JOURNAL OF ADVANCED MATERIALS AND TECHNOLOGIES
Year:2017 | Volume:6 | Issue:3 |Papers Count:9

In this paper, photocatalytic activity of mechanothermally synthesized Fe-39%FeS nanostructured composite powder is investigated. Fe and S powders mixture with atomic ratio of 2: 1 (Fe: S) is mechanically activated and then heat treated at 850◦C for 2 h. X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM) and UV-vis spectroscopy are applied for characterization of composite powder. XRD results are shown that Fe-FeS powder was synthesized successfully. FESEM images showed that powder with the size of less than 2 μm is formed after heat treatment. Also, the effect of pH as an effective factor is investigated. It can be seen that the degradation efficiency in basic solution is higher than acidic and neutral solution. Dyes degradation reached to 91% after 195 min irradiation of visible light in pH=11. In addition, kinetic study showed that the photocatalytic dedradation is initially (0-75 min) followed by first order model and after that the mechanism is possibly changed to the second order model.

Li-Ion and Ni-MH batteries are the best candidate for Electric Vehicles. Despite higher energy densities of Li-Ion batteries, because of economical reason Ni-MH Batteries are still attractive for scientist. In this investigation Cerium rich MmNi3.55Co0.75Mn0.4Al0.3 has been produced via Vacuum Arc Remelting Process. Phase characterization has shown that the predominant crystallographic phase is Hexagonal type with AB5 chemical formulation. Volumetric Sievert test has shown that the alloy could store 1%wt percent hydrogen at room temperature. Electrochemical analysis with Evium-Stat has shown that the energy density which the alloy can reversibly deliver is about 150 mAh/g.

In this study, the structural, magnetic and microwave absorption properties of a microwave absorber composite fabricated through electrophoretic deposition (EPD) of Fe3O4 nano-particles on carbon fibers (CFs) were studied. Firstly, co-precipitation method was employed to synthesize the Fe3O4 nano-particles. Then, these assynthesized Fe3O4 nano-particles were successfully deposited on CFs using a modified EPD process. The measured magnetic properties of the as-synthesized Fe3O4 nano-powder and the Fe3O4/CFs nano-composite showed that the saturation magnetization of the bare Fe3O4 was decreased from 72.3 to 33.1 emu/g for the Fe3O4/CFs nano-composite and also its corecivity was increased from 4.9 to 168 Oe for the nano-composite. The results of reflection loss (RL) measurements in the 8.2- 12.4 GHz frequency range indicated that the RL of Fe3O4/CFs nano-composites are significantly influenced by their thickness. The maximum RL value of -10.2 dB at 10 GHz with an effective absorption bandwidth about 2 GHz was obtained for the sample with the thickness of 2 mm.

In this study, alumina-iron composites have been prepared by slip casting in order to provide gradient iron in alumina.5 wt.% of iron was used under the magnetic fields by the magnitude of 0.8 and 0.08T. Two dispersants were examined as the dispersing agent using 70, 75 and 80 wt.% of solid loading in slips. Samples were sintered in a microwave oven at the temperature of 1350˚C and 1450˚C for 30 minutes, at 1500oC for 1 minute, and in a conventional tube oven at the temperature of 1485˚C for 2 hours using argon gas. The apparent and optical microscope pictures of green and sintered samples revealed that using PCN and 70 wt.% of solid loading under the mild magnetic field results in the best sample regard as density (3.7 g/cm3), strength (82.7 MPa) and iron gradient.

In the present paper, ZrB2-SiC nanocomposite was developed by pressureless sintering method. Micro sized AlN powder and SiC powderes at nano and micro-sized scale were used as additive. In order to produce composite samples, the primary powders were milled and blended in planetary ball mill apparatus with rotational speed of 200rpm and then processed using hot pressing (80oC and 100MPa), cold isostatic press and sintering at 2150oC. The values of relative density and porosity of samples were measured to evaluate the effect of presence of micro-sized SiC and SiC nano particles simultaneously on the pressureless sintering behavior of ZrB2-SiC. In order to compare the microstructure and mechanical properties of samples Scanning Electron microscopy (SEM), equipped with EDS spectroscopy, XRD analysis, hardness and toughness tests were used. The results show that as the volume percentage of nano SiC decreases to 15 vol.% and AlN increases to 7.5 vol.% the hardness (17.1 GPa), toughness (5.7 MPa.m1/2) and relative density (98.1%) increase.

