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In this study, we demonstrated the temperature effect of our previously developed topotatic catalysis for the formation of Mn0.005Co2.995O4 (MnCoO) spinel nanoparticles. Topotatic catalysis induces spinel MnCoO nanoparticles through the redox reaction of the metal cation (Co2+ and Mn2+) on the Co(OH)2 nanosheet surface, acting as a growth template. This study particularly elucidates the temperature effect on spinel MnCoO nanoparticles' size, morphology, and crystallinity based on their electrocatalytic performance in an oxygen reduction reaction (ORR). We found that lower temperature produces an amorphous phase, whereas higher temperature induces a large aggregate. We obtained the monodispersed MnCoO nanocubes at approximately 90°C, exhibiting the best ORR performance with an electron‐transfer number of 3.86. [ABSTRACT FROM AUTHOR]

Abstract: This work describes the role of temperature and rolling method on density and microstructure changes in Cu–15% In (wt%) alloy powder during normal and cross-roll rolling. The rolled specimen consisted of two distinct microstructures: α-Cu and Cu7In3 intermetallic compounds. The specimen obtained with 5° of cross rolling degree and 60% of rolling reduction ratio at 600°C has the highest density of 8.812g/cm3. A detailed analysis of these results in terms of the microstructural changes and densification mechanisms is also presented. [Copyright &y& Elsevier]

Abstract: Zirconium-based ceramics and composites such as ZrC, ZrB2, ZrC–SiC, ZrB2–SiC–ZrC, and ZrB2–SiC–ZrC–ZrSi were synthesized in fine powder form via combustion synthesis (CS) using ZrSiO4, Mg, C, B, and NaCl as raw materials. Temperature distributions in the combustion wave were measured by thermocouples and used to estimate the combustion temperature and wave propagation velocity. The influence of the NaCl mole fraction on the combustion parameters, phase composition, and particle size of the composite powders was investigated. The experimental results revealed that the combustion temperature and particle size of the composites have a stable decreasing tendency with increase in the NaCl mole fraction in the starting mixture. It was found that near the combustion limit (1.5mol NaCl), the combustion temperature drops below 1500°C and the particle size reaches the nanometer scale. [Copyright &y& Elsevier]

In this study, a combustion process for a TiO 2 + 0.12Al + (2.5 + 6 k )Mg + 0.021V 2 O 5 + k MgCl 2 ·6H 2 O mixture was studied to fabricate Ti-6Al-4V alloy spherical particles. From the temperature-time profiles, the average value of the synthesis temperature was estimated to be 1650 ± 20 °C. Based on FESEM observations, spherical shape particles were obtained when 0.05–0.1 mol MgCl 2 ·6H 2 O was added to the initial reaction mixture. Therefore, spherical alloy particles were achieved by consecutive processes of cooling and acid purification of the burned down sample. According to laser particle size analysis, the average diameter of the spheres was between 5 and 25 μm. A selective laser melting process was applied to build dense Ti-6Al-4V alloy samples. The tensile properties and the microhardness were evaluated and compared to those characteristics of a reference sample prepared from commercial Ti-6Al-4V alloy spherical powder. [ABSTRACT FROM AUTHOR]

Abstract: Herein, we present the low-temperature solid-phase combustion synthesis of tantalum carbide (TaC), TaC/tantalum silicide (TaSi2), and TaC/tantalum boride (TaB) nanoparticles by the silicothermic reduction of potassium fluorotantalate (K2TaF7) in the presence of carbon, boron, and polytetrafluoroethylene (PTFE, 1 [1] BJH, Barrett–Joyner–Halenda; HRTEM, high-resolution transmission electron microscopy; MMC, metal matrix composite; PFTE, polyfluorotetraethylene; PTFE; polytetrafluoroethylene; RF, radio frequency; SAED, selected area electron diffraction pattern; T c , combustion temperature; TEM, transmission electron microscopy; U c , combustion velocities; XRD, X-ray diffractometer. (C2F4) n ). The temperature–time profiles of the combustion wave were measured by thermocouples and used to calculate the combustion parameters: temperature and wave velocity. The flame temperature was found to increase with the concentration of PTFE. Using high resolution transmission electron microscopy, a homogeneous distribution of highly crystalline nanoparticles was observed. The thermal–kinetic activation energy, the heat released during each of the individual reactions, and the chemical mechanism of the overall combustion process are discussed with respect to the final products. [Copyright &y& Elsevier]

