List of articles (by subject)
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Open Access Article
1 - Effect of zirconium addition on microstructure and hardness of Al-6Zn-2.5Mg-1.5Cu alloy produced by mechanical alloying
محمد امین شافعی سید جمال حسینی پور محمد رجبی -
Open Access Article
2 - Investigating the properties of porous Al/SiC nanocomposite with different creep testing methods
یاسمن صابری کاخکی سعید ناطق شمس الدین میردامادیIn the present study, Al-4 vol .% SiC composites were produced by mechanical alloying and the correspondence of the creep results were obtained from different methods (the advantages of lower time of test). The coefficient between impression and compression creep rate f MoreIn the present study, Al-4 vol .% SiC composites were produced by mechanical alloying and the correspondence of the creep results were obtained from different methods (the advantages of lower time of test). The coefficient between impression and compression creep rate for stresses of 30 and 32.5 MPa and 35 MPa and impression stresses of three times of compression stresses (90, 97 and 111 MPa) were constant (2.5) in different microstructures. This constant coefficient showed that the condition of composite production was similar to the steady state condition of mechanical alloying process and has been proved with composite microstructure. According to the relaxation results, the different nano SiC distribution and the porosities lead to the variations in the steady state relaxation rate and the relaxation rate decrease with time was due to the work hardening mechanism. Also the high amount of coefficient showed that the effect of porosity was more than nano SiC in impression and relaxation rate increase. Manuscript profile -
Open Access Article
3 - Effects of size and type of coating of iron powders and copper additive on the properties of hollow steel spheres
Hamid Sazegaran علیرضا کیانی رشیدMetal hollow spheres are successfully used for manufacturing of cells and porosities in the cellular structures and metallic foams that important production methods of them are based on powder metallurgy. In this paper, steel hollow spheres are produced by powder metall MoreMetal hollow spheres are successfully used for manufacturing of cells and porosities in the cellular structures and metallic foams that important production methods of them are based on powder metallurgy. In this paper, steel hollow spheres are produced by powder metallurgy method and polystyrene beads are used as substrate materials. Polystyrene beads are separated from a polystyrene block and sorted by sieving. Then, mixture of sodium silicate, as binder, and iron powder was sprayed on prepared beads. After drying, a thin layer of iron powder was covered polystyrene beads. Finally, two different heat treatment processes to produce high strength steel hollow spheres was undertaken. These processes are involving the pyrolysis of polystyrene beads and sintering process. For shell thickness measurements, determination of porosity content and flaws evaluation, shell section of hollow spheres were studied by optical microscopy. Produced hollow steel spheres are nearly uniform thickness in shell. Size of iron powder particles, cupper content and type of coating of iron powder are strongly affected on shell thickness, porosity percent and shell flaws. Manuscript profile -
Open Access Article
4 - A Study on Effect of Processing Parameters on Electrical Conduction and Micro-hardness of Nano-crystalline Cu-5%at Ta Alloy.
Roohollah Rahmanifard mohsen asadi asadabad سید میثم جاویدانAt the present study, the mechanical alloying method was used to produce the nanocrystalline Cu-5Ta alloy. In order to achieve a specimen with desirable properties, effects of size of milling ball, atmosphere and temperature of sintering were investigated on crystalline MoreAt the present study, the mechanical alloying method was used to produce the nanocrystalline Cu-5Ta alloy. In order to achieve a specimen with desirable properties, effects of size of milling ball, atmosphere and temperature of sintering were investigated on crystalline structure, electrical conduction and microhardness of specimen. The microstructural studies indicated that a finer crystallite size was attained when the complex size of milling balls being composed of 10 and 5 millimeters was applied rather than simple one of 10 millimeters. After milling, cold press and subsequent sintering were done under different atmospheres such as nitrogen, argon and vacuum at temperature of 550C. The sintered specimen under vacuum showed the better properties compared to the others. The further evaluations on specimen properties was conducted by sintering at temperatures of 700 and 850C under vacuum. The results indicated that with increasing the sintering temperature, electrical conduction and microhardness increase. Overall, the specimen milled by the complex ball size and sintered at temperature of 850C under vacuum experienced a electrical condition of 15.7% IACS and microhardness of 196.2 HV which was the best conditions to produce Cu5Ta. Manuscript profile -
