Advanced Materials Research Vols. 378-379

Abstract: Microstructural evolution of a copper alloy processed by accumulative roll-bonding (ARB) was investigated by EBSD analysis. The grains became thinner and elongated to the rolling direction with increasing the number of ARB cycles. The subdivision of the grains to the rolling direction actively begins to occur after 5 cycles of the ARB, resulting in formation of ultrafine grains with small aspect ratio. After 8 cycles, the ultrafine grained structure with the average grain diameter of 250nm developed in almost whole regions of the sample. In addition, the fraction of high-angle grain boundaries increased with the number of ARB cycles and reached about 0.7 after 8 cycles. The texture development of the ARB processed samples was different depending on the number of ARB cycles and the positions in the thickness.

Abstract: This study investigates the preparation of the three main layers of a CdS/CdTe thin film solar cell using a single vacuum system. A Close Space Sublimation System was constructed to deposit CdS, CdTe and CdCl2 solar cell layers. Two hot plates were used to heat the source and the substrate. Three fused silica melting dishes were used as containers for the sources. The properties of the deposited CdS and CdTe films were determined via Atomic force microscopy, scanning electron microscopy, X-ray diffraction and optical transmission spectroscopy. An J-V characterization of the fabricated CdS/CdTe solar cells was performed under solar radiation. The short-circuit current density, Jsc, the open-circuit voltage, Voc, fill factor, FF and conversion efficiency, η, were measured and yielded values of 27 mA/cm2, 0.619 V, 58% and 9.8%, respectively.

Abstract: This paper investigates the effect of soft X-ray irradiation various energy and times on P-N junction diodes. X-ray energy irradiated on P-N junction diode with 55 and 70 keV with various time in the range 5-50 sec. After irradiations were study on the current-voltage (I-V) characteristics and capacitance-voltage (C-V) characteristics. Leakages current after irradiated by X-ray are not change, while forward current are increase about 3 orders. The change of current-voltage characteristics can analyze by many parameter such as carrier lifetime and series resistance. Capacitance-voltage characteristics after irradiation are not change. The results show that soft X-ray technique can be improving performance of the P-N junction diodes. These techniques are importance to use for improving device performance in industry work.

Abstract: the most common forms of damage mechanisms in water transportation pumps are cavitaion, erosion and corrosion. Type and intensity of failure mechanisms are affected by type of fluent, operation condition, and materials which are used in pump fabrication. Realizing the active mechanisms on failure of booster pump's inner surface was the aim of this investigation. In this study, scanning electron and optical microscopy and image analyses software were used to investigate morphology. Corrosion rate was measured by electrochemical test and water analyses. The results showed that cavitaion was the main mechanism of failure. In addition, scanning electron microscopy images and total hardness of feed water prove the erosion mechanism.

Abstract: The steam reforming of toluene as a model compound of biomass gasification tar was carried out over Mg and La oxide-promoted Ni-metal oxide/Al2O3 catalysts. Catalysts were prepared by two different methods, co- and sequential impregnation. The findings indicate that conversion of gas products was improved with the use of prepared catalysts especially on syn-gas (H2 and CO) species and the highest conversions were obtained at the reaction temperature of 800°C. LHV’s of product gas when using catalysts at 800°C were over 4 MJ/m3 and ratios of H2 to CO were between 2.49-2.77. For long term test, Carbon and hydrogen conversion to CO and H2 of the catalysts with respect to time on stream in the steam toluene reforming for 480 min were studied. La2O3+MgO+Ni/Al2O3 catalyst revealed the highest and stable conversion rate of closely 50% and 70% for CO and H2, respectively. Whisker carbon species and encapsulating carbon were found on used catalysts after reaction. The La2O3+MgO+Ni/Al2O3 catalyst showed lesser amount of whisker carbon and encapsulating carbon.

