Showing 9 results for Alizadeh
M. A. Massoumnia, Gh, Alizadeh and H. R. Momeni,
Volume 17, Issue 2 (4-1998)
Abstract
In this paper, a new guidance method for surface to surface ballistic missiles without mandatory engine cut-off will be presented. The complexity of solid fuel engine cut-off demands a comprehensive method for guiding these missiles. In the method presented in this paper, a certain guidance law is applied such that by transmitting appropriate commands to the control system, by changing the missile's path and also through wasting additional fuel energy, the missile velocity will be equal to the desired one at the end of the burning time. The results of the simulation indicate that the aforementioned guidance method is quite effective and practical with long-range missiles having thrust vector control.
M. Alizadeh and H. Edriss,
Volume 21, Issue 2 (1-2003)
Abstract
In recent years many different ways have been investigated by steel producers to increase ductility, impact strength and formability of steels. More important ways are steels with very low amounts of inclusion, small size inclusions and modified inclusions. In this study, experiments have been performed on the API-X42 steel produced by the electric arc furnace in Mobarekeh Steel Co. After the preparation of the melt in the electric arc furnace, it is taped in a 200-ton ladle and ladle treatment was preformed in a ladle furnace (LF) in the steelmaking shop. In this study the effects of amount and the rate of CaSi wire addition on the shape and structure of inclusion were investigated. The optimum conditions for adding CaSi for inclusion shape control were also determined. Scanning electron microscope (SEM) and chemical energy analysis dispersive system (EDS) showed that adding calcium to the melt affects the chemical composition of inclusions present in steel melt. The effects of CaSi wire injection treatment, injection amount and inclusion shape control on the impact property and formability of steel were shown using charpy impact test.
Keywords: Inclusion shape control, calcium treatment, ladle furnace and inclusion modification
M. Alizadeh, H. Edris, and A. Shafyei,
Volume 27, Issue 2 (1-2009)
Abstract
M. Talebian, M. Alizadeh, M. Ehteshamzadeh,
Volume 33, Issue 2 (Journal of Advanced Materials-fall 2015)
Abstract
In this study, Al/Steel multilayer composite was produced by accumulative roll bonding (ARB) process using Al-1100 and St-12 strips. Microstructure, mechanical properties and corrosion behavior of the composite were studied by scanning electron microscopy (SEM), tensile test, Vickers microhardness tests, cyclic polarization and electrochemical impedance spectroscopy (EIS) measurement in 3.5 wt% NaCl solution. After one ARB cycle (2 roll-bonding cycles), the multilayer composite of 4 layers of Al and 2 layers of steel was produced. The tensile strength of the Al/steel multilayer composite reached 390.57 MPa after the first ARB cycle, which was 1.29 times larger than that of the starting steel while composite density was almost half the density of the steel. Corrosion behavior of the composite revealed a considerable improvement in the main electrochemical parameters, as a result of enhancing influence of cold rolling. The results indicated that strength and corrosion resistance of Al/steel composite generally decreases and elongation increases after annealing.
Z. Ansari, M. Alizadeh, A. Sadeghzadeh Attar,
Volume 33, Issue 2 (Journal of Advanced Materials-fall 2015)
Abstract
In this study, mixed metal oxides Al2O3/MgO/TiO2 coatings with Al/Mg/Ti ratios of 5:1:3 and 2.5:3:4 were coated on AA1100 aluminum by sol-gel method. The surface morphology, phase analysis and the corrosion behavior of the Al2O3/MgO/TiO2 coatings were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), and electrochemical impedance spectroscopy measurements (EIS) in 3.5 wt.% NaCl solution. The thermal behaviors, the bonds configuration, and functional groups of the coated samples were studied by thermo-gravimetric and differential thermal analysis (TG-DTA) and Fourier transform infrared spectroscopy (FTIR), respectively. The results demonstrated that heat treatment at
450 °C caused an increase in porosity and coating cracking, finally leading to the decrease of corrosion resistance. The best corrosion resistance was achieved for the sample with Al/Mg/Ti molar ratio of 5:1:3 without any heat treatment. The structure of this sample was amorphous, and heat treatment resulted in crystallization and decrease of the corrosion resistance.
