فهرست مطالب

Advanced Materials and Processing - Volume:5 Issue: 2, spring 2017

Journal of advanced materials and processing
Volume:5 Issue: 2, spring 2017

  • تاریخ انتشار: 1396/05/17
  • تعداد عناوین: 8
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  • Mohsen Nouri, Parvin Alizadeh, Majid Tavoosi * Pages 3-10
    The structural and optical characterization of bulk GeO2-PbO glasses was the goal of this study. In this regard, six different (100-x)GeO2-xPbO (15
    Keywords: Germinate glass, Anomalous behavior, Optical glasses, Optical Properties
  • Akbar Heidarpour *, Saeed Ahmadifard, Shahb Kazemi Pages 11-24
    In the present study, Al5083- Al2O3 nanocomposite was successfully prepared by friction stir processing (FSP) with rotational speed of 710 rpm and travel speed of 14 mm/min. In order to improve distribution of Al2O3 particles, a net of holes were designed on the surface of Al5083 sheet. The samples were characterized by optical and scanning electron microscopy (SEM), microhardness, tensile and wear tests. Results showed that FSP is an effective process to fabricate Al5083- Al2O3 surface nanocomposite. Microstructural observation demonstrated fine and equiaxed grains and homogenous distribution of Al2O3 nanoparticles in the stir zone (SZ). The presence of Al2O3 nanoparticles lead to a decrease in the grain size from 45 to 7 μm and an increase in microhardness from 80 to 140 Hv and tensile strength from 280 to 335 MPa. Wear test results showed improved wear resistance due to its higher hardness and the mode of wear in the all samples was abrasive.
    Keywords: Friction Stir Processing, Nanocomposite, Microhardness, Grain refinement, Wear
  • Behrooz Shayegh *, Nima Zaghian Pages 25-37
    In this study the effect of crystallite size reduction and microstructure on the electrochemical corrosion behavior of nanocrystalline nickel (NC Ni) were investigated using Tafel polarization and electrochemical impedance spectroscopy (EIS) measurements in 10 wt.% NaOH. NC Ni coatings were produced by direct current electrodeposition using chloride baths in presence and absence of saccharin as a grain refining agent. The crystallite size of NC surface coatings was calculated and analyzed by X-ray diffractometry (XRD). Field emission scanning electron microscopy (FE-SEM) and atomic force microscopy (AFM) were used to study coatings microstructure. The chemical composition of NC surfaces was determined using X-ray energy dispersive spectroscopy (EDS). Our results showed Saccharin decreased the crystallite size but increased the grain size. In addition, corrosion resistance of NC Ni in presence of saccharin increased, which is ascribed to the formation of more stable and protective film. The behavior of passive film growth and corrosion were discussed.
    Keywords: Electrodeposition, Nanocrystalline Ni, Passivation, Corrosion resistance, Microstructure
  • Siroos Ahmadi *, Vali Alimirzaloo, Meysam Abdollahzade Gavgani Pages 38-51
    Defects of the roll forming process are affected by amount and situation of the strains distribution. The effect of the process parameters on the strain distribution in the round cross section roll forming process has been studied. Finite element and response surface method have been used for process modelling. Then desirability functions approach and overlaid counter plots have been employed for optimization of the process. Three factors included roll diameter, distance between the stations and linear speed of the sheet are considered as input parameters. Sum of longitudinal maximum strain and transverse strain distribution uniformity were taken as response functions. Response function model for each function was obtained using the RSM. Finally, optimization of the process has been done using the desirability function approach and overlaid contour plots .Results show that both of the response surface models have good model adequacy. Optimization by desirability functions approach was presented as points which according to the type of the process and production requirements can only be used to start and preliminary design. But the overlaid contour plots have flexibility in output for manufacturing processes. Output overlaid contour plots provide optimum area that there is wide range of values for choices in different condition.
    Keywords: Roll forming process, Strain distribution, Finite element method, Response surface method, Desirability function
  • Abbas Fahami *, Majid Abdellahi Pages 52-60
