Showing 6 results for Abdi
M. M. Mohammadi Samani, H. R. Baharvandi, H. Abdizadeh, J. Rezapour,
Volume 11, Issue 4 (December 2014)
Abstract
B4C and its composites with TiB2 as second phase continues to be extensively used as the preferred ceramic material in military applications as armor systems for absorbing and dissipating kinetic energy from high velocity projectiles. It also exhibits a high melting point (2427 °C), and high neutron absorption cross section. Pressureless sintering of the B 4C-nanoTiB2 nanocomposite using small amount of Fe and Ni (≤3 Wt%) as sintering aids was investigated in order to clarify the role of Fe and Ni additions on the mechanical and microstructural properties of B4C-nanoTiB2 nanocomposites. Different amount of Fe and Ni, mainly 1 to 3 Wt% were added to the base material. Pressureless sintering was conducted at 2175, 2225 and 2300 °C. It was found that Addition of 3 Wt% Fe and 3 wt% Ni and sintering at 2300 °C resulted in improving the density of the samples to about 99% of theoretical density. The nanocomposite samples exhibited high density, hardness, and microstructural uniformity.
N. Ghanbarpourabdoli, Sh. Raygan, H. Abdizadeh,
Volume 13, Issue 4 (December 2016)
Abstract
In this study, the adsorption of hexavalent chromium and zinc ions from the solution is investigated by raw red mud and mechanical-chemical activated red mud along with the possibility of selective reclamation of these ions from the solution. The mechanical-chemical activation of red mud was done by employing high-energy milling and subsequent acid treatment with HNO3. Raw red mud (RRM) and mechanical-chemical activated red mud (MCARM) adsorbents were characterized with Fourier transform infrared spectroscopy (FTIR), X-ray fluorescence (XRF), X-ray diffraction (XRD), scanning electron microscope (SEM), and Brunauer–Emmett–Teller (BET) methods. In order to determine the suitable adsorption conditions, effects of pH of the solution, amount of adsorption, temperature, and time of adsorption were investigated. It was found that the optimum pH for the adsorption of hexavalent chromium and zinc ions by MCARM adsorbent was 2 and 6, respectively. According to these pH values, MCARM had the ability to separately adsorb more than 95 and 79% of hexavalent chromium and zinc ions from the solution, respectively. Experimental results were in good agreement with Langmuir and Freundlich isotherms. By considering the kinetic models of adsorption, the kinetics of the adsorption of both ions followed the pseudo-second-order reaction model. It was also determined that almost 25.8 and 61.8% of the hexavalent chromium and zinc ions adsorbed in MCARM could be recovered
Najwa Gouitaa, Lamcharfi Taj-Dine, Bouayad Lamfaddal, Abdi Farid, Mohamed Ounacer, Mohammed Sajieddine,
Volume 18, Issue 2 (June 2021)
Abstract
Najwa Gouitaa, Lamcharfi Taj-Dine, Abdi Farid , Ahjyaje Fatima Zahra,
Volume 18, Issue 3 (September 2021)
Abstract
In this study we have synthesis the Zr substituted BaTi0.80Fe0.20O3 ceramics at different content of Zr from x=0.00 to 0.10 by using the solid-state route. The room temperature X-ray diffraction results confirmed the coexistence of the two tetragonal and hexagonal phases for x ≤ 0.050 of Zr content. While above 0.050 the hexagonal phase disappears in benefit of tetragonal phase. The Raman results confirmed the formation of these phases obtained with XRD. The scanning electron micrographs consist of both spherical and straight grain forms for x=0.000 to 0.075, and only spherical grain form for x=0.100 attributed to the tetragonal phase. Also, the grain size increases accompanied with a decrease in density of ceramics with increasing Zr content up to 0.050 then decreases accompanied with an increase in density. Detailed studies of dielectric permittivity measurement have provided a presence of two anomalies Te and TR-O at different temperatures, with a relaxation phenomenon and diffuse behavior which is very important for ceramic at x=0.075 of Zr content. The dielectric permittivity values of the two anomalies of Zr substituted BaTi0.80Fe0.20O3 ceramics increase with increase of Zr content and the dielectric loss is minimal at x=0.100 of Zr content. The conductivity increases with the increasing of Zr substitution from 0.025 to 0.075 levels while for x = 0.100 the dielectric conductivity decreases. And the Cole-Cole analysis indicates a negative thermal resistivity coefficient (NTCR) behavior of these materials and an ideal Debye-type behavior.
Ata Abdi, Mehrdad Aghaie-Khafri,
Volume 19, Issue 1 (March 2022)
Abstract
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.
Ahabboud Malika, Najwa Gouitaa, Ahjyaje Fatimazahra, Lamcharfi Taj-Dine, Abdi Farid,
Volume 20, Issue 1 (March 2023)
Abstract
In this paper, Pb1-xFex(Zr0.52Ti0.48)O3 (PFZT) nanopowders, with x from 0.00 up to 0.20, were synthesized by using the sol-gel method. The PFZT samples were characterized by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), and impedance spectroscopy. According to the experimental results, PFZT combines rhombohedral and tetragonal symmetries for all the samples without a change in phase structure. The SEM investigation indicated that the grains are homogeneous with regular form and the average grain size of PFZT ceramics changed with Fe concentration. The dielectric characterizations show that the dielectric permittivity increases with increasing temperature, and the Fe amount shifts down the temperature of transition. Moreover, a dielectric resonance phenomenon is observed for all the PFZT ceramics.
