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Open Access Article
1 - Effect of heat treatment on mechanical properties, solidification structure and segregation of Inconel 625 alloy in additive manufacturing process by DLMD method
mohammad gavahian jahromi Reza Shoja Razavi hamed Naderi fareed kermaniIssue 1 , Vol. 18 , Spring 2024Direct metal laser deposition is using for rebuilding and manufacturing parts. In this method, it is imperative to check the melting and solidification conditions. In this research the effect of the primary process parameters on the microstructure has been investigated. MoreDirect metal laser deposition is using for rebuilding and manufacturing parts. In this method, it is imperative to check the melting and solidification conditions. In this research the effect of the primary process parameters on the microstructure has been investigated. Distance of the dendritic arms, and the segregation of alloy elements, to determine the mechanical properties of IN625. According to the examination of the scanning electron microscope image, by moving from the interface to the top of the cladding. The solidification structure changed from columnar dendritic to coaxial dendritic with decreased G/R ratio. From the interface to the sample’s surface, the cooling rate increased, and the spread between the dendritic arms decreased. By moving away from the interface, the distance of the dendritic arm increases. By changing the laser power from 250 to 450 watts, the G/R ratio decreased from 1252.08 ℃/〖mm〗^2 to 970.34℃/〖mm〗^2 . It was conducting heat treatment led to the uniformity of alloy elements in the background phase. Also, with heat treatment, tensile strength, and elongation increased and yield strength decreased. Manuscript profile -
Open Access Article
2 - Characterization and investigation of biocompatibility of bioactive glass 60 mol%SiO2-36 mol%CaO-4 mol%P2O5-5 mol%SrO containing zinc
Amirhossein Moghanian Noushin Nankali Morteza SaghafiyazdiIssue 1 , Vol. 18 , Spring 2024In this research, bioactive glasses 60mol%SiO2-36mol%CaO-4mol%P2O5-5mol%SrO containing 0, 5, and 8 mol% zinc were synthesized by sol-gel method, and the effect of adding ZnO microstructure, in vitro bioactivity and biocompatibility was investigated. To investigate the i MoreIn this research, bioactive glasses 60mol%SiO2-36mol%CaO-4mol%P2O5-5mol%SrO containing 0, 5, and 8 mol% zinc were synthesized by sol-gel method, and the effect of adding ZnO microstructure, in vitro bioactivity and biocompatibility was investigated. To investigate the in vitro bioactivity, glass powders were placed in the simulated body solution (SBF) for 14 days, and before and after the mentioned periods, the changes and process of hydroxyapatite (HA) phase formation on BGs surfaces, using characterization methods. Fourier transform infrared (FTIR), checking the release rate of different ions by inductively coupled plasma spectroscopy (ICP_AES), pH changes, and microstructure studies using a scanning electron microscope (SEM) were investigated. In the infrared Fourier transform spectroscopic analysis of the surface of the synthesized bioactive glasses after immersion in SBF solution, phosphate and carbonate bands were detected, indicating the synthesized glasses' bioactivity. Also, the scanning electron microscope images showed that the microstructure of HA created was spherical. Finally, among all the bioactive glasses synthesized in this research, S5Z5 bioactive glass was introduced as a new multi-functional biological bio-material in bone tissue engineering due to its osteogenic, biocompatibility, and bioactivity in vitro properties. Manuscript profile -
Open Access Article
3 - Production and characterization of WC-10Co-4Cr-xGr composite coating produced by thermal spraying method
mohammad razazi boroujeni Ayat Muayad Lafta Al Nidawi Farhad AzimifarIssue 1 , Vol. 18 , Spring 2024One of the most widely used methods to Improving the surface resistance of industrial parts is applying composite coatings such as WC-10Co-4Cr. But this coating, despite its excellent corrosion resistance, does not have a good tribological behavior compared to other tun MoreOne of the most widely used methods to Improving the surface resistance of industrial parts is applying composite coatings such as WC-10Co-4Cr. But this coating, despite its excellent corrosion resistance, does not have a good tribological behavior compared to other tungsten carbide base coatings. For this purpose, in this research, by adding graphite in two amounts of 7% and 14% by weight to WC-10C-4Cr powder and applying coatings by thermal spraying on the steel substrate, their tribological behavior was compared. Investigations were carried out with the help of SEM images, XRD test, roughness measurement and hardness measurement. Pin-on-disk test was also used to evaluate the wear resistance behavior of coatings and substrate. The results showed that despite the relative decrease in hardness and increase in the roughness of the tungsten carbide base coating, graphite leads to a significant improvement in the tribological behavior of the substrate and the tungsten carbide coating. Among the coatings, coating with 7% graphite It had the best wear resistance due to the combination of suitable hardness, low porosity and low friction coefficient. The wear mechanism of the coatings was also investigated with the help of SEM images and EDS analysis. It was found that the dominant mechanism of coatings containing graphite, dellamination and WC-10Co-4Cr coating was adhesive. The most important reason for increasing the tribological properties of coatings in the presence of graphite was the formation of a protective layer of these reinforcing particles in the wear path and around the pin. Manuscript profile -
Open Access Article
4 - Effect of Graphite on the Mechanical Properties and Tribological Behavior of Aluminum Matrix ‎Nanocomposite
Elham Bakhshizade Ali Shokuhfar Ashkan Zolriasatein Mehdi KhodaeiIssue 1 , Vol. 18 , Spring 2024This 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
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Open Access Article
1 - Synthesis of (CZTS) Cu2ZnSnS4 Nanoparticles by Hydrothermal Method for Solar Cell Application
Mahnaz karbassi Saeid Baghshahi Nastaran Riahi Noori Roozbeh Siavash MoakharIssue 2 , Vol. 15 , Autumn 2021Traditional photovoltaic devices for replacing fossil fuels have problems, including high construction and installation costs. Hence, there is now more focus on the new generation of solar cells, including solar tiles with higher efficiency and lower const. Due to the e MoreTraditional photovoltaic devices for replacing fossil fuels have problems, including high construction and installation costs. Hence, there is now more focus on the new generation of solar cells, including solar tiles with higher efficiency and lower const. Due to the emergence of nanolayers and the extensive advances in the selection of raw materials and devices for the application of this type of layers, in the present study, the preparation and achievement of optimal conditions for the main layer of solar tile has been considered. The best sample containing adsorbent layer film ink was obtained from CZTS and was made by solothermal method at 550 ºC. Using X-ray diffraction (XRD) and Raman spectroscopy analysis, phase studies of the synthesized samples as well as the identification of functional groups in the compounds were performed. Field emission scanning electron microscopy (FESEM) was used to study the surface morphology and the microstructure of the prepared inks. A UV-Vis spectrophotometer was used to analyze the ultraviolet-visible absorption spectrum. XRD analysis showed the formation of pure cassiterite as well as the presence of secondary phases of CZTS in some samples. and the results were confirmed by Raman spectroscopy. In the studies, the sample synthesized at 550 ºC with crystalline structure of cassiterite with suitable peak intensities was selected as the most suitable sample. FESEM microscopy showed that all samples of CZTS nanoparticles had a petal-like shape and with increasing temperature the petals bended. Finally the best conditions for the homogeneity of the morphological particles of the sample were observed at 550 ºC. Also, based on the results of the EDS, the sample with the highest weight percentage of copper and the lowest weight percentage of sulfur had priority in terms of application in solar cell structures, such characteristics were observed in the sample synthesized at 550 ºC. UV-Vis results showed that the optical cleavage band of CZTS nanoparticles in the best sample was 1.49 eV. In general, the results of the studies in this work showed the appropriateness of the solothermal synthesis method and also the effect of temperature on the final characteristics of the thin film, including the type of structure, morphology, transmition and energy bandgap. Manuscript profile -
Open Access Article
2 - Fabrication and evaluation of (chitosan / poly-vinyl-pyrrolidone) scaffold properties containing gum tragacanth by freeze-drying method
hamed ghomi Azadeh Sepyani Marjan MirhajIssue 1 , Vol. 14 , Summer 2020Chitosan as a component of the extracellular matrix is extensively investigated for preparation of porous scaffolds for tissue engineering. In this study, chitosan and (chitosan/polyvinylpyrrolidone) scaffolds as control and (chitosan/polyvinylpyrrolidone) / tragacanth MoreChitosan as a component of the extracellular matrix is extensively investigated for preparation of porous scaffolds for tissue engineering. In this study, chitosan and (chitosan/polyvinylpyrrolidone) scaffolds as control and (chitosan/polyvinylpyrrolidone) / tragacanth composite scaffolds with 25:75, 50:50, and 75:25 ratios were fabricated by the freeze-drying method. The effect of tragacanth on the structural and antibacterial properties of the samples was evaluated. Surface morphology, mechanical properties, porosity and functional groups on the surface of the samples were evaluated by scanning electron microscopy (SEM), compressive strength test, and FTIR. The results showed the porosity of scaffolds with tragacanth increased in comparison to scaffolds without tragacanth. Biodegradable behavior of the scaffolds was examined by retaining the samples in phosphate buffer solution (PBS) for 14 days and the results showed an increase in the degradation of the (chitosan/polyvinylpyrrolidone) / tragacanth scaffold with the ratio of 75:25. The results showed decreased growth of E.coli and Staphylococcus aureus bacteria in the presence of three-component scaffold with tragacanth. Therefore, according to the results of this study, tragacanth containing scaffolds improve antibacterial properties. Manuscript profile -
