Applied Mechanics and Materials Vols. 117-119

Abstract: The Nano-Bi₂MoO₆ was prepared using Bi(NO₃)₃•5H₂O and Na₂MoO₄•2H₂O as starting materials by a hydrothermal process. The prepared Bi₂MoO₆ product was characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and UV-visible diffuse reflectance spectroscopy (DRS). It was found that the prepared nano-Bi₂MoO₆ show narrow band gap of 2.88 eV. Consequently, the prepared nano-Bi₂MoO₆ show high visible-light photocatalytic activity for decomposition of Rhodamine B in comparison with the commercial Degussa P25, which was ascribed to the visible-light absorption.

Abstract: The technique of hydrothermal synthesis is used to prepare nanometer molybdenum trioxide through controlling the parameters such as the acidification condition, the reaction temperature, the reaction time and so on. The technique is under high temperature and high pressure by water as the solvent. Synthesized molybdenum trioxide powder is characterized by XRD, SEM, and HRTEM. The optimal reaction time is 40h, the optimum reaction temperature is 170°C, and the optimum pH value is 1.0. The results indicate that powder has an ultrafine particle size, high purity, and narrow size distribution, good fluidity, light agglomerate and is perfect in crystal.

Abstract: The effect of Fe doping on the structure, local electron density and electronic transport properties of DyBa₂Cu_3-XFe_xO_7-δ (x = 0.00- 0.30) superconductors have been investigated by X-ray diffraction (XRD), positron annihilation and other experimental methods. XRD results indicate that the compound undergoes an Orthorhombic–Tetragonal (O-T) phase transition at about x = 0.10. The electrical transport measurements show that the superconductivity was strongly suppressed by Fe doping, and the superconducting transition temperature decreases with the increase of Fe doping content. The results of local electron density calculated using positron annihilation data show that the local electron density of the systems is strongly changed by the Fe doping, and the local electron density vary noticeably at the range of O-T phase transition. From the results of local electron density and the superconductivity, it can be found that the superconducting transition temperature decreases with decreasing the local electron density. These investigations reveal that the crystal phase transition and the local electron density could strongly affect the superconductivity in the Fe doped DyBa₂Cu_3-XFe_xO_7-δ systems.

Abstract: Thermal stability and thermal fatigue performance tests of four kinds of cold work roll steels were done. There are indications that after isothermal 2～6 hours under conditions of 400°C～720°C, the best is 8Cr5SiMoV steel, its thermal stability grows up as isothermal time increase; the second is 8Cr4MoV steel; the worse are 8Cr5MoV steel and 9Cr3MoV steel; and all the thermal stability of four kinds of cold work roll steels are lower than 400°C. Thermal fatigue performance of four kinds of cold work roll steels are basically same as their thermal stability, i.e. the best is 8Cr5SiMoV steel, and the second is 8Cr4MoV steel.

Abstract: This paper studies the application in different cast iron brake drum the thermal fatigue properties of materials. The results show that the stress concentration factor of grey cast iron, hot fatigue crack initiation, low intensity, and easy to expand, organization crack initiation poor stability, antioxidant ability is poor, thermal fatigue is poorer. 35% of vermicular cast iron and of ductile iron high strength, toughness, good stress concentration factor small, thermal fatigue is well.

Abstract: The silver-modified sponge-like titanium dioxide arrays were prepared by a hydrothermal method. The effects of the hydrothermal reaction temperature, template agents were studied. The obtained products of Ag/TiO₂ arrays were investigated by scanning electron microscope in combination with X-ray diffraction. Results show that polyvinylpyrrolidone plays a key role in the formation of titanium dioxide arrays. Compare to the commercial P25 (Degussa), the optimized TiO2 array-structures exhibit an obvious enhanced photocatalytic activity, that enhancement is attributed to its sponge-like biomimetic structure and silver modification. The products have potential applications in degrading organic pollutants.

Abstract: Recently, development of porous calcium phosphates ceramics has raised considerable interest. A porous structure promotes cell attachment, proliferation and provides pathways for biofluids. Therefore, a high porosity with interconnected pore structure generally favors tissue regeneration. In this work, replication of 0, 2, 5, 10 and 15% SrHA (strontium-doped hydroxyapatite) porous scaffolds via polymeric sponge method has been employed using the sol-gel derived SrHA powders. To prepare the porous samples, the synthesized SrHA powders were mixed with distilled water and dispersing agent followed by drying in the ambient air and specific sintering process. Morphological evaluation by FESEM measurement revealed that the SrHA scaffolds were characterized by macro-micro interconnected porosity, which replicates the morphology of the cancellous bone. Compression test on the porous scaffolds revealed that doping 10 mol% of strontium in HA has increased the compressive strength by a factor of two compared to the undoped HA with 1.81±0.26 MPa at 41% porosity.

Abstract: In order to improve the agglomerate drum strength, through a series of experiments study on the alkalinity and Al₂O₃/SiO₂ and carbon content to drum strength relations. The results show that the drum strength enhances gradually along with the alkalinity increasing;when the Al₂O₃/SiO₂ reach 0.35 and the carbon content reach 4.0%,the drum strength achieve the best.

Abstract: Sn-In₂O₃ nanoparticles were synthesized by Sol-Gel method and dispersed steady Sn-In₂O₃ colloid solution was gained. Sn-In₂O₃ nanoparticles are body-center cube ferromanganese mine structure proved by XRD. And they are spheres and 15~25nm studied by HRTEM. The average size of nanoparticles is 21.7 nm with a narrow width 10.8nm measured by granularity instrument. Zeta potential is +33.4mV which means that there are very strong electrostatic repulsion to prevent the bird nesting of Sn-In₂O₃ nanoparticles.

Abstract: The novel lithium enriched lithium tantalate (LiTaO₃) targets were papered by employing the sol-gel process and the high temperature sintered process. The sol of LiTaO₃ was firstly prepared through reacting lithium ethoxide with tantalum ethoxide. The LiTaO₃ powder was fabricated by presintered LiTaO₃ dry gel 4 hour, at 800°C. The 11cm13cm1cm lithium enriched LiTaO₃ target samples were prepared by sintered the pressed LiTaO₃ powder billet 4 hour in the 850°C muffle furnace. The density of the 5% overdose lithium enriched LiTaO₃ target is measured 5.96g/cm³. The XRD measured results show that the ion beam enhanced deposited (IBED) thin film samples using the prepared 5% overdose lithium enriched LiTaO₃ target have the polycrystal structure of LiTaO₃, but there has remanent Ta₂O₅ existed in the IBED thin film samples. The main reason for the remanent Ta₂O₅ growth was due to the stoichiometric proportion mismatch between Li and Ta in the IBED thin film samples during the high temperature annealed process, which caused the lithium oxide evaporation loss from the IBED thin film samples and made the proportion of Ta₂O₅ increase. After multipule repeated target prepared experiments, the 8.76% overdose lithium enriched LiTaO₃ target is suitable for fabricating the 550°C annealed IBED LiTaO₃ thin film. After the repeated process experiments, the suitable deposited process parameters of the IBED-C600M instrument for the 8.76% overdose lithium enriched LiTaO₃ target were obtained. The SEM micrographs of the 550°C annealed IBED LiTaO₃ thin films prepared by the 8.76% overdose lithium enriched LiTaO₃ target reveal the prepared thin films are uniform, smooth and crack-free on the surface, and the perfect adhesion between the thin film and the substrate. The successfully fabricated LiTaO₃ thin film samples verify the prepared processes of novel LiTaO₃ sputtering target are effective.