Advanced Materials Research Vol. 853

Abstract: High-reactive {001} facets dominated anatase TiO₂ nanosheets were synthesized successfully by a simple hydrothermal method. CNTs were used to couple with as-prepared TiO₂ nanosheets to further improve the photocatalytic activity of TiO₂. Photocatalytic activities of the photocatalysts were tested by the degradation of Rhodamine B (RhB) aqueous solution under the xenon lamp irradiation. The results indicate that the introduction of CNTs will improve the photocatalytic activities of TiO₂ which can be ascribed to the enhanced light absorption and separation efficiency of photogenerated holes and electrons. There was also an optimal content of CNTs to modify TiO₂, and a possible mechanism for this idea was also proposed.

Abstract: This paper elaborates Ni_0.8-Cu_0.2-coated YSZ material prepared with the hard template method and the polyol method, with the composition and microstructure being analyzed with X-Ray Diffraction (XRD) and Scanning Electron Microscope (SEM). With YSZ as electrolyte material, LSM as cathode material and Ni_0.8Cu_0.2O_x prepared with sol-gel method and partially-tubular YSZ material coated with Ni_0.8-Cu_0.2 as anode material, electrolyte-supported cells were prepared, and with methane as fuel gas, the electrical properties of cells were determined. It was indicated that Ni and Cu prepared with traditional sol-gel method and YSZ were granular structure, and the contact area was small relatively. The new material prepared was a mixture of Ni, Cu and YSZ, where the YSZ was of partial fiber-tubular structure and the Ni and Cu granules were applied to the interior and exterior surfaces of the structure. It was able to effectively increase the contact surface of catalytic metal and electrolyte, which added to the three phase boundary of the SOFC anode and lead to power performance 80% higher than the former.

Abstract: Pressure infiltration casting technique is widely used to manufacture open-cell metal foam and it has been well performed in manufacture practice in our research group. In the present study, an attempt is made to highlight the influence of the infiltration casting process on the physical structure of metal foam. According to the production practice, several parameters: the pressure difference, the temperature condition, the particle size and the mould dimension, need to be well considered. A 2D model coupling porous zone and multiphase is created with a fixed grid. The cooling and solidifying process of molten metal are as well carried out with enthalpy method. Reasonable convergence rules are used to proceed high quality calculations. This work provides excellent experimental and numerical comprehension of pressure infiltration casing process to manufacture open-cell metal foam. These understandings can well guide and optimize the product manufacture, the physical structure and the mechanical behaviors of open-cell metal foams within their industrial application.

Abstract: B2 ordered FeAl intermetallic is an important candidate for high-temperaturestructural materials, and its hydrogen embrittlement problem has attracted wide attentions in recent decades. In this paper, we prepared single-crystal-like B2-FeAl (111) thin films on Si (111) substrate using the conventional magnetron sputtering method, and studied the phase composition and the influences of hydrogen on FeAl (111) films by X-ray diffraction (XRD), scanning electron microscopy (SEM), Atomic force microscope (AFM) and transmission electron microscope (TEM) analysis. The preffered growth mechanism of FeAl (111) film and its hydrogen induced modification were discussed.

Abstract: High strength aluminum alloys have been widely used in aviation manufacturing due to their favorable combination of intensity, stress corrosion resistance and toughness. However, the research and control of residual stress distribution in aluminum components have become a key issue to be solved during the heat treatment and subsequent processes. By means of the analysis of micro-indentation method and ANSYS finite element method, the residual stress distribution in 2A02 aluminum components after water quenching were systematically investigated, mainly considering two factors of the symmetry of structure and the variation of surface constraint. This study may give great help to the technology of relieving forgings residual stress of two alloys.The results of micro-indentation method show that the absolute value of the residual stress within the sample tends to decrease as the condition of constraint increase at the location of the same thickness; the absolute value of the surface residual stress also tends to decrease as the thickness of the sample increase with the same constraint conditions. The tested results by micro-indentation method are in consistent with the results of finite element simulation to a great extent.The results of finite element simulation are as follows: for these two aluminum alloy, the stress field distribution during the process of quenching is mainly influenced by the thickness of the samples. In general, at the initial stage of the quenching process, the stress state at the components surface are controlled by tensile stress in the direction of both thickness and width, while the residual stress within the samples is dominated by compressive stress; at the end of the quenching process, the stress field distribution just turn to the opposite. These results are in great agreement with the corresponding results of the indentation method.

Abstract: This paper presents the results of an experimental investigation on the effects of orientation and grain size on nanoindentation measurements of hardness and modulus of elasticity for three polycrystalline metals: copper, nickel, and iron. Three geometrically different indenter tips were used, and the pile-ups were characterized with a surface probe instrument. The electron backscatter diffraction (EBSD) technique and a scanning electron microscope (SEM) were used to characterize grain orientation and microstructure. It was found that additional contact areas due to pile-ups have a significant effect on determination of mechanical properties by the nanoindenter.

Abstract: In this paper, the experiment research and theory analysis about the effects of surface of old concrete in different way, adherence agent and the freeze-thaw circulation times to the adherence capability of new on old concrete are completed. The adherence capability of new on old concrete is tested in normal and low temperature environment, and the analysis of tests give some advices to the practical engineering of maintain and reinforcement of aircraft-pavement.

Abstract: Corrosion behaviors and mechanical properties of CrN film were evaluated. The CrN film was deposited on the surface of H13 steel by the magnetron sputtering method. The corrosion behaviors of the uncoated and CrN coated samples were studied in air-saturated 3.5 wt.% NaCl solution with various solution pHs, i.e., pH 2, 7 and 10 at 27°C by the electrochemical technique. The mechanical properties of the CrN coated samples were evaluated using nanohardness, ball on disk and scratch testers. The results revealed that the CrN coated samples had higher corrosion resistance than the uncoated samples at all pHs. Smooth substrate roughness enhanced corrosion resistance and also decreased the wear rate of the CrN coated samples on H13 steel. Corroded area was evaluated by synchrotron X-ray photoemission electron spectroscopy. It revealed that corrosion resistance of the CrN film was from oxidation of Cr into Cr₂O₃.

Abstract: Laves phase NbCr₂ intermetallics porous materials were in-situ synthesized by mechanical alloying followed by hot pressing. The influence of the process parameters of pressing pressure and sintering temperature on porosity of intermetallic NbCr₂ porous materials was studied. The results show that in a certain range of pressing pressure from 135MPa to 405 MPa, with the pressure increasing, the porosity of NbCr₂ intermetallics porous materials decrease. With the sintering temperature increasing from 1500°C to 1600°C, the porosity decrease.

Abstract: The absorbing performance have been tested and analyzed by taking cement as matrix, blending material silica fume and culver zed fuel ash, graphite and carbon fibers, nanoTiO₂ and steel fibers for absorbing agent trial Sample, in the 8 ~ 18 GHz frequency band. By using ANSYS software for computer simulation of the specimen to test experimental data and found the issue to be cement-based composite absorbing material in design, the electrical conductivity, complex permittivity, complex permeability, Dielectric loss tangent, etc of the material are all the main parameters of evaluate absorbing materials. When blending material as a composite wave-absorbing agent applications, two kinds of materials dielectric loss played a attenuation role in common, it can significantly improve the absorbing properties of the specimen, and also broaden the band, it's more advantage than adding a single wave-absorbing agent.