Iranian Journal of Materials science and Engineering
Volume:19 Issue: 1, Mar 2022

Phosphate glass with different Al2O3 and Na2CO3 compositions [80NaH2PO4-(20-x) Na2CO3-xAl2O3 with a step from 0 to 4] were prepared through melt quenching technique furnace at 900 °C. In order to determine the structure and microstructure modification of the samples after heat treatment the IR and Raman spectroscopy were performed. The X-ray diffraction (XRD) result shows an amorphous character of the prepared glass. The result obtained by differential scanning calorimetry (DSC) reveals a good thermal stability in the temperature range of 25 to 400 °C. The impedance Nyquist diagrams were investigated and modeled by resistors and constant phase elements (CPE) equivalent circuits. These measurements show a non-Debye type dielectric relaxation. Both AC and DC conductivity, dielectric constant, and loss factors were determined. Thermal activation energies were also calculated. A changes in the electrical conductivity and activation energy depend upon the chemical composition were observed. Also, a transition in the conduction mechanism from ionic to mixed ionic polaronic was noted. In the same line, electrical modulus and dielectric loss parameters are also deduced. Their frequency and temperature dependency exhibited relaxation behavior. Likewise, activation energies value obtained from the analysis of M’’ and those obtained from the conductivity are closes, which proves the optimal character of the preparation conditions.

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

In this study, CrN/ZrN multilayer nanostructured coatings with different bilayers (10, 20, and 30) were created by the cathodic arc evaporation. The electrochemical behavior of samples was evaluated by polarization and impedance spectroscopy tests in the Ringer medium and the pin on disk test was used to investigate the tribological behavior of the samples. The results of measurements showed that the electrochemical and tribological behavior of the coatings depends on the number of bilayers and by rising the number of bilayers, the coating shows higher corrosion resistance and better tribological performance. Field emission scanning electron microscopy (FE-SEM) images of the specimens after exposure to the corrosion medium showed that the number of surface cavities were formed by the coating that had the highest number of bilayers comparing with other coatings were quite fewer in number and smaller in diameter. The results of the pin on disk test showed that by increasing the number of bilayers from 10 to 30, the coefficient of friction and wear rate decreased and the 30L coating ‌showed better wear resistance.

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.

In this study, the effects of heat treatment of aluminum alloy on the tube bending process were investigated in the rotary draw bending process. As two experimental and numerical simulation methods were used to determine the wall-thinning, ovality, and spring back for extruded, annealed, and aged AA6063 aluminum alloy tubes in different bending angles and bend radii. Numerical simulations were done by the finite element method with Abaqus software. The results indicated that in comparison with annealed and extruded parts, wall-thinning reduced whereas the amount of ovality and spring-back increased in the aged tubes. Also, in each case, the percentage of wall-thinning decreased with increasing bend radius, and the effect of bend radius was greater in the reduction of ovality from the bending angle. Investigations showed that the spring-back rate also decreased with an increasing bending angle.

The synthesed foam-shaped zeolite ZSM-5 material w:::as char:::acterized by X-ray diffraction (XRD), (FTIR) spectroscopy, scanning electron microscopy (SEM) and BET technique. The adsorption performances of the material were evaluated for the basic blue-41 dye removal. A maximum removed amount of 161.29 mg/g  at 323K was achieved. Experimental kinetic data of this new adsorbent fitted well the pseudo-second order model. The apparent diffusion coefficient values was in the range of 10-12 cm2/s. The regeneration tests revealed that the adsorption efficiency of the foam-shaped zeolite was retained after three  regeneration runs, with a loss of 6% of the original adsorbed value.

In the present study, the effects of boron on the structural and magnetic properties of AlCrFeNiMnSiBx high entropy alloys (HEAs) were investigated. In this regards, different percentages of boron element were added to the based composition and the samples were identified using X-ray diffraction (XRD), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM) methods. Based on results, the tendency of Si element to formation of silicide phases prevents from the stabilization of single FCC and BCC solid solution phases in AlCrFeNiMnSi alloy. The boron element has significant effects on destabilization of silicide phases and by increasing in the percentage of this element, the simple BCC solid solution phase has been dominate phase. Of course, boron has distractive effects on magnetic properties of prepared alloys and the saturation of magnetization of AlCrFeNiMnSiBx HEAs decrease from 29.8 emu/g to about 6 emu/g by increasing the boron content.

