Advanced Materials Research Vols. 418-420

Abstract: In order to ensure the stable and standard discharge of mixed nitrogen sewage, Guangzhou Datansha Wastewater Treatment Plant has made a test using an inverted A² / O process, with the actual Wastewater as entry water. When the ratio of mixed fecal sewage is 0.33%, the results showed that, extending the HRT(Hydraulic Retention Time) can help to enhance the effect of removing nitrogen, and HRT should be ensured at least 8 hours under the test conditions. And the increase of the concentration of dissolved oxygen can promote the effect of removing nitrogen ranging from 1.0 to 1.5 mg/L. And the sludge reflux ratio should be remained at 60%. Besides, the growth of sludge age has positive effect on nitrification, so the sludge age should be controlled in more than 20 days under the experimental conditions.

Abstract: The different concentration La₂O₃-doped BaTiO₃ ceramics were prepared by sol-gel method. The ferroelectric and dielectric properties of the ceramics are characterized by TF analyzer 2000. With the increased amount of La₂O₃-doped, the dielectric constant increase gradually, when the sintering temperature is 1250 °C, the dielectric constant has reached 4648 for La₂O₃ with 0.4％-doped. With the temperature increased the dielectric constant of La-BaTiO₃ increase gradually, when the sintering temperature is 1290 °C, the dielectric constant has reached 7066 for La₂O₃ with 0.4％-doped.

Abstract: It was analyzed by metallographic observation and X-ray diffraction method that the microstructure and texture in two kinds of Ti-IF steels, which produced by different hot rolling process,and it also was discussed that the formability and the texture in Ti-IF steels. The results showed that the microstructures of these two kinds of steels are Equiaxed ferrite grains, but the grain sizes are greatly different. Respectively the average grain size of steel A and B are 24.85μm and 11.85μm, and the average grain size number are 7.4 and 9.5. The {111} texture of steel B is stronger than A, besides, the deep drawing properties of steel B is better than A in the reason that disadvantaged texture{001} and {112} are not founded in steel B.

Abstract: Developing automatic assembly techniques is essential for the application of advanced nanomaterials such as carbon nanotubes (CNTs). This paper presents a review of current research progress towards the automatic assembly of CNTs by dielectrophoresis (DEP). The mechanisms and experimental set-up of three methods for controlled DEP assembly of CNTs are introduced. One is using a limiting resistor to control the electric field after the deposition of a single CNT or a bundle of CNTs. The other two measure electrode gap electrical signals, gap impedance and current respectively, indicating CNT connections to stop the DEP process. The real-time electrical signal monitoring during the DEP process and controlling the DEP using the detected signals represent a research direction in the manipulation of a wide category of nanomaterials and will speed up the industrial applications of the materials.

Abstract: We show theoretically that the optical absorption of one-dimensional metallic photonic bandgap (MPBG) materials, which consist of alternating Ag and MgF2 layers, can be substantially enhanced by modifying the structure properly through decreasing the thickness of top MgF2 layer to half and increasing the thickness of bottom Ag layer to fivefold. Using transfer matrix method, absorption spectra and the electric field distribution profiles are numerically calculated. The absorption spectrum under reverse-direction incidence is also investigated. Based on strong and direction-dependent absorption properties, the proposed MPBG structure could allow many potential applications such as unique photothermal absorbing materials.

Abstract: The soil nailing wall is a kind of technology for supporting and strengthening the in-situ soil. The nails are integrated with the soil around tightly, so that they can form into a type of composite soil, relying on the frictional force of contact surface. Based on the analysis of the constructional scheme of the national stadium, the key factors for controlling the quality of the construction were found. The quality system during the project should be managed strictly. And the diameter, length and strength of the anchorage ought to be executed exactly. This scheme provided reasons for the national stadium’s soil nailing wall’s safety and quality assurance.

Abstract: Dislocation loop was generated by electron irradiation in nickel aluminum alloy. It is important to know dislocation characteristics obtained from a high energetic electron irradiation. If b is the Burger vector of a dislocation loop and g is the diffraction vector, dislocation loop will appear larger, smaller or disappear for g.b>0, g.b<0 or g.b=0, respectively. Dislocation loop was determined as follows – first, the appearance of dislocation loops is arranged in observation table. Second, based on type of dislocation loop, Burger vector and diffraction vector, appearance of dislocation loop is arranged in calculation table. Third, based on observation and calculation table, Burger vector and type of dislocation loop is determined. The results show that dislocation loops consist of perfect dislocation loops and Frank dislocation loops. The perfect dislocation loops have Burger vectors of ½[0 ] and ½[ 0] while Frank dislocation loops have Burger vectors of ⅓[1 1], ⅓[11 ], ⅓[ 11], ⅓[111], ⅓[1 1], ⅓[11 ] and ⅓[ 11]. All dislocation loops are interstitial types.

Abstract: Micro-arc oxidation coating on AZ91D magnesium alloy is prepared in a NaAlO2-NaOH-montmorillonite-acacia gum electrolyte solution with adaptive electric parameters. The morphologies, composition, phase component of the coatings are analyzed by SEM, EDS and XRD. And CHI600B electrochemistry workstation is employed to investigate the corrosion resistance of the coatings. The results show that the MAO coating has the relatively uniform in thickness. The coating is mainly composed of MgO and MgAl2O4 phases. It provides corrosion protection by acting as a barrier. The MAO coating enhances the corrosion resistance of the magnesium alloy AZ91D to some extent.

Abstract: The Ni-P coatings were deposited on AM60 magnesium alloy by electroless plating process without or with accelerators. Without accelerators, the deposition rate is slow and required high bath temperature to obtain compact coating. There have many defects on the surface of the Ni-P coatings which deposited at high bath temperature. The composite accelerators were introduced into the bath for improving the growth rate and the quality of the Ni-P coating. Uniform, with no pores or cracks, “cauliflower-like” structure and complete Ni-P coatings were deposited only taken 20 min with additives at low bath temperature. The XRD result indicates that the structure of the Ni-P coating is amorphous nickel. The corrosion test results indicated that the corrosion resistance of this coated AM60 magnesium alloys increases distinctly as compared to bare alloys.

Abstract: To account for the adverse effects of white spot defects onto the performance of gear wheel, physicochemical properties are studied based on the conducted surface carbonization experiment. Further, the geneses for white spot defects are discussed and the solutions to this problem are also clarified. It is found from the physicochemical analysis that the white spot defects occurred on gear surface can be classified into two parts: a) the ‘single white spot’, which originates from the sick point produced during the carbonization process, and b) the ‘multiple continuous spots’, which are produced by either the non-uniformity surface carbonization or the grinding burn or otherwise the micro ecarbonization caused by overheat on gear surface. For different white spot defects, different strategies should be employed: ultrasonic cleaning technique should be performed for the single white spot case, while for the ‘multiple white spot’ case, not only should the vacuum carburizing technique be employed to avoid surface non-uniformity of carbonization, but also vacuum oil quenching are needed to clear up the defects induced by micro decarbonization.