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Showing 8 results for Subject: Polymers

Hettal Souheila, Ouahab Abdelouahab, Rahmane Saad, Benmessaoud Ouarda, Kater Aicha, Sayad Mostefa,
Volume 19, Issue 1 (3-2022)

Copper oxide thin layers were elaborated using the sol-gel dip-coating. The thickness effect on morphological, structural, optical and electrical properties was studied. Copper chloride dihydrate was used as precursor and dissolved into methanol. The scanning electron microscopy analysis results showed that there is continuity in formation of the clusters and the nuclei with the increase of number of the dips. X-ray diffractogram showed that all the films are polycrystalline cupric oxide CuO phase with monoclinic structure with grain size in the range of 30.72 - 26.58 nm. The obtained films are clear blackin appearance, which are confirmed by the optical transmittance spectra. The optical band gap energies of the deposited films vary from 3.80 to 3.70 eV. The electrical conductivity of the films decreases from 1.90.10-2 to 7.39.10-3 (Ω.cm)-1
Zainab J. Shanan, Huda M.j. Ali, H.f. Al-Taay,
Volume 19, Issue 3 (9-2022)

         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. 

Chitnarong Sirisathitkul, Patchara Sukonrat, Pongsakorn Jantaratana, Thanida Charoensuk,
Volume 19, Issue 3 (9-2022)

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.

S. M. Alduwaib, Muhannad M. Abd, Israa Mudher Hassan,
Volume 19, Issue 3 (9-2022)

Background: Superhydrophobic materials which have contact angle higher than 150°, considering their widespread applications, are very important for researchers.
Method: 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.
Results: 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°.
Conclusion: The synthesized thin films have superhydrophobic properties and the method used in this research can be developed for use in industrial applications.
Veeresh Kumar G B, Gantasala Sreenivasulu, Mohan C B, Ananthaprasad M G,
Volume 19, Issue 4 (12-2022)

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.
Revathi Baskaran, Perumal Perumal, Deivamani Deivanayagam,
Volume 20, Issue 2 (6-2023)

In this research, praseodymium (Pr) doped titanium oxide was deposited onto a glass substrate by nebulizer spray pyrolysis technique. The rare earth-doped thin film was subjected to studies on structural, morphological, optical, and gas sensing properties. The structural properties of the deposited thin films exhibit varied texture along with (101) direction. The grain size of the thin film varies with various mole percentages of doped TiO2 thin films. As various doping concentrations increase, the prepared thin films show different optical properties like band gap, extension coefficient, refractive index, and dielectric constant. Fourier transform infrared (FTIR) results revealed that the reflectance spectra conformed to the existence of functional groups and chemical bonding. Gas sensing studies were carried out for undoped and Pr-doped TiO2 films. The sensor was exposed to ethanol gas. The response of a TiO2 thin film at different ethanol concentrations and different operation temperatures was studied. The gas sensitivity of ethanol gas was measured when the fast response of the film with 0.004M Pr-doped TiO2 thin film showed a response time of 99 s and recovery time of 41 s, as well as the resistance falling to 0.6x106Ω. The sensor operated at maximum effectiveness at an optimum temperature of 200°C.

Mohammad Porhonar, Yazdan Shajari, Seyed Hossein Razavi, Zahra-Sadat Seyedraoufi,
Volume 20, Issue 3 (9-2023)

In this research, after pressing in a cylindrical mold, the AA 7075 alloy swarf was melted and cast in a wet sand mold. After rolling and cutting, sheets with two different thicknesses of 6 and 20 mm were obtained. The sheets after homogenization were solutionized at 485°C for 30 and 90 minutes, respectively, due to differences in thickness and thermal gradients. The solutionized samples were quenched in 3 polymer solutions containing 10, 30, and 50% Poly Alekylene Glycol. The results showed that melting, casting, rolling, and heat treatment of AA7075 alloy swarf similar properties to this alloy is achievable. Microstructural studies by optical microscopes (OM), Field Emission Scanning Electron Microscopy (FESEM), and X-ray diffraction (XRD) showed that by increasing the quenching rate after the solutionizing process, precipitation increases during aging. The tensile test results indicated that as the quench rate and internal energy increase, the diffusion driving force would increase the precipitation of alloying elements. Hence, this leads to an increase in hardness and reduction of its strain after aging.
Bahram Azad, Ali Reza Eivani, Mohammad Taghi Salehi,
Volume 20, Issue 4 (12-2023)

Microstructure evolution and mechanical properties of Zn-22Al alloy after post-ECAP natural/artificial aging were investigated. A homogenization treatment was applied to the casting samples. In addition, after preparing the samples for the ECAP, secondary homogenization treatment was done and then the samples quenched in the water to form a fine grain structure. After 8 passes of ECAP, some ECAPed samples were naturally aged and some ECAPed samples were artificially aged. Natural aging after 8 passes of ECAP showed that Zn-22Al alloy has a quasi-stable microstructure because limited grain growth occurred. Two-phase structure of Zn-22Al alloy prevented excessive grain growth after natural aging. On the other hand, artificial aging after 8 passes of ECAP caused a relatively much grain growth took place. In shorter times of artificial aging, the grain growth rate is faster due to the high surface energy of grain boundaries. On the contrary, as the time of artificial aging increased, the surface energy of grain boundaries decreased, which leads to a decrease in the grain growth rate. In addition, texture evolution was studied after aging artificial. Therefore, the main texture of α and η phases was determined.

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