Open Access Article
3 - Optimization of HVOF thermal spraying parameters to improve the oxidation resistance of MCrAlY coating using Response
mostafa tahariIssue 3 , Vol. 11 , Winter 2017In this research, effects of different coating process parameters on the final properties of thermal spray coatings obtained from HVOF method are investigated. For this aim, five different levels are considered for four effective parameters (Fuel injection rate, oxygen MoreIn this research, effects of different coating process parameters on the final properties of thermal spray coatings obtained from HVOF method are investigated. For this aim, five different levels are considered for four effective parameters (Fuel injection rate, oxygen injection rate, powder injection rate and spray distance) on HVOF process by response surface method (RSM) and minimum porosity and minimum oxidation layer thickness are considered as the responses. To investigate the microstructure of coatings, Thermal Grown Oxide (TGO) thickness and porosity, a Scanning Electron Microscopy (SEM) and image analysis method are applied. Oxidation test has done at1100ºC for 50 hours on coated samples. Results show that (oxygen injection rate and powder injection rate), (fuel injection rate and powder injection rate), (powder injection rate and spray distance) have a reaction on each other in the TGO thickness value. Also, (oxygen injection rate and powderinjectionrate), (fuel injection rate and powder injection rate) have a little reaction on the porosity against the other parameters which haven’t any effect on it. Investigation of the coated sample with optimized parameters reveals that porosity of the coating is about 0.5% and TGO thickness is about 5.3 micrometer. Manuscript profile -
Open Access Article
4 - Influence of pH of Electroplating on Microstructure and Mechanical Properties of Ni-P-Tio2 Composite Coating Fabricated on AISI 430 Steel
Mina Afzali Grouh Morteza Zandrahimi Hadi EbrahimifarIssue 4 , Vol. 14 , Winter 2021One of the best ways to improve the abrasion resistance and toughness of stainless steels is to apply surface coatings. Among these coatings are nickel base alloy and composite coatings. In this research, nickel-phosphorus-titanium oxide coatings were developed using el MoreOne of the best ways to improve the abrasion resistance and toughness of stainless steels is to apply surface coatings. Among these coatings are nickel base alloy and composite coatings. In this research, nickel-phosphorus-titanium oxide coatings were developed using electrical plating technique and the effect of pH (3, 3.5 and 4) on microstructure and their wear and tear behavior were studied. In this research, nickel phosphorus-titanium oxide coating was deposited onto the AISI 430 steel using electrical plating technique and the effect of TiO2 particles concentration on microstructure and wear behavior was studied. X-ray analysis (XRD) was used to determine the available phases and calculate grain size. Characterization of the coating was performed using SEM (Scanning Electron Microscopy). The michardness was measured by Vickers microhardness device. To test the abrasion resistance of the phosphorus-titanium oxide coated and uncoated samples, a pin on the disk test was used. The results of X-ray analysis showed that the increase of pH causes the increase of grain size. Also the results of microhardness and pin on disk tests showed the increase of pH causes decrease of microhardness and abrasion resistance. The highest hardness (618.18 Vickers) was related to the coating created at pH =3 and TiO2 =40 gr / L. The highest wear resistance and lowest weight loss (0.15 mg) were also observed in the same coating. Manuscript profile -
Open Access Article
5 - Effect of Hydroxyapatite Nanoparticles on Differentiotion of Mesenchymal Stem Cells into Bone cells in Polycaprolacton/Keratin/Hydroxyapatite Scaffolds
