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Open Access Article
1 - 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
2 - Investigation of hydrogen desorption temperature of MgH2-10wt% (Ti, Mn, V and Fe) nanocomposite produced by mechanical alloying
حسین محمدی سید جمال حسینی پور محمد رجبیMagnesium hydride is one of the attractive hydrogen storage materials because of its hydrogen storage capacity (7.6 wt %), low cost and light weight. However, high hydrogen desorption temperature and a high reactivity toward oxygen limit the use of MgH2 in practical app MoreMagnesium hydride is one of the attractive hydrogen storage materials because of its hydrogen storage capacity (7.6 wt %), low cost and light weight. However, high hydrogen desorption temperature and a high reactivity toward oxygen limit the use of MgH2 in practical applications. Many efforts have focused on Mg-based hydrides in recent years to reduce the desorption temperature. These can be accomplished to some extent by changing the microstructure of the hydride by mechanical alloying and also by using proper catalysts. In this work, Ti, Mn, V and Fe elements were added to MgH2 either in the form of powder mixture or prealloyed powder and after 30 h mechanical alloying, the properties of obtained nanocomposites were investigated by X-ray diffractometery, scanning electron microscopy and thermal analysis. The results showed that the addition of prealloyed powder to MgH2 and 30 h mechanical alloying of powder mixture is more effective in dehydrogenation properties. Manuscript profile -
Open Access Article
3 - Investigation nitride coating surface properties and wear on the hot work tool steel AISI H11 in the method pulsed plasma nitriding
کیانوش طاهرخانی خیرالله محمدی حسین تارقلی زادهIn this research, the effects of plasma nitriding parameters investigated on samples with different geometry. Samples were prepared were nitrided under the atmosphere content of 20%H2-80%N2, at the temperature of 520 c, the duty cycles of 30%, 50%, 80% and with frequenc MoreIn this research, the effects of plasma nitriding parameters investigated on samples with different geometry. Samples were prepared were nitrided under the atmosphere content of 20%H2-80%N2, at the temperature of 520 c, the duty cycles of 30%, 50%, 80% and with frequencies of 10 kHz for 6 hours. Then the property of grooves surfaces investigate by experiments of the SEM, Roughness and Micro Hardness measurement. The results of the experiments showed that the surface of the plasma nitriding samples are covered by cauliflower form of particles that formation of this particles in plasma nitriding samples are due to sputtering of the surface during the process. With increasing thickness of the groove, frequency and duty cycle, roughness of surfaces raise. Also micro hardness rise with increasing the thickness of the groove and duty cycle resulting from the increase in percent of deposition particle nitride. The Hollow cathode phenomena occurred in sample with 2mm groove and 80% duty cycle in CPN. This will result in over heating of the sample which leads to a decrease hardness of the surface and an increasing in the Roughness of the surface. Then after the process plasma nitriding, the results of the pin on disk wear test showed that the nitrides coating have wear resistance better than the reference sample before treatment plasma nitriding. Manuscript profile -
Open Access Article
4 - Investigating the Effect of Al Temper type on Microstructure and Mechanical properties of Al 6061/Mg AZ31 alloys Diffusion Bonded Joint
مجتبی جعفریان علیرضا خدابنده مرتضی جعفریانIn this study, the effect of Al alloy temper type on the microstructure and mechanical properties of Al 6061 (T6,O) and Mg AZ31 (O) were investigated. The interface of joints was investigated by optical microscope (OM) and Scanning Electron Microscope (SEM) equipped wit MoreIn this study, the effect of Al alloy temper type on the microstructure and mechanical properties of Al 6061 (T6,O) and Mg AZ31 (O) were investigated. The interface of joints was investigated by optical microscope (OM) and Scanning Electron Microscope (SEM) equipped with EDS and Linescane analysis. Mechanical properties of joints were measured by using a Vickers microhardness and shear strength tests. According to the results, in Al 6061-O/Mg AZ31 joint, less plastic deformation in the Mg alloy, further diffusion rate of Mg atoms in the Al alloy and the formation of diffusion region with the lowest amount of microhardness (140 HV) and the highest amount of shear strength (32 MPa) was occurred compared to Al 6061-T6/Mg AZ31 joint. Evaluation of fracture surfaces indicates the occurrence of the failure in brittle phase of Al3Mg2. Manuscript profile -
Open Access Article
5 - Preparation of polystyrene – multi walled carbon nanotube nanocomposite with improved mechanical properties using response surface methodology
