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Shabani M.O.,Iranian Materials and Energy Research Center | Mazahery A.,University of Tehran
JOM | Year: 2011

In this paper, a relatively new approach is presented in order to predict the microstructure of A356 using finite element technique and artificial neural network. In the training and test modules of the neural network, different primary and secondary dendrite arm spacing obtained from finite element method were used as inputs and eutectic volume percentage, silicon volume percentage, silicon rod spacing, average length of silicon rods and silicon rod diameter were used as outputs. After the training set was prepared, the neural network was trained using different training algorithms, hidden layers and neurons number in hidden layers. The results of this research were also used to form analytical equations followed with solidification codes for SUT Cast software. © 2011 TMS.


Sharifi N.,University of Kashan | Tajabadi F.,Iranian Materials and Energy Research Center | Taghavinia N.,Sharif University of Technology
ChemPhysChem | Year: 2014

The knowledge of dye-sensitized solar cells (DSCs) has expanded considerably in recent years. They are multiparameter and complex systems that work only if various parameters are tuned simultaneously. This makes it difficult to target to a single parameter to improve the efficiency. There is a wealth of knowledge concerning different DSC structures and characteristics. In this review, the present knowledge and recent achievements are surveyed with emphasis on the more promising cell materials and designs. © 2014 Wiley-VCH Verlag GmbH & Co. KGaA.


Hashemi S.H.,Birjand University | Mohammadyani D.,Iranian Materials and Energy Research Center
International Journal of Pressure Vessels and Piping | Year: 2012

The variation of microstructure and mechanical properties in various sub-zones of double submerged arc welded line pipe steel of grade API X65 was investigated. Instrumented Charpy V-notch tests and Vickers hardness experiments were conducted on the fusion zone, base metal and heat affected zone of the weld joint in 14.3 mm thick, 1219 mm outside diameter spiral pipeline. The lowest impact energy and the highest hardness level (160J and 218 HV, respectively) were recorded in the fusion zone. The low energy and high hardness characteristics of the seam weld can be attributed to its cast microstructure and the presence of grain boundary phases (such as proeutectoid ferrite), confirmed by standard metallographic observation. Despite this, service requirements set by the API 5L industry code (minimum impact energy of 73J, maximum hard spots of 350 HV) were fulfilled by the tested steel. © 2012 Elsevier Ltd.


Esmaily H.,Iranian Materials and Energy Research Center | Nuranian H.,Iranian Materials and Energy Research Center
Construction and Building Materials | Year: 2012

In this study, the use of alkali activated slag (AAS) in place of usual cementitious materials in the production of autoclave aerated concrete (AAC) was studied. This substitution altered autoclave curing stage by steam curing in AAC production process. In this way, after mixing of AAS paste with aluminum powder, enough time was given to the mixture. The resultant green body was then cured at 70, 78 and 87 °C. To achieve the best results, microscopic pore structure, compressive strength of the body and mini-slump of initial paste were studied. The results approved that AAC can be produced without autoclave by using AAS. © 2011 Elsevier Ltd. All rights reserved.


Aminikia B.,Iranian Materials and Energy Research Center
Powder Technology | Year: 2012

NanocrystallineTiB 2-TiC composite was readily prepared by self-propagating high-temperature synthesis (SHS) of the mechanically milled powders. Mixture of Ti and B 4C as the starting materials were initially milled for 1, 3, 6 and 9h, and pressed to form the pellets. The green compacts were placed in a tube furnace preheated to 1100°C and 1200°C in argon atmosphere. The samples were characterized by XRD, SEM and TEM analytical techniques. The results showed that, increasing the milling time enhances the formation of TiC and TiB 2 phases and reduces the furnace temperature necessary for the synthesis process. In fact, the powder milled for the longer time, required the lower temperature for the SHS process to occur. © 2012 Elsevier B.V.


Mazahery A.,Iranian Materials and Energy Research Center | Shabani M.O.,Iranian Materials and Energy Research Center
Powder Technology | Year: 2012

In the current research, nano-composites of commercial casting aluminum alloy reinforced with nano-silicon carbide were produced. Experimental and modeling investigations were carried out on the porosity, wear, hardness, elongation, yield strength and ultimate tensile strength (UTS) of these nano-composites. The density measurements showed that the amount of porosity in the composites increased with increasing the volume fraction of nano-particles. The wear sliding test revealed that composites offer superior wear resistance as compared to the alloy irrespective of nano-particles volume fraction. The tensile strength results show that the yield strength and ultimate tensile strength of the composites increased with increasing volume fraction of nano-particles. The incorporation of nano-particles deteriorates the ductility of A356 alloy. However, the elongation remains rather constant with increasing the volume fraction of nano-particles. In the other word, increasing the nano-sized ceramic particles content helps to strengthen the composites, while the ductility is retained. In this paper, a technique based on artificial neural network (ANN) and finite element method (FEM) was proposed to investigate on nano-silicon carbide reinforced commercial casting aluminum alloy matrix. It was observed that prediction of this study is consistent with experimental measurements for aluminum matrix composites. © 2011 Elsevier B.V.