Mahboobeh Mahmoodi Mina Kalantari Marjan MirhajIssue 1 , Vol. 14 , Summer 2020The human body process can spontaneously repair small bone defects, while large bone defects cannot be repaired without medical interventions. Efforts to eliminate these shortcomings have led to the foundation of bone tissue engineering. In this research, polycaprolacto MoreThe human body process can spontaneously repair small bone defects, while large bone defects cannot be repaired without medical interventions. Efforts to eliminate these shortcomings have led to the foundation of bone tissue engineering. In this research, polycaprolactone/keratin scaffold and Polycaprolactone/keratin/hydroxyapatite scaffold were fabricated using electrospinning method and were evaluated. Then, in order to evaluate the cellular differentiation, adipose tissue-derived mesenchymal stem cells were cultured on scaffolds and the process of differentiation of mesenchymal stem cells into bone cells for 7 and 14 days was investigated by alkaline phosphatase and alizarin red test. Increase of the activity of the enzyme alkaline phosphatase, the presence of the minerals and the red-orange-color extended on the scaffolds containing hydroxyapatite nanoparticles that confirmed the presence of Ca + 2 , demonstrated the differentiation of mesenchymal cells into bone cells. Therefore, the results of this study suggest that the polycaprolactone/keratin/hydroxyapatite scaffold is a suitable substrate for proliferation and differentiation of stem cells for bone tissue engineering. Manuscript profile -
Open Access Article
6 - Investigating the oxidation and electrical behavior of AISI 304 steel coated with cobalt for the application of solid oxide fuel cell
Mohammad Reza Ashorzadeh Morteza Zandrahimi Hadi EbrahimifarIssue 1 , Vol. 14 , Summer 2020Oxidation resistance and electrical conductivity of stainless steels used as interconnects in solid oxide fuel cells can be improved by using a conductive and protective coating layer. In this study, AISI 304 austenitic stainless steel was coated in a cobalt powder base MoreOxidation resistance and electrical conductivity of stainless steels used as interconnects in solid oxide fuel cells can be improved by using a conductive and protective coating layer. In this study, AISI 304 austenitic stainless steel was coated in a cobalt powder base pack mixture. Isothermal oxidation test was used to investigate the oxidation resistance of coated and non-coated steel. Area specific resistance (ASR) was also measured as a function of oxidation time at 800 °C. Microstructure of coated and oxidized samples was studied by scanning electron microscopy (SEM) and X-ray diffraction (XRD) device. The results showed that cobalt coated samples showed better oxidation resistance than non-coated samples. The results showed that increasing the temperature would increase the area specific resistance. The cobalt coating layer also converted to CoFe2O4, Co3O4 and CoCr2O4 spinels during the isothermal oxidation process. Cobalt spinels exhibited less ASR (27.4 mΩ cm2) compared to the uncoated sample (60.5 mΩ cm2). Manuscript profile -
Open Access Article
7 - Adsorption and Kinetics Studies of Heavy Metals Removal by MnO2 Modified Zeolite
Mehdi Irannajad Mehrdad Soleimanpour Hossein Kamran haghighiIssue 1 , Vol. 13 , Summer 2019Zeolites can be used as one of natural adsorbents for the removal of heavy metals. Treatment of natural zeolites with various chemicals enhances their removal capacity. In this study, manganese dioxide was used to activate the natural zeolite. The modified zeolite sampl MoreZeolites can be used as one of natural adsorbents for the removal of heavy metals. Treatment of natural zeolites with various chemicals enhances their removal capacity. In this study, manganese dioxide was used to activate the natural zeolite. The modified zeolite sample and several combinations of the synthetic wastewater were contacted together to adsorb heavy metals. The wastewater used contained heavy metal ions with various concentrations such as Cu2+, Cd2+, Zn2+, Co2+, Pb2+, and Ni2+. The adsorption isotherms of Langmuir, Freundlich, BET, and Temkin, as well as adsorption kinetic models, were used to develop models imaging the behavior of adsorption. The BET isotherm provides a model being more acceptable than the other isotherms; however, in term of the prediction of adsorption amounts (qe), its description is weaker than the Langmuir isotherm. Maximum adsorption capacities with respect to Langmuir parameters were obtained under optimal conditions as follows: Ni2+ (10.51 mg/g), Co2+ (14.87 mg/g), Zn2+ (8.97 mg/g), Cu2+ (10.59 mg/g), Cd2+ (13.69 mg/g) and Pb2+(40.65 mg/g). In addition, the pseudo-second kinetic model is more accurate than the pseudo-first order. Thus, the pseudo-second kinetic model was selected to describe the adsorption kinetics. Manuscript profile -
Open Access Article
8 - Efect of temperature on microstructure and intermetallic compound formation of Diffusion Bonded Mg/Al joints