In this study, two- and three-dimensional polyester fabrics were coated with nickel via electroless plating method in order to produce X-band radar absorbing coatings. Morphology, thickness, coating composition, conductivity and radar absorption behavior of them were evaluated. After coating, the conduction of two- and three-dimensional fabrics was increased to 0.023 and 0.0043 cm2/Ω, respectively. Checking the morphology of the coatings by scanning electron microscopy showed that the nickel particles on the surface of fibers have the dome-shaped structures.Microstructure investigation of fabricated polyester coatings by X-ray spectral energy distribution showed that the amount of loaded nickel is 64.56%. The study of the radar absorption behavior of two- and three-dimensional coatings showed that the both of them can absorb more than 96.45% X-band radar waves (8-12 GHz). The investigation of the washing, rubbing and light fastness of fabricated coatings showed that electroless plating method can fix nickel on the surface of fibers well so that these coatings show high stability against these environmental factors.

In this research, nanostructured cobalt oxide and nickel cobalt oxide active materials were successfully synthesized by a hydrothermal route. Structural characterizations of the prepared active materials were performed using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and elemental analysis (EDS). The results of these experiments showed that nickel has been successfully doped in the cobalt oxide spinel structure. Also, the microscopic examination showed the nano-rod morphology for the cobalt oxide and nickel cobalt oxide, which yields the high specific surface area for electrochemical reactions, leading to increase energy storage capacitance.Energy storage performance of the prepared active materials was investigated using electrochemical experiments of cyclic voltammetry and galvanostatic charge-discharge in a solution of 6 M KOH in Swagelok standard cell. The specific capacitance of nickel containing cobalt oxide sample (1624 F g-1) was obtained higher than that of cobalt oxide (1020 F g-1) at a current density of 2 A g-1.

Zinc and its alloys have been recognized as sacrificial anodes due to being widely used in cathodic protection systems. Problems caused by the high vapor pressure of this metal in the process of melting and casting have caused that reform processes of the microscopic structure in the solid state for zinc attract a lot of attention. Straininduced melt activation (SIMA) process is one of the semi-solid forming processes in the production of parts with nondendritic structure. In this study, the effect of SIMA process on microstructure and electrochemical behavior of zinc sacrificial anode has been examined. The samples were placed under the strain rates of 20-50%, different temperatures in the range of 425-435oC and time periods of 10-40 minutes. Optimal spherical microstructure was obtained in 50% cold work conditions, temperature of 430oC and 10 minutes. The results obtained from the polarization test and anode test on the optimal spherical sample indicate a tangible reduction in electrochemical corrosion current density by 90% and a slight decrease in anode efficiency compared to the raw sample. Elemental analysis (EDX), metallography images and microhardness profile show the concentration of alloying elements on grain boundary and turning of uniform corrosion into localized corrosion and thus reduced anode efficiency after SIMA process.

In this study the effect of sintering parameters on the microstructure and electrical properties of the barium strontium titanate sputtering target is investigated. For optimizing the sintering temperature, BST compacts sintered at various temperatures ranging from 1200 to 1400 oC for 2 hours. The sintered Barium Strontium Titanate sputtering target comprising with a high density, purity and a fine-grained microstructure has been also fabricated. Optimized calcining and sintering condition was obtained by controlling sintering temperature and time to fabricate single phase, high relative density sintered body. A relative density of up to 95% and mean grain size of 8 μm were reached at the sintering temperature of 1250oC. The relative permittivity of thin films at 10 KHz was around 4400. Also the thin film bandgap was around 3.2 eV. The densities of the sintered samples were measured using the Archimedes method.Characteristics of the body were analyzed by X-ray diffraction (XRD), optical microscopy. Dielectric permittivity (er) were measured with an HP 4192A impedance analyzer and thin film bandgap was analyzed by UV-Vis method.