Advanced Materials Research Vols. 652-654

Abstract: The uniaxial deformation properties of a SiC/6061 Al alloy co–continuous composites (CCCs) where both phases are continuous have been studied using the Solidwork Simulation software applied the finite element method (FEM). The simulated results have shown that the composites are relatively anisotropy, 6061 Al alloy matrix and SiC network ceramic exhibit different mechanical behaviour. The ultimate stress is found near the interface of composites. The configuration of SiC has relatively great influence on intensity and distribution of stress in the composite. The material behaves in a nearly bilinear manner defined by the Young’s modulus and an elastic-plastic modulus. The large deformation appears inside 6061 Al alloy matrix. The 6061 Al alloy matrix and SiC can restrict each other to prevent from producing the strain under the load.

Abstract: Most of the mold-filling simulation theories for RTM were based on Darcy law and combined with mass conservation equation. Considering the unsaturated region in the experiment, the followings have been done in this paper: (1) first, explaining this un-saturated phenomenon as a sink effect, and amending the saturated filling mold by introducing a sink term to the mass constant equation; (2) second, achieving a simple 1d mold’s unsaturated simulation of the filling process through the compiled software pore-flow.

Abstract: With the technological progress in the synthesis of multi-walled carbon nanotubes and single-walled carbon nanotubes, more attention was attracted to the synthesis of carbon nanotubes with diameter distribution, ideal length, different chirality and certain orientation. In recent decade, all these factors have been investigated and a number of progresses have been made for the application of carbon nanotubes. The latest researches on the growth of diameter-controlled single-walled carbon nanotubes are reviewed and discussed. The existing problems and challenges of the synthesis processes have been addressed in the future directions.

Abstract: Au-Cu alloy nanowires with diameters 50-100nm and lengths of 500nm have been obtained by direct electrochemical deposition.The fabrication of highly ordered Au-Cu alloy nanowires arrays was used as a Anodic aluminum oxide (AAO) template. This template was fabricated with two-step anodizing method. In this paper, we report electrochemical deposition fabrication of Au–Cu alloy nanowire arrays by AAO. Use SEM, TEM can detect morphology of Au-Cu alloy nanowires, And use EDS to analyse the elements.The electrocatalytic activities of the Au-Cu alloy nanowires for the oxidation of ethanol in acidic medium were investigated by cyclic voltammetry.

Abstract: Epoxy-clay nanocomposites were prepared by high shear mixing method using Nanomer I.30E nanoclay as nano-reinforcement in diglycidyl ether of bisphenol A (DGEBA). The effect of mixing speed and time on the nature and degree of clay dispersion were investigated by varying the mixing speed in the range of 500-8000 RPM and mixing time in the range of 15-90 minutes. The effect of degassing temperature on the morphology of the resultant nanocomposites was also studied. Scanning and transmission microscopy (SEM & TEM) along with x-ray diffraction (XRD) have been used to characterize the effect of shear mixing speed, mixing time and degassing temperature on the structure of the resultant nanocomposites. The SEM, TEM and XRD examinations demonstrated that the degree of clay dispersion was improved with increasing the high shear mixing speed and mixing time. The results showed that the optimum high shear mixing speed and mixing time were 6000 rpm and 60 min, respectively. It was observed that the structure of the nanocomposites that have been degassed at 65oC was dominated by ordered intercalated morphology while disordered intercalated with some exfoliated morphology was found for the sample degassed at 100oC for the first 2 hours of the degassing process.

Abstract: Proper dispersion of nano thin layered structure of nanoclay in polymer matrix offers new and greatly improved properties over pristine polymers. The degree of nanoclay dispersion and hence the improvements in the physical and mechanical properties depend greatly on the technique used and processing parameters. In this work, 2 wt.% epoxy-clay nanocomposites were fabricated using different mixing techniques to study the effect of mixing methods on the nanoclay dispersion and thus on the enhancement of the properties of the resultant nanocomposites. Three mixing techniques were explored: high shear mixing (HSM), ultrasonication and their combination as well as hand mixing. The effect of mixing techniques on morphology and mechanical properties of the resultant nanocomposites was investigated using scanning electron microscope (SEM), X-ray diffraction (XRD), transmission electron microscope (TEM) and tensile testing. The results of XRD and TEM showed that both exfoliated and disordered intercalated morphology were developed for the nanocomposites synthesized by HSM, while ordered intercalated morphology was observed for samples prepared by sonication. The tensile test results show that among the mixing techniques considered in this study HSM results in the optimum mechanical properties as a whole while hand mixing resulted in the worst physical and mechanical properties.

Abstract: A detailed analysis by thermogravimetric analysis was carried out on multiwalled carbon nanotubes after air and acid treatment. When MWCNTs are treated in air at 300 oC for 2 h and then refluxed with 6 mol/L HCl solution, the weight percent of residual iron is near zero. The result can also be verified by the contrast of SEM photographs of untreated and treated MWCNTs.

Abstract: By analysis of X-ray diffraction and infrared absorption spectrum, we obtained the microstructure parameters of the MgO powders sample and found that the main character infrared absorption peak was at 416 cm-1. And we calculated out the average grain-size of sample according to the breadth of diffraction peak and the line broadening formula.

Abstract: Nano structured polyaniline was intensively studied for its low price, fascinating tunable conductive properties by dope-dedope process. While the nanostructural formation mechanism still not clear. In this work, PANI nanostructures were obtained in acidity PEG solution, and the polymerization process was monitored by a pH instrument. Moreover, the morphology evolution was monitored, based on which a self-assemble mechanism was issued. The oxidation products of anilinium cations were consider as the seed template for the formation of nanostructures, and appropriate acidity is propitious to the formation of PANI nanostructures.

Abstract: A Modified Monte-Carlo Method (MMCM) in which phonon bundles take non-energy is developed to model the steady state phonon radiative transfer in nanoscale materials. Heat transfer in silicon thin films is analyzed to examine the validity of the developed method. The temperature distributions and cross-plane thermal conductivity are determined by using the developed method for the silicon thin films and compared with the results in reference. The results indicate that the developed method has a good accuracy in solving the phonon radiative transfer in nanoscale materials. In addition, numerical accuracy can be improved by the increase of the number of samples in the simulations.