Iranian Journal of Materials science and Engineering
Volume:19 Issue: 3, Sep 2022

The objectives of this work is to synthesize TiO2/MgO nanocomposites using a pulse laser deposition technique. At a vacuum pressure of 2.5 10-2 mBar, TiO2/MgO nanocomposites were synthesized on substrates with a laser power of 600 mJ and a wavelength of 1064 nm. This search utilizes various pulses (500, 600, and 700) at a 6-Hertz repetition rate. X-ray diffraction was utilized to investigate crystallography of the phases in the samples, as well as average crystallite size (XRD). An increase in the average crystal size was observed with an increase in the number of shots (from 35.15 to 38.08) nm at (500 to 700) shots respectively. The impact of the number of laser shots on the surface characteristics of TiO2/MgO nanocomposites was also evaluated using atomic force microscopy (AFM) and field emission scanning electron microscopy (FE-SEM). Finally, optical characteristics were evaluated using UV-Vis spectroscopy. Increasing the number of shots increased the absorbance and thus reduced the energy gap.

In this paper, novel Nanohybrid CuO-Fe3O4/Zeolite nanocomposites (HCFZ NCs) have been synthesized to improve the adsorption capacity and activity for removing the Arsenic and Lead cations from the contaminated water solutions. The nanohybrid 4, 10, and 20 -HCFZ NC samples were investigated by XRD, FT-IR, TEM, FESEM, EDX, and BET. The characterization results of these catalysts confirmed the presence of CuO and Fe3O4 NPs in nanospherical shapes as Nanohybrid Cu and Fe oxides on the zeolite surface. Notably, the 10-HCFZ NC sample showed the highest removal efficiency of harmful metallic pollutants from the water in comparison to the prepared neat zeolite, 4-HCFZ NC, and 20-HCFZ NC samples, with a percentage removal of (97.9 %) for Pb ions and (93.5 %) for As ions within 30 minutes (100 ppm). According to the adsorption isotherms results, R2 values for the Langmuir isotherm were the highest, suggesting that the experimental results fit better the Langmuir isotherm model. Generally, according to the obtained results, there is a possibility of enhancing the efficiency of Nanohybrid CuO-Fe3O4/Zeolite NCs to remove Arsenic and Lead ions from polluted aqueous solutions.

In this research, zinc oxide quantum dots and graphene nanocomposites were synthesized via two different methods; In the first (direct) method, ZnO-graphene Nanocomposites were made mixing the synthesized zinc oxide and graphene. In the second (indirect) method, zinc nitrate, graphene, and sodium hydroxide were used to made ZnO-graphene Nanocomposites. XRD, FTIR and Raman spectroscopy analyses were used for phase and structural evaluations. The morphology of the nanocomposites w::as char::acterized by SEM. The specific surface area and porosity of the samples were characterized by BET analysis. The optical properties of the samples were investigated by photoluminescence and ultraviolet-visible spectroscopy analyses. Results showed that using graphene, increased the photoluminescence property and shifted the photoluminescence spectrum of the composites towards the visible light spectrum. The photoluminescence of the synthesized graphene-zinc oxide composite, in the visible light region, was closer to white light than that of pure zinc oxide. According to the results of BET test, the nanocomposite synthesized by direct method had a higher surface area (25.7 m2.g-1) and a higher porosity (0.32 cm3.g-1) than the nanocomposite synthesized by the indirect method with a specific surface area of (16.5 m2.g-1) and a porosity of 0.23 cm3.g-1).

The goal of the present study is to prepare a room temperature cured hydrophobic and self-cleaning nano-coating for power line insulators. As a result, the installed insulators operating in power lines can be coated without being removed from the circuit and without the need to cut off power. For this purpose, hydrophobic silica nanoparticles were synthesized by sol-gel method using TEOS and HMDS. The synthesized hydrophobic silica nanoparticles were characterized by XRD, FTIR, SEM, and TEM analyses to investigate phase formation, particle size, and morphology. Then the surface of the insulator was cleaned and sprayed by Ultimeg binder solution, an air-dried insulating coating, as the base coating. Then the hydrophobic nano-silica powder was sprayed on the binder coated surface and left to be air-cured at room temperature. After drying the coating, the contact angle was measured to be 149o. Pull-off test was used to check the adhesion strength of the hydrophobic coating to the base insulator. To evaluate the effect of environmental factors, UV resistance and fog-salt corrosion tests were conducted. The results showed that 150 hours of UV radiation, equivalent to 9 months of placing the samples in normal conditions, did not have any significant effect on reducing the hydrophobicity of the applied coatings.

