Materials Letters: X最新文献

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.

Herein, we report a feasible approach for preparation of crosslinked alginate (Alg) and poly(amido amine) (PAMAM) nanogels (Alg-PAMAM NGs), using a water-in-oil-in-water (w/o/w) double emulsion route, via strong electrostatic interactions between anionic groups coming from alginate and previously incorporated Cu²⁺ ions. CuO nanoparticles (NPs) with average diameter about 65 nm were in situ obtained into Alg/PAMAM nanogels by treatment of embedded Cu²⁺ ions in NGs with NaBH₄ at 25 °C under air atmosphere. The prepared Alg-PAMAM and Alg-PAMAM-CuO NGs were characterized using FT-IR and UV–visible spectroscopy, as well as scanning transmission electron microscopy (STEM). The presence of PAMAM dendrimers helped both to obtain structurally compact nanogels and an adequate stabilization of CuO NPs. Finally, the photocatalytic performance of the Alg-PAMAM-CuO NGs was tested via the decomposition of methyl orange in aqueous solution, under visible light irradiation.

Ga₂O₃ has attracted significant attention for various applications such as power-switching applications and deep-ultraviolet optoelectronics. In this study, we demonstrated a lattice-matching κ-(In_1−xGa_x)₂O₃ thin film grown on an ε-GaFeO₃ substrate via the mist chemical vapor deposition process. The X-ray diffraction peak of the thin film was almost coincident with that of the substrate and exhibited Laue oscillations. Atomic force microscopy revealed that the surface of the κ-(In_1−xGa_x)₂O₃ thin film exhibited a step-terrace morphology and was atomically flat. The selected area electron diffraction of transmission electron microscopy showed that the diffraction spots of the thin film and substrate overlapped, indicating that the thin film was almost lattice-matched with the substrate. We believe that the lattice-matched κ-(In_1−xGa_x)₂O₃ thin film with an ε-GaFeO₃ substrate will contribute significantly to the demonstration of ferroelectric κ-Ga₂O₃ based high electron mobility transistors.

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.

Polyurethane (PU) foams are inevitable for many applications from comfort materials or energy saving to aerospace. Today, greener routes for their production have gained thoughtful attention among the scientific community by avoiding mainly the use of toxic isocyanates. An easily scalable process for the realization of self-blown isocyanate-free PU (poly (hydroxy urethane)-PHU) foams by exploiting suitable amines and cyclic carbonates is demonstrated in this work. The foaming is attributed to the release of CO₂, from the reaction of cyclic carbonate of resorcinol diglycidyl ether (RDGCC) with amine terminated oligomeric phenyl hydroxy amine (AOPHA), where a parallel reaction of the hydroxyl groups and amino groups with the cyclic carbonate groups are competing during polymerization and culminate in poly (hydroxy urethane) foam. The released gas was confirmed as CO₂ from GC–MS and temperature dependent FTIR. The realized flexible PHU foam is thermally stable (>250 ℃) with adhesive strength between Al-Al as 1.5 to 2.0 MPa, and with a closed cell structure possessing a density of 480 kg/m³.

Ni60 coating is prepared utilizing laser cladding on 45 steel assisted by magnetic-ultrasonic-electric field. The effect of multi-physical fields on the cracking tendency, microstructure, phase composition, mechanical properties and corrosive resistance of coating is investigated. As results indicate, the macro-morphology of coating is affected by the multi-physical field and the microstructure is refined, which uniformizes the element distribution and prominently optimizes the tribological and anti-corrosive performance of coating, the number of cracks in the coating under multi-physical field reduce by 76.92%, compared with that without physical field, the average microhardness increases by 37.89%, the average friction coefficient decreases by 61.96%, the average wear loss decreases by 61.05%, the corrosive rate decreases by 93.01%.

Mixed-valent perovskite manganite has gained considerable research interest due to the increasing demand for energy storage materials. Herein, we show that colossal magneto-resistance properties of La_0.7Ca_0.3MnO₃ (LCMO) can be changed via nickel oxide (NiO) doping. A two-step conventional solid-state reaction method is used to synthesize LCMO-10% NiO composite. The phase purity, structural, electrical (resistivity), and magneto-transport properties of as-synthesized LCMO-10% NiO composite are detailed. NiO doping shifts metal–insulator transition temperature (T^MI) from 263 K to 195 K and increases resistivity. The magneto-resistance (MR) measurements showed 10% NiO doping resulted in a maximum MR of ∼ -70.32% at 200 K (near T^MI) and 10 T applied magnetic field. However, -0.0849% MR is seen at 290 K (RT) and 0.3 T. The increased ∼ -63.85% MR is found at 100 K and at 10 T, which is comparatively much higher than the pristine LCMO sample. This is due to the addition of NiO in LCMO that improves physical properties (i.e., grain size).

The combination of electrospinning and sol-gel methods is attracting the interest of the scientific community for developing three-dimensional bioactive glass (BG)-based fibers. This paper reports the fabrication of cotton-like copper-doped BG fibers by combining electrospinning and sol-gel techniques. Acellular bioactivity in simulated body fluid, ion release, cell viability and scratch cell tests were performed. Results showed that copper was successfully incorporated in the fibers and Cu ions were released in limited concentration over seven days. The presence of copper delayed the mineralization of the fibers upon immersion in simulated body fluid (SBF), but it did not affect keratinocyte viability and migration. Wound closure in the scratch cell test was achieved in 48 h for all the investigated samples.

In this article, the authors have explored the changes caused in structural, morphological and magnetic properties of magnesium ferrite nanoparticles (MgFe₂O₄ NPs) under dynamic shock wave exposure situations. Interestingly, the observed XRD and VSM results reveal that the MgFe₂O₄ NPs have outstanding crystallographic and magnetic phase stability against the impact of shock waves and found that the title NPs are having higher shock resistance than other potential materials such as TiO₂, Co₃O₄ and ZnFe₂O₄ NPs.

Materials obtained by cold spraying (CS) are subjected to post-spray treatment to increase cohesion between the particles. In this work, spark plasma sintering (SPS) was used for reactive processing of cold spray deposits for the first time. A mixture of a Ti-C-3Cu ball-milled powder and copper was used as a feedstock material for the formation of Cu matrix composites by CS. SPS treatment of CS deposits was used for the in-situ synthesis of TiC, formation of a dense structure and elimination of microcracks at the interface between the substrate and the deposit. The mechanism of structural changes in the composite agglomerates upon reaction was discussed. The TiC-Cu composite particles in the microstructure of the SPS-treated material possess a microhardness of 390 ± 40 HV_0.025, which makes them suitable as reinforcing elements of composite nature in the design of Cu matrix materials. This study shows that SPS treatment is a promising solution for post-spray processing of cold spray coatings.