Iranian Journal of Materials Science and Engineering

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The present study used a hydrothermal technique to synthesize undoped and Mn2+ doped CdS/Zn3(PO4)2 semiconducting nanocomposite materials. Powder X-ray diffraction, scanning electron microscopy, UV-Vis diffuse reflectance spectrometer, Fourier transform-Infrared Spectroscopy-FT-IR, and photoluminescence techniques were employed to study structural, optical, and luminescence properties of produced nanocomposites. The hexagonal structure of CdS and the monoclinic structure of Zn3(PO4)2 are both reflected in the powder X-ray diffraction spectra. When Mn2+ ions are present in the host lattice, a lattice distortion occurs, causing a phase change from the phase of γ-Zn3(PO4)2 to the β-phase of Zn3(PO4)2, without affecting the hexagonal phase of CdS. The average crystallite size of produced nanocomposites was 22-25 nm, and also calculated the lattice strain and dislocation density to better understand internal deformation of the samples. The FT-IR spectra were used to investigate the molecular vibrations and functional groups in the samples. The surface morphology of the nanocomposites is hexagonal spheres on rectangular shaped nano-flakes, and the interatomic distance between the hexagonal spheres is decreased as the doping concentration increases, forming a rod-like structure on the flakes. EDAX results confirm the presence of various relevant elements in the prepared samples. The quantum confinement of produced samples reduces as the Mn2+ doping concentration in the host lattice increases. The photoluminescence results demonstrate shallow trapped states due to the transition: d-d (4T1 → 6A1) of the tetrahedrally coordinated Mn2+ states and the impact of Mn2+ ions exhibiting several peaks in the UV-Visible region (365-634 nm) generating RGB (Red, Green, Blue) luminescence. Color coordinates and CCT values were calculated using the CIE diagram, and color correlated temperatures in the range of 2513–7307 K were discovered, which might be used in solid state lighting applications.

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The principal goal of this research is to produce a CrN/Cu multilayer coating and a CrN single-layer
coating and also compare their electrochemical and antibacterial behavior. In this investigation, the coatings were
applied to the stainless steel substrate by cathodic arc evaporation a sub-division of physical vapor deposition
(CAE-PVD). The present phases were characterized and the thickness of the coatings was measured using X-ray
diffraction (XRD) and field emission scanning electron microscopy (FE-SEM), respectively. Rockwell-C tester was
used to evaluate the adhesion quality. Also, to evaluate the mechanical properties of the coatings such as modulus
of elasticity and hardness, a nanoindentation test was used and the indentation effect and coating topography were
evaluated using atomic force microscopy (AFM). Studying the electrochemical behavior of the coatings was done
using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP) tests in Ringer's
solution. The results of EIS tests showed that the CrN coating had higher polarization resistance in comparison to
the CrN/Cu coating and an increasing trend of polarization resistance related to both coatings was identified by
rising the time of immersion. Also, using the PDP curves, the CrN and CrN/Cu coating current densities were
estimated at 1.835×10-8 and 2.088×10-8, respectively. The antibacterial activity of CrN and CrN/Cu coatings was
evaluated by the spot-inoculation method. The results of the antibacterial test indicated that compared to CrN
coating, CrN/Cu coating had a better impact on the control of the bacteria growth.