Mohammad Ammar Mofid Mostafa Hajian Heidary Ehsan Loryaei Hatef ShakeriIssue 1 , Vol. 14 , Summer 2020The diffusion bonding of two dissimilar alloys Al 5083 and Mg AZ31 was carried out at 420,430.440 and 450 °C for bonding time of 60 min. In order to characterize the microstructure evolution in the joint zone, scanning electron microscopy (SEM), energy dispersive sp MoreThe diffusion bonding of two dissimilar alloys Al 5083 and Mg AZ31 was carried out at 420,430.440 and 450 °C for bonding time of 60 min. In order to characterize the microstructure evolution in the joint zone, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) were applied. The results show that joint formation is attributed to the solid-state diffusion of Mg and Al into Al 5083 and Mg AZ31 alloys followed by eutectic formation and constitutional liquation along the interface. At bonding temperature of 430°C diffusion induced grain coarsening was observed at the interface. With increase in bonding temperature, the atomic diffusivity increases, results in easier and speeder chemical bonding. In bonding temperature of 440°C the weld had an irregular shaped region in the weld center, having a different microstructure from the two base materials. The irregular shaped region contained a large volume of intermetallic compound Al12Mg17 and showed significantly higher hardness in the weld center. The present study suggests that constitutional liquation resulted in the intermetallic compound Al12Mg17 in the weld center. Manuscript profile -
Open Access Article
9 - Investigation of 6061 aluminum alloy pulsed laser welding based on the physical models for prediction of hot cracks
hossain ebrahimzadeh hassan farhangi seyed ali asghar akbari mousaviIssue 3 , Vol. 13 , Winter 2019It is necessary to use a physical model for the relationship between welding parameters and hot cracks. These models are available in micro, meso, and macro-scale. In this research, a sheet of 6061 aluminum alloy was welded by a Nd:YAG laser machine. For the first time, MoreIt is necessary to use a physical model for the relationship between welding parameters and hot cracks. These models are available in micro, meso, and macro-scale. In this research, a sheet of 6061 aluminum alloy was welded by a Nd:YAG laser machine. For the first time, the diameter of the dendritic arm spacing in the aluminum laser weld was measured and the results were compared with the solidification models. Contrary to the prediction of hot crack models, increasing the dendritic arm spacing, decreasing the solidification rate, and the reduction of the strain rate did not reduce hot cracking. However, based on the pre-existing models, preheating should reduce hot cracks, but inversely increases the amount of cracks. The images of high speed cameras and the assessment of crack surface by a field emission scanning electron microscopy showed that in pulsed laser welding, hot cracks will be created in three steps: 1) initiation 2) the first step of propagation 3) the second step of propagation. Propagation in the second step will occur in the newly solidified weak grain boundary of the weld metal. What is finally seen as a crack in the weld seam is the solidification and high temperature cracks and therefore, the models that are considered for continuous fusion welding are required to be modified based on the conditions of the pulsed solidification and melting and the fracture of weak grain boundaries after solidification should also be taken into account. Manuscript profile -
Open Access Article
10 - Fabrication and Characterization of Chitosan/ Polycaprolactone Core-Shell Nanofiber Scaffold Containing Platelet-Rich Fibrin by Coaxial Electrospinning Method for Biomedical Applications
AmirAbbas Rastegar Mahboobeh Mahmoodi Mohammad Mirjalili Navid NasirzadehIssue 2 , Vol. 15 , Autumn 2021Platelet-rich fibrin (PRF) is a natural fibrin matrix containing platelets and growth factors in the blood that increases the bone tissue repair. In this study, polycaprolactone/chitosan (scaffold A) and polycaprolactone/chitosan core-shell scaffold containing PRF (scaf MorePlatelet-rich fibrin (PRF) is a natural fibrin matrix containing platelets and growth factors in the blood that increases the bone tissue repair. In this study, polycaprolactone/chitosan (scaffold A) and polycaprolactone/chitosan core-shell scaffold containing PRF (scaffold B) were fabricated by uniaxial electrospinning and coaxial electrospinning methods, respectively and were characterized. Surface morphology, fiber diameter, porosity, mechanical properties, and functional groups on the scaffolds surface were evaluated by scanning electron microscope (SEM) and transition electron microscopy (TEM), displacement liquid method, tensile strength test, and fourier transform infrared (FTIR) spectroscopy, respectively. The average fibers diameter of the scaffold B decreased to 160 nm as compared to 179 nm for the scaffold A. Also, the presence of chitosan containing PRF in the core with the formation of hydrogen bonding with polycaprolactone in the shell of the scaffold B caused a scaffold with excellent mechanical properties and elastic modulus 40 MPa. Cell viability and adherence of bone cells on the surface scaffolds were evaluated via MTT assay. Due to the present of PRF in the scaffold B, the bone cells growth and cells adhesion on the surface of scaffold B increased compared to the scaffold A. Therefore, according to the results of this study, the core-shell scaffold containing PRF can be a good suggestion for use in biomedical applications. Manuscript profile