It has long been thought-provoking and challenging as well for researchers to design and produce a special low-modulus β titanium alloy such as Ti‐35Nb‐7Zr‐5Ta, representing optimal mechanical properties that is needed to successfully simulate bone tissue. In order to identify the key effects of processing pathways on the development of microstructure, Young’s modulus, and strength, a nominal Ti-35Nb-7Zr-5Ta alloy was made via casting, hot forging, homogenizing, cold rolling and finally annealing. Results from tensile test alongside microscopic and XRD analysis confirm the importance influence of processing method on fully β phase microstructure, low elastic modulus and high strength of the alloy. The specimen with post-deformation annealing at 500 °C demonstrated the Young’s modulus of 49.8 GPa, yield strength of 780 MPa and ultimate tensile strength of 890 MPa, all of which are incredibly close to that of bone, hence suitable for orthopedic implants. At temperature above 500 °C, a sharp fall was observed in the mechanical properties.

The effect of the milling time & ageing on the hardness, density, and wear characteristics of Al 7150 alloy specimens made via powder metallurgy has been studied. The different constituents of Al 7150 alloy were processed in a planetary ball milling set up with a BPR of 10:1 for 5 hours, 10 hours, and 20 hours. At 400 °C, the milled powders were subsequently hot compacted in a punch die setup. The hot-pressed specimens were solutionized initially, then aged artificially at 115 °C for 3, 6, 12, 24, 30, 45, 60, and 96 hours. The relative density was inversely proportional to the milling time. Microhardness tests showed a maximum VHN of 255 was measured for the 24 h aged T6 specimens produced from 20 h milled powders whereas the non-aged specimens, made from unmilled 7150 alloy powders showed a VHN of 40. However the samples showed a decline in microhardness beyond 24 h of ageing. Under various conditions of sliding distance and loading conditions, the samples subjected to T6 aging showed a reduced volumetric wear rate indicating the beneficial effect of artificial aging up to 24 hours. The volumetric wear rate gradually declined for the samples aged beyond 24 hours of aging. The HRTEM studies revealed a high density of uniformly scattered (MgZn2) precipitates in the base matrix, as well as (MgZn2) phases precipitating along grain boundaries. The presence of such second phase precipitates in the matrix improved the wear characteristics of the alloy matrix. The results showed that optimization of process parameters such as milling time, ageing as well as reducing the particle size of the base powders, the hardness and wear behavior of Al 7150 alloy may be improved.

This study investigates the synthesis of Al/MoS2 nanocomposite coating by the electro spark deposition (ESD) method for its lubricating properties. ESD method was selected because it is a very easy, rapid, and cost-saving method and the resulting coating has a strong bonding with the substrate. As a substrate, a Ti-6Al-4V alloy sheet containing 6.12 % Al, 4.06 % V, 0.19% Fe, and 0.05 % Ni was used. For coating, an aluminum-molybdenum disulfide composite electrode in the form of a cylindrical rod was employed. Three frequencies of 5, 8, and 11 kHz, three current limits of 15, 25, and 35 amps, and three duty cycles of 50, 60, and 70% were used in the coating operation. AFM analysis was used to study the topography, morphology, and calculate roughness. The samples were then subjected to hardness tests. To determine the wear resistance of the samples, pin on disk tests were performed. XRD analysis was performed to identify the phases on the surface of the coated samples. SEM was used to examine the microstructure of the coating before and after wear testing, in order to determine the wear mechanism. The results indicated that the Al/MoS2 nanocomposite coating was synthesized on the substrate surface. The hardness of the reference sample is 353 Vickers, and that of the coated samples is about 200 Vickers. For the reference sample, the roughness was measured at 15.7 nm, and for the coated sample at 268.1 nm. As spark energy increased, the coefficient of friction increased by approximately 0.09. As spark energy increased, the wear rate increased by 27%. A significant increase in the Lancaster coefficient occurred around 5 joules of energy. According to the wear rate results, the sample with the lowest thickness wears 4% less than the sample with the highest thickness. The wear rate of sample 351170 is 78% lower than that of sample 150550.

The present study aimed to assess the effect of replacing copper as a multi-functional ingredient in the brake pad material with potassium titanate platelet (PTP) and a particular type of ceramic fiber (CF) copper-free composite. Chase dynamometer tests were conducted to compare a brake padchr('39')s tribological behavior when PTP and CF are added to the composition with that of the copper-bearing pad. The results concluded that PTP and CF demonstrated promising outcomes such as a stable coefficient of friction (COF), lower wear rate, and better heat resistance in copper-free friction composite. Scanning electron microscope (SEM/EDS) analysis was conducted to investigate the role of main elements such as Ti, Fe, K, O, and C on the formation of contact plateaus (CPs) upon the worn surface of friction composites. PTP maintained both continuous contact and smooth friction braking application of a brake pad. The uniform distribution of Ti on the wear track on the disc worn surface depicts the role of PTPs on stabilizing the friction film formation and eventually on the stability of COF.

