Advanced Materials Research Vol. 699

Abstract: A floating zone (FZ) silicon wafer produced from a Czochralski (CZ) single-crystal ingot was subjected to prolonged annealing at a high temperature. Precipitates were formed in a N2(70%)+O2(30%) ambient atmosphere. The precipitate regions manifested themselves as dark concentric rings in the X-ray topographs. According to the results of cross-sectional transmission electron microscopy observations and energy-dispersive X-ray spectroscopy elemental analyses, nitrogen was distributed throughout the precipitate regions, while oxygen was rich in the periphery of the regions. A high concentration of nitrogen was also directly detected by secondary ion mass spectrometry in the mid-depth of the wafer in the precipitate regions. Electron diffraction analysis of the precipitates showed that their phase was α-Si3N4.

Abstract: In this paper, thin rectangular steel plates with stiffeners are examined under compressive loading. Consequently, nonlinear buckling finite element analysis (FEA) solutions are obtained by using ANSYS®. The local and global buckling patterns of stiffened steel plate geometries with simply supported boundary conditions are generated and critical buckling stresses are studied. Geometrically nonlinear buckling analyses are compared in order to evaluate the distributions of compressive stresses versus in-plane contractions and compressive stresses versus out-of plane deflections. Hence, it is concluded that there are critical load intervals. It is also observed that for critical loads, segments between stiffeners may switch from stable to unstable configurations under compressive stresses.

Abstract: We used Magnetic Resonance microimaging (MRI) to study the compressive behaviour of synthetic elastin. Compression-induced changes in the elastin sample were quantified using longitudinal and transverse spin relaxation rates (R1 and R2, respectively). Spatially-resolved maps of each spin relaxation rate were obtained, allowing the heterogeneous texture of the sample to be observed with and without compression. Compression resulted in an increase of both the mean R1 and the mean R2, but most of this increase was due to sub-locations that exhibited relatively low R1 and R2 in the uncompressed state. This behaviour can be described by differential compression, where local domains in the hydrogel with a relatively low biopolymer content compress more than those with a relatively high biopolymer content.

Abstract: Porous SiC foamed ceramics used raw material of SiC were prepared by adjusting slurry viscosity at 1400°C. Formed technology was dipping organic precursors. The result showed that the section of the sample presents three-dimensional net structure, wall of hole thickness is proper, the distribution of the hole are homogeneous, and have high porosity, apertures are small than 30 μm, the main crystal appearance is SiC. The strength of samples is been improved by dealing organic precursors. The slurry on the ribs is been increased.

Abstract: With excellent physical and chemical properties, aluminum phosphate is a great potential high temperature protective coating of fiber. In this paper, a kind of aluminum phosphate low in acidity was prepared from aluminum isopropoxide (AIP) and diammonium phosphate ((NH4)2HPO4) by hydrothermal and liquid-phase reaction methods respectively. The performance of aluminum phosphate prepared by the two methods was comparatively evaluated using FTIR, XRD, TG techniques. As a protective coating, aluminum phosphate was applied to the pre-treatment of high silica reinforced fiber cloth. After added 1% MgO, The SEM images indicated that aluminum phosphate prepared by hydrothermal method could cover the surface of the fiber more uniformly. The mechanical testing results showed that tensile strength of the obtained coated material was improved at high temperature.

Abstract: All-ceramic crown restorations are more widely used, however the brittleness of ceramics and stress mismatch of porcelain interlaminar often leads to damage of all-ceramic crown, and damage mechanism is not very clear. In this paper, a two dimensional model of Empress all-ceramic crowns is constructed using the RFPA (realistic failure process analysis) system to simulate the fracture process and analysis the fracture mechanism. The most advantage of this system is that the crack initiation, propagation and failure process of all-ceramic crown can be clearly observed and the research results provide guidance for clinical application.

Abstract: All-ceramic crown restorations are more widely used. The mechanical properties of different type of all-ceramic crown are evident different because of the differences of materials and production process. To study the failure pattern of different all-ceramic crown under load, two dimensional finite element model of three different all-ceramic crown models are constructed using the RFPA (realistic failure process analysis) system in this paper. Due to the difference of stress mismatch between different porcelain layers, it is found that the failure modes of different all-ceramic crown model are significantly different in the study. The advantage of this system is that the crack initiation, propagation and failure process of all-ceramic crown can be clearly observed and the research results provide guidance for clinical application.

Abstract: The physicochemical and surface properties of steelmaking flue dust were characterized by transmission electron microscopy, BET specific surface area, chemical composition analysis, X-ray diffraction analysis, thermogravimetry and differential scanning calorimetry, potentiometric titration, zeta potential and metal ion adsorption. The results show that the dust consists mostly of spherical shaped iron and calcium oxides fine particles, the surface of the dust is negatively charged at pH > 3. The dissolution of iron oxides can be used as a resource of Fe(II) and Fe(III) ions, together with hydrogen peroxide through a Fenton like process to degrade organic dyes in waste water treatment; The existence of calcium oxide gives the dust a high capacity to neutralize strong acid in solution; Owing to the negatively charged surface, large surface area and high alkalinity the dust can also be used as a cheap and very efficient adsorbent for removing metal ions from waste water.

Abstract: Zinc selenide nanoparticle has been synthesized using soft chemical routes. The particles were capped using 2-mercaptoethanol to achieve the stability and avoid the coalescence. The as-obtained particles were characterized by X-ray diffraction (XRD), Transmission electron microscopy (TEM), UV–VIS absorption and photoluminescence (PL) spectra. The impedance studies were carried out as a function of frequency (100 Hz–1 MHz) and temperature (298–373 K) by impedance spectroscopy. An analysis of the complex impedance (z' and z") with frequency is performed assuming a distribution of relaxation times.

Abstract: Titanium dioxide has been used for environmental applications. However, pure TiO₂ has low photocatalytic efficiency outdoors because of its large energy band gap. Higher nitrogen-doping level would have lower band-gap energy and it would make it possible to improve the utilization ratio of solar energy. Heavily nitrogen-doped TiO2 could be obtained by using ion beam assisted deposition (IBAD) technique. Acceleration voltage is a very important parameter of IBAD technique and will affect the processes of depositing thin film. Under the given experiment condition, acceleration voltage had little effect on the structure and absorbance spectra of the obtained nitrogen-doped titanium oxide thin films, but had great effect on the deposition rate, composition and surface morphology of the thin films. When the accelerate voltage was 250V, the deposition rate was the highest (about 9.0 nm/min), the resulting TiO2-xNx films contained nitrogen levels up to x =0.45, the structures were mostly crystalline anatase and the amount of shift was observed about 500 nm. The optimum acceleration voltage is about 250V under the given condition.