate curved human bodies or other non-flat surfaces. Moreover, the NiFe@NiFeDH/CF could also be used to decolorize sewage with an electro-Fenton reaction under a small voltage. Thus, this work constituted a breakthrough on multifunctional energy storage materials and their eco-friendly and sustainable usage.
查看更多>>摘要：? 2022 Elsevier B.V.Sodalites are one of the potential candidate forms for the radioactive 129I immobilization. In this work, the synthesis, structure and thermal stability of iodine-contained sodalites Na8(AlSiO4)6Cl2-xIx (x = 0–2) were studied. The high temperature solid phase method combined with high pressure tableting and NaOH solution scrubbing was proposed to synthesize iodine-contained sodalites with single phase. The X-ray diffraction Rietveld analysis shows that, the crystal structure of Na8(AlSiO4)6Cl2-xIx varies as a function of the iodine content, x. The thermal stability of iodine-contained sodalites was studied by thermogravimetric analysis and high temperature annealing experiments. The iodine-contained sodalites exhibit good stability below 750 °C. A phase decomposition from the sodalite phase into the nepheline phase was observed for each composition at higher temperatures. The quantitative analysis of phase decomposition of Na8(AlSiO4)6Cl2-xIx annealed at 900 °C for 3 h further confirms the negative effects of iodine-doping on the thermal stability of samples.
查看更多>>摘要：? 2022 Elsevier B.V.In order to elaborate stoichiometric CuSbS2 and Cu12Sb4S13 (CAS) thin films by co-electrodeposition on FTO substrates, the copper concentration was varied between 0.015 M and 0.030 M at ? 0.98 mV co-electrodeposition potential (vs. saturated calomel electrode (SCE)). After a sulfurization step in a quartz tube at 410 °C under an argon flow for 45 min, the samples formed are analyzed by different techniques: The XRD technique has shown the existence of characteristic peaks of the CuSbS2 phase at 28.53, 28.79, 29.73 and 29.99° clearly for the 0.015 M concentration, but this XRD spectrum has shifted to that of Cu12Sb4S13 phase when the copper concentration increases to 0.030 M. Likewise the Raman spectroscopy has indicated the principal peak of CuSbS2 located at 337 cm?1 on the spectrum of the 0.015 M concentration, but this peak have disappeared for the 0.030 M concentration and was replaced by a new principal peak of Cu12Sb4S13 at 317 cm?1. This effect was confirmed by the UV-Visible spectrophotometry technique which shows an increase of optical gap from 1.46 eV (CuSbS2) to 1.81 eV (Cu12Sb4S13) when the copper concentration passes from 0.015 M to 0.030 M. The morphological study and EDS analysis have proved that the layers CuSbS2 and Cu12Sb4S13 were elaborated with good stoichiometry.
查看更多>>摘要：? 2022 Elsevier B.V.A series of Cu@PNC (porous nitrogen–doped carbon) samples was successfully prepared through the reduction of Cu2+/g-C3N4 (graphitic carbon nitride) using magnesium, which was used to construct an efficient electromagnetic wave (EMW) absorber. The Cu content in Cu@PNC was adjusted by changing the amount of Cu(NO3)2?3 H2O added. Of the three prepared samples, Cu@PNC-1 exhibited the best EMW absorption properties; that is, the minimum reflection loss (RLmin) was ?79.8 dB (d = 3.7 mm) at 5.93 GHz and the effective absorption bandwidth (RL<?10 dB) was up to 5.1 GHz (d = 1.6 mm), with only 5 wt% filled in paraffin. Copper has high electrical conductivity and chemical stability, and these factors helped to enhance the EMW absorption ability and corrosion resistance of the composites. The EMW absorption ability of Cu@PNC only changed slightly after soaking in acid (1 M) for 28 days. The findings of this research provide a potential route for preparing a Cu-based acid-resistant EMW absorber.
查看更多>>摘要：? 2022 Elsevier B.V.The crystal structure, photoluminescence properties, thermal stability and corresponding mechanisms of the novel Bi3+, Eu3+-doped La2SrSc2O7 (LSS) phosphors have been measured and analyzed in details. The emission spectrum of LSS: 1.0%Bi3+ phosphor shows a novel green emission centered at 530 nm under 340 nm excitation, which is attributed to the 3P1→1S0 transition of Bi3+ ions. By designing Bi3+→Eu3+energy transfer strategy, luminescence colors of LSS: 1.0%Bi3+, yEu3+ (y = 0–5.0%) phosphors can be tuned from green to orange with increasing Eu3+ concentration, which achieve multiple emission colors in LSS host. The photoluminescence decay curves, average decay lifetimes, energy transfer efficiency and time-resolved emission spectra of LSS: 1.0%Bi3+, yEu3+ (y = 0–5.0%) phosphors prove the existence of energy transfer from Bi3+ to Eu3+. The prototype pc-WLED device with green-emitting LSS: 1.0%Bi3+ possesses high color rendering index (CRI = 96.0) and low correlated color temperature (CCT = 4306 K). These results provide clear evidences that LSS: Bi3+and LSS: 1.0%Bi3+, Eu3+ phosphors would be novel promising green-to-orange tunable phosphor candidates for pc-WLED applications.
查看更多>>摘要：? 2022 Elsevier B.V.Flexible surface-enhanced Raman spectroscopy (SERS) substrates enable fast sampling and real-time detection, offering greater potential for practical applications. However, whether the flexible substrate will adversely affect the SERS effect when it is bent has rarely been examined in previous studies. In this study, we have tentatively confirmed through theoretical simulations using Ag nano-trees as a model that the effect of bending detection on the SERS effects is negligible. Then, Ag nano-trees were deposited on the surface of a flexible Cu mesh (AgNTs@Cu mesh) by a facile electrochemical method for SERS applications. Successful detection of ultra-low concentrations of rhodamine 6G (R6G, 10?11 M) and crystal violet (CV, 10?10 M) demonstrated the excellent sensitivity of the flexible AgNTs@Cu mesh SERS substrate. In addition, using MG as the target molecule, the SERS signals at different curvature positions on the shrimp surface were detected. In agreement with the theoretical results, the bending did not affect the SERS effect of the substrate. Furthermore, it was experimentally confirmed that the flexible AgNTs@Cu mesh had outstanding in-situ detection capabilities for both solids with uneven surfaces and liquid substances. Therefore, we believe that this work has the potential to provide a universally applicable SERS substrate.
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