Iranian Journal of Materials Science and Engineering

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Oxynitride glasses are found as grain boundary phases in silicon nitride ceramics. They are effectively alumino-silicate glasses in which nitrogen substitutes for oxygen in the glass network, and this causes increases in glass transition and softening temperatures, viscosities (by two to three orders of magnitude), elastic moduli and microhardness. Calcium silicate-based glasses containing fluorine are known to have useful characteristics as potential bioactive materials. Therefore, the combination of both nitrogen and fluorine additions to these glasses may give useful glasses or glass-ceramics with enhanced mechanical stability for use in biomedical applications. This paper reports glass formation and evaluation of glass thermal properties in the Ca-Si-Al-O-N-F system. Within the previously defined Ca-Si-Al-O-N glass forming region at 20 eq.% N, homogeneous, dense glasses are formed. However, addition of fluorine affects glass formation and the reactivity of glass melts. This can lead to fluorine loss as SiF4, and also nitrogen loss, leading to bubble formation and porous glasses. The compositional limits for both dense
and porous glass formation at 20 eq.% N and 5 eq.% F have been mapped. At high fluorine contents under conditions when Ca-F bonding is favoured, CaF2 crystals precipitate in the glass. The role of the different cations on glass formation in these oxyfluoro-nitride glasses is discussed.

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Weight loss technique has been used to study the corrosion inhibition efficiency of tin in HNO3 solution by using the leaves and stem extract of different varieties of Holy Basil viz. ocimum basilicum (EB), ocimum cannum (EC) and ocimum sanctum (ES). The results show that all the varieties under study are good corrosion inhibitors, among which leaves extract of EB is the most effective. Corrosion inhibition efficiency increases with increasing concentration of inhibitor and it also increases with increasing concentration of HNO3 solution. Inhibition efficiency was found maximum up to 95.83% for tin in 3.0 M HNO3 solution, with 0.6% leaves extract whereas it was 81.25% in same concentration of HNO3 solution for stem extract

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A full factorial design of experiment was applied running 36 experiments to investigate the effects of milling parameters including cutting speed with three levels of 62.83, 94.24 and 125.66 m/min, feed rate with three levels of 0.1, 0.2 and 0.3 mm/tooth, cutting depth with two levels of 0.5 and 1 mm and machining media with two levels, on surface integration properties of magnesium AZ91C alloy such as grain size, secondary phase percent, surface microhardness and surface roughness. In all cases, a fine grained surface with higher secondary phase sediment and microhardness obtained comparing the raw material. According to analysis of variance results, the most effective parameter on grain size, secondary phase percent and microhardness was cutting depth and the most effective parameter on surface roughness was feed rate. although the grain size in all machined samples was smaller than that of the raw material but due to the dual effect of cryogenic conditions, which both cool and lubricate and reduce the temperature and strain rate at the same time, the direct effect of this parameter on grain size was not significant. Also, the all interaction effects of parameters on grain size and microhardness were significant.

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Copper oxide (CuO) nanostructure particles were prepared using KOH/NaOH catalyst by low cost precipitation method and characterized by powder X-ray diffraction (PXRD), scanning electron microscope (SEM) and energy dispersive X-ray spectra (EDX) analysis. The photocatalytic dye degradation study of pure CuO nanostructure particles are analysed against two azo dyes (Direct black 38 (Black-E) and Congo red) under ultraviolet (UV) and solar irradiation. The release of major active species (*OH) in the photocatalytic degradation by as prepared CuO nanostructure particles were investigated by photoluminescence (PL) spectra with two different excitation wavelength (325and 355nm). The band gap of CuO nanostructure particles was calculated from diffuse reflectance spectra. The photocatalytic effect of CuO nanostructure particles is confirmed from the UV – Vis and photoluminescence spectra and also, further confirmed from the kinetic studies under UV and solar radiations. The photocatalytic degradation results revealed that 16.35% and 7.5% of black E and Congo red dye was degraded under UV, while it was 47.2% and 17.6% under solar light. The influence of pH on the photodegradation and change in the reaction temperature under solar irradiation were also analysed

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Hybrid composite finds wide application in various fields. In this present study, the hybrid composites are developed using stir casting technique as per Taguchi’s L9 orthogonal array. Hybrid composites were fabricated using Aluminium Al6082 as the base material and reinforced with the combinations of reinforcements Al2SiO5 and B4C at three levels (4%, 8% and 12%).The developed composites were analyzed for micro structural  investigations and mechanical tests were done as per ASTM standards. The micro structural analysis was done using optical Microscope and Scanning electron microscope while composition studies were done using X-ray diffraction and EDAX. Mechanical test like tensile, impact and flexural were conducted and their damage assessment was done using Scanning electron microscope. The fatigue characteristics like high cycle fatigue and fatigue crack propagation was studied both experimentally and numerically. The experimental data and numerical modeling analysis data obtained for the hybrid composite system, agree with each other.           

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In this research, the effect of RSW parameters including current intensity, welding time and welding force (coded by A, B and C) on the radius, thickness and area of ​​the nugget and the radius of the HAZ of TRIP steel joints was investigated by DOE and RSM. A 3D coupled thermal-electrical-structural FEM was used to model RSW. To validate the FE model, two TRIP steel sheets were welded experimentally. During welding, the temperature was measured and the results were compared with the FE results and a good agreement was obtained. The boundaries of the welding zones were determined according to the critical temperatures and the responses in all samples were calculated. Using analysis of variance, direct, quadratic and interaction effects of parameters on the responses were studied and a mathematical model was obtained for each response. The direct linear effects of all parameters on all responses were significant. But among the interaction effects, the effect of B×C on the nugget radius, the effect of A×B on the nugget thickness, the effect of A×B on the nugget area and the effects of A×B and B×C on the HAZ radius were significant.  Also, current intensity had the greatest effect on all responses.
 

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Biogenic synthesis of papain-conjugated copper metallic Nanoparticles and their antibacterial and antifungal activities Papain metallic conjugated nanoparticles (Papain-CuNPs) were synthesised using Papain and CuSO4.5H₂O. Papain-CuNPs were characterized using UV-visible spectroscopy, FT-IR, HR-TEM, XRD, FE-SEM, zeta potential, and a zeta sizer. The antibacterial activity of papain-CuNPs against human infectious microorganisms (Citrobacter spp, Pseudomonas aeruginosa and Candida albicans) was investigated. The mechanism of action of papain-CuNPs was evaluated using FE-SEM and HRTM. UV spectroscopy confirmed the plasma resonance (SPR) at 679 nm, which indicated the formation of papain-CuNPs. The FT-IR spectrum absorbance peaks at 3927, 3865, 3842, 3363, 2978, and 2900 cm^-1 indicate the presence of O-H and N-H of the secondary amine, and peaks at 1643 and 1572 cm^-1 represent C=O functional groups in Papain-CuNPs. EDAX analysis confirmed the presence of copper in the papain-CuNPs. The zeta potential (-42.6 mV) and zeta size (99.66 d. nm) confirmed the stability and size of the nanoparticles. XRD confirmed the crystalline nature of the papain-CuNPs. FE-SEM and HRTM showed an oval structure, and the nano particles' 16.71244–34.84793 nm. The synthesized papain-NPs showed significant antibacterial activity against clinical P. aeruginosa (15 mm). MIC 125 µg/ml) showed bactericidal activity against P. aeruginosa and the mechanism of action of Papain-NPs was confirmed using an electron microscope by observing cell damage and cell shrinking. Papain-CuNPs have significant antibacterial activity and are thus used in the treatment of P. aeruginosa infections