Advanced Materials Research Vols. 160-162

Abstract: This paper compares two methods for synthesizing a carbonate compound, Mg-Al-CO3 (Mg:Al=2:1), which is a layered double hydroxides (LDHs). The methods are mechanochemical method and hydrothermal method. The products characterized by XRD、SEM、FT-IR and TG-DTA. The results indicated that the target material was synthesized by different methods. The two kinds of well-crystallized materials with the same basal spacing d003=0.77nm, but their morphology were not same. The crystallite size of hydrothermal was larger than mechanochemistry.

Abstract: Magnesium alloys are more and more researched and used as engineering materials in recent years. In the paper, the AZ91D casting magnesium alloy was as basic material by the proper chemical pre-treatment and then was coated with epoxy resin (EP) coatings modified with polyurethane (PU) for protection. The coatings’ adhesion strength, hardness, and corrosion resistance were studied by electronic universal tester, pencil scratch hardness tester, immersion test and electrochemical test. The effect of polyurethane addition on the properties of the coating was ales investigated. The results show that PU / EP ratio of 20% mass fraction can make the basic alloy good mechanical properties and excellent corrosion resistance. The interpenetrating network formed between the epoxy resin modified with polyurethane is of more excellent mechanical and corrosion resistance than pure epoxy resin to protect the magnesium alloy matrix.

Abstract: To obtain more detail information about the cathode of La0.7Sr0.3Cu1-xFexO3-δ（x= 0.1,0.3,0.5,0.7,0.9）in IT-SOFCs, the cathode material La0.7Sr0.3Cu1-xFexO3-δ（x=0.1, 0.3, 0.5, 0.7, 0.9）was synthesized by a sol-gel method. X-ray diffraction revealed it to be form a single phase of perovskite. The high temperature electrical conductivity was measured by using the four-point dc technique, and cathodic overpotential with SDC（Sm0.15Ce0.85O1.925） electrolyte support was measured by using a current-interruption technique. The investigation of electrocheimical properties suggested that La0.7Sr0.3Cu0.7Fe0.3O3-δ has the highest electrical conductivity and the lowest cathodic polarization. Using La0.7Sr0.3Cu0.7Fe0.3O3-δ as cathode and 65%NiO/SDC as anode based on SDC electrolyte one can obtain higher current density and power density at intermediate temperatures, La0.7Sr0.3Cu0.7Fe0.3O3-δ is considered to be a possible cathode adapted to IT-SOFCs.

Abstract: A series of Iron-Ruthenium composite catalyst were prepared by precipitation and immersion, the effect of potassium and copper were studied by the slurry bed reactor at 260°C、2MPa、CO／H2＝1∶1，and the reduction behavior of Iron-Ruthenium composite catalyst was studied by TPR. The experimental results showed that the performance of Iron-Ruthenium composite catalyst was better than single Iron-based catalyst. The addition of potassium and copper caused the catalytic performance of Iron-Ruthenium composite catalyst improve significantly, and Copper could improve significantly reduction effect on Iron-Ruthenium composite catalyst.

Abstract: A biodegradable films were prepared by blending sodium lignosulfonate (LS) with poly(vinyl alcohol) (PVA) and with borax as cross-linking agent, in an aqueous system. The suitable process conditions of preparing the blend films with good water-resistance and mechanical properties were determined by single-factor experiments. SEM, FT-IR, TGA and DSC analysis were performed to examine the contribution of LS and borax to the properties of the blend films. The results indicated that the introduction of a moderate LS mass ratios to PVA from 1/8 to 4/8 in the blend films could simultaneously enhance the tensile strength of blend films up to 43.98MPa. SEM showed that the intermiscibility of blend films was satisfactory with appropriate LS. Studies of the water sorptive capacity of the materials suggested that the water sorptive capacity at equilibrium less than 17% and water-resistance improved. The results of TGA indicated blend films have greater thermal stability than the pure polymers.

