Showing 26 results for Arab
H. Safabinesh, A. Arab Fatideh, M. Navidirad, M. Ghassemi Kakroudi,
Volume 11, Issue 3 (september 2014)
Abstract
In order to improve the corrosion resistance of aluminosilicate refractories by molten aluminum, alkaline
fluoride NaF and cryolite Na3AlF6 powders were studied. Both physical and chemical properties are known to
influence wetting and corrosion behavior. This paper devoted to determine the influence of alkaline fluoride and
cryolite added to andalusite based castable on the reaction with aluminum alloys. These additives led to the in-situ
formation of celsian phases within the refractory matrix that led to improved corrosion resistance at 1300°C. Phase
analysis revealed that celsian formation suppressed the formation of mullite within refractories, thereby reducing
Penetration
R. Katal, A. Azizi, M. Gharabaghi,
Volume 17, Issue 2 (June 2020)
Abstract
Present paper investigates the dissolution behavior of copper from chalcopyrite concentrate sample using cupric chloride solution in detail. Response surface modeling (RSM) in combination with d-optimal design (DOD) was utilized for modeling and optimizing the cupric chloride leaching process. At first, a quadratic polynomial model was developed for the relationship between the recovery of copper and influential factors. The predictions indicated an excellent agreement with the experimental data (with R2 of 0.9399). Then, the effects of main factors including pH (1-4), liquid/solid ratio (2-7 mL/g), temperature (70-90 °C), CuCl2 concentration (6-35 g/L), and leaching time (0.5-16) were determined. The findings demonstrated that the temperature and CuCl2 concentration were the most effective factors on the dissolution rate of copper from chalcopyrite sample, while liquid/solid ratio had the lowest impact. The recovery of copper increased linearly with an increment in the liquid/solid ratio and the decrease in the pulp pH. Additionally, the recovery enhanced by increasing the temperature and CuCl2 concentration owing the generation of Cu–Cl complexes species and reached a plateau point and then almost remained unchanged. Meanwhile, it was found out that the recovery of copper was independent of the interaction between factors. Moreover, the optimization of leaching process was carried out by Design Expert (version 7) software and desirability function method and the highest recovery of copper was found to be about 86.1% at a pH of ~1.4, temperature of 89 °C, liquid/solid ratio of 6.8 mL/g, CuCl2 concentration of 21.79 g/L and leaching time of ~8 h.
S. Mortezaei, H. Arabi, H. Seyedein, A. Momeny, M. Soltanalinezhad,
Volume 17, Issue 3 (September 2020)
Abstract
Dynamic Recrystallization (DRX) is one of the likely mechanisms for fine-graining in metals and alloys. The dynamic recrystallization (DRX) phenomena occurs in different thermo-mechanical processing (TMP) conditions for various metallic materials. DRX depends on various materials and thermo-mechanical parameters such as temperature, strain rate, strain, stress and initial microstructure. in the present study, the restoration mechanism of the 17-7PH stainless steel has been investigated using a hot compression test under different conditions of thermo-mechanical treatment. The microstructural characteristics and the behavior of the hot deformation of the under study steel are investigated using flow curves and microstructure images obtained from optical microscopy. The results show that the maximum and steady state stresses are significantly affected by the strain rate and the deformation temperature. So that, the flow stress increases with decrease in the deformation temperature and increase in the strain rate. Microstructural studies confirm the occurrence of DRX as a restoration mechanism in the microstructure for the two phases of austenite and ferrite.
Yaser Moazzami, Mahdi Gharabaghi, Ziadin Shafaei Tonkaboni,
Volume 19, Issue 4 (Desember 2022)
Abstract
Ionic liquids as green solvents with high thermal stability, recyclability, low flash point, and low vapor
pressure, have been considered as a viable alternative in hydrometallurgical processes. In this study the leaching
kinetics of chalcopyrite concentrate was investigated using 1-Butyl-3-methylimidazolium hydrogen sulfate
(BmimHSO4) as an acidic ionic liquid. The Effect of operational parameters, including temperature, BmimHSO4
concentration, H2O2 concentration, stirring speed, solid-to-liquid ratio, and particle size on the rate of copper
dissolution of CuFeS2 were examined systematically. The highest Cu efficiency (ca. 97%) was achieved using 40%
(w/v) BmimHSO4, 30 %v/v H2O2, and 10 g.L-1 solid to liquid ratio for particle sizes less than 37 μm at 300 rpm and
45°C after 180 min leaching time. Kinetics study using Shrinking Core Model (SCM) revealed that CuFeS2 leaching
process using BmimHSO4 follows chemical reaction-controlled process. Under these circumstances, the calculated
activation energy was 46.66 KJ/mol. Moreover, the orders of reaction with respect to BmimHSO4 and H2O2
concentration, solid to liquid ratio and particle size were estimated to be 0.539, 0.933, −0.676 and −1.101
respectively. The obtained Arrhenius constant was found to be 0.26 106. The calculation of apparent activation
energy using “time given to a fraction method” revealed that the leaching mechanism remains the same over the
course of time.
Mohammad Abankar, Hossein Arabi, Mohammad Taghi Salehi, Majid Abbasi,
Volume 20, Issue 1 (March 2023)
Abstract
The aims of this research were to evaluate the effects of different thermomechanical treatments on the microstructure and investigate some of the mechanical properties of a TWIP steel rich in Mn & Al. So, a block of a TWIP steel with nominal composition Fe-17.5Mn-1.36Al-0.8C was cast and then subjected to hot rolling followed by cold rolling and heat treatment. Cold rolling was performed before heat treatment in order to reduce the grain size and improve the tensile and fatigue properties. X-ray diffraction technique was used before and after the heat treatment to evaluate the possibility of any phase formation. No sign of martensitic transformation after cold deformation was observed. However, by increasing the amount of cold deformation, the number of mechanical twins and slip band increased resulted to an increase in hardness and strength. The best tensile and fatigue result were obtained after 47% thickness reduction and annealing at 715˚C for 10 min. Under these conditions, the mean grain size reduced from 138 to 9 μm resulted to an increase in yield strength from 395 to 510 MPa, and the fatigue life improvement from the mean life of 10200 for the cast sample to 21500 cycles for the treated sample, when these samples underwent fatigue tests at a stress range of 650 MPa and R=0. In addition, the diameter and depth of dimples in fracture surfaces decreased by reducing the grain size but the fracture mode was remained ductile and adequate plastic deformation occurred before failure.
Hadi Sharifidarabad, Alireza Zakeri, Mandana Adeli,
Volume 21, Issue 0 (IN PRESS 2024)
Abstract
The sensitivity of lead dioxide coating properties to the deposition conditions and electrolyte composition has allowed the preparation of coatings with different properties for different applications. In this study, the effects of electrolyte additives on the electrodeposition process were investigated using electrochemical measurements such as cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy. The results showed that the presence of fluoride ions significantly reduce the possibility of TiO2 formation. The addition of copper ions not only prevents lead loss at the cathode, but also leads to the formation of copper oxide on the surface at initial stages, which hinders nucleation of PbO2. The presence of sodium dodecyl sulfate (SDS) also interferes with the nucleation process as it occupies active nucleation sites. The α-PbO2 interlayer prevents copper oxidation and solves the problem of lead dioxide nucleation. Finally, it was found that the simultaneous use of all additives together with the α-PbO2 interlayer has a positive effect on the coating process.