Open Access Article
5 - Characterization of Cu-Yttria Stabilized Zirconia composite produced by Spark Plasma Sintering
جعفر میرعظیمی پروین عباچی کاظم پورآذرنگ وحید باباییIn applications like sliding electrical contacts good electrical/thermal conductivity as well as wear resistance is required besides suitable mechanical properties. Furthermore, in these types of applications it is necessary to be prevented from local welding of various MoreIn applications like sliding electrical contacts good electrical/thermal conductivity as well as wear resistance is required besides suitable mechanical properties. Furthermore, in these types of applications it is necessary to be prevented from local welding of various parts of pieces to each other. Although the addition of ceramic particles to a conductive metal like copper can lead to decrease of above mentioned physical properties, the producing of copper matrix composites can induce high tensile strength, better wear resistance, and resistance to electrical current with high amperage improvement. Hence, at the present study, the copper based composites containing 2, 3 and 5 vol. % ultra-fine grained yttria stabilized zirconia (YSZ) particles were produced by powder metallurgy and spark plasma sintering (SPS) method. The distribution of reinforcing particles at the microstructure was carefully studied using electron microscopy. Additionally, the density, hardness and thermal conductivity values of the specimens were measured. Referring to the results, microstructural analysis showed satisfactorily distribution of reinforcement particles in copper matrix and the clustering of particles is not so noticeable. The relative density up to 95% for all specimens was obtained due to the sintering procedure. As a result of the presence of hard stabilized zirconia particles, an increase of 60 percent in the Brinell hardness of the Cu-5 vol.% YSZ composite sample was observed in comparison with unreinforced copper. Moreover, the determined thermal conductivity values decreased from 397 to 241 W/m K with increasing of reinforcement content from 0 to 5 vol. %. The variation in the thermal conductivities can be related to the microstructural characteristics such as reinforcement and porosity volume percent as well as other microstructural defects. Manuscript profile -
Open Access Article
6 - Synthesis of ZnWO4 nanoparticles and manufacturing scintillator for detecting Gama- rays
رسول صراف ماموری آرزو عبدالرحمانی خیراله محمدی محسن روشنIn this study, ZnWO4 nanoparticles were synthesized through co-precipitation method with sodium tungstate dehydrate (Na2WO4.2H2O) and zinc nitrate hexahydrate (Zn (NO3)2.6H2O) as starting materials. In order to optimize the conditions for obtaining smallest mean particl MoreIn this study, ZnWO4 nanoparticles were synthesized through co-precipitation method with sodium tungstate dehydrate (Na2WO4.2H2O) and zinc nitrate hexahydrate (Zn (NO3)2.6H2O) as starting materials. In order to optimize the conditions for obtaining smallest mean particle size, Central Composite Design (CCD) was used and three parameters of temperature, weight ratio of precursors, and pH value were studied in five levels. The obtained ZnWO4 nanoparticles were characterized by Field Emission Scanning Electron Microscopy (FE-SEM), powder x-ray diffraction (XRD), thermal gravimetric- differential scanning calorimetry (TG-DSC) and photoluminescence (PL). The results showed that optimal conditions for smallest mean nanoparticles with particle size of 37.3 6.9 nm were temperature =83 , weight ratio of precursor equal to 1.1, and pH=6. The resulting ZnWO4 nanoparticles were dry- pressed to green compact pellets with a diameter of 11mm and thickness of 1.5 nm at the compaction pressure of 500 MPa. The densification of nanoparticles compacts was carried out by a pressure less sintering at 950 for 2 hours in air atmosphere. Scintillation properties of pellets were determined by means of Gama-rays spectroscopy. The results showed that manufactured ZnWO4 pellets illustrated counting sensitivity to Cs137 and Am241 irradiation sources and couldn’t detect energy of Gama-rays emitted from this two source. Manuscript profile -
Open Access Article
7 - Preparation and Characterization of Porous Titanium Scaffold Coated with Akermanite
