Advanced Materials Research Vol. 699

Abstract: Rod-shaped Fe3O4 nanocrystals have been prepared with a high yield using a facile poly (vinyl pyrrolidone) (PVP)-mediated hydrothermal synthesis method at a low temperature of 90 °C. The formation mechanisms related to the chemical reaction, Fe3O4 nuclei and Fe3O4 rod-shaped crystal growth were discussed in detail. Furthermore, magnetic characterization showed that the Fe3O4 nanorod exhibited a strong magnetic response property, which leads to their potential applications in the bioseparation fields.

Abstract: The silicone rubber composites filled with various contents of alumina (Al2O3) microparticles were prepared by the solution mixing process. The fractured surface morphology, thermal diffusivity and dielectric property of the composites were investigated by scanning electron microscopy (SEM), the laser flash thermal diffusivity analyzer, a LCR digital meter and a resistor tester, respectively. The results show that with Al2O3 content increasing from 8 vol. % to 35 vol. %, the thermal diffusivity increases from 0.13 mm2/s to 0.31 mm2/s, while the dielectric property reduces slightly. At a given Al2O3 content, the thermal diffusivity of the composites exhibits a reduction tendency with the increasing temperature. The Nielsen model is generally suitable to predict the thermal diffusivity of the composites.

Abstract: Organofunctionalized phyllosilicates containing both amino and mercapto groups were synthesized and used as support for silver nanoparticles in situ deposition. Depending on silver concentration in relation to phyllosilicate different amount of nanoparticles size and distributions were obtained, even with smallest silver used causes strong exfoliation of the phylosilicate lamella. Also such condition favors nanoparticles formation with homogeneous distribution with smaller diameters and narrower particle particles size distributions. With highest silver amounts preferential external phyllosilicate surface crystallization is obtained, as given by particle diameters up to 30 nm. Scanning and transmission electron microscopies were successfully employed to characterize morphological and structural features for these synthesized materials, enabling atomic visualization for the silver nanoparticles. These new phyllosilicates containing silver nanoparticles are extensively employed to design inorganic light emission diodes and also in applying in biological fields.

Abstract: In this investigation, waste printed circuit board resin powder (WPCBRP) was used to replace 0-30% of the fine aggregate in controlled low-strength materials (CLSM), to explore their rheological behavior, mechanical behavior, and durability. The results thus obtained demonstrate that when 10% of the fine aggregate was replaced by WPCBRP, the adjusted slump flow, setting time, and compressive strength could all met the standards at the ages of 12 hours and 28 days, with a high impedance of 1.54-1.63 kΩcm. CLSM with WPCBRP has a similar water permeability, of between 10-8 and 10-9 cm/s, to that of compacted clay. Therefore, this form of CLSM is impervious, and has a lower compacted settlement when compared with clay.

Abstract: Two types of three layered particleboard composite, homogeneous (Acacia mangium core-face/back) and heterogeneous (Acacia mangium core, mixed sawdust face/back) were fabricated with three different resin contents and densities. Three different resin content; 8:10:8, 10:10:10 and 12:10:12, were use with 500, 600 and 700kg/m3 board densities. Urea Formaldehyde (UF) was used as a binder and 1% of wax was added. The properties of bending strength (MOR & MOE) and internal bond strength (IB) were evaluated based on Japanese Industrial Standard; JIS A 5908:2003 Particleboard (2003). The results showed that there were relationship between resin contents and densities on homogeneous and heterogeneous particleboard composites. Result obtained indicated that bending and internal bond strength of homogeneous composite bonded using ratio of 12:10:12 resin content with 700kg/m3 density was better compared to ratio of 8:10:8 and 10:10:10 resin contents. When the densities were increased, the mechanical properties also increased.

Abstract: Nonlinear oscillations of a simply-supported symmetric cross-ply composite laminated rectangular thin plate are investigated in this paper. The rectangular thin plate is subjected to the transversal and in-plane excitations. Based on the Reddy’s third-order shear deformation plate theory and the stress-strain relationship of the composite laminated plate, a two-degree-of-freedom non-autonomous nonlinear system governing equations of motions for the composite laminated rectangular thin plate is derived by using the Galerkin’s method. Numerical simulations illustrate that there exist complex nonlinear oscillations for composite laminated rectangular thin plate.

Abstract: Similar welds composed of 5083 were produced by friction stir welding. In the solution of 0.2 M NaHSO3 and 0.6 M NaCl, with the addition of a given concentration sodium molybdate as the inhibitor, the electrochemical corrosion behaviors of the friction stir welds (FSW) and 5083 were comparatively investigated by potentiodynamic polarization curve tests and electrochemical impedance spectra (EIS) at the ambient temperature for different test periods. The results indicated that : with the extension of period, the inhibition efficiencies (IE) for both the weld and 5083 base materials enhanced, at the same period, the inhibition efficiency (IE) for the weld was beyond that for 5083 base materials, sodium molybdate may be thought of as an effective inhibitor for 5083 aluminum alloy, the interaction between inhibitor and weld is stronger than that between inhibitor and base materials.

Abstract: Samples of copper-aluminum reinforced metal matrix composite (MMC) were prepared by liquid metallurgy method using micron–sized silicon carbide (SiC) particulate. The resultant MMC samples were characterized to determine their thermal, electrical and mechanical properties in respect to varying particle sizes (212, 425, 710 and 1200 mm) of the SiC. The analyses of the results obtained showed that the thermal conductivity of the composite increased with decrease in particle size and volume fraction of the SiC. Also with decrease in grains size, high thermal conductivity was achieved by increasing the volume fraction. The results obtained in this study showed that alloying Cu matrix with aluminium is effective in reducing the interfacial reactions of a typical Cu-SiC matrix composite. The synthesized MMC samples also possessed a combination of high thermal and electrical conductivities with a low coefficient of thermal expansions which is synonymous to a low tensile strain at a maximum load. These properties were achieved for a 60%Cu/Al(40%SiC) at 212 µm, 50%Cu/Al(50%SiC at 12 µm and 70%Cu/Al(30%SiC) at 710 µm. The microstructural evaluation using optical microscopy (OM) indicated good dispersion of the SiC particles in all the samples which consequently enhanced the microhardness obtained in the MMC samples.

Abstract: Large structures are usually made by joining different elements. Fusion welding is one of the most fundamental technique, which is used to make large metallic joints. During fusion welding a large amount of heat is generated which melts the joint surroundings and a joint is created after solidification. Joint configuration is mostly affected by the material parameters and process type. In this paper, a thermo-mechanical simulation of fusion welding of submerged arc welding is performed using ANSYS. A moving heat source model based on Double-Ellipsoidal heat flux distribution is modelled. The transient temperature distributions and temperature variations of the welded plates are calculated during welding process. Effect of welding speed, welding current on temperature profile and angular distortion of plates is further investigated.

Abstract: By XRD, UV-Vis, and X-ray absorption spectroscopy, it seems that copper is inserted in the framework of TiO2 nanotube (Cu-TNT), which was prepared for photocatalytic splitting of H2O. The Cu-TNT has light absorption extended into the visible range (400-550 nm) and decreased the band gap to 2.95 eV. Under UV/Vis light irradiation for six hours, H2 yielded from photocatalytic splitting of H2O on the Cu-TNT is greater than that on the TNT by 2-3 times.