Zinc Oxide (ZnO) nanorods and titanium dioxide (TiO2) nanostructures thin films were prepared onto glass substrates by the chemical bath deposition (CBD) method. The ZnO was structured as nanorods (NRs) while TiO2 was formed as nanoflowers plate as confirmed by Field-Emission Scanning Electron Microscope (FESEM) images. The ZnO/Fe3O4 and TiO2/Fe3O4 nanostructures thin films were prepared via drop-casting Fe3O4 NPs onto the grown ZnO and TiO2 nanostructures thin films. The diameter of Fe3O4 NPs was deposited onto ZnO NRs thin films and TiO2 nanostructures thin films was ranged from 8nm to 59nm with dominated range between 10nm to 30 nm.  The crystalline structure of prepared samples was investigated through X-ray diffraction (XRD) method. However, the particles size of Fe3O4  was estimated  by XRD as well as FESEM images was around 22 nm. The photocatalytic activity of the as-prepared ZnO/Fe3O4 and TiO2/Fe3O4 nanostructures thin films was investigated against methylene blue (MB) dye at room temperature with a pH value of 10 under different exposure time by visible light. The photodegradation rate of MB dye by ZnO/Fe3O4 and TiO2/Fe3O4 nanostructures thin films was higher than that obtained by ZnO and TiO2 nanostructures thin films. The best photodegradation rate of MB dye was 100% after exposure time of 180 min was obtained by ZnO/Fe3O4 nanostructures thin film whereas it was 82% for TiO2/Fe3O4 nanostructures thin films after exposure time of  240 min.

Li7La3Zr2O12 (LLZO) garnets are one of the promising materials as electrolytes for solid-state batteries. In this study, Li7-3xAlxLa3Zr2O12 (x= 0.22, 0.25, and 0.28) garnet is synthesized using the combustion sol-gel method to stabilize the cubic phase for higher ionic conductivity. The X-ray diffraction (XRD) results of as-synthesized powders reveal that by addition of 0.22 and 0.25 mole Al, the tetragonal phase still co-exist, whereas 0.28 mole Al addition resulted in a single cubic phase. Afterward, the as-synthesized powders are pressed and sintered at 1180°C for 10h. The hardness evaluation revealed that Al addition increases the hardness that shows better resistance against Li dendrite formation. Besides, the secondary electron microscopy results demonstrate that the dopant has not a huge impact on particle size and grain growth whereas the porosity content has been changed. Finally, the investigation of samples' electrochemical behavior reveals that the addition of Al increases the ionic conductivity of samples by increasing the density and stability of the cubic phase as well. The results declare that the 0.25 Al sample has the highest ionic conductivity. This behavior is thought to be due to the promotion of sintering and increment of bulk ionic conductivity by doping Al.

Repeated heat treatment on manganese-bismuth (MnBi) in a tube furnace increases the homogeneity of rare-earth-free magnets. Ferromagnetic low temperature phase (LTP) MnBi is formed after heating Mn and Bi in a ratio of 2:1 at 1000 °C for 1 h and then 400 °C for 1 h. Areas with comparable compositions of Mn and Bi are detected, but some Mn and Bi remains segregate after using this stepped heating 3 times. The subsequent annealing at 340 °C gives rise to higher magnetizations and coercivity than those using 410 °C annealing. Increasing the starting Mn:Bi ratio to 4:1 reduces the coercivity and remanent magnetization due to the increase in Mn oxidation at the expense of ferromagnetic phase.

Superhydrophobic materials which have contact angle higher than 150°, considering their widespread applications, are very important for researchers.

In this research, silica nanopowder was synthesized successfully using inexpensive sodium silicate source and very simple and facile method. Synthesis of hydrophobic solution was carried out by sol-gel method. The surface modification of silica nanopowder was performed using different silane/siloxane polymers and was deposited on glass slides. For characterization of the samples XRD, FESEM, EDX, TEM, FTIR, and Raman analysis were used.

The XRD result shows a very wide peak at 2q = 24.7° which indicates the amorphous nature of the silica particles. The results of the performed characteristics confirm the synthesis of silica nanopowder with the size of less than 25 nm. The EDX spectrum shows that only Si and O elements are present in the structure and no impurities are visible. The contact angle between water droplet and thin films was measured and the effect of different synthesis parameters on the contact angle was studied. Among the studied polymers and solvents, the most hydrophobicity was obtained using TMCS polymer and xylene solvent. The optimized sample has a maximum contact angle of 150.8°.

The synthesized thin films have superhydrophobic properties and the method used in this research can be developed for use in industrial applications.