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In the present research work physical, mechanical and tribological behavior of Aluminum (Al) alloy LM13 reinforced with Nano-sized Titanium Dioxide (TiO₂) particulates were fabricated, mechanical and tribological properties were investigated. The amount of nano TiO₂ particulates in the composite was added from 0.5% to 2% in 0.5 weight percent (wt %) increments. The Al-LM13-TiO₂ Metal Matrix Composites (MMCs) were prepared through the liquid metallurgical method by following the stir casting process. The different types of Al LM13-TiO₂ specimens were prepared for conduction of Physical, Mechanical, and Tribological characteristics by ASTM standards. Microstructural images, hardness, tensile, and wear test results were used to evaluate the effect of TiO₂ addition to Al LM13. Scanning Electron Microscope (SEM), Energy Dispersive Spectroscopy (EDS), and X-Ray Diffractometer (XRD) were used to examine the microstructure and distribution of particulates in the matrix alloy. In the Al LM13 matrix, microstructure analysis indicates a consistent distribution of reinforced nanoparticles. The attributes of the MMCs, including density, hardness, tensile strength, and wear resistance, were improved by adding up to 1 wt% TiO₂. Fractured surfaces of tensile test specimens were studied using SEM pictures.  The standard pin-on-disc tribometer device was used to conduct the wear experiments; the tribological characteristics of unreinforced matrix and TiO₂ reinforced composites were investigated. The composites’ wear resistance was increased by adding up to 1 wt% of TiO₂.  The wear height loss of Al LM13-TiO₂ composite increased when the sliding distance and applied load were increased. Overall, the Al LM13 with one wt% of TiO₂ MMCs showed excellent Physical, Mechanical and Tribological characteristics among all the percentages considered in the present study.

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This paper investigated the optimization, modelling and effect of welding parameters on the tensile shear load bearing capacity of double pulse resistance spot welded DP590 steel. Optimization of  welding parameters was performed using the Taguchi design of experiment method. A relationship between input welding paramaters i.e., second pulse welding current, second pulse welding current time and first pulse holding time and output response i.e, tensile shear peak load was established using regression and neural network. Results showed that maximum average tensile shear peak load of 26.47 was achieved at optimum welding parameters i.e., second pulse welding current of 7.5 kA, second pulse welding time of 560 ms and first pulse holding time of 400 ms. It was also found that the ANN model predicted the tensile shear load with higher accuracy than the regression model.

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The article discusses the effect of calcined clays on the properties of Portland cement. An optimal method for calcining clays is proposed, which makes it possible to reduce the proportion of Portland cement clinker in cement to 60% and increase the strength characteristics from 55 MPa to 79 MPa. The study of the composition and structure of clays made it possible to select the optimal heat treatment parameters, at which the calcination products are characterized by the highest pozzolanic activity. It is shown that the use of alkali-activated calcined clays significantly increases the strength and durability of hardened cement binders compared to the composition without additives. In addition, calcined clays increase the frost resistance of cement in a 5% NaCl solution. The obtained experimental data are confirmed by thermodynamic calculations and the results of scanning electron microscopy.

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The beneficiation of coal tailings is usually difficult by common oily collectors in the flotation process, so
it is necessary to use a suitable method for clean coal recovery from coal tailing dams. Thus, this study was aimed
to investigate the behavior of dissolved air flotation by zero prewetting time for the clean coal recovery and to
optimize the conditions of zero prewetting time for an effective flotation. In this regards, the effects of the process
parameters, i.e., pH, frother type, collector type on the rougher flotation recovery of coal tailings were assessed and
optimized. Additionally, Fourier transform infrared (FTIR) spectroscopy was used to understand the functional
groups of oily collectors on the surface of floated products. The findings indicated that the frother type and the
interactive effects between the type of frother and collector had the most effect on the performance of flotation. It
was also found that under the optimal conditions (150 g/t Methyl isobutyl carbinol, 1500 g/t gas oil, and pH 4), the
combustible recovery, yield reduction factor, and flotation efficiency index of coal reached to 67.79%, 0.056%, and
37%, respectively. Meanwhile, the FTIR analysis confirmed that the less adsorption of gas oil collector occurred in
the presence of SDS (Sodium dodecyl sulfate) as frother due to the interaction of SDS and collectors

