Showing 7 results for Rezaei
S.a. Shojaosadati, M.r. Rezaei and B. Rasouli,
Volume 18, Issue 1 (4-1999)
Abstract
In this research the microorganism was initially isolated and selected after evaluation based on COD reduction of cheese whey and biomass production. The selected microorganism was identified as Trichosporon sp. The cultivation conditions of the microorganism were optimized under batch: temperature 30˚C initial pH = 6 aeration speed = 2 ν.ν.m and agitation rate: 800 rpm. Under these conditions, the specific growth rate and biomass doubling time were measured as 0.59 h-1 and 1.16 h, respectively. The COD reduction and biomass production under optimized batch conditions after 24 hours were obtained as 52% and 8.73 g L-1, respectively. The optimized conditions under continuous cultivation were: temperature, 30˚C agitation rate, 800 rpm aeration speed, 2 ν.ν.m dilution rate, 0.42 h-1 pH in fermentor, 4-5. Under these conditions the biomass production, COD reduction and productivity were obtained as: 8.17 g L-1, 53.21%, and 3.4 g L-1 h-1 respectively.
The nutritional value of biomass was evaluated for crude protein, nucleic acid, fat, ass and moisture content. According to the results, the single cell protein obtained in this research is suitable and valuable for animal and poultry feed.
A.h. Khosrovaninezhad, M. Shamanian, A. Rezaeian , M. Atapour,
Volume 34, Issue 2 (Journal of Advanced Materials- Summer 2015)
Abstract
This paper reports on the mechanical properties of the dissimilar joints between AISI 316 austenitic stainless steel and St 37 low carbon steel achieved using friction stir welding technique. The welding was carried out by means of rotational speed of 800 rpm and linear speeds of 50,100,150 mm/min. EDS and XRD techniques were employed in order to determine possible phase transformations. Tensile test, shear punch test and microhardness measurements were conducted to evaluate the mechanical properties of the joints. The results of phase investigations showed that no carbide and brittle phase were detected at the joint boundary. Also, tensile test results demonstrated that failure occurred in the St 37 base metal. According to the shear punch test, the highest ultimate shear strength and yield shear strength was achieved for the sample welded at rotational speed of 800 rpm and linear speed of 150 mm/min, while this sample showed the least elongation. In addition, the highest microhardness was measured in the stir zone of austenitic stainless steel sample welded in the above mentioned welding condition, which can be attributed to the decrease in grain size caused by recrystallization process.
S. Deljavan, M. G. Kakroudi, J. Zaroodi, F. Rezaei,
Volume 35, Issue 1 (Journal of Advanced Materials-Spring 2016)
Abstract
Perovskite structures including oxygen vacancies are the most important group of the oxygen preamble membranes. These membranes have potentially attractive applications in the membrane reactors for partial oxidation of methane. Doping Perovskite phase in order to increase the oxygen vacancies and oxygen permeation, besides Perovskite structure stability, has been the main approach of the recent researches. In this research, tantalum was chosen as the appropriate dopant for Ba(Co0.8Fe0.2)O3−δ Perovskite phase, according to the tolerance factor calculations. The X ray patterns of synthesized Ba (Co0.7Fe0.2Ta0.1)O3−δ indicate that the Perovskite structure was formed. Powder density, thermal expansion coefficient measurements and bond strength studies using FT-IR analysis revealed that the chosen dopant not only increases the oxygen vacancies volume but also reduces the thermal expansion coefficient without significant changes of bond strength. Results showed that the novel Ba (Co0.7Fe0.2Ta0.1) O3−δ is a good choice for the membrane fabrication of methane partial reduction reactors.
