Advanced Materials Research Vols. 311-313

Abstract: The composites composed of PVC, NBR and BaSO₄ particles were prepared by melt blending method. The mechanical properties, microstructure and thermal stability of the composites were investigated. The results indicated that the elongation at break of PVC was greatly improved by addition of NBR, while the tensile strength was decreased. The elongation at break and the tensile strength of PVC/NBR composites first increased and then decreased with the increasing content of BaSO₄, and the maximum were emerged at 5phr BaSO₄ addition. The initial decomposition temperature of the composites composed of PVC, NBR and BaSO₄ is 10.79°C greater than that of the composites composed of PVC and NBR. The scanning electron microscopy photograph showed that NBR and BaSO₄ particles were uniformly dispersed in the PVC matrix when the addition of NBR and BaSO₄ particles was low.

Abstract: EPS composite soil is a new kind of lightweight fill material. Its engineering properties have been widely studied. However, the creep behavior has not been well investigated. In this study, triaxial undrained creep test is conducted on EPS composite soil regarding various confining pressures. Based on the testing results, a modified Singh-Mitchell creep model is established for EPS composite soil considering the influence of the deviator stress on the parameter m. Compared with the original Singh-Mitchell model, the modified creep model can well describe the creep behavior of EPS composite soil. It can provide references for engineers to design the project using EPS composite soil.

Abstract: Compared with ordinary coatings, nano-composite coating usually has a higher hardness and better wear and corrosion resistance. As coating materials, the nano-CeO₂/Zn composites were prepared by nano-CeO₂ and Zn powder. The microstructure was investigated by XRD and FESEM. The corrosion resistance and hardness of nano-CeO₂/Zn composites with different amount of nano-CeO₂ were comparatively studied. The results show that the metal corrosion resistance, hardness and density of the composites may be improved significantly by addition of nano-CeO₂, and the optimal amount of nano-CeO₂ is 1%.

Abstract: A facile hydrothermal process has been employed to synthesize WO₃ nanocubes using urea as an assistant agent. The crystal structure and morphology of WO₃ nanocubes have been characterized by X-ray diffraction (XRD), scanning electron microcopy (SEM) and transmission electron microcopy (TEM). XRD, SEM and TEM images of the products illustrate that WO₃ square nanostructures have a single orthorhombic phase, length of ~ 100-200 nm and thickness of ~ 40 nm. The ethanol sensing property of as-prepared tungsten oxide nanocubes is studied at ethanol concentration of 10-1000 ppm and working temperature of 160-400 °C. The result shows that the WO3 nanocubes have high sensitivity to ethanol because of their small size and special morphology.

Abstract: According to the dynamic theory and characteristics of the bridge modal analysis theories and methods for bridge were introduced which mainly included solving the nature frequency, mode shape, and damping ratio with the Rayleigh-Ritz method, subspace iteration method. And the application of bridge modal shape sequences and frequencies with their changes were illustrated in the diagnosis of the bridge disaster. Dynamic testing of the bridge should be measured for vibration mode and frequency which could be used to analyze the change of supports, constraints and other facilities of the bridge and to predict the working condition of the structure.

Abstract: By using dual number, the dynamic property of gas-lubricated thrust bearings or non-contacting face seals is analyzed in the small perturbation approximation, then an essential conclude, that the perturbation dynamic Reynolds’ equations independently of its whirl frequency, is advanced. According to this, the calculation of the stiffness and damping coefficients independently of system motion equations of bearings and seals is expedited.

Abstract: This paper represents the synthesis and characterization of NiFe single segment and NiFe/Au multisegmented nanowires. We fabricated these nanowires by electrodeposition technique using track etched polycarbonate membrane as a template with a nominal pore diameter of 50 nm. In recent years, much attention has been drawn to magnetic and nonmagnetic multisegmented nanowires because the magnetic properties of the nanowires can be useful for the manipulation and detection of biomolecules in a suspension by the application of relatively small magnetic fields where as the nonmagnetic segment has biocompatibility with high surface functionality. So in this work we studied the growth of NiFe/Au multisegmented nanowires. The length of the nanowires is found to be very uniform. The magnetic properties are measured by VSM. The measured coercivity and saturation magnetization of NiFe/Au multisegmented nanowires are lower than the NiFe nanowires. The structural morphology was observed by SEM. The EDS result shows the purity of both NiFe nanowires and NiFe/Au multisegmented nanowires.

Abstract: The chitosan-ibuprofen sustained release mcrospheres have been prepared by the emulsion cross-linked method, and the samples are characterized by EMS(electron microscope) and vitro.UV spectrophotometer. Research results indicate that the concentrations of IBF in solution are different with the different pH conditions. The quantities of cross linking agent, the mass ratio and temperature are selected to optimize on the MIC’s size and morphology.

Abstract: An easy synthesis route of YSZ (Yttria-Stabilized Zirconia) nanopowder with the formation of Zr_0.92Y_0.08O_1.96 is synthetized by using thermal decomposition of ZrOCl₂ and Y(NO₃)₃, with polyvinyl alcohol (PVA) as surface active agent and with quantitative filter paper as carrier. The roasting temperature of YSZ precursor was 650oC. The results of SEM and XRD analysis showed that the pure ZrO₂ and YSZ powders prepared via thermal decomposition had better crystallinity, and YSZ powders had perfect crystalline t-ZrO₂ phase after heating at 650 °C, and changing the amount of PVA or the reaction precursors could obtain YSZ powders sized 20-50 nm.

Abstract: Micro-vibration of aerostatic bearings has been the bottleneck in the improvement of the moving and positioning accuracy of ultra-precision fabrication and metrology equipments. In this study, a new type of aerostatic bearing restrictor has been proposed. The prototype of arrayed microhole restrictor, instead of the conventional single hole restrictor was developed with the aim of reducing the harmful micro-vibration of aerostatic bearings. Computational fluid dynamics (CFD) was employed to numerically calculate the air flow field. It is found that the employment of arrayed microhole restrictors can reduce the amount of micro-vibration while maintain the load carrying capacity and stiffness of the aerostatic bearing. Experimental measurement of the micro-vibration confirms the effectiveness of this new type of restrictor.