    This study focuses on the estimation of the mean grain size of mechanically induced Hydroxyapatite (HA) through the artificial neural network (ANN) model. The mean grain size of HA and HA based nanocomposites at different milling parameters were obtained from previous studies. The data were trained and tested by the neural network modeling. Accordingly, all data (55 sets) were based on the mechanically alloying process and were randomly divided into 40 sets for training and 15 sets for testing data, respectively. The data used in the multilayer feed forward neural networks models and input variables of models were arranged in a format of 13 input parameters. The results indicated a very good agreement between the experimental data and the predicted ones. R2 value of the trained and tested suggested model confirmed this situation. Given the broad range of the parameters used, it was found that our analysis and model were fully functional to accurately estimate the optimal conditions for experiments. This shows the potential application of these calculations and analysis in a wide range of numerical studies.
    Keywords: Articial neural network, Mechanical alloying, Hydroxyapatite, Bioceramics
  • Lahcen Mountassir *, Touriya Bassidi, Hassan Nounah Pages 61-74
    The object of this research is to characterize the porous bones by an ultrasonic method using Lamb waves. In recent years, the characterization of such materials has attracted many authors and takes a perfect place in the field of medicine. It requires the development of more efficient technology for getting the necessary quality and security. This paper aims to exploits the dispersion curves of the Lamb wave, as a new originate alternative, to characterize the porous bone. The method used in this work is modeled using the Schoch theory for the measurement of the ultrasonic parameters, namely the longitudinal and transversal velocities, and densities, then we deduce the mechanical properties of samples with different porosity in a theoretical way. The theoretical results were compared with experimental data, and it is found that the predicted values were of the same order of measurement as experimental measurements. The correlation coefficient between the experimental ultrasound velocities and the theoretical velocities predicted by Schoch theory was R=0.96.
    Keywords: Bone, Porous materials, Elastic properties, Lamb waves, Ultrasound
  • M. M. Samandari, S.H.R. Torabi, Ghader Faraji * Pages 75-86
    Deformation of the material during cyclic expansion extrusion (CEE) is investigated using upper-bound theorem. The analytical approximation of forming loads agrees very well with the FEM results for different amounts of chamber diameter, friction factor and also for lower die angles. However, the difference between analytical and numerical solution increases at higher die angles which are explained by the formation of dead-metal zones at these angles. The results show that the forming load increases at higher friction coefficients, higher chamber diameters and lower amounts of corner fillet radius, but for the die angle there is a maximum value of laod at about 60o. Forming load enhanced by the increase of the die chamber diameter and friction factor. Increasing the die chamber diameter causes to higher strains and, therefore, higher rate of homogenous work. The load decreased slightly by an increase of die corner radius because of the lower and more homogeneous strain distribution in the material.
    Keywords: Severe plastic deformation, Cyclic expansion extrusion, Upper bound analysis, Finite element method
  • Sedigheh Abbasi *, Farid Nourivatan Pages 87-98
    In this paper, we investigated the statistical analysis of thermal conductivity of nanofluids containing of decorated Ag nanorods with Cu nanoparticles. For this purpose Ag-Cu hybrid is synthesized and characterized using transmission electron microscopy (TEM) and X-ray diffraction pattern (XRD). TEM image shows that Cu nanoparticles successfully decorate on the outer surface of Ag nanorods. The XRD pattern of decorated Ag nanorods with Cu nanoparticles reveals that Ag-Cu hybrid is displayed both the peaks assigned to the Ag and Cu, respectively. Investigation the effect of temperature and mass fraction on thermal conductivity of nanofluids show that the thermal conductivity of all nanofluids increases with temperature and mass fraction. The results of the statistical analysis of thermal conductivity confirm that there is a significant difference among five temperatures and three tested weight fractions for thermal conductivity of all nanofluids. However the influence of temperature is more significant than that of mass fraction.
    Keywords: Ag-Cu hybrid, Decoration, Thermal Conductivity, Statistical analysis