مریم فربودی مهیا ترابیIn this research, with the aim of improving mechanical properties of polystyrene (PS), multi walled carbon nanotube (MWCNT) was selected as reinforcement agent. PS-MWCNT nanocomposite was prepared by mixing of MWCNT nanostructurs with a solution of PS. The effects of th MoreIn this research, with the aim of improving mechanical properties of polystyrene (PS), multi walled carbon nanotube (MWCNT) was selected as reinforcement agent. PS-MWCNT nanocomposite was prepared by mixing of MWCNT nanostructurs with a solution of PS. The effects of three factors containing MWCNT percentage, film drying temperature and stirring time were investigated in different levels by Box Behnken design of response surface methodology (RSM). According this method, 15 experiments were performed. The tensile strength values of nanocomposite films were used as response for data analyzing by variance analysis. The linearity of normal probability plot of the residuals established the correctness of the proposed model. The contour and surface plots of RSM were studied and the optimal conditions of nanocomposit preparation were determined. The results showed that increasing of MWCNT percentage and stirring time cause to increase of tensile strength, while the increasing of film drying temperature causes to decrease of tensile strength. Also, some physicochemical properties of the nanocomposite film were examined using FT-IR spectroscopy and TGA techniques. Manuscript profile -
Open Access Article
6 - Investigation of kinetics behavior high temperature isotherm oxidation MCrAlY coatings applied by HVOF method
Seyed sina khalifeh soltani Reza ebrahimi kahrizsangi Farid naeimiToday, in Power plant industry, especially gas turbine hot corrosion and oxidation resistance of high temperature superalloys used. These superalloys good resistance to attack and entry of hot gases and ash fines resulting from fuel combustion, as well as atmospheric co MoreToday, in Power plant industry, especially gas turbine hot corrosion and oxidation resistance of high temperature superalloys used. These superalloys good resistance to attack and entry of hot gases and ash fines resulting from fuel combustion, as well as atmospheric corrosion of the show. As a result of these superalloys used in Power plant industry, especially are considering today. The thermal spray coating on these superalloys can be hot corrosion resistance and high temperature oxidation increase. In this research isothermal oxidation behavior of CoNiCrAlY coating and kinetic of growth thermally grown oxide layer (TGO) was investigated. For deposit of the CoNiCrAlY Amdry 9954 coating on superalloy nickel-base (Inconel 738) substrate used to the high-velocity oxygen-fuel (HVOF) technology. These specimens coatings were oxidized at 1100°C for 5 upto 100 h in a normal electric furnace under air atmosphere. The test specimens were examined using scanning electron microscope (SEM) and energy dispersive spectrometry analysis (EDS) together with the X-ray diffraction (XRD) analysis. Microstructural characterization showed that the growth of continuous and uniform TGO scale onto bond coat. Also, in oxidation process observed the formation of mixed oxides (as spinel) CoCo2O4 and Ni(Cr,Al)2O4 and CrO3 and Y3Al5O12 onto Al2O3 (TGO layer). Manuscript profile -
Open Access Article
7 - Fabrication of in situ Al-Ni surface composite on 2024 aluminum alloy by friction stir processing
ابراهیم بهرامی مرتضی شمعانیان حسین ادریسIn this research, in situ Al-Ni surface composite produced on 2024 aluminum alloy using friction stir processing (FSP). FSP performed at a tool rotating rate of 1250 rpm and travel speed of 24 mm/min with and without nickel powder. Metallographic images show that the gr MoreIn this research, in situ Al-Ni surface composite produced on 2024 aluminum alloy using friction stir processing (FSP). FSP performed at a tool rotating rate of 1250 rpm and travel speed of 24 mm/min with and without nickel powder. Metallographic images show that the grain size after FSP has reached about 30% of primary metal grain size. With the addition of nickel powder, intermetallic compound of Al3Ni is formed in situ. Micro-Vickers test demonstrates that the reinforcement particles (Ni) have uniform distribution near the surface of primary metal. After FSP, primary metal hardness of about 54 vickers reached to in its maximum value of 120 vickers and 129 vickers in stir zone without and with addition of nickel powder, respectively. The results show that the fabrication of in situ composite using FSP has improved the wear resistance of the primary metal. Manuscript profile -
Open Access Article
8 - Electrophoretic deposition of SiC nanoparticles