M. Alizadeh, M. Mirzaei,
Volume 34, Issue 1 (Journal of Advanced Materials-Spring 2015)
Abstract
In this study, at first Al-Al2O3 composite powders having different volume fractions of Al2O3 (0, 10, 20, 30 and 40 vol.%) were produced by low energy mechanical alloying, which were used as foam materials. Then, composite foams with 50, 60, and 70 percent of porosity were produced by space-holder technique. Spherical carbamide particles (1-1.4 mm) were used to achieve spherical porosities. In order to investigate the compressive behavior of foams, the compression test with strain rate of 10-3 S-1 was performed on the foam samples. The results showed that the compressive properties depended on the volume fraction of Al2O3 and porosity fraction. Generally, by decreasing the porosity fraction, the compressive properties were improved. The composite foams containing 10 vol.% Al2O3 showed superior compressive properties in comparison to other foams studied in this work.
M. Alizadeh, M. Hajizamani,
Volume 34, Issue 3 (Journal of Advanced Materials-fall 2015)
Abstract
Sodium molybdate (Na2MoO4) as a grain refiner was used to refine the microstructure of Al-0.7Fe alloy. Al-Fe samples with the addition of 0.1, 0.2, 0.3, 0.4 and 0.5 wt.% sodium molybdate were fabricated by casting in sand molds at 750 ͦC. The microstructures of the as-cast samples were investigated by scanning electron microscopy (SEM) and the present phases were revealed by X-ray diffraction (XRD). The effect of sodium molybdate on the microstructure was examined by measuring the average grain sizes of the alloys, determining the widths of intermetallic compounds and carrying out hardness and tensile tests. The results showed that the addition of sodium molybdate modified the microstructure of Al-Fe alloy by reducing the average grain sizes. Also, it was found that the optimum amount of sodium molybdate to add to Al-0.7Fe alloy melt was 0.3 wt.% in this study.
Mr M. Hajizamani, Dr. M. Alizadeh, Dr. S.a. Jenabali-Jahromi, Dr. A. Alizadeh,
Volume 36, Issue 2 (Journal of Advanced Materials-Summer 2017)
Abstract
Al-Zn-Mg/3 wt-% Al2O3 nanostructured composite powder was synthesized through Mechanical Alloying (MA). At first, the 7014 alloy matrix constituents were milled in a planetary ball mill for 20 hours. Then, 3 wt.% µ-Al2O3 particles were added to the pre-milled matrix and the nanostructured composite powder was produced at different MA times to investigate the effects of MA time on the characteristics of the produced composite powders such as morphology, crystallite size, lattice strain and microhardness. The characterization results proved that synthesizing nanostructured composite powder with a low amount of micrometric reinforcements in addition to pre-milled micrometric matrix is possible. Also, synthesis of the nanostructured composite powder with the minimum crystallite size of 24 nm and the minimum mean particle size of 5 µm was confirmed. Moreover, the steady state occurred after around 20 hours milling and further milling did not affect the powder characteristics excluding crystallite size, lattice strain and microhardness. In addition, sinterability of the composite powders increased with increasing the milling time due to decreased average particle size. However, after the steady state, the sinterability did not change.
M. Alizadeh, A. Cheshmpish,
Volume 37, Issue 2 (Journal of Advanced Materials-Summer 2018)
Abstract
In this research, Ni-Mo-Al2O3 composite coatings were electro-deposited on the mild carbon steel in a citrate bath containing micro- sized Al2O3 particles. Afterward, the effect of the particle concentration in the electrolyte bath (ranging from 0 g/L to 30 g/L) on the microstructure, microhardness, and corrosion performance was evaluated. To investigate the microstructural changes and the surface morphology of the coatings, as well as the particle distribution in the deposits, optical and scanning electron microscopy coupled with the energy dispersive X-ray spectroscopy was utilized. The corrosion behavior of the prepared coatings was investigated in a 3.5 wt. % NaCl solution. The results showed that the presence of the Al2O3 particles in the Ni-Mo coatings changed the microstructure and also, increased the microhardness and corrosion resistance of them. It was also found that the desirable structure of the protruding crystallite morphology with no detectable pores could be achieved at the medium concentrations of reinforcement (e.g. 20 g/L). Further the optimum concentration of the particles in the electrolyte bath to attain the composite coating with the desirable microstructure and consequently, the desirable corrosion resistance was found to be 20 g/L.