Abstract: 8,285 tons/day of sewage sludge was discharged in 2009. Our study investigated improving sewage sludge’s recyclability by making lightweight bricks from it. The bricks’ compressive strength, specific gravity, water absorption and so on were measured to evaluate its characteristics. Its compressive strength ranged from 1.11 MPa to 10.92 MPa (3-class clay brick, the Korean standard, is 10.78 MPa or more). Its highest compressive strength was obtained at the mixing ratio of SS:MBA:BFS:WA = 6:1:1:2, and its range of specific gravity was 0.73–1.02 g/cm3. Heavy metal did not leach from it. Therefore, sewage sludge can be prepared and used to make lightweight brick.

Abstract: NiTi shape memory alloy is widely used in dental applications such as orthodontics arch wire, mini screw implant, orthodontics spring, etc., because of its favorable superelasticity and shape memory effect. Wire drawing is a fundamental manufacturing process used for producing orthodontics arch wires. It is well known that cold-work occurred during wire drawing operation is also important to control mechanical properties and transformation temperature of NiTi wires. Thus, the purpose of this work is to study the effect of cold working by means of reduction ratio of cross -sectional area and heat-treatment temperatures on transformation and mechanical behavior of the drawn wires for utilized as orthodontic wires. The wire material used in this study is Ni51.4Ti48.6 (at%) alloy with various initial diameters with targeted wire diameter of 0.51mm (0.02 inch). The die for wire drawing is made of tungsten carbide which is inserted into a steel case. The dies were designed to have different reduction ratio of cross sectional area for 4 levels; 10%, 20%, 30% and 40%, respectively. The lubricant used in this study is sodium stearate powder. In order to investigate the influences of heat-treatment temperatures, the drawn wires are heat-treated at 400 °C and 600 °C for 3.6ks. The results showed that percentages of reduction of cross sectional area and heat-treatment temperature strongly affect mechanical properties and transformation temperatures. Superelasticity was confirmed in an alloy heat-treated at 400 °C. The results obtained can be used to determine the optimum properties of NiTi wire in order to utilized as orthodontics arch wires.

Abstract: 4,4’-Diglycidyloxy-α-methylstilbene (DOMS) was synthesized and characterized with cross-polarized optical microscopy (POM), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Activation energies for decomposition (Ed) by TGA were determined as a function of conversion by weight loss process.

Abstract: Magnetic fluid (MF) shows an increased saturation magnetization when exposed to a magnetic field. In order to improve the quality of servo-valve products by depressing and overcoming the self-excited high-frequency pressure oscillations and noise appearing in pilot stage of a hydraulic servo-valve, application of magnetic fluid in a hydraulic servo-valve is developed in this paper. Large damping can be introduced by the magnetic fluids into the servo-valve if magnetic fluids are filled into the working gaps of the hydraulic servo-valve torque motor. After the construction and working principle of a hydraulic servo-valve with magnetic fluids are introduced, the high-frequency pressure oscillation signals are tested and recorded when magnetic fluids are applied or not in the servo-valve. Experimental results are compared and analyzed by using FFT analysis method. It is shown that pressure oscillations of the servo-valve are depressed when magnetic fluids are applied.

Abstract: This study examined the nanostructure InN compact layer and Au nano particles to dye-sensitized solar cells (DSSCs).We presents the DSSCs with Nitrided indium compact layer (InN-CPL) prepared by radiofrequency magnetron sputtering and doping Au particle in photoelectrode. The InN-CPL effectively reduces the back reaction in the interface between the indium tin oxide (ITO) transparent conductive film and the electrolyte in the DSSC. The Au particles effect conduction band of the TiO2 to rise open-circuit voltage to 0.7 v. The Au particles effectively rise inject electrons efficiency. For the DSSC without InN-CPL, the short-circuit current density and solar energy conversion efficiency are 15.6 mA/cm2 and 6.35 %, respectively. However, DSSCs with InN-CPL effectively rise short-circuit current density. The DSSC fabricated on 90 nm InN-CPL and doping Au particle showed the maximum power conversion efficiency of 8.9 % (AM1.5G) due to effective prevention of the electron transfer to electrolyte.