علی گلشنی عجب شیر حسین آقاجانی محمد جعفرپور سهند بهرنگیThe aim of this research is to investigate the stability of SiC nanoparticles for deposition on C/C composite by EPD method. Thus, different suspensions were prepared with different solvents and in presence of PEI as dispersant. The stability of suspensions was studied MoreThe aim of this research is to investigate the stability of SiC nanoparticles for deposition on C/C composite by EPD method. Thus, different suspensions were prepared with different solvents and in presence of PEI as dispersant. The stability of suspensions was studied by using their macroscopic pictures after 24 h, and measurement of zeta potential values and particle size distribution. Thereafter, the coating was applied onto the substrate using the optimized suspension. The results showed that the suspension prepared in ethanol, with pH=10 and addition of 6 wt% PEI has the best stability. Also, SEM micrographs revealed that the coating applied with the voltage of 30 V results in a better quality and has a uniform and pitiless surface. Manuscript profile -
Open Access Article
9 - The effects of deposition variable on the pulse electrodeposition FeNi-WC nanostructure composite
آمنه وحیدیان علی سعیدی محمد علی گلعذارThe increasing demand for magnetic materials in the industry has led to the production of Fe-Ni composite magnetic alloys with ceramic particles. In this research, FeNi-WC nanostructure composite was produced using pulse electrodeposition. The effects of pH, current den MoreThe increasing demand for magnetic materials in the industry has led to the production of Fe-Ni composite magnetic alloys with ceramic particles. In this research, FeNi-WC nanostructure composite was produced using pulse electrodeposition. The effects of pH, current density and the amount of reinforcement on composition and morphology of products were examined, because morphology and chemical composition and structure of samples were studied by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) and X-ray diffraction analysis (XRD). The result showed an increasing pH, increased slightly nickel and decreased iron, and spherical morphology led to change star one. Due to importance of energy saving, effects of variables on the efficiency parameters such as the current efficiency and specific energy consumption were studied. By increasing pH, current efficiency was increased and specific energy consumption was reduced. When the current density increased, current efficiency was reduced and specific energy consumption was increased. In general, more current density (100 mA/cm2) and lower reinforcement (5 g/L) was observed more uniform morphology. Manuscript profile -
Open Access Article
10 - Study the phase transformation of Ti-6242 alloy and Determination the beta-transus temperature
علیرضا حجاری مریم مرکباتی رامین حسینی یاور منصوری مهدی عباسیThe aim of this research is to determine the beta transus temperature of two Ti-6242 alloys and to study the effect of different amount of alloying elements on alpha and beta phase stabilization by microstructural observation and hot torsion test. Determination of beta MoreThe aim of this research is to determine the beta transus temperature of two Ti-6242 alloys and to study the effect of different amount of alloying elements on alpha and beta phase stabilization by microstructural observation and hot torsion test. Determination of beta transus temperature has an important influence on designing thermomechanical and heat treatment cycles of titanium alloys. Hence, this is an effective parameter to control mechanical properties of two phase titanium alloys. In this regard, hot torsion tests were performed at temperature range of 960 °C to 1090 °C using the strain rate of 0.001 s-1 by cooling with the rate of 0.5 °C/s. besides, in order to deduce the temperature of grain boundary alpha phase nucleation and microstructural evolution, the specimens were heat treated at temperature range of 980 °C to 1020 °C for 40 minute and water quenched. It was found that, 10 % increase in Aleq/Moeq ratio, makes a 5 °C increase in beta transus temperature of the Ti-6242 alloy. Accordingly, this temperature was estimated in the temperature range of 1000 °C to 1010 °C for these alloys. Furthermore, there is a 10 °C deviation in the hot torsion test results and microstructural analysis, which is attributed to dynamic strain-induced transformation phenomenon. Manuscript profile -
Open Access Article
11 - The effect of addition nano boron carbide on the mechanical properties and pressurless sintering of B4C-5% vol TiB2 composites
Nahid Ahmadi Hamaidreza Baharvandi Naser EhsaniIn this study the effect of the addition of nano boron carbide on mechanical properties and sintering behavior of B 4 C-TiB 2 composite has been investigated. 0, 7, 14 and 20 wt% nano boron carbide were added to the starting powder and sintered by pressurless sinte MoreIn this study the effect of the addition of nano boron carbide on mechanical properties and sintering behavior of B 4 C-TiB 2 composite has been investigated. 0, 7, 14 and 20 wt% nano boron carbide were added to the starting powder and sintered by pressurless sintering at 2200 ° C. Under the experimental conditions of this study, the maximum properties of boron carbide composite with 20 wt% nano boron carbide was obtained so that the relative density equal to 97/2 %, micro- hardness was 31/9 GPa, and fracture toughness was 3/59 MPa.m 1/2 . Manuscript profile
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