Advanced Materials Research Vols. 535-537

Abstract: Carbon nanotubes have better physical and mechanical behaviors than the traditional materials, in this study cups-stacked carbon nanotubes (CSCNTs) were filled into epoxy nancomposites to fabricate CSCNTs/epoxy nanocomposites. RTM6 was used by epoxy resin system. The cups-stacked carbon nanotubes (CSCNTs) were dispersed into the RTM6 matrix. In this study, damping properties of the CSCNTs/RTM6 were measured; effect of different weight percentages of the CSCNTs was investigated. And the morphologies of fracture surface of CSCNTs/epoxy nanocomposites were observed by scanning electron microscope (SEM); damping behaviors of the nanocomposites were studied by DMA tester at frequency domain.

Abstract: The first-principles with pseudopotentials method based on the density functional theory was applied to calculate the geometric structure, the formation energy of impurities and the electronic structure of Li-doped ZnO. In the system of Li-doped ZnO, LiZn can not result in lattice distortion. In contrast with that case, LiO and Lii result in lattice distortion after Li doping in ZnO. In Li-doped ZnO, LiO is the most unstable than the other cases. Simultaneously, Lii is more stable than LiZn according to that Lii has smaller formation energy. Furthermore, the electronic structure of Li-doped ZnO indicates that that LiZn behaves as acceptor, while Lii behaves as donor. In conclusion, in Li-doped ZnO, Lii is always in the system to compensate the acceptor. Singly doping Li in ZnO is difficult to gain p-ZnO for the self-compensation. The results are in good agreement with other calculated and experimental results.

Abstract: TiO2/FeOOH nanocomposite was fabricated by a hydrolysis-precipitation approach, using TiCl4 as precursor and FeOOH as support. The crystal phase, diameter and morphology of the sample particle were characterized by X-ray diffraction, transmission electron microscope. The results show that the samples are composed of goethite and rutile. The morphology and diameter of rutile particle, the weight percentages of goethite and rutile, and the microstructure of the samples are related to its preparing temperature and molar ratio of Fe/Ti. The photo-absorption properties of the samples and support were measured by an UV-vis spectroscopy. The results show that the absorption ability of the nanocomposite for visible light is well than that of phase pure rutile. The photocatalytic activity of the nanocomposite as prepared was estimated by degradation of methyl orange (MO) under UV or visible light in an aqueous solution at 303 K. The results indicate that the photocatalytic degradation activity of the nanocomposite for MO is higher than that of phase pure rutile, and the photocatalytic property of the sample is related to its molar ratio of Fe/Ti and preparation temperature. This can be attributed to the microstructure of the nanocomposite, which can improve solar utilization and reduce the recombination rate of solar induced electron-hole pair. This implies that a synergistic effect exists between titania and goethite in the nanocomposite.

Abstract: Four kinds of single-bar modified tricot fabrics are knitted on a Raschel latch needle warp knitting machine with glass continuous-filament yarns. The glass warp knitted fabric/ unsaturated polyester resin composites are produced by manual molding technology. The tensile properties of composite samples are tested on the universal material testing machine. The stress-strain curves, elastic modulus, fracture strengths of composites are analyzed in the course, wale and diagonal directions. The results show that the tensile stress/strain curves of single-bar modified tricot warp knitted fabric reinforced composites were nonlinear. The tensile properties of composites possess obvious anisotropic characteristics. The values of elastic modulus and tensile strength were in relation to the yarn numbers bearing tensile load in tensile directions

Abstract: ZL101 Al alloy reinforced with 55% silicon carbide particulate metal-matrix SiCp/Al composite has been fabricated by pressureless-infiltration. The microstructure characterization of composite has been studied by optical microscope (OM), scanning electron microscope (SEM), X-ray spectroscopy (EDX), respectively. The results show that the SiCp are uniformly distributed in Al alloy matrix, however, there are some casting defects such as shrinkage and gas porosities in the matrix. When Mg was added into the composite, it can improve wettability property of between Al matrixes and strengthen particle SiCp and decrease micro-defects such as gas porosities, the Microstructure of SiCp/Al composite prepared was compact and uniform. The SiCp particles evenly distributed in the matrix and without significant partial segregation phenomenon. It improves the whole performance of the composites.

Abstract: The structure of composites formed by explosive welding of thin sheets of tool and austenitic steels was studied by structural analysis methods. It is shown that the quenching and tempering of composites leads to the formation of complicated structure containing, along with layers of dissimilar steels, layers with new chemical compositions. Due to the structural changes there is an 2-fold increasing of impact toughness.

Abstract: Al2O3/epoxy resin composite materials were prepared with alumina as filler in this paper, and the effects of particle size and added quantity of Al2O3 powers on the thermal conductivity of the composites have been investigated. The results show that, thermal conductivity of the composites increases with the increase of the added quantity of Al2O3 powders, and suitable particle size of alumina filler could help to form heat conductive chain which can improve the thermal conductivity of the composites effectively. The thermal conductivity could reach 0.48 W/(m•K), which is five times than that of pure epoxy resin, when the amount of alumina powders is 60% and its mean particle size is 100µm.

Abstract: Recycling of materials is an important point of sustainable construction. The aim is to find a compromise between energy saving, economy and ecology. The contribution discusses the production of thermal insulation composite material made of polymers. Uniform dispersion of grains of foamy glass waste (filler) in polymer filling from recycled thermoplastics induces formation of particle composite. The production supports usage of secondary raw materials. Decisive properties in choosing the materials to be applied include mainly the coefficient of thermal conductivity, density, compressive strength and water absorption.

Abstract: Poly (phenylene sulfide) (PPS)/nano-ZnO composites were prepared by DAKA miniature blending instrument. Isothermal crystallization behavior of PPS composites at 245°C, 250°C, 255°C and 260°C were investigated by means of DSC. The crystallization time of PPS composites is shorter than which of neat PPS at the same crystallization temperature. The Avrami equation was used to analyze DSC data. Results showed that neat PPS is homogeneous nucleation at lower crystallization temperature, which is heterogeneous nucleation at higher crystallization temperature contrarily. PPS/nano-ZnO composites are heterogeneous nucleation at various crystallization temperature, nano-ZnO particles play a role of nucleating agent.

Abstract: In order to simplify the performance analysis of woven fabric composites, the parametric micro-geometry model and APDL program are applied on elastic properties prediction. Firstly, the internal microstructure of woven fabric composites were observed using microscope. Seconldy, the parametric micro-geometry model was built using the defined equations to describe the shape of cross-section, the yarn path and their relations in Pro/e software. The cross-section of yarn was defined as ellipse curve ,while the yarn path was defined as sinusoidal and straight lines. Finally, the model was imported into ANSYS software, and the finite element analysis was carried out using the developed APDL program to obtain the elastic constants. With the proposed approach, several kinds of micro-geometry model of woven fabric composites were built automatically and their elastic constants were predicted quickly. It is shown that the predicted elastic constants are consistent with other references.