Iranian Journal of Materials science and Engineering
Volume:14 Issue: 4, Dec 2017

Ion conducting gel polymer electrolytes based on poly acrylonitrle (PAN) complexed with different weight percent ratios of Sodium Fluoride (NaF) salt were prepared by using solution cast technique. Structural characterization was performed using X-ray diffraction (XRD) technique and Fourier transforms infrared (FTIR) spectroscope technique. From the X-rd results increase in amorphous phase with the increase of dopant salt concentration was observed. Fourier transform infrared (FTIR) spectroscopic analysis confirmed the complexation of the salt with the polymer matrix. Electrical conductivity was measured that the magnitude of ionic conductivity increased with the increase in the salt concentration as well as temperature. The surface morphology was observed by using Scanning Electron Microscope (SEM), the optical band gap measured from UV-Vis Spectroscopy. The sample containing 30 wt% of NaF exhibited the highest conductivity of 1.82x10-4 S cm-1 at 303K and 2.96x10-3 S cm-1 at 373K. The temperature dependence of ionic conductivity of these films followed Arrhenius relation. Transference number measurements were carried out to investigate the nature of the charge transport species in the polymer electrolyte systems. The transference number data showed that the charge transports in these systems are predominantly due to ions. Using these polymer electrolyte films, electrochemical cells were fabricated and their discharge characteristics were studied. Various cell parameters, such as open circuit voltage, short circuit current, power density and energy density were determined.

Formation of stray grain defects particularly around re-entrant features of the turbine blade airfoils is one of the major problems in directional and single crystal solidification processes. In this work, directional solidification tests of the GTD-111 Ni-based superalloy were conducted at different withdrawal velocities of 3, 6 and 9 mm.min-1 using various stepped cylindrical and cubic designs. The process was also simulated using ProCAST finite element solver to characterize the crystal orientations. The phase transformation temperatures of the superalloy were estimated by the differential scanning calorimetry test. A process map was developed to predict the formation of stray grains in the platform regions of the stepped cylindrical and cubic specimens using the experimentally-validated simulation model. The process map shows critical values of the platform size, withdrawal velocity and initial sample size for the stray grain formation. The withdrawal velocity, platform size and initial sample size all had an inverse effect on the formation of stray grains.

Effects of annealing treatment after equal channel angular pressing (ECAP) on the interface properties and shear bond strength of Al/Cu bimetallic rods were investigated. For the as-deformed samples, the one with two passes of ECAP indicated higher shear bond strength. Formation of a layer of intermetallic compounds after annealing treatment is confirmed. In general, by increasing annealing temperature, thickness of intermetallic compounds at the interface increases. Shear bond strength was initially reduced by annealing at 200, 250 and 300 ͦ C and increased at 350 ͦ C. With further increase in annealing temperature to 400 ͦ C, shear bond strength slightly decreased which is correlated to the increased thickness of the intermetallic compounds.

The inhibition performances of nafcillin (III), methicillin (II) and penicillin G (I) on the corrosion of copper in HCl was studied and tested by weight loss, Tafel polarization, SEM, UV-vis spectrophotometry, molecular dynamics method and quantum chemical calculations. Polarization curves indicated that the studied inhibitors act as mixed-type inhibitors. The values of inhibition efficiency and surface coverage were found to follow the order: Blank ads, indicated that the adsorption of three inhibitors was a spontaneous process. The SEM micrographs confirmed the protection of copper in a 1 M HCl solution by penicillin G, nafcillin, and methicillin. The shape of the UV/vis spectra of inhibitors in the presence of the immersion of Cu showed a strong support to the possibility of the chemisorbed layer formation on Cu surface by nafcillin (between nafcillin and Copper) and physisorption between penicillin and methicillin with copper. DFT calculations were performed to provide further insight into the inhibition efficiencies which were determined experimentally. Molecular dynamics (MD) simulations were applied to find the most stable configuration and adsorption energies of penicillin G, nafcillin and methicillin molecules on Cu (110) surface. The interaction energy followed the order: nafcillin (III)> methicillin (II)> penicillin G (I), which confirmed that nafcillin has the strongest interaction with the metal surface. The obtained results from experimental and theoretical methods were in reasonable agreement.

The redox behavior for bulk and nano silver nitrate (NSN) were studied by cyclic voltammetry technique in absence and presence of cefdinir antibiotic (CFD) using glassy carbon electrode (GCE) in 0.1 M KNO3 as supporting electrolyte at two different temperatures. Scan rates were studied for the redox reactions of bulk and nano silver nitrate (NSN) in absence and presence of cefdinir antibiotic (CFD) and mechanism of the electrode reactions were discussed. The stability constant of complexation and thermodynamic parameters for a system were evaluated

Recently, magnesium and its alloys have attracted great attention for use as biomaterial due to their good mechanical properties and biodegradability in the bio environment. In the present work, nanocomposites of Mg - 5Zn - 0.3Ca/ nHA were prepared using a powder metallurgy method. The powder of Mg, Zn and Ca were firstly blended, then four different mixtures of powders were prepared by adding nHA in different percentages of 0, 1, 2.5 and 5 %wt. Each mixture of powder separately was fast milled, pressed, and sintered. Then, the microstructure and mechanical properties of the fabricated nanocomposites were investigated. The XRD profile for nanocomposites showed that the intermetallic phases of MgZn2, MgZn5.31 and Mg2Ca were created after sintering and the SEM micrographs showed that the grain size of nanocomposite reduced by adding the nHA. The nano composite with 1wt. % nHA increased the density of Mg alloy from 1.73 g/cm3 to 1. 75 g/cm3 by filling the pores at the grain boundaries. The compressive strength of Mg alloy increased from 295MPa to 322, 329 and 318MPa by addition of 1, 2.5 and 5wt. % nHA, respectively.

Finite element simulation of stretch flanging process was carried out in order to investigate the effect of process parameters on maximum thinning (%) in stretch flanging process. Influences of initial flange length, punch die clearance, width of sheet metal blank and blank holding force were investigated on maximum thinning (%). Finite element simulation was done using FEM software package ABAQUS. Sheet metal blanks of AA 5052 were utilized for numerical simulation of stretch flanging process. Mesh convergence study was carried out to ascertain the accuracy of present FEM model. It is found that circumferential strain and shell thickness decreases with decrease in initial flange length and punch-die clearance while both decreases with increase in blank-holding force. Radial strain increases with decrease in initial flange length and punch-die clearance and with increment in blank-holding force and width of sheet. It is found that width of sheet metal blank and blank holding force have greater influence on maximum thinning (%) as compared to initial flange length and punch die clearance.

Hardened nickel coating is widely used in many industrial applications and manufacturing processes because of its benefits in improving the corrosion fatigue life. It is clear that increasing the coating thickness provides good protection against corrosion. However, it reduces the fatigue life. Thus, applying a thin layer of coated nickel might give an acceptable corrosion protection with minimum loss of the fatigue life. In the present study, the effects of hardened nickel coating with different thicknesses on the fatigue behavior of CK45 mild steel were experimentally investigated. After conducting the experimental tests, we carried out two different modeling approaches of finite element method (FEM) and artificial neural network (ANN). In the FEM modeling, an attempt was made to analyze the fatigue of the components by modeling the interface phase between the base metal and coating more accurately and using the spring elements; ANNs were developed based on the back propagation (BP) error algorithm. The comparison of the obtained results from FEM and ANN modeling with the experimental values indicates that both of the modeling approaches were tuned finely.