Materials Letters: X最新文献

Cobalt-copper-zinc ferrite (CoCuZnF) nanoparticles were synthesized using the precipitation method. The characterization of CoCuZnF was carried out using powder XRD, Raman, IR, UV–vis, and FEG-SEM. The TG-DSC data of NTO, and nNTO containing the catalyst was used to study the thermal decomposition behavior. Three non-isothermal methods were used to evaluate the kinetic parameters. The kinetics data suggests that incorporation of CoCuZnF additive can effectively decrease the high activation energy of NTO by ∼83–88 kJ mol⁻¹ and nNTO (∼205–216 kJ mol⁻¹). The decomposition of both NTO and nNTO was faster in the presence of CoCuZnF, suggesting its plausible use in the high explosive munitions containing NTO.

This paper presents results of application of Ultrasonic Waves UW in civil engineering. The measurement has been performed by ultrasonic reflection technique using a transducer with central frequency 0,5MHz. Several methods of analysis and signal processing have been applied to detect the position of reflections and to measure the time of flight between two echoes related to the reflection at the mortar interfaces. The experiments performed in the laboratory are carried to determine the ultrasonic velocity of the wave backscattered by samples. This allowed determining the ultrasonic velocity of UW in the mortar in order to deduce the durability of each mortar according to its microstructure. The objective is to make a comparative study of the various methods of analysis of the ultrasonic signals as: Continuous Wavelet Transform (CWT), Wigner Ville (WVD), Pseudo Wigner–Ville distribution (PWVD), Smoothed Pseudo Wigner–Ville Distribution (SPWVD) and Hilbert Transform (HT).

In today’s scenario, a number of nanocomposites are evidencing handy control in in vitro biological studies like anti-inflammatory and antidiabetic activity. Since the nanocomposite action and mechanism are totally different from others, like simple molecules of antibiotics. This work described a facile one-pot hydrothermal synthesis of the rGO-MnO₂ nanocomposite. The prepared samples were characterized and confirmed by XRD, UV, SEM, EDX, and XPS studies. Furthermore, the catalytic performance evolved through in vitro biological applications such as anti-inflammatory and antidiabetic activities. rGO-MnO₂ nanocomposite has more biological activity than pure MnO₂ nanoparticles, as demonstrated by the results.

Zinc-Nickel Ferrite (Zn_(1−x)Ni_xFe₂O₄) nanoparticles were synthesized by solution combustion method using urea as a fuel and varying the cation concentration (x = 0, 0.2, 0.4, 0.6, 0.8, 1). The effects of cation concentration, on the crystallite size, morphology, absorption properties have been studied. The X-ray diffraction and FTIR results confirm the formation of single-phase spinel structure of Zinc-Nickel Ferrite nanoparticles. FESEM and TEM study reveals the formation of uniform spherical shape distribution of Zn_(1−x)Ni_xFe₂O₄ nanoparticles. The bandgap values were calculated for the prepared samples using UV–Visible spectrophotometer.

Surface-enhanced Raman spectroscopy (SERS) exhibits intriguing analytical application owing to their non-invasive method, specificity, and sensitivity. However, development of tunable SERS active substrate remains a challenge. Herein, we report a straightforward chronoamperometric co-deposition strategy, utilizing a reducing agent, to form bimetallic coating comprised of Cu/Ag on silica substrate, where alteration of deposition current endows fractional variations in the nucleation/growth of Cu²⁺ → Cu⁺/Cu⁰ and Ag²⁺ → Ag⁺/Ag⁰. Properties of optical reflectance, surface chemistry, topography, and nanocrystallite cluster orientation were characterized. Experimental results confirm bimetallic coating with large proportion of Ag on Cu matrix could enable better SERS behavior with studied model, Rhodamine 6G.

This work demonstrates how an interference pattern can improve the performance of remote laser cutting of pure copper foils, making the cutting process effective even for a low power laser source. The proof of concept is carried out by using a nanosecond laser source with a pulse duration of 5 ns, coupled with a two-beam scanning interference setup, producing a spatial period of 12.5 µm. In the experiments, processing parameters as pulse-to-pulse distance, laser power and scanning speed are varied, to optimize the foil breakthrough and their effect on the generated material modifications are investigated. A comparison between the processing results employing the interference pattern and single beam with a Gaussian energy distribution is carried out. While the single beam process is not sufficient for cutting a 10 µm thin metallic foil, the interference treatment shows an improvement over 100%. In addition, only small spatter formations are detected, with average particle sizes of 1.75 ± 0.82 µm on the top side of the foil. The bottom side of a fully separated copper foil only depicts small spatter formations of less than 1 µm.

This article considers the nanoparticles suspended in the gas phase in the vicinity of a 3D-printed surface during additive manufacturing via Laser Beam Powder Bed Fusion (LB-PBF) and Directed Energy Deposition (DED). The results of this research show that the primary pollutants during the laser additive manufacturing using metal powder are aggregated core–shell nanoparticles with an average particle size of about 10 nm. High-resolution microscopy shows the chemical composition of the volume and surface of each particle; in particular, the “core” consists of Fe, Cr, and Ni atoms and the “shell” is a thin oxide layer.

In this study a novel approach was adopted to couple cloisite functionalised with PEO nanoparticles to modify the polyether sulfone (PES) at low pressure nanofiltration membrane for the removal of salts and dyes from waste water. PES/f-(PEO-Cloisite) nanocomposite membranes were fabricated by phase inversion process in presence of DMF as solvent. The functionalised PEO-Cloisite mixture was characterised by SEM-EDX and the membranes were characterised by hydrophilicity and morphology. The highest water flux of 152.77 Lm⁻²h⁻¹ was observed for 4.5 wt% of PEO-Cloisite in PES membrane. Contact angle values reduced from 74.3° to 60.9° with the increase in the concentration of PEO-Cloisite and confirmed the increase of hydrophilicity. The membrane performance was tested using model saline and dye solutions by low pressure nanofiltration under longer run mode. This study infers that modification of PES membranes using functionalised PEO-Cloisite increase the membrane stability can be used to alleviate the fouling in the treatment of industrial waste water.

Uniaxial tensile tests were carried out on nickel sheets containing only few grains across the thickness thus presenting a so-called multicrystalline state. Pristine sheets used as reference and substrates covered by a nickel layer deposited by physical vapor deposition (magnetron sputtering) were studied. Results attest that the surface treatment affects the plastic deformation mechanisms by playing the role of a blocking barrier to dislocation movement which leads to a significant improvement of mechanical performances. The surface restructuring of the nickel sheets is efficient to stop dislocation escape through free surfaces and allows a mechanical improvement of the well-known strong mechanical softening of the multicrystals.

Aiming to improve the surface properties of copper, a Ni-Cr-B-Si coating was fabricated by plasma transferred arc (PTA) cladding. The coating formed a good metallurgical bonding with the copper substrate, and the dilution rate was about 15.9%. The coating mainly contained γ-(Cu, Fe, Ni), Cr₂₃C₆, CrB and Ni₃Si phases, which played a role of solid solution strengthening and dispersion strengthening. The hardness of the coating was significantly improved compared to the copper substrate, which was approximately 7.8 times that of the substrate. The wear resistance of the coating was 5.0 times higher than that of the copper substrate, and the wear mechanism was abrasive wear.