Advanced Materials Research Vols. 391-392

Abstract: The study of core@shell magnetic nanoparticles (MNPs) has a wide range of applications because of the unique combination of the nanoscale magnetic core and the functional shell. In this paper, a brief review is presented on the different methods for the preparation of gold-coated composite magnetic nanoparticles, along with our preliminary work on the synthesis of gold-coated alloy nanoparticles.

Abstract: Microstructure, mechanical properties and electrical conductivity in Cu-0.73%Cr alloy after HPT process and the subsequent aging treatment have been investigated. Ultrafine grained structure with the grain size ~150 nm has been achieved after the HPT and the subsequent aging treatment. Ultrafine grains with some growth twins were preserved in the overaged state, showing high thermal stability. The peak microhardness and tensile strength of Cu-0.73%Cr alloy after the HPT was found at 480 °C for 2 hours. Electrical conductivity shows an increase trend in the different aging states.

Abstract: In order to improve the properties of titania nanotubes (TNTs), Fe-doped TNTs were prepared by impregnation method. The crystalline phase, tubular structure and special surface area of TNTs were characterized by XRD, TEM and BET. XRD spectra results revealed that the crystalline phase of TNTs was unchanged after doping iron. The TEM revealed that the materials prepared by hydrothermal method had a complete tubular structure and that structure was completely intact after doping iron. The special surface areas of Fe-doped and bare TNTs were 233.9m²/g and 298.2m²/g , respectively, which indicated that the surface area was decreased after doping iron. The adsorption amount of As(Ⅴ) results reached 35.5 mg/g at 15°C for the Fe-doped TNTs, while just 10.5 mg/g for the bare ones at the same condition, suggesting the application in the treatment of low concentrations of pollutants in water as an efficient adsorbent for Fe-doped TNTs.

Abstract: The turtle shell, as the oldest amphibian, has developed a rigid calcified shell to protect the soft body against environmental pressures and predators. The paper has studied the effect of microstructure on the mechanical behavior of the turtle shell. Furthermore the porous Fe-Cr based alloy was manufactured by the method of powder metallurgy. The results showed that turtle shell was composed of the element of Ca, P, C, Cl and Na etc. The microstructure of turtle shell is a sandwich structure typical of flat bones with the compact layer, the spongy layer with many pores and the fibrous inner layer. The unique structure affected the mechanical behavior of turtle shell very seriously. The sandwich structure can absorb the energy during transferring load, and very little energy is transferred to the endocortical bony and the internal organs. In this sense the soft part of turtle shell was protected by the shell. The porous Fe-Cr based alloy was manufactured by powder metallurgy and the pores are irregular and the porosity of alloy Fe-Cr is 19.4%. The microhardness of Fe-20Cr is 77.5 HV.

Abstract: Quasi-spherical gold nanoparticles(Au NPs) prepared by trisodium citrate reduction of HAuCl₄ were dispersed into cellulose acetate(CA) ultra-fine fibers by electrospinning. The optical properties of Au NPs before and after electrospinning were measured by UV-vis spectrometer. The morphology and distribution of Au NPs in CA ultra-fine fibers were observed by transmission electron microscopy (TEM). The morphology and diameter of Au NPs/CA fibers were studied by scanning electron microscopy (SEM). The crystallinity change of CA fiber before and after adding Au NPs was characterized by X-ray diffraction (XRD).

Abstract: The effect of initial copper concentration, particle diameter of wheat husk and the determination of the kinetic parameters of copper ion adsorption onto wheat husk were performed to understand the adsorption mechanism. The pseudo-second order kinetic model was fitted to the experimental data and found it was good to predict the adsorption behavior using nonlinear regressive method, suggesting that the mechanism may be a chemisorption process. The diffusion coefficient was also estimated and the pore diffusion was not significant.

Abstract: Cover scales and ground scales are found to be responsible for the greenish blue color of Morpho menelaus. From simulation predictions, different colors can be engineered by controlled thickness coatings on surface of scales. By replicating the morphologies of scales with low-temperature atomic layer deposition (ALD) methods, tunable colors are achieved successful by regulations of deposition cycles of Al₂O₃ in the organic-inorganic hybrid structures. After removal of original structures by means of high temperatures, inverted nanostructures exhibiting colors sealed by Al₂O₃ shell are fabricated. Simulation results of the hybrid and inverted structures are in accordance with experimental results well. The predictable spectra and the executable precisely controlled deposition by ALD provide us the potential of designing and constructing diversified structural colors.

Abstract: A simple model, without any free parameter, is introduced to predict the size-dependent diffusion coefficient of nanocrystalline materials in this contribution. It is found that as the size of the nanocrystals decreases, the diffusion activation energy of atoms decreases and the corresponding diffusion coefficient strongly increases due to the Arrhenius relationship between them, which leads to evident diffusion at the room temperature. The model prediction is in agreement with the experimental diffusion results of Cu and Ag diffusion in Cu nanocrystalline materials.

Abstract: This paper presents a uniform design methodology for computer assisted experimental design for intumescent fire retardant coating (IFRC) formulations, exemplifies the benefits of using experimental design together with software to facilitate the formulation of an IFRC for structural steelworks. By applying a multivariate design for the screening experiments, many intumescent fire retardants were evaluated in comparatively few experiments. In this work, prior information has been used in the form of a model, based on historical experiments. A uniform design criterion is used to design a few additional experiments so that the resulting model can have an acceptable prediction power. A confirmatory experiment step is shown that a design which uses the uniform design methodology taking advantage of the experimental data collected from the DOE that using fewer trials gives a model with equivalent prediction capability. This can be critical where experiments are expensive to perform.

Abstract: In this paper, aluminum sheet was activated by sodium hydroxide, and treated by the radio frequency Ar plasma. The sodium acrylate monomer aqueous was polymerized on the surface of treated aluminum sheet through surface initiated polymerization. The surface properties and microstructure of AS-PSA were analyzed by X-ray photoelectron spectroscopy (XPS), Fourier transfer infrared spectroscopy (FTIR). The feasibility of the surface modification and surface initiated polymerization by plasma was proved