Tantalum nitride nanoparticles were produced from a (K2TaF7 +5NaN3) exothermic mixture under the combustion regime. The effects of the K2TaF7/NaN3 ratio and KF and NH4F concentrations on the combustion parameters, product composition, and size of the tantalum nitride particles were studied. Depending on the synthesis conditions, the combustion temperature was maintained in the 700–1200°C range, resulting in hexagonal ε-TaN, TaN0.8, and Ta2N phases. The dominant phases were TaN and TaN0.8 in the 1000–1200°C range, whereas only the Ta2N phase was present in the 700–100°C range. Pure-phase cubic tantalum nitride (δ-TaN) was produced with 4.0mol of NH4F at a combustion temperature of ~800°C. Under controlled reaction conditions, the size of the tantalum nitride particles was about 10–50nm. We also found that during the synthesis, the stainless steel tube located inside of the reaction mixture was partially coated with fine TaN crystals. The mechanism of the combustion process is discussed in regards to the experimental results. [ABSTRACT FROM AUTHOR]

Abstract: In this study, a method which is environmentally sound, time and energy efficient has been used for recovery of indium from used liquid crystal display (LCD) panels. In this method, indium tin oxide (ITO) glass was crushed to micron size particles in seconds via high energy ball milling (HEBM). The parameters affecting the amount of dissolved indium such as milling time, particle size, effect time of acid solution, amount of HCl in the acid solution were tried to be optimized. The results show that by crushing ITO glass to micron size particles by HEBM, it is possible to extract higher amount of indium at room temperature than that by conventional methods using only conventional shredding machines. In this study, 86% of indium which exists in raw materials was recovered about in a very short time. [Copyright &y& Elsevier]

Abstract: We studied the purification of metallurgical grade Si from solutions of K2SiF6 in fluoride melts using a molten salt electrorefining process at 700 °C. Electrorefining close to the deposition potential gave dense, coherent, and well-adherent deposits. It was shown that the deposition rate and microstructure of Si strongly depend on the process temperature. Deposited polycrystalline silicon has a well defined rod shape and crooked structure that varies with current density. The anodic dissolution rate is affected by the initial concentrations of K2SiF6 and the applied current density. The results of an inductively coupled plasma (ICP) analysis indicated that recovered silicon fiber deposits with purities greater than 99.98% can be obtained using the developed technique. The morphology of the electrodeposited silicon on silver substrates is discussed in the context of a cathodic reaction on the electrode surface, and a comprehensive explanation of the purification mechanism with salt removal is provided. [Copyright &y& Elsevier]

Abstract: The effect of Si content in Al–Si alloy powder with NaOH on H2 production was investigated. The total amount of H2 produced decreased as Si content increased, which is inconsistent with the results predicted by the chemical reaction. Si caused a delay in the rate of H2 production. Energy dispersive spectrometry showed that a large amount of unreacted Si remained in the matrix, and the unreacted fraction increased as the Si content increased. As the evolution reaction of Al and Al–Si alloys is exothermic, the temperature of all the specimens increased. Si addition reduced the hydroxide removal rate, which decreased the average H2 production rate. The initiation time for H2 evolution depends on the elimination rate of the oxide film formed during production of the powder. On increasing the Si content, SiO2 was formed, which is harder to eliminate than Al2O3; this delayed the initiation. [Copyright &y& Elsevier]