Advanced Materials Research Vols. 328-330

Abstract: The influencing effects of the content of wood fiber, particle size and content of titanate coupler on the tensile properties of wood fiber (include the pine powder and the rice husk powder )/PVC composites (WPC) were investigated. The results showed that the tensile modulus of WPC are increased, the tensile strength and the elongation at break of WPC are decreased slightly when the wood fiber changed from 30 to 60( phr method) . Between 150μm and 165μm in the size of the diameter, the tensile strength of WPC increased by 11.5%, however it is increased by 5% between 165μm and 315μm. The content of titanate coupler affected significantly, the tensile properties of WPC appeared first increased and then decreased when the content of titanate coupler is increased from 0 to 3.5 shares( phr method). Added the same content of pine powder or rice husk powder, the tensile modulus and the tensile strength of WPC which filled pine powder are bigger, but the elongation at break of WPC which filled rice husk powder are bigger.

Abstract: In the present study, Al2124 and Al6061 alloys were consolidated through spark plasma sintering at 400, 450 and 500 °C using three different combinations of pressure and time (35 MPa - 20 min, 40 MPa - 15 min and 45 MPa - 10 min). The microstructure, density and hardness of sintered samples were evaluated. Full densification and the highest hardness were obtained at 450 °C. Beyond 450 °C, there was only small change of hardness. Densification of specimens was less sensitive to the applied pressure. However, the lowest pressure of 35 MPa led to the highest hardness. At higher temperatures, the increase in pressure resulted in grain growth which decreased the hardness.

Abstract: The pure aluminized layer and RE-aluminized layer on industrial pure iron were prepared by hot dip aluminizing method, and the thickness and composition of the layer were investigated by means of scanning electronic microscopy (SEM) and energy dispersive spectroscopy (EDS), respectively. The results showed that the RE was permeated into the alloy layer after hot dip RE-aluminizing and the thickness of the alloy layer increases by about 30% as against hot dip pure aluminizing. The binding energy between the vacancy and aluminum atom was calculated. According to the energy condition of the solute-vacancy complex diffusion, it points out that the solute-vacancy complex diffusion is the main mechanism of aluminum atoms diffusion in hot dip RE-aluminizing and the main reason why the thickness of alloy layer increases after hot dip RE-aluminizing.

Abstract: The tendency for coiled tubing to grow in diameter and thin in wall under a combination loading of internal pressure and cyclic bending. This can occur in spite of the fact that nominal stresses due to internal pressure loading are well within elastic limits in both hoop and radial directions. The deformation mechanisms are described. Fatigue tests of 10 coiled tubing specimens are finished. The results show that the trends in coiled tubing deformation behavior are according with the context of theory.

Abstract: The novel biodegradable poly (ε-caprolactone)/TiO₂ nanocomposites were prepared by in situ polymerization of ε-caprolactone in the presence of modified-TiO₂ nanoparticles as initiator. The molecular weight of poly (ε-caprolactone) (PCL) matrix was dependent on the amount of the TiO₂ fillers. The incorporation of TiO₂ did not significantly affect the crystalline structure of PCL. An astounding nucleating effect of TiO₂ on PCL crystallization was observed. The enhanced thermal stability of PCL nanocomposites was observed. The novel biodegradable poly (ε-caprolactone)/TiO₂ nanocomposites were prepared by in situ polymerization of ε-caprolactone in the presence of modified-TiO₂ nanoparticles as initiator. The molecular weight of poly (ε-caprolactone) (PCL) matrix was dependent on the amount of the TiO₂ fillers. The incorporation of TiO₂ did not significantly affect the crystalline structure of PCL. An astounding nucleating effect of TiO₂ on PCL crystallization was observed. The enhanced thermal stability of PCL nanocomposites was observed.

Abstract: This study explored an approach to suppress plasticizer DOP migrating from flexible PVC. MMT/PVC composite materials were prepared using MMT modified by CH₃(CH₂)₁₇NH₃⁺, and tortuous paths for DOP were created by MMT dispersion in PVC matrix. Short time soaking in hexane treatment on PVC specimen formed two membranes that did not contain DOP on the PVC surface, which came into being barrier for DOP molecules. DOP migration tests showed that hexane-treated PVC’s migration curve presented time lag compared to that of none-treated neat PVC, and migration rate of hexane-treated MMT/PVC was much lower than the reference. Hexane-treated MMT-2/PVC sample exhibited the best performance on the prevention of DOP migration.

Abstract: This paper presents the experimental results on electric field-assisted synthesis of spherical Zinc Oxide (ZnO) micro-flower in an homogeneous precipitation method. The synthesis processes with and without an electric field were compared. The products were characterized via SEM, XRD, TGA and FT-IR spectrum. The results show that the spherical ZnO micro-flower composed of ZnO single crystalline nanoparticles have thickness of about 10nm, width of about 50nm.The SEM results show that the application of an electric field caused the morphology transformation from flake-like to flower-like. It was found that an electric field had an effect on the crystal structure,the particle size and morphology.

Abstract: Aluminium silicon alloys are the most used raw material for automotive applications. One of the main limitations on using aluminium high silicon alloys is the formation of coarse brittle phases under conventional solidification conditions. However, rapid solidification processing (RS) (for example, through melt spinning) is very effective in limiting the coarsening of primary silicon due to the high cooling rate. In the present work, characterisation of the material at the first stage of production as melt-spun ribbon and flake has been carried out. The microstructures show typical characteristics of a ‘featureless zone’ on the wheel-side and coarser microstructures on the air-side, with clusters of silicon particles evident. At high magnification, on the wheel-side, TEM and FEGSEM reveal local variations in the silicon and aluminium content (although on average there is no macrosegregation from the wheel-side to the air-side during solidification). In FEGSEM, the ‘rosette-structure’ also displays local variations in Al, Si, Fe, Cu and Ni over a scale of a few microns.

Abstract: The purpose of this research is to systematically study the influence of artificial aging (T6) on evaluation of microstructure changed and hardness of Al-Al₂O₃ composite produced by stir casting route. The Al₂O₃ particle reinforced previously was coated by electroless coating method to improve wetting system between Al-AC8H and Al₂O₃ when aluminium composites fabricated by stir casting route. The volume fraction of Al2O3 which added into Al melts was various from 2% to 22.5%. The stirring process was carried out at 500-700 rpm to achieve vortex in alumnium melt using graphite impeller for 15 minutes. The prepared aluminium composites then heat treated by T6 treatment with different aging time. Microstructure and hardness after T6 treatment were investigated. It was observed that microstructure changed after T6 while hardness increase after T6 due to the Mg₂Si precipitation hardening was present in Al matrix as well as Si eutectic accumulated on the surface of Al₂O₃. It was found that the optimum hardness occurred after aging for 3 hours.

Abstract: Based on thermodynamic theory, a phenomenological model of shape memory alloy is provided. Simulations under different loading illustrate the influence of large-strain deformation and small-strain deformation on the characteristics of the model. The results indicate that the difference between the two methods is small under uniaxial tension case, while the influence is very large under shear deformation case.