Masoud Arastooei Ali DoostmohammadiThis work aimed at manufacturing and characterizing of titanium scaffolds which is coated with Akermanite for using in bone tissue engineering. In order to creating titanium scaffolds, the primary titanium powder was prepared with spacer particle elements (sodium chlori MoreThis work aimed at manufacturing and characterizing of titanium scaffolds which is coated with Akermanite for using in bone tissue engineering. In order to creating titanium scaffolds, the primary titanium powder was prepared with spacer particle elements (sodium chloride). Akermanite coating was prepared through sol-gel method and applied on the scaffold. The prepared structure was evaluated using scanning electron microscopy (SEM). Coated scaffolds were evaluated after heat treatment by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). In terms of assessing the bioactivity of titanium scaffolds, the samples were immersed in simulated body fluid (SBF). Scanning electron microscopy images of the uncoated and coated titanium scaffolds was prepared after 3,7,14 and 21 days immersing in simulated body fluid (SBF); X-Ray Diffraction analysis (XRD) confirmed the peaks of Akermanite phase in coated samples. According to the results, our study showed that coating of Akermanite on Ti scaffold can increase the bioactivity of titanium scaffolds. The final conclusion of this study confirmed that titanium scaffolds coating with Akermanite will be a suitable and useful choice in bone tissue engineering. Manuscript profile -
Open Access Article
8 - Effect of Powder Morphology on Thermal properties and strentgh of High Heat Flux Porous Coatings Synthesized by Powder Metallurgy
علی کفلو مونا معیریRecently, with decreasing energy resources, it is favorable to use new materials to increase efficiency. High heat flux coating is one of the porous coatings that are created on base plate with pressure less sintering of powders. These coatings increase surface, besides MoreRecently, with decreasing energy resources, it is favorable to use new materials to increase efficiency. High heat flux coating is one of the porous coatings that are created on base plate with pressure less sintering of powders. These coatings increase surface, besides increasing bubble nucleation sites and permeability. Porosity volume, deboning strength and permeability are the most important physical property of these coatings that affected by powder size and powder morphology as well as sintering conditions. In this research, the effect of powder morphology on physical properties (porosity, deboning strength and permeability) of High Heat Flux porous coatings was investigated. Spherical, dendritic and irregular powders by using a polymeric binder were created on Cu base plate in an atmospheric control furnace (H2-N2) with specified heat treatment cycle (without any pressure). Porosimetery test was carried on porous coating samples. Results for spherical, dendritic and irregular powders were 24.5, 49.5 and 58% respectively. For mentioned samples, deboning strength was, 1.4, 0.52 and 0.82 (kN). Permeability of samples was in 3.3×10-12 to 4.8×10-12 (m2) range. Results show that maximum permeability and porosity were belonged to the irregular powder with minimum strength and spherical powder with maximum strength has minimum permeability and porosity. Manuscript profile -
Open Access Article
9 - A study of hardness and wear properties in the powder hard covering established in the Fe- Cr –C- Mo system on the carbonic simple steel by GTAW welding method
Mohammad Mehdi Ghaffari Hossein Paydar محمدرضا خانزاده قرهشیرانIn this research, a combination of Ferro- chromium powders (variable amount) and ferromolybdenum and graphite (constant amount) were coated on the st37 carbon steel substrate through Gas Tungsten Arc Welding (GTAW). In order to study properties of the layer established MoreIn this research, a combination of Ferro- chromium powders (variable amount) and ferromolybdenum and graphite (constant amount) were coated on the st37 carbon steel substrate through Gas Tungsten Arc Welding (GTAW). In order to study properties of the layer established under the layer, scanning electron microscope (SEM), EDS element microanalysis and microhardness assessment have been used, and x-ray diffraction analysis (XRD) specified that microstructure of the samples consists of austenite and (Cr,Fe)7 , C3 carbides. In addition, it was specified that by the increase of carbon and chromium containing hard face layers, a part of carbon is spent on the formation of Cr7C3 chromium carbide, and the remainder has played a role in the formation of molybdenum carbide and chromium led to the increase of hardness. Results of the wear test specified that the highest wear resistance relates to a sample containing 13.45 chromium percentage. SEM investigation of worn surfaces in the samples specified that wear mechanism was plowing type, cutting type and cracking type. Manuscript profile -
Open Access Article
10 - Investigation of Microstructural and Mechanical Properties of Tungsten Disulfide (WS2) /Aluminum Matrix Nanocmposite