Hot Workability and Processing Map of High Gd Content Mg-Gd-Zn-Zr-Nd Alloy Hot deformation behavior of homogenized Mg-4Sn binary alloy was studied using compression tests at the temperature range of 300-500  and strain rates of 0.001-1s-1. The material showed typical single peak flow behavior followed by a steady state flow as a plateau, which is more evident at the high value of Zener-Hollomon parameter. Constitutive analysis showed that in spite of the original Johnson-Cook (J-C), conventional strain compensated Arrhenius model based on Sellars-McTegart model has a reasonable agreement with the experimental data. Moreover, the well-known hyperbolic sine function fits the experimental data for predicting of the peak stress with a fair degree of accuracy.

The aim of the present research work is to evaluate the feasibility of processing and utilizing steel slag in binary and ternary cement blends with limestone. The physical and microstructural properties of binary and ternary composite cements produced by inter-grinding mixtures of ordinary Portland cement clinker, processed steel slag and limestone in a laboratory ball mill with replacement levels varying from 0 wt.% to 30 wt.% were studied. The effects of processed steel slag and limestone incorporation on density of dry cement mixes and water consistency, setting time and volume stability of fresh and hardened cement pastes were investigated. Also, density, water absorption, total open pore volume (%) and compressive strength of cement mortars were measured. The mix with 15 wt.% limestone and 15 wt.% processed steel slag was selected as a typical ternary cement mix for complementary studies including X-ray diffractometry, thermal gravimetry, Fourier-transform infrared spectroscopy, and scanning electron microscopy analyses. The results show that removal of relatively high metallic content of steel slag increases its grindability for mechanical activation and improves its hydraulic properties effectively and makes it suitable for being recycled in cement industry. The results show that mechanical activation of the cement mixes enhances the poor hydraulic activity of the processed steel slag and compensates the strength loss to some extent. The physical and chemical properties of all studied composite cement mixes comply with ASTM standard specifications, except the compressive strength of the cement mixes at 28-days containing 20 wt.% or higher amounts of limestone ground to the relatively low Blaine specific surface area of about 3000 cm2/g.

In this research, the effect of initial microstructure and solution treatment on rollability and crystallographic texture of a Cu-Mn-Ni-Sn alloy has been investigated. The initial tests indicated that the rolling of the alloy at different temperature conditions is not possible due to formation of second phases. Herein to eliminate the segregated phases, according to DTA analysis, proper temperature for solution treatment was selected as 750°C applied at different periods of time. The obtained results showed that after 15-hour solution treatment, the complete elimination of Sn, Mn, Ni, and Fe-rich phases can be achieved. Also, the peaks of XRD shifted to the higher angles indicating that the alloying elements are dissolved. Meanwhile, the intensity of the texture reduced and the dominant texture changed from Goss and Brass-texture to Copper-texture. Accordingly, the amount of maximum total reduction at the rolling process increased from 16.37 to 109.46 after solution treatment.

ꞵ-tricalcium phosphate (ꞵ-TCP) and anorthite are the main crystalline components in bone china bodies. The difference in their thermal expansion coefficients causes a decrease in the thermal shock resistance of the body. In this study, anorthite was replaced with bone ash at the bone china body, and the effect of this new composition on different properties of bone china, after curing at 1260 °C for 3 hours, was investigated. The results showed that the physical and mechanical properties of the sample containing 50 wt% anorthite compared to the typical bone china improved and only 8.7% of the whiteness index diminished. Also the microstructure of samples containing Anorthite were observed without thermal crack and almost uniform distribution of Anorthite and quartz crystals in the heterogeneous glass matrix.

In present work Ni0.7Cd0.3NdxFe2-xO4 ferrite samples (0≤x≤0.03) were prepared by using oxalate co-precipitation technique. The different characterization techniques were achieved using X-ray diffraction (XRD), FT-infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), DC electrical resistivity and dielectric measurements. The crystallographic parameters such as crystal structure, crystallite size, lattice constant, unit cell volume and theoretical density have been systematically analysed. The XRD and FT-IR measurements confirmed the formation of single phase spinel ferrite structure. The cation distribution among the octahedral and tetrahedral sites has been proposed on the basis of analysis of XRD patterns by employing Rietveld refinement analysis. The samples exist as a mixed type spinel with cubic structure. The DC electrical resistivity confirms the semiconducting behaviour and the Curie temperature decreases with increase in Nd3+ content. The dielectric constant and loss tangent decreases with frequency and higher frequencies remain constant, which shows the usual dielectric dispersion due to space charge polarization. The AC conductivity reveals that the small type polarons responsible for conduction process.