Advanced Materials Research Vols. 512-515

Abstract: Microstructure and electrode characteristics of Ti-V-Cu-Cr-Ni metal hydride electrode alloy have been investigated by XRD, FESEM-EDS and EIS measurements. The result shows that the alloy is mainly composed of V-based solid solution phase with body-centered-cubic structure and TiNi-based secondary phase. The discharge capacity increases with increasing temperature in a wider temperature region from 303 K to 343 K. The result of electrochemical impedance spectrometry indicates that the charge transfer resistance decreases with increasing temperature, while the exchange current density in the bulk of the alloy increase with increasing temperature.

Abstract: Microstructure and Some Dynamic Parameters of Ti-V-Pd-Cr-Ni metal hydride electrode alloy have been investigated by XRD, FESEM and EIS measurements. The result shows that the alloy is mainly composed of bcc phase and TiNi-based secondary phase. The discharge capacity increases with increasing temperature in a wider temperature region from 303 K to 343 K. The result of electrochemical impedance spectrometry indicates that RT decreases with increasing temperature, which is 2.392Ω, 0.531Ω and 0.156Ω at 303K, 323K and 343K, respectively. However, I₀ increases with increasing temperature, which is 72.76 mA g^-1, 327.75 mA g^-1 and 1262.88 mA g^-1 at 303K, 323K and 343K, respectively.

Abstract: The most important part to be highlighted in developing a reliable microwave absorber is the material used to fabricate the absorber. As an alternative in managing the increase of the oil palm residues throughout the country, this study is focusing on developing a microwave absorber coating using oil palm fly ash. The software uses for design and simulation of microwave absorber is CST Microwave Studio (CST MWS) which enables the fast and accurate analysis of high frequency devices. The simulation design is fabricated to a number of layers which is coated by oil palm ash as a lossy element. The measurement and performance are carried out in the high broadband frequency of 8 to 12 GHz (X-band).

Abstract: A series of HPA-containing Poly(phthalazinone ether ketone) (PPEK) membranes was prepared and their microstructure and conductivities were studied in this work. The results showed the composite membrane had no proton conducting ability with PWA content less than 75%, while the conductivity for the PWA/(PEEK-PVP) membranes with 35% of PWA was higher than 4×10^-4 S/cm. Proton conductivities up to 4.86×10^-3 S/cm have been measured at temperatures up to at 140°Cand 100% RH for PWA/(PEEK-PVP) membranes with 35% of PWA and 70% PVP. The relationship of conductivity and the morphology of the PPEK/PWA membranes showed that the PWA particle dispersion is the key parameters.

Abstract: The thermoelectric SiC structural materials for supersonic vehicles can convert intense aerodynamic heat to electricity simply by temperature difference. A general model of nose tip is developed to predict the thermal-electrical energy con-version performance of the thermoelectric SiC materials. The temperature distributions of model was obtained by solving the Navier-Stokes (N-S) equations and the heat conduction equation. The largest temperature difference between the hot side and cold side of the hypothetical thermoelectric module is about 275 K. With the thermoelectric properties assumed constant in the presence of temperature gradient, the output power and thermoelectric efficiency of the model are calculated. The maximum of thermoelectric efficiency and output power of the model are 0.4×10^-3 W and 1.6×10^-4 %, respectively, at a current of 0.014 A. The thermoelectric performance of the model shows great potential for the application of SiC ceramic structures to thermoelectric generation from aerodynamic heat on supersonic vehicles.

Abstract: Salt rock is think of ideal storage location for oil and natural gas and radioactive waste deposited, interlayer has negative effect on stability of cavern of storage for oil and natural gas and radioactive waste deposited in salt rock, It is difficult to make complete specimen layered salt rock with interlayer. In this paper Based on Rock Failure Process Analysis Code RAFP^2D, influence of mudstone interlayer on uniaxial compressive strength of salt rock is investigated by numerical simulation. Numerical simulation shown that when mechanical parameters such as elastic modulus poison’s ratio and uniaxial compressive strength for salt rock and pure mudstone interlayer and content of mudstone interlayer in salt rock are known, compressive strength and mechanical behavior for salt rock with mudstone interlayer can be effectively and accurately analyzed using RFAP^2D. The results for numerical simulation are agreement with true physical experiment of salt rock with mudstone interlayer. It should be noticed that the true physical experimental uniaxial compressive strength of rock is in range of 30% mean uniaxial compressive strength of rock element in RFPA^2D，in this case the results for numerical simulation can reflect phenomenon and behavior for true physical experiment of salt rock with mudstone interlayer. That provides new method and avenue to analyze and investigate mechanical behavior for multilayer rock mass based on RAFP^2D

Abstract: Dynamic similarity criteria for large deformation of huge steel structure were derived according to Dimensional Matrix Analysis of the Buckingham Pi theorem and the similarity relations that must be satisfied by the physical quantities of model and prototype in huge steel structure model test are obtained. The 1/50 scale model of TC power is designed and made based on the similarity theory and the dynamic experiment is done. The calculation data with similarity theory are in agreement with that of experiment. So the model test can substitute for prototype test when they satisfy the similarity relations. A new way to solve dynamic analysis problem of huge steel structure is explored.

Abstract: Aluminum-doped zinc oxide (AZO) films were deposited on polyethylene terephthalate (PET) by radio frequency magnetron sputtering. The influence of the various deposition parameters (R.F. power, substrate-to-target distance, substrate temperature, deposition time) on electrical, morphological and optical properties of AZO/PET films was investigated. The use of grey-based Taguchi method to determine the optimization of the process parameters by considering multiple performance characteristics has been reported. The electrical resistivity and the average transmittance of the AZO films were improved by increasing the substrate temperature. Finds based on the grey relational analysis show that the lowest electrical resistivity of AZO films to be about 1.6 × 10^-3Ω-cm, and visible range transmittance about 80%.

Abstract: Overlaying pinch roller has higher surface hardness. If the overlaying technology is improper, small circumferential cracks may occur on the welded surface and even peel off. From failure analysis, it is indicated that the contents of C, S, and O were higher around the cracking area in the deposited metal. Optical microscopic observation shows that some cracks grew along the direction of columnar crystals and residual austenite. Due to high content of inclusions and austenite in the deposited material and poor plasticity of the deposited metal, small cracks are easy to be found at the defect such as blue flecks. In addition, a large number of cracks intersect on the deposite surface, resulting in large peeled area.

Abstract: Coating a heterogeneous layer outside the core nanoparticles has become a common method to protect the properties of nanoparticles and may extend the application range of core nanoparticles. Rare earth ion-doped nanoparticles NaYF₄:Yb ³⁺ ,Er ³⁺ is one of the most efficient up-conversion nanosystems. In this work, a multi-functional NaYF₄:Yb ³⁺ ,Er ³⁺ @TiO₂ core-shell structure nanocomposite was synthesized. The structure, optical and photoluminescence properties of the up-converting nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and room temperature up-conversion luminescence (UCL) spectrofluorimetric measurements.