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The lean duplex stainless steels (LDSS) have excellent features due to the microstructural phase
combination of austenite and ferrite grains. These steels have low Ni and Mo contents which can reduce the cost
and stabilize the austenite fraction in the microstructure. In recent years, welding is used to enhance the
microstructural behaviour of LDSS. In this paper, Gas tungsten arc welding (GTAW) was performed on LDSS
S32101 with different heat energy inputs and varying welding currents. The influence of heat inputs (0.85 and 1.3
kJ/mm) on welded samples was investigated to study the microstructural behaviour, phase balance, and mechanical
& corrosion performance. The microstructures studies were carried out using an optical microscope, scanning
electron microscope and X-ray diffraction. The effect of Heat input led to the significant microstructural evolution
in weld metals with high austenite reformation. The microstructure of weldments consisted of inter-granular
austenite (IGA), grain boundary austenite (GBA) and Widmanstatten austenite (WA). Important mechanical
properties such as tensile strength and micro-hardness were investigated to understand the performance of
weldments. The polarization method was used to understand the corrosion behaviour of weldment in a 3.5% NaCl
solution. The experimental results showed enhanced properties of welds that could be suitable for industrial
applications.

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Ionic liquids as green solvents with high thermal stability, recyclability, low flash point, and low vapor
pressure, have been considered as a viable alternative in hydrometallurgical processes. In this study the leaching
kinetics of chalcopyrite concentrate was investigated using 1-Butyl-3-methylimidazolium hydrogen sulfate
(BmimHSO4) as an acidic ionic liquid. The Effect of operational parameters, including temperature, BmimHSO4
concentration, H2O2 concentration, stirring speed, solid-to-liquid ratio, and particle size on the rate of copper
dissolution of CuFeS2 were examined systematically. The highest Cu efficiency (ca. 97%) was achieved using 40%
(w/v) BmimHSO4, 30 %v/v H2O2, and 10 g.L-1 solid to liquid ratio for particle sizes less than 37 μm at 300 rpm and
45°C after 180 min leaching time. Kinetics study using Shrinking Core Model (SCM) revealed that CuFeS2 leaching
process using BmimHSO4 follows chemical reaction-controlled process. Under these circumstances, the calculated
activation energy was 46.66 KJ/mol. Moreover, the orders of reaction with respect to BmimHSO4 and H2O2
concentration, solid to liquid ratio and particle size were estimated to be 0.539, 0.933, −0.676 and −1.101
respectively. The obtained Arrhenius constant was found to be 0.26  106. The calculation of apparent activation
energy using “time given to a fraction method” revealed that the leaching mechanism remains the same over the
course of time.

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In this paper, an investigation was carried out to test the suitability of potential additive materials in
WOKA 3533 (WC-10Co4Cr) cermet HVOF coating subjected to slurry erosion in ash conditions. The additives
namely molybdenum carbide, yttrium oxide, and zirconium oxide were added in equal percentages (3 wt.%) in
WOKA cermet powder. High-velocity oxy-fuel (HVOF) spraying was performed to develop the additive-based
WOKA cermet coatings. The slurry erosion in ash conditions was tested using the pot tester. Microstructural and
mechanical properties of traditional and additive-based WOKA cermet coatings were also tested in the present
study; for example, microstructure, crystalline phases of as-sprayed coatings, and microhardness. Results present a
comparison of surface erosion wear of different cermet coatings. It was found that the yttrium oxide was a suitable
additive for the WOKA cermet coatings than the molybdenum carbide. However, zirconium oxide is unsuitable for
WOKA cermet coatings in erosion wear applications.

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Materials that are applied to combat vehicles require an innovation as the development of the military world advances. The material innovation in this research is a lightweight hybrid laminated Al7075 composites. The main materials used in this research are aluminum 7075 plate, kevlar 29, silicon carbide (SiC) nano powder, and epoxy resin. SiC nano powder is mixed with polyethylene glycol-400 (PEG-400), then ethanol is added so that it becomes a shear thickening fluid (STF) solution which is used to impregnate kevlar. Laminate composites were prepared using the hand lay-up method with epoxy resin as an additive between layers of kevlar and aluminum 7075 plates. The thickness of laminates is various due to the number of kevlar used different of each laminated that is 8, 16, and 24 layers. The results of this study show that the composite with impregnated kevlar has higher ballistic and impact resistance values than the composite with non-impregnated kevlar, which has good potential as a base material for combat vehicles such as tanks. This is also supported by the Fourier Transfer Infrared Spectrometry (FTIR) results to determine the level of absorbance of the functional groups identified in impregnated kevlar and Scanning Electron Microscopy (SEM) results of the distribution of nano SiC filler that infiltrated to the empty space in the kevlar fiber.

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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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The aims of this research were to evaluate the effects of different thermomechanical treatments on the microstructure and investigate some of the mechanical properties of a TWIP steel rich in Mn & Al. So, a block of a TWIP steel with nominal composition Fe-17.5Mn-1.36Al-0.8C was cast and then subjected to hot rolling followed by cold rolling and heat treatment. Cold rolling was performed before heat treatment in order to reduce the grain size and improve the tensile and fatigue properties. X-ray diffraction technique was used before and after the heat treatment to evaluate the possibility of any phase formation. No sign of martensitic transformation after cold deformation was observed. However, by increasing the amount of cold deformation, the number of mechanical twins and slip band increased resulted to an increase in hardness and strength. The best tensile and fatigue result were obtained after 47% thickness reduction and annealing at 715˚C for 10 min. Under these conditions, the mean grain size reduced from 138 to 9 μm resulted to an increase in yield strength from 395 to 510 MPa, and the fatigue life improvement from the mean life of 10200 for the cast sample to 21500 cycles for the treated sample, when these samples underwent fatigue tests at a stress range of 650 MPa and R=0. In addition, the diameter and depth of dimples in fracture surfaces decreased by reducing the grain size but the fracture mode was remained ductile and adequate plastic deformation occurred before failure.
 

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This work aims to prepare and study amorphous carbon nitride (CNx) films. Films were deposited by reactive magnetron radiofrequency (RF) sputtering from graphite target in argon and nitrogen mixture discharge at room temperature. The ratio of the gas flow rate was varied from 0.1 to 1. Deposited films were found to be amorphous. Highest Nitrogen concentration achieved was 42 atomic percent which is very rare and therefore, the highest nitrogen to carbon atomic ratio was 0.76. The incorporation of nitrogen promotes the clustering of diamond-like sites at the expense of graphitic ones leading to the decrease of the disorder. The film surface becomes rough with increasing nitrogen concentration. Films are optically transparent in the 200-900 nm wavelength range with a wide gap varying between 3.59 and 3.63 eV. There is an increase in resistivity from 15 to 87.4 x10^-3Ω.cm for a-CN_x thin films for 0.1< R_F < 0.8 and a less decrease for   R_F > 0.8. Pore size increases in the films, but has little influence on band gaps. On the other hand, increasing the pore size reduces electrical interaction between particles by increasing resistivity.

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Considering the widespread use of aluminum composites in various industries and the emergence of nanomaterials such as graphene and boron nitrite (BN) with their unique properties, aluminum-based nanocomposite reinforced by the graphene-BN hybrid was fabricated at different percentages. For this purpose, the graphene-BN hybrid was prepared and subjected to wet milling along with the aluminum powder. The mechanical properties of the final nanocomposite which was consolidated using the spark plasma sintering (SPS) method were examined. Aluminum-based composite specimens containing 1 wt.% graphene–0 wt.% BN (AGB1), 0.95 wt.% graphene–0.05 wt.% BN (AGB2), 0.90 wt.% graphene–0.1 wt.% BN (AGB3), and 0.85 wt.% graphene–0.15 wt.% BN (AGB4) were fabricated and compared with non-reinforced aluminum (AGB0). The hardness values of 48.1, 51.1, 56.2, 54.1, and 43.6 Hv were obtained for AGB0, AGB1, AGB2, AGB3, and AGB4, respectively. Additionally, tensile strengths of these specimens were 67.2, 102.1, 129.5, 123.7, and 114.7 MPa, respectively. According to the results of the hardness and tensile tests, it was revealed that the AGB2 specimen had the highest tensile strength (93% higher than AGB0 and 27% higher than AGB1) and hardness (17% higher than AGB0 and 10% higher than AGB1).

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In this work, blast furnace slag (BFS) was used as an adsorbent material for the removal of Pb(II) ions in solution in batch mode. The physico-chemical analyzes used indicated that the BFS is essentially composed of silica, lime, and alumina. Its specific surface area corresponds to 275.8m²/g and its PZC is around 3.8.
The adsorption study indicated that the maximum amount of Pb(II) adsorbed under optimum conditions (agitation speed (V_ag): 150rpm; pH: 5.4; particle size (Øs): 300µm, T: 20°C) is 34.26mg/g after 50 minutes of agitation, and adsorption yield is best for feeble initial concentrations. The most appropriate isothermal model was that of Langmuir, and the adsorption speed was better characterized by the pseudo-second order kinetic model. The adsorption mechanism revealed that internal diffusion is not the only mechanism that controls the adsorption process; there is also external diffusion, which contributes enormously in the transfer of Pb(II) from solution to adsorbent. Thermodynamic study indicated that the Pb(II) adsorption on the blast furnace slag (BFS) was spontaneous, exothermic, and that the adsorbed Pb(II) is more ordered at the surface of the adsorbent. Finally, we estimate that BFS is a superb adsorbent for water containing Pb(II).
 

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This contribution evaluates the influence of Cr doping on the ground state properties of SrTiO3 Perovskite using GGA-PBE approximation. Results of the simulated model infer agreement with the previously published literature. The modification of electronic structure and optical properties due to Cr3+ doping levels in SrTiO3 has been investigated. Structural parameters infer that Cr3+ doping alters the electronic structures of SrTiO3 by shifting the conduction band through lower energies for the Sr and Ti sites. Substituting Ti site by Cr3+ results the energy gap in being eliminated revealing a new electrical case of conducting material for the system. Furthermore, it has been noticed that Cr doping either at Sr or Ti positions could effectively develop the SrTiO3 dielectric constant properties. Consequently, Cr3+ is an effective dopant due to enhancing the optical absorption properties, thus opening up new prospects for optoelectronic applications.

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Novelty: Most of the open literature research has focused on the microstructural evolution and mechanical properties of AA2050 alloy. Also, a significant study discusses the corrosion behavior of AA2050 alloy based on immersion and electrochemical characteristics. The influence of heat treatment on the microstructure and mechanical properties of friction stir processed AA2050 alloy is scarcely discussed in the open literature. The hot salt corrosion characteristics of friction stir processed AA2050 seldom exists in the available literature. This study concentrates on microhardness, tensile strength, and corrosion properties of friction stir processed AA2050. Also, the work focuses on the influence of artificial aging on the microhardness, and tensile strength of the friction stir processed AA2050.

 

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In this work, we demonstrate the beneficial effect of introducing a superficial porous silicon layer on the electronic quality of multi-crystalline silicon for photovoltaic cell application. The porous silicon was formed using an acid vapor etching-based method. The porous silicon layer rich in hydrogen and oxygen formed by vapor etching is an excellent passivating agent for the mc-Si surface. Laser beam-induced current (LBIC) analysis of the exponentiation parameter (n) and surface current mapping demonstrates that oxygen and hydrogen-rich porous silicon led to excellent surface passivation with a strong electronic quality improvement of multi-crystalline silicon.  It was found that the generated current of treated silicon by acid vapor etching-based method is 20 times greater as compared to the reference substrate, owing to recombination centers passivation of the grains and grain boundaries (GBs); The actual study revealed an apparent decrease in the recombination velocity of the minority carrier as reflected by 25% decrease in the exponentiation parameter (n) of the LBIC versus X-position measurements. These results make achieved porous silicon a good option for advancing efficient photovoltaic cells.