Mazahery A.,Iranian Materials and Energy Research Center | Shabani M.O.,Iranian Materials and Energy Research Center
Ceramics International | Year: 2012

The purpose of this paper is to provide a deeper understanding of the wear behavior of the sol-gel coated B 4C particulate reinforced A356 matrix composites. A typical microstructure of the composite consists of relatively large primary phase globules which are surrounded by B 4C particles. In fact the globules themselves are B 4C particles free and consequently the sample is not homogeneous on a scale smaller than the globule size. The wear sliding test disclosed that the wear rate of the coated B 4C reinforced composites is less than that of the unreinforced alloy and decreases with increasing volume fraction of B 4C particulates. As the hardness of the composites is higher, this reduces the cutting efficiency of the abrasives and consequently the abrasion wear loss. Once the particles fracture or loosen from the matrix alloy, they can be removed easily from the matrix, contributing to the material loss. Two kinds of debris present irregular-shaped flake, which has withstood a large of plastic deformation and then pull off from the surface. During the sliding wear, Iron is transferred to the surface of the composites from the steel counterface forming the iron-rich layer on the contact surfaces which increases with increasing the B 4C content and is substantially harder than the bulk material largely because it contains a fine mixture of Fe phase, Al and B 4C. © 2011 Elsevier Ltd and Techna Group S.r.l.


Ebadzadeh T.,Iranian Materials and Energy Research Center
Journal of Alloys and Compounds | Year: 2010

Nano-structured mullite was produced from the microwave heating of a mixture of clay and alumina activated mechanically in a planetary ball mill for 30, 50 and 70 h. XRD results showed after 30 h milling time, clay disappeared and alumina and quartz appeared as the only crystalline phases. The maximum specific surface area was 34.92 m2/g for the sample activated mechanically for 30 h. The mullitization was completed for powders milled for 30 and 50 h and heated for 30 min (equal to 1376 °C) in a microwave oven. The maximum density and flexural strength values were measured for samples milled for 30 and 50 h, respectively, and sintered for 30 min. The flexural strength values of these samples were 3 and 4.7 times of the strength value of the sample milled for 2 h and sintered at the same conditions. © 2009 Elsevier B.V. All rights reserved.


Torabi M.,Iranian Materials and Energy Research Center | Sadrnezhaad S.K.,Iranian Materials and Energy Research Center
Journal of Power Sources | Year: 2011

Nanocrystalline tin oxides were synthesized using electron beam evaporation (e-beam) and further heat treatment. X-ray diffraction (XRD) revealed that as-deposited samples were amorphous SnO. Heat treatment of the as-deposited thin films at 250 °C for 2 h and 500 °C for 10 h led to the formation of romarchite SnO and tetragonal SnO 2, respectively. Scanning electron microscopy (SEM) showed a compact morphology of the coatings. Elemental mapping of the films also represented homogeneous distribution of the zinc atoms in the SnO 2 structure. Atomic force microscopy (AFM) images demonstrated a fine and smooth surface of the e-beam evaporated films for the SnO samples, and rough topography for the SnO 2. Doping led to the formation of finer and more uniform surface morphology. Anodic behavior of the thin film during charge/discharge process showed that specific capacity of the pure SnO 2 increased from 502 to 903 μAh cm -2 μm -1 for nanocrystalline Zn-doped SnO 2. Moreover, specific capacity of the doped film enhanced to 137.6 that is, higher than 69.5 μAh cm -2 μm -1 for the pure SnO 2. XRD results also show that Zn doping decreased Sn clustering during cycling. © 2010 Elsevier B.V.


Mahmoodi K.,Iranian Materials and Energy Research Center | Alinejad B.,Iranian Materials and Energy Research Center
International Journal of Hydrogen Energy | Year: 2010

The aim of this investigation is to enhance hydrogen generation rate in aluminum-water reaction by improving the activity of aluminum particles and using the heat released during the reaction. This was accomplished by developing fresh surfaces by milling aluminum particles together with salt. Salt particles not only serve as nano-millers, but also surround activated particles and prevent re-oxidation of bare surfaces in the air. Therefore, the activated powder can be easily stored for a long time. Immersing the powder in warm water, the salt covers are washed away and hydrogen begins to release at a high rate until efficiency of 100% is achieved. The rate of reaction depends crucially on initial temperature of water. Hence, the mass of water was reduced to employ released energy to increase water temperature and, consequently, to increase hydrogen production rate. The optimum value of salt-to-aluminum mole ratio for achieving high activation, air-storage capability and 100% efficiency was obtained to be 2. When immersed in water, at initial temperatures of 55 and 70 °C, the powder lead to average hydrogen generation rate of ∼101 and ∼210 ml/min per 1 g of Al, respectively. To increase the rate of corrosion, three different alloys/composites of aluminum were prepared by mechanical alloying and activated with optimum salt-to-aluminum mole ratio. The alloys/composites formed galvanic cells after being immersed in water. In the case of aluminum-bismuth alloy, the average hydrogen generation rate increased to ∼287 and ∼713 ml/min per 1 g of Al, respectively. © 2009 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.

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