JOURNAL OF ADVANCED MATERIALS AND TECHNOLOGIES
Year:2016 | Volume:5 | Issue:1|Papers Count:8

Dissimilar 6061Al alloy/DP590 dual phase steel joints were fabricated using friction stir spot welding. The influence of rotation speed and dwell time on the feasibility of sound joints were examined by microstructural and mechanical evaluations. Microstructural examinations by optical and scanning electron microscopy exhibited fine grains structure in the stir zone of aluminum and dominant ultrafine ferrite grains with mean grain size of less than a micron and minor martensite at ferrite grain boundaries in the steel side. In addition, an intermetallic component layer was produced along the joint interface; its thickness was a function of process parameters. The tensile-shear strength of the joint was initially found to increase with increasing of tool rotation speed at constant dwell time and then decrease with further increasing. Same trend was observed with increasing of dwell time at constant tool rotation speed. Tensile-shear strength is influenced by the thickness of the intermetallic layer. A maximum tensile-shear strength of 205MPa was achieved for the joint produced using tool rotation and dwell time of 2000rpm and 4s, respectively; this is higher than the shear yield strength of 6061-T6 Al.

In this research, deposition pattern of tin oxide nanoparticles in acetone media under non-uniform AC electric fields on planar gold electrodes have been studied. Particle size is one of the basic parameters affecting the electrokinetic behavior of particles under applied electric fields. Based on deposition pattern observations, micron size particles were deposited on electrode surface at frequency of 10 kHz. In this study, Clausius- Mossotti factor was depicted for different particle sizes. It indicates that for coarse particles dielectrophoretic force is negative and for fine particles dielectrophoretic force is positive.

In this research, ZnxNi1-x(OH)2 nanostructured layered double hydroxide active materials were successfully synthesized by a chemical co-precipitation route using polyethylene glycol as the structure-directing reagent. Structural characterizations were performed using X-ray diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR), and morphology of materials was obtained by Field Emission Scanning Electron Microscopy (FESEM). The results show that the as-prepared materials have a porous structure with nanoscale walls and their crystal structure was mainly?-phase. Electrochemical experiments using cyclic voltammetry, galvanostatic charge-discharge and cyclability show that Zn0.33Ni0.67(OH)2 active material has the highest initial specific capacitance of 926 F g-1 at a current density of 1 A g-1 and a capacity retention of about 98% after 100 charge-discharge cycles.

In this study seven combination of Alumina and Zircon was selected by ratio of Alumina to Zircon of: 100.0, 85.15, 70.30, 45.55, 35.65, 20.80, 0.100. After weighing the powder raw material, mill for 24 hours and then were using press forming . The samples was sintered in temperatures of 1550, 1600 , 1650 . To identify the phases and percentage of phases formed, X -ray diffraction pattern produced parts were investigated. The effect of Alumina to Zircon ratio and sintered temperature on the formation of mullite and zircon phases were investigated. All samples porosity were measured and the effect of combination and temperature and the final phases on this characteristic were studied .The results showed that zircon improved alumina sintered body of alumina and zircon are also accelerate decomposition.

In this study, lead titanate nanopowder was synthesized using mechanical activation. Raw materials including titanium oxide powder (anatase) and Lead oxide (II) with a ball to powder weight ratio of 1:10 and the powder ratio of 1:1 were milled in a planetary ball mill for 30 hours. Then, they were heated at 800, 900 and 1000 C. The obtained nanopowder was investigated by field emission scanning electron microscope (FESEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). The UV absorption spectroscopy was used to calculate the energy gap. Photocatalytic activity of nanopowder by dye degradation of methyl orange under UV light was evaluated. The effects of various influential parameters including initial dye concentration, photocatalyst dose and pH on the dye decolorization were also optimized. The optimum value for initial dye concentration and photocatalyst dose, were 10 ppm and 0.042 g respectively. Also, the best rate of decolorization observed at pH=4. Our results showed that, the photocatalytic degradation of methyl orange dye in the presence of lead titanate nanopowder was done.

The purpose of this study, Alumina and Silicon carbide-based nano-composite processing is due to the special properties and wide applications of these nano-composites have attracted much attention in various industries. In this paper, the mechanical properties of Al2O3 -4.1% wt SiC nanocomposites sintered without pressure by adding a weight percent of nano-MgO has been studied .Nano powders of a-Al2O3, -SiC and MgO were used as starting materials in this study .At First, a certain amount of nano-powders Al2O3 - SiC for the first sample and Al2O3, b- SiC-MgO for a second sample to powder ratio of 20 to 1 by a planetary ball mill for 4 h speed 250 RPM mixture and the resulting powder Mesh 150 Mu passes and was calcined at 600 oC. The effect of MgO nano powder obtained samples for mechanical properties of nano-composites, Al2O3 - SiC were tested for hardness.

Titanium and its alloys have widely been used in orthopedic and dental applications due to their good corrosion resistance, good mechanical strength and low density. However, Ti alloys are bioinert when implanted in the body. To overcome this drawback and in order to improve their bioactivity properties, Hydroxyapatite (HA) coatings have been deposited on the surface of the Ti alloys using different synthesis strategies. In the present study, hydroxyapatite-Cu and hydroxyapatite-CuO nanocomposite coatings with different percentages of Cu and CuO (10, 20 and 30 wt.%) were deposited on Ti6Al4V using electrophoretic deposition (EPD). The surface morphology, composition, and microstructure of the nanocomposite coatings were investigated by scanning electron microscopy (SEM), and X-ray diffractometry (XRD), respectively. In addition, corrosion behavior coatings on Ti6Al4V in solution simulated body fluid at 37oc test was evaluated by polarization. Polarization test results showed that the applied coating improves the corrosion resistance of the substrate. HA-CuO coatings for corrosion resistance as well as greater coverage of the HA-Cu.

In this study for investigation of severe plastic deformation effect on microstructure of Ti-6Al-4V alloy the accumulative roll bonding (ARB) process applied up to four cycles (equivalent strain of 3.2) at 300 oC. X-ray Diffraction (XRD) test was done for study of phase variation and observations of grain size variations. The results shows after the end of first cycle of ARB, many variations in XRD patterns were made which are results of grain size and texture in material. In addition, variations in XRD pattern are very low, as a result of happening in dynamical recovery because of stacking fault energy high rate of this alloy. For investigating of microstructural alloy of optical microscopy and field emission scanning electron microscopy (FESEM) and for measuring of grain size of transmission electron microscopy (TEM) are used. The results shows that ultra fine grain structure are including b+a phases in fourth cycles of ARB and shall produce grain with about approximately 80 nm.