Iranian Journal of Materials Science and Engineering

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The paper investigates the solar photodegradation of Methylene Blue dye using copper oxide (CuO) thin films synthesized by the Successive Ionic Layer Adsorption and Reaction (SILAR) method. The structural, morphological, and optical characteristics of the CuO thin films have been investigated by employing a variety of methods, such as Fourier transform Infrared (FTIR) spectroscopy, UV-Vis spectroscopy, Scanning electron microscopy (SEM), and X-ray diffraction (XRD). The outcomes showed that CuO thin films with excellent surface shape and a highly crystalline nature had been successfully deposited. Methylene Blue was subjected to solar radiation during its photodegradation process, and the outcomes showed a significant decrease in the dye's concentration over time. To maximize the photo degradation process, the effects of other experimental factors were also assessed, such as the starting concentration of MB, the quantity of CuO thin film, number of SILAR cycles and the pH of the solution. Good photocatalytic activity is demonstrated by CuO thin films produced using the SILAR approach in the solar photodegradation of methylene blue. The development of affordable and ecologically friendly wastewater treatment technology that can use sun energy to break down persistent organic contaminants is affected by these findings.
 

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Heterostructure photocatalyst of CuWO₄ modified SnO₂ (CuWO₄/SnO₂) was fabricated by in simple wet-impregnation process and evaluated via degradation of rose Bengal (RB) under visible light irradiation. The samples had been completely characterized by Ultraviolet-visible diffuse reflectance spectroscopy (UV-vis-DRS), X-ray diffraction (XRD), Scanning electron microscopy (SEM) combined with energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), High-resolution TEM (HR-TEM), X-ray photoelectron spectroscopy (XPS) and Brunauer-Emmett and Teller surface analysis (BET). The result divulged that amongst the catalysts, CuWO₄/SnO₂ displayed higher photocatalytic activity than CuWO₄ or SnO₂. The enhanced photocatalytic efficiencies are attributed to the charge transfer from SnO₂ to CuWO₄ nanoparticles, which efficiently decrease electron-hole recombination energy level. The time required for maximum degradation of rosebengal (RB) under visible light over CuWO₄/SnO₂ was 180 min. The other parameters such as pH (pH=8), photocatalyst dosage (0.2 g/L) and dye concentration (20 µM) were optimized to achieve high degradation efficiency (98.5%). The excellent photocatalytic activity of CuWO₄/SnO₂ is due to efficient separation of photogenerated electron-hole pairs. The holes (h⁺) and superoxide radicals (O₂^•-) are the reactive species involved in photocatalytic mechanism for gdegradation of RB.

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The present work deals with the hot deformation behavior of commercial Nb alloy C-103 and its microstructure evolution during uniaxial compression tests in the temperature range of 700-1100 °C and the strain rate range of 0.001-0.4 s^-1. Strain rate sensitivity, calculated from the compression tests data, was almost constant and showed a negative value in the temperature range of 700-900 °C but increased significantly beyond 900 °C. Dynamic strain aging was found to have a predominant effect up to 900 °C, beyond which dynamic recovery and oxidation influenced the compressive properties. The microstructure of the deformed samples showed indications of dynamic recrystallization within the high strain rate sensitivity domain and features of flow instability in the regime of low strain rate sensitivity. The 950–1000 °C temperature range and strain rate range of 0.001-0.1 s-1 were suggested as suitable hot deformation conditions. The constitutive equation was established to describe the alloy's flow behavior, and the average activation energy for plastic flow was calculated to be 267 kJ/mol.
 

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In this research, Lanthanum (La)-doped Strontium Titanate (STO) with the formula of Sr_1-xLa_xT_iO₃ (LSTO; x=0, 0.03, 0.05, and 0.07) powders have been successfully fabricated by co-precipitation route. The impacts of La³⁺ on the structural, microstructure, band-gap, and photocatalytic activity for the degradation of organic pollutants, in this case, methylene blue, under UV exposure, were reported in detail. The formation of undoped and La-doped STO samples with cubic perovskite structures was confirmed by X-ray Diffraction (XRD) results. The presence of La doping affected the microstructure morphology by producing LSTO powders with a larger specific surface area. Besides, the UV absorption of the LSTO powders was enhanced due to the narrowed band gap caused by La³⁺ dopants. Accordingly, an improvement in photocatalytic activity applied for the photodegradation of methylene blue solution was exhibited by the LSTO samples.

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In this study, the hot deformation and dynamic recrystallization behavior of low carbon steel containing 21 ppm boron was investigated. After homogenizing the samples at 1250 ℃ for 1-hour, hot compression tests were conducted at temperatures ranging from 850 ℃ to 1150 ℃ and strain rates from 0.01 to 10 s⁻¹, resulting in strain-stress flow curves. Following corrections, calculations and modeling were performed based on Arrhenius equations. Among them, the hyperbolic sine relationship provided the most accurate estimate and was selected as the valid model for the applied strain range. According to this model, the deformation activation energy (Q), was determined to be 293.37 KJ/mol. Additionally, critical and peak stress and strain values were obtained for each temperature and strain rate, and power relationships were established to describe their variation with respect to the Zener-Hollomon parameter (Z). Recrystallization fractions were derived by comparing the hypothetical recovery curves with the material flow curves, and the results were successfully modeled using the Kolmogorov-Johnson-Mehl-Avrami (KJMA) equation. The Avrami exponent was measured at approximately 2, indicating that nucleation predominantly occurred at grain boundaries. Microstructural analysis revealed that at higher Z values, recrystallization occurred along with a fraction of elongated grains, while lower Z values resulted in a greater fraction of equiaxed dynamic recrystallization (DRX) grains. The average grain sizes after compression tests at 950 ℃, 1050 ℃, and 1150 ℃ were measured as 21.9 µm, 30.4 µm, and 33.6 µm respectively at a strain rate of 0.1 s⁻¹, and 17.7 µm, 28.7 µm, and 31.3 µm at 1 s⁻¹. The overall microstructure displayed a more uniform grain size distribution with increasing deformation temperature.

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In this study, we thoroughly examine β-Bi₂O₃ thin films as potential photocatalysts. We produced these films using an environmentally friendly Sol Gel method that is also cost-effective. Our research focuses on how different precursor concentrations, ranging from 0.1 M to 0.4 M, affect the photocatalytic performance of these films. We conducted a comprehensive set of tests to analyze various aspects of the films, including their structure, morphology, topography, optical properties, wettability, and photocatalytic capabilities. These tests provided us with a well-rounded understanding of the films' characteristics. To assess their photocatalytic efficiency, we used Methylene Blue (MB) as a contaminant and found that the films, particularly those with a 0.1 M concentration, achieved an impressive 99.9% degradation of MB within four hours. The 0.1 M film had a crystalline size of 39.7 nm, an indirect band gap of 2.99 eV, and a contact angle of 51.37°. Our findings suggest that β-Bi₂O₃ films, especially the 0.1 M variant, have promising potential for treating effluents from complex industrial dye processes. This research marks a significant step in utilizing sustainable materials to address pollution and environmental remediation challenges.

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The investigation of SUP9 steel under the hot-rolling conditions for applications to leaf spring suspension focused on its tensile and fatigue crack growth (FCG) properties. In order to investigate the tensile properties, tensile specimens were fabricated in the longitudinal-transverse (LT) direction. Furthermore, in order to evaluate fatigue crack growth (FCG) behaviour, compact tensile (CT) specimens with different crack plane orientations in both the LT and transverse-longitudinal (TL) directions were employed. Microstructural and fractographic analyses were conducted using optical microscope (OM) and scanning electron microscopy (SEM). The hot-rolling process reduced the interlamellar spacings of Fe₃C, enhancing the tensile properties through strain hardening. A high yield-to-ultimate strength ratio (~0.623) indicates excellent plastic deformation capability and resistance to fatigue crack growth, making SUP9 steel suitable for the leaf spring suspension system. Furthermore, the exponential crack growth rate constant, m, was found to be 3.066 in the TL direction and 3.265 in the LT direction, indicating that cracks propagate more rapidly in the LT orientation. Additionally, non-metallic inclusions, such as spherical oxides and MnS precipitates in LT specimens, were observed to facilitate faster crack growth in the transverse direction.