Current Issue : April-June Volume : 2026 Issue Number : 2 Articles : 5 Articles
Gold (Au) is one of the noble metals most used as a catalyst in the growth of onedimensional nanostructures. Usually, an ultra-thin Au film is coated followed by thermal annealing to obtain Au nanoclusters. Although annealing temperature, duration and film thickness parameters have been heavily studied, there are no studies on the sputter working gas pressure, which also greatly affects the film microstructure. In this study, low (5 mTorr) and high (15 mTorr) working gas pressures were examined in addition to Au film thicknesses of 2 nm, 5 nm and 8 nm. Additionally, copper indium gallium selenide (CIGS) films were deposited on Au films with different thicknesses and argon (Ar) gas pressures. It was confirmed from SEM and AFM images that the Au films undergo drastic morphology change from smooth to extremely porous film surfaces with increasing thickness regardless of gas pressure. However, the porosity of films is increased at higher growth pressure for each thickness. Specifically, the most porous film was obtained at a 5 nm thickness with 15 mTorr, and it was filled with nanomounds. Not surprisingly, the only apparent columnar-type formation was observed for CIGS deposition, which was carried out on the most porous film. It can be interpreted that Au nanomounds behave like catalysts on which the CIGS nanocolumns grow....
This work prepared SnO2 coatings on 304 stainless steel via the sol–gel and dip-coating techniques, using tin (II) chloride (SnCl2) and tin (II) oxalate (SnC2O4) as precursors. The crystal structure analyzed by X-ray Diffraction (XRD) confirmed the cassiterite-type SnO2 in both cases. The corrosion resistance in a 3 wt.% NaCl solution was evaluated by polarization resistance (Rp) and anodic potentiodynamic polarization. Coatings derived from the SnC2O4 precursor demonstrated exceptional performance, reducing the corrosion rate by up to three orders of magnitude (from 0.0973 mpy for uncoated steel to 0.00015 mpy), corresponding to a protection efficiency of 99.8%. In contrast, coatings from the SnCl2 precursor increased the corrosion rate. X-ray Photoelectron Spectroscopy (XPS) analysis confirmed that this detrimental effect was due to the presence of chlorine (5.54 wt.%), which acted as an initiation site for pitting corrosion. Atomic force microscopy (AFM) and XRD of the effective SnC2O4-derived coatings revealed a homogeneous surface with low roughness and a textured cassiterite structure. The primary limitation of this work is that the sol–gel synthesis route using SnCl2 is unsuitable for corrosion protection in chloride environments due to the incorporation of aggressive chlorine ions, whereas the chlorine-free SnC2O4 precursor yields highly protective SnO2 coatings....
In today’s chemistry, greener and more energy-efficient ways of making new materials are becoming increasingly important. In this work, two types of (3-aminopropyl) triethoxysilane-grafted silica were synthesized using a one-pot method with two different porogens: Pluronic P123 and cetyltrimethylammonium bromide, and then modified with silver nanoparticles. Both syntheses produced amorphous silica with crystalline silver. EDX and EDX elemental mapping confirmed that the modification with silver nanoparticles was successful, and an even distribution of silver on the silica surface with an average silver load of around 16% was determined. After silver nanoparticle modification, silica synthesized using cetyltrimethylammonium bromide as a porogen was mesoporous, whereas silica synthesis using Pluronic P123 as a porogen yielded a nonporous product. The synthesized silicas exhibited surface areas of 345 ± 2 and 8.80 ± 0.05 m2/g for samples prepared using cetyltrimethylammonium bromide and Pluronic P123 as porogens, respectively, and both silicas were stable below 250 ◦C....
Combustion at the meso-scale is constrained by large surface-to-volume ratios that shorten residence time and intensify wall heat loss. We perform steady, three-dimensional CFD of two asymmetric vortex combustors: Model A (compact) and Model B (larger-volume) over inlet-air mass flow rates .m (40–170 mg s−1) and equivalence ratios φ (0.7–1.5), using an Eddy-Dissipation closure for turbulence–chemistry interactions. A six-mesh independence study (the best mesh is 113,133 nodes) yields ≤ 1.5% variation in core fields and ~2.6% absolute temperature error at a benchmark station. Results show that swirl-induced CRZ governs mixing and flame anchoring: Model A develops higher swirl envelopes (S up to ~6.5) and strong near-inlet heat-flux density but becomes breakdown-prone at the highest loading; Model B maintains a centered, coherent Central Recirculation Zone (CRZ) with lower uθ (~3.2 m s−1) and S ≈ 1.2–1.6, distributing heat more uniformly downstream. Peak flame temperatures (~2100–2140 K) occur at φ ≈ 1.0–1.3, remaining sub-adiabatic due to wall heat loss and dilution. Within this regime and .m ≈ 85–130 mg s−1, the system balances intensity against flow coherence, defining a stable, thermally efficient operating window for portable micro-power and thermoelectric applications....
Brass components are widely used in heat dissipation and thermal emission devices due to their high thermal conductivity and ease of processing. However, these applications demand good thermal oxidation resistance, high emissivity, and excellent corrosion resistance. In this study, nickel coatings were deposited on brass substrates by direct current electroplating, and the effects of current density and cathode configuration on the microstructure, emissivity, and corrosion resistance of the coatings were systematically investigated. The results show that the emissivity of the coatings first increased and then decreased with increasing current density. Optimal performance was achieved when the cathode and anode were positioned perpendicular to the horizontal plane at a current density of 3.0 A·dm−2. Under these conditions, the coatings exhibited a smooth, uniform, and dense microstructure, with evenly distributed metallic grains. Electrochemical polarization and impedance measurements further confirmed the superior corrosion resistance of this coating, with a minimum corrosion current density of 0.259 μA·cm−2, a maximum polarization resistance of 6381.55 Ω·cm2, and a minimum corrosion rate of 0.023 mm/a. These findings demonstrate a simple and effective approach to enhancing both the emissivity and corrosion resistance of brass substrates, offering practical value for thermal management applications....
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