Iranian Journal of Materials Science and Engineering

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Ultrafine hydroxyapatite (HAp) powders with crystallite size in the range of 10-90 nm were synthesized by chemical precipitation process using Ca(OH)2 and H3PO4 solutions as starting materials. Molar ratio of Ca/P=1.68 was kept constant throughout the process and alkaline condition for the reaction was maintained using ammonium hydroxide. The role of raw material concentration on HAp crystallite size and morphology were investigated using X-ray diffraction (XRD) and scanning electron microscope (SEM) techniques. The results revealed that variations in crystallite size and morphology of synthesized HAp are strongly affected by the concentration of acid solution. To study the sintering behavior of HAp particles, the powders were pressed at 200 MPa using a uniaxial press. Sintering experiments were carried out at temperatures of 1100, 1250 and 1300°C with various soaking times at maximum temperatures. XRD was also used in determining thephases present after sintering process. The results indicated the decomposition of HAp into a-tricalcium phosphate (TCP) and b-TCP phases at 1300°C. The microstructure of the sintered HAp ceramics was characterized by SEM.

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Abstract: Efforts have been carried out in order to use microsilica to develop a forsterite bond rather than other types of binders in the basic refractory castables. According to the higher drying rate and sinterability of colloidal silica, it has been proposed in the recent years. In the present work, effects of replacement of microsilica by colloidal silica evolution of forsterite bond have been studied in magnesia based refractory castables. In this way, Physical properties of prepared samples with different amount of colloidal silica versus temperature were investigated. In addition, phase variation and microstructural evolution of sintered specimens at 1000, 1200 and 1400 °C were studied by X-ray diffraction (XRD) and scanning electron microscope (SEM) respectively. Results showed that, due to Reaction of magnesia with microsilica and colloidal silica, magnesium hydrate and magnesium silicate hydrate formed in the dried samples strengthening the texture of the samples while forsterite formed from about 1000 °C and gradually increased with temperature rise. Also, better forsterite formation would be appeared by increasing the colloidal silica content. Further investigation carried out on the type of silica addition on properties of the castable refractory samples. It was found that the presence of micro silica and colloidal silica simultaneously (MS3C3 sample) at 1400 °C, caused modifying mechanical strength in compare with sample with only micro silica (MS sample).

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In this study, an epoxy-based nanocomposite reinforced with copper oxide-graphene oxide hybrid was investigated. Initially, the hybrid powder of CuO–GO with a weight ratio of 9:1 was prepared. The hybrid filler with different weight percentages ranging from 0.1–0.5 was used to reinforce the epoxy resin. The prepared samples were analyzed using XRD, FTIR, FESEM, TEM, and tensile testing. According to the XRD results and SEM images, the hybrid powder was successfully prepared, and the mechanical testing results showed an improvement in tensile strength in the composite samples. The best composite sample in terms of tensile strength was the one containing 0.3 wt% of hybrid reinforcement, which exhibited a 73% increase in strength compared to the neat resin sample.

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  Fe₃O₄/ZnO/CuO nanocomposites with various molar ratios of CuO were successfully synthesized. Sol-gel method was used to syntehesize nanocomposite materials at a low temperature. A set of experiments, including X-ray diffraction (XRD), Dynamic Light Scattering (DLS), scanning electron microscopy (SEM), and UV-Vis spectroscopy, was used to confirm the successful synthesis of Fe₃O₄/ZnO/CuO nanocomposites in crystalline form.
The photocatalytic activity of the samples was investigated via the degradation of methylene blue (MB) dye
from synthetic wastewater under three distinct conditions: visible light, ultraviolet light, and a combination of visible light with ultrasonic treatment. Fe₃O₄/ZnO/CuO nanocomposite with a molar ratio of 1:1:0.5 showed the highest photocatalytic activity when irradiated with either visible or ultraviolet light. Furthermore, when visible light was combined with ultrasonic treatment, complete (100%) removal of methylene blue was achieved within 120 minutes. The results demonstrate that these nanocomposites are efficient catalysts for wastewater treatment through the removal of organic pollutants Fe₃O₄/ZnO/CuO nanocomposites with various molar ratios of CuO were successfully synthesized. Sol-gel method was used to syntehesize nanocomposite materials at a low temperature. A set of experiments, including X-ray diffraction (XRD), Dynamic Light Scattering (DLS), scanning electron microscopy (SEM), and UV-Vis spectroscopy, was used to confirm the successful synthesis of Fe₃O₄/ZnO/CuO nanocomposites in crystalline form.
The photocatalytic activity of the samples was investigated via the degradation of methylene blue (MB) dye
 from synthetic wastewater under three distinct conditions: visible light, ultraviolet light, and a combination of visible light with ultrasonic treatment. Fe₃O₄/ZnO/CuO nanocomposite with a molar ratio of 1:1:0.5 showed the highest photocatalytic activity when irradiated with either visible or ultraviolet light. Furthermore, when visible light was combined with ultrasonic treatment, complete (100%) removal of methylene blue was achieved within 120 minutes. The results demonstrate that these nanocomposites are efficient catalysts for wastewater treatment through the removal of organic pollutants