Papers by Author: Bing She Xu

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Authors: Jin Ling Zhang, She Bin Wang, Ming Zhao Li, Xu Guang Liu, Bing She Xu
Abstract: Rare earth was added in foundry magnesium alloy in vacuum melting. Analysis and measurement showed that the quantity of inclusions was decreased and the mechanical properties were improved. The size of crystal grain was decreased by 59%, the yield strength was increased by 38% and elongation percentage was increased more than 7 times. On the basis of this experiment, the approaches of improving the mechanical properties of magnesium alloy were brought up.
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Authors: Jun Shou Li, Liang Li, Jian Jiang Wang, Bing She Xu, Yu Jun Yin
Abstract: Al2O3-TiO-TiO2 multiphase foam ceramic was prepared with Al powders and TiO2 powders by combustion synthesis, Direct observation and metallographic microscope indicated that the pore diameter is 100~6000μm, and Archimedean method showed that the porosity is 35~50%. The influencing factors of the pore diameter and porosity and, the effects of adding SiO2 on compression strength of the Al2O3- TiO-TiO2 multiphase foam ceramic were discussed. It was shown that the addition of proper high temperature foaming agent can increase porosity and adding SiO2 can decrease porosity. The Al2O3-TiO-TiO2 multiphase foam ceramic has good mechanical properties and high-temperature resistance.
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Authors: Jin Ling Zhang, She Bin Wang, Xiao Ye Qi, Bing She Xu
Abstract: Microstructure changes brought by the addition of La element to AZ91 magnesium alloy are studied, also, the precipitating phases were identified and their influence on the mechanical properties of alloys was investigated. Results show La makes refinement of microstructure of the AZ91 alloy, and decrease the size of Mg17Al12 phase. La element takes a priority to react with Al element over Mg, forming binary phase Al11La3 with high melting point. Certain amount of La increases tensile strength, yield strength and elongation. With more addition, La would combine more Al in matrix and decrease strengthening effect, because Al11La3 phase would become coarsening. The mechanical poroerties tests indicate that AZ91+0.16%La alloy has the best properties. Maximum tensile strength, maximum yield strength and elongation are 245MPa, 178MPa and 14.5% respective, increased by 21%, 19% and 48% respectively. The mechanism of La strenthing mechanical properties is proposed that Al11La3 phase enriched on solid-liquid interface, increased the degree of supercooling, refined the grain size and changed the crystal style.
1650
Authors: Xiang Hua Gao, Li Qiao Wei, Jing Wang, Bing She Xu
Abstract: Stable silver nanoparticles were synthesized from AgNO3 through a simple green route using biodegradable and renewable starch as stabilizing agent. Nanoparticles have been studied for their formation, structure, morphology and size using UV–vis spectroscopy, X-ray diffraction (XRD) and HRTEM analysis. XRD showed that the nanoparticles were of face centered cubic structure. UV–Vis and HRTEM revealed that the spherical particles having radius 5-20 nm are mostly stabilized by starch. Further, antibacterial properties of these starch-stabilized nanoparticles show promising results for S.aureus in growth inhibition ring test.
1945
Authors: Jun Yu, Bing She Xu
Abstract: Preliminary study on the preparation and performance of vapor grown carbon fibers (VGCF) reinforced cement composites was carried out. VGCF were prepared from de-oiled asphalt (DOA) by chemical vapor deposition (CVD). Results demonstrated that compressive strength and electrical conductivity of VGCF reinforced cement could be significantly enhanced with very low fiber content. The resistivity decreased and compressive strength increased of cement-matrix composites with weight fraction of VGCF increasing from 0 to 0.6% fiber in the paste. The fiber content of 0.4% by mass of cement was recommended, which yielded the resistivity of 1.49×103Ωcm. That was two orders of magnitude lower than that for the same paste without VGCF (3.25×105Ωcm). Furthermore, the compressive strength increased by 28.8% as the VGCF content increases from 0 to 0.4% by mass of cement.
1641
Authors: Jun Yu, Bing She Xu
Abstract: Carbon-encapsulated Ni nanoparticles with the size of 5 to 30 nm were synthesized from de-oiled asphalt (DOA) by heat-treatment at 1800 °C with nickel powder. The nanoparticles exhibited well-constructed core-shell structures, with Ni cores and graphitic shells. High resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD) examinations confirmed that the carbon-encapsulated Ni nanoparticles were uniformly dispersed in carbon matrix and the Ni nanoparticles were surrounded by several carbon layers with well ordered arrangement. The formation of the core-shell nanoparticles was selectively controlled by adjusting the ratio of de-oiled asphalt to nickel powders. The possible growth model for the carbon-encapsulated Ni nanoparticles was discussed briefly. This result presents a simple and controllable way to synthesize carbon-encapsulated nickel nanoparticles.
202
Authors: Jin Fang Ma, Lan Qing Hu, Xu Guang Liu, Bing She Xu
Abstract: After surface mechanical attrition treