Iranian Journal of Materials science and Engineering
Volume:19 Issue: 4, Des 2022

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.

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

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.

The optimization of biomaterials biodegradation rate similar to tissue regeneration, is one of the main goals in the field of tissue engineering. However, the necessity to assess their possible toxicity is always considered. The aim of this study was cytotoxicity and genotoxicity evaluation of fluorapatite/bioactive glass (FA/BG) nanocomposite foams with two various weight ratios to determine the optimal composition. Nanocomposite foams were made by gel-casting method with FA and BG as precursors in two weight ratios (A and B). Nanocomposite foam extracts (CFEX) were prepared by shaking 100 mg/mL of each foam in a complete culture medium for 72 h in a shaker incubator at 120 rpm/37ºC. Saos-II cells were exposed to different concentrations of CFEXs for 24 and 48 h and then cytotoxicity and genotoxicity were evaluated by MTT and comet assay, respectively. Based on the MTT assay results after 24 h exposure, CFEX A at concentrations ≥75% and CFEX B at concentrations ≥50% had a cytotoxic effect, while after 48 h, both CFEXs showed similar cytotoxicity at concentrations ≥25%. According to the result of the comet assay, DNA damage increased with the increase of CFEXs concentration and exposure time. Both CFEXs showed significantly higher comet tails elongation scores at concentrations ≥50% and ≥25% after 24 and 48 h exposure, respectively. Both composite foams could be considered as a non-toxic candidate for tissue engineering at concentrations <25% which was less than FA50%/BG50% composite. Therefore, the composite with equal FA/BG proportion has priority if similar results are obtained in in vivo complementary experiments.

In this work, the addition of a combination of Graphene Oxide Nanoplatelets (GONPs) and Ground Granulated Blast Furnace Slag (GGBFS) was studied as admixture in concrete. Tests on physical and mechanical properties and chloride permeability were conducted. GGBFS was replaced with Ordinary Portland Cement (OPC) and it was determined that GGBFS Up to 50% by weight improves the physical and mechanical properties of concrete. GONPs with an optimal amount of 50% by weight of GGBFS were added to the concrete and the physical and mechanical properties of the samples were determined. It was observed that the addition of GONPs was effective in improving the mechanical strength and physical properties of specimens. The results indicated that addition of 0.1 wt.% GO and 50 wt.% GGBFS would increase the compressive strength of the concrete sample up to 42.7% during 28 days and 46% during 90 days compared to OPC. Concrete with a combination of 0.1 wt.% GONPs and 50 wt.% GGBFS witnessed an increase in its flexural strength up to 58.5% during 28 days and 59.2% during 90 days. The results indicated that by adding 0.1 wt.% GO and 50 wt.%, concrete chloride permeability decreased substantially 72% for 90 day cured samples compared to OPC. GONPs as an alternative to cement up to 0.1% by weight can accelerate the formation of C-S-H gel, thereby increasing the strength and improving the resistance of water absorption and chloride permeability. The effects of pozolanic reaction in the concrete leading to the filling of the pores were significant factors in the proposed curtailment mechanism

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.

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.

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.

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.

Temperature is one of the key factor that affecting the electrical, physical, structural, and morphological properties as well as the crystallinity of the nanomaterials. The current study investigates the effect of annealing temperature on the structural and electrical properties of lanthanum oxide (La2O3) thick films. La2O3 thick films were prepared on a glass substrate using a conventional screen printing technique. In this work, T1 is an unannealed prepared film, whereas T2 and T3 are annealed in a muffle furnace for 3 hours at 350°C and 450°C, respectively. XRD technique was exploited to investigate the crystallization behavior of the films. It was found that the crystal structure of La2O3 thick films are pure hexagonal phase. The annealing temperatures were revealed to have influence on the crystallite sizes of the films. SEM and EDS was used to study the morphology and elemental analysis of the films respectively. The electrical properties of the films were explored by measuring resistivity, temperature coefficient of resistivity (TCR), and activation energy at lower and higher temperatures regions. The film annealed at 450°C has high resistivity, a high TCR, and small crystallite size. The thickness of the La2O3 thick films was also found to decrease as the annealing temperature increased.

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.

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.

This paper aims to study the tribological and electrochemical properties of the CrN/AlCrN nano-layer deposited on H13 tool steel. Arc physical technique was employed to deposit multilayer coating. X-ray diffraction technique, thermionic and field emission scanning electron microscopy and energy dispersive spectroscopy have been used to determine the characteristics of the samples. To study the samples' wear behavior, coating adhesion, and surface hardness, reciprocating wear test, Rockwell-C test, and microhardness Vickers tester were employed, respectively. The measured values of the coefficient of friction and the calculated wear rates showed that the CrN/AlCrN multilayer coating has a much higher wear resistance than the uncoated sample. The coefficient of the friction of the coated sample was 0.53 and that of the uncoated sample was 0.78. Moreover, the wear rate of the coated H13 steel was about 127 times lower than the bare H13 steel sample. The results obtained from electrochemical impedance spectroscopy and polarization tests demonstrated that the corrosion current density of the H13 steel sample was 8 μA/cm2 and that of the CrN/AlCrN multilayer-coated sample was 3 μA/cm2. In addition, the polarization resistance of the treated and the substrate specimens was estimated at 4.2 and 2.7 kΩ.cm2, respectively.