hossein salehi vaziri ali shokuhfar Seyyed Salman Seyyed AfghahiIn this research, WS2 nanoparticles were synthesized using hydrothermal method and then added to aluminum matrix as reinforcement. Nanocomposites were fabricated by powder metallurgy processing followed by Spark Plasma Sintering (SPS) consolidation. Transmission electro MoreIn this research, WS2 nanoparticles were synthesized using hydrothermal method and then added to aluminum matrix as reinforcement. Nanocomposites were fabricated by powder metallurgy processing followed by Spark Plasma Sintering (SPS) consolidation. Transmission electron microscopy (TEM) and XRD of synthesized powder showed WS2 nanoparticles were synthesized successfully. Microstructural properties of nanocomposites were investigated using optical microscopy (OM), field emission scanning electron microscopy (FESEM) and energy dispersive spectroscopy (EDS). Nanoparticles were well distributed in the aluminum matrix and have a good dispersion. The presence of nanoparticles in the matrix reduces the size of the grain less than 20 µm so that the size of the grain becomes smaller by increasing the amount of nanoparticles .The density of the sample showed that the nanocomposite had a very good compressibility and relative density reach to near 99% in 4wt. %WS2. Hardness and compressive strength of nanocomposites were evaluated. Mechanical evaluations indicated that, the increase in weight fraction of WS2 nanoparticles, resulted in improvement of hardness and compressive strength of aluminum. Concentration of tungsten disulfide nanoparticles has a direct effect on increasing the mechanical properties of nanocomposite. The compressive strength increased up to 120 MPa, about twice the base metal, and the hardness raised up to 30%. Manuscript profile -
Open Access Article
11 - Synthesis of nanostructured bornite by mechanical alloying and investigate the effect of co-doping Zn and Co on its thermoelectric properties
Ahmad Ostovari Moghaddam Ali ShokuhfarTo improve current solid state thermoelectric devices, high performance materials based on safe and abundant elements is required. Here, the thermoelectric properties of Cu5-2xZnxCoxFeS4 (0 ≤ x ≤ 0.06) nanostructured samples were investigated. First, Cu5-2xZnxCoxF MoreTo improve current solid state thermoelectric devices, high performance materials based on safe and abundant elements is required. Here, the thermoelectric properties of Cu5-2xZnxCoxFeS4 (0 ≤ x ≤ 0.06) nanostructured samples were investigated. First, Cu5-2xZnxCoxFeS4 nanoparticles were synthesized by high energy ball milling and then consolidated into pellets by hot pressing. X-ray diffraction (XRD) analysis was employed for structural study, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used for microstructural analysis, and the thermoelectric properties were evaluated by electrical conductivity and thermal conductivity measurements. XRD data revealed that the crystal structure of the materials to be consistent with a pure bornite phase up to x = 0.04 for Cu5-2xZnxCoxFeS4. The power factor of un-substituted sample was 0.25 mWm-1K-2 which decrease after Co and Zn substitution. Concurrent substituting of Co and Zn for Cu in the range of 0.02 ≤ x ≤ 0.04 changed the p-type conduction of bornite to n-type at room temperature and up to 527 K. Extremely low thermal conductivities of k < 0.30 Wm-1K-1 were obtained for all double substituted samples as a results of the significant mass and strain field fluctuations and the nanostructured nature of the samples. The highest ZT value of 0.35 was attained for x = 0.06. Manuscript profile -
Open Access Article
12 - Effect of Graphite on the Mechanical Properties and Tribological Behavior of Aluminum Matrix Nanocomposite
Elham Bakhshizade Ali Shokuhfar Ashkan Zolriasatein Mehdi KhodaeiThis study aims to compare the effect of graphite content (0–5 wt.%) on the mechanical and ‎tribological properties of aluminum matrix nanocomposites. The bulk samples were prepared ‎by the mechanical milling/hot pressing (temperature 420 °C/ pressure MoreThis study aims to compare the effect of graphite content (0–5 wt.%) on the mechanical and ‎tribological properties of aluminum matrix nanocomposites. The bulk samples were prepared ‎by the mechanical milling/hot pressing (temperature 420 °C/ pressure 400 MPa/ time 1h) ‎process. According to the obtained results in this work, the addition of graphite to an ‎aluminum matrix significantly improves the wear properties of aluminum (wear rate and ‎coefficient of friction). The best wear performance was obtained with the sample containing ‎‎5wt.% graphite, which showed a 62% reduction in the wear rate and a 2.5-fold reduction in ‎coefficient of friction compared to the unreinforced aluminum sample. Although increasing ‎the amount of graphite in the range of 0-5 wt.% leads to a continuous improvement in the ‎wear behavior of the composite material, it results in a simultaneous deterioration of the ‎mechanical properties (hardness and compressive strength) and the density of the Aluminum- ‎Graphite composites.‎ Manuscript profile