M. Rezazadeh, R. Emadi, A. Saatchi, A. Ghasemi, M. Rezaeinia,
Volume 35, Issue 3 (Journal of Advanced Materials-Fall 2016)
Abstract
Simultaneous application of mechanical pressure and electrical charge on powder samples in spark plasma sintering process, has resulted in a sample with a density close to the theory. In the present study, a thermal-electrical-mechanical coupled finite element model of spark plasma sintering system using multi-objective optimization algorithm is proposed to optimize the mold variable. The simulation performed for Si3N4-SiO2 (1:1 mol) specimen has good agreement with the experimental results. Multi-objective genetic algorithms was used for optimization of mold design in order to maximize the temperature of sample core and minimize the mises stress in the mold. The results show that the optimized dimensions cause 8% increase in sample temperature and about 18% decrease in temperature difference between mold surface and sample core. This leads to better uniformity in the porosity distribution of final sample.
S. E. Mousavi, M. Meratian, A. Rezaeian,
Volume 36, Issue 4 (Journal of Advanced Materials-Winter 2018)
Abstract
Equal Channel Angular Pressing (ECAP) is currently one of the most popular methods for fabricating Ultra-Fine Grained (UFG) materials. In this study, mechanical properties of the 60-40 two phase brass processed were evaluated by ECAP. The samples were repeatedly ECAP-ed to strains as high as 2 at a temperature of 350 ◦C using route C. The microstructure of the samples showed that small grains were formed in the boundaries which indicates the occurrence of recrystallization in different passes. Observation of slip trace in the microstructure of the samples showed that even in such alloy with a low-stacking fault energy, dislocations slip trigger the deformation. Investigation of mechanical properties showed that with increasing the number of passes, tensile strength, microhardness and ducility improved at the same time.
N. Alirezaei Varnosfaderani, S. E. Mousavi Ghahfarokhi, M. Zargar Shoushtari,
Volume 38, Issue 3 (Journal of Advanced Materials-Fall 2019)
Abstract
In this paper, W-type SrCo2Fe16O27 hexaferrite nanostructures were synthesized by sol-gel auto-combustion method. Effect of annealing temperature on the structural, magnetic and optical properties of these SrCo2Fe16O27 nanostructures was investigated. In order to determine the annealing temperature of samples, the prepared gel was examined by thermo-gravimetric and differential-thermal analyses. Morphology and crystal structure of the prepared samples were characterized by field emission scanning electron microscopy and X-ray diffraction pattern. Based on X-ray diffraction results, at annealing temperature of 1000 °C, the maximum amount of main phase formed. A planar morphology was spectroscopy for the synthesized samples through scanning electron microscope images. Fourier transform infrared analysis was used to confirm the synthesis of the main properties obtained of samples were measured by the vibrating sample magnetometer and the results showed that by increasing temperature, magnetic saturation increases. Moreover, optical properties of samples were investigated by ultraviolet–visible absorption and photoluminescence spectroscopies. The result of measurements of the energy gap approximately is same in the ultraviolet- visible and photoluminescence spectroscopes and also the energy gap is constant with increasing temperature.
A. Zolriasatein, S. Navazani, M. Rezaei Abdadchi, N. Riahi Noori ,
Volume 39, Issue 3 (Journal of Advanced Materials-Fall 2020)
Abstract
In this paper, the effect of adding aluminum trihydrate (ATH) on electrical (including dielectric constant, dielectric loss and strength, volume and surface resistivity) and hydrophobic properties of two-part room temperature volcanized (RTV) silicone rubber resin coatings were investigated. For this purpose, the RTV-ATH nanocomposite was made by physical mixing and its electrical and hydrophobic properties were compared with those of pure RTV. The results showed an increase in the dielectric constant (from 3.11 to 4.13), the dielectric loss (by ~ 0.06) and the dielectric strength (by ~ 4 KV/mm) of the RTV-ATH composite compared to the pure RTV. Moreover, ATH increased volume resistivity and reduced the surface resistivity of composite coatings. On the other hand, by spraying of coatings, no improvement in the hydrophobicity class of composite coating compared to pure RTV was observed and both samples were standardized in the HC2 standard class. Structural analysis of samples was performed by X-ray diffraction, optical microscopy and scanning electron microscopy and the presence of the main phases in them was confirmed.