Abstract: The uniaxial tensions of single crystal Cu nanowires (NWs) with different circular cross-section radiuses are simulated by molecular dynamics (MD) method. Atomic interactions in Cu NWs are described by EAM potential. The results show that the plastic deformation of NWs under uniaxial tension is dominantly controlled by dislocation nucleation and gliding. The mechanical properties of NWs are size-dependent. The NWs with larger radius of cross-section possess higher strength and ductility. Furthermore, the site of neck formation and following break of NWs has strong dependence on size scale of NWs.

Abstract: Rapid solidification of CuFe10 alloys was carried out by melt spinning at three wheel speeds 4, 12 and 36 m/s. The microstructure and solidification behavior of the ribbons was investigated by scanning electron microscopy (SEM). The results showed that the ribbons generally have a microstructure consisting of a fine dispersion of a Fe-rich phase in a Cu-rich matrix, and that the morphology and size of the Fe-rich phase vary with the wheel speed. For lower wheel speeds, the Fe-rich phase shows dual morphologies, dendrites and spheroids. The Fe-rich spheroids show a wide distribution of size, and have a larger mean size on the free surface than on the wheel surface. Some Fe-rich dendrites are distributed around the Fe-rich spheroids, this means liquid phase separation occurred during rapid solidification. The Fe-rich phase shows one morphology-spheroids and the size of Fe-rich spheroids decreasing as the wheel speed increasing. The results were discussed with respect to the formation of the Fe-rich spheroids during rapid solidification. The microhardness of the ribbons increasing with the increasing of the wheel speed for the grain refining and the increasing of supersaturated solid solution.

Abstract: Through adding different amounts of rare earth into the crack sensitive 30CrMnSi steel samples used in investment casting, the cracking tendency of the steel was evaluated and the optimum amount of rare earth addition was obtained. The results show that the cracking susceptibility decreases with the increase of the amount of rare earth added. The cracking susceptibility was lowest at the addition amount of rare earth ferrosilicon alloy being 450g per 50kg of 30CrMnSi steel, while increasing again thereafter with the addition amount up to 600g. It was revealed that the addition of rare earth with an appropriate amount can refine grains, reduce sulfur content, change the volume fraction and size of inclusions as well as improve their distribution, reduce or eliminate ferrite network in castings, and improve the hardness of the matrix, thus finally reduce the cracking susceptibility of the steel.

Abstract: It is obviously a simplification to consider the tunnel lining as uniformly permeable.In reality it is more likely that there are specific leaks assocoated with segmental lining joints. In the case of in situ concrete linings, construction joints can provide leakage paths, accounting for most of the water leakage. In this paper, based on the mechanical model of segment joint, the analytical expression of magnitude of joint opening was developed, in light of which, the occurrence of water leakage through the joint system can be judged. Taking the metro line No.1 in Shanghai as an example, effects of such parameters as joint flexural stiffness, bolt location, bolt stiffness, bolt prestress, etc. on the magninitude of the joint opening were analyzed respectively through the analytical solution. The results not only help us realize the influence mechanism of segment design on the magnitude of joint opening of the segmental linings, but also provide the guidance for waterproof design of the shield tunnel.

Abstract: The surface of the wafer is easy to be polluted by the organic pollution material. The supercritical fluid extraction technology works well in extracting organic pollution material. Whether the extraction process influences the surface performance of the wafer can be determined through the SEM(scanning electron microscope), AFM (atomic force microscope), and XPS (X-ray photoelectron spectroscopy). Compare the feature and the electronic structure of the wafer before and after supercritical CO2 extraction to get how supercritical CO2 extraction process influences the wafer surface performance. The conclusion helps to determine whether the extraction technology can be applied in the wafer surface cleaning technology. Tests show that supercritical CO2 extraction process almost does not influence the surface performance of the wafer, and, the supercritical CO2 extraction technology has a good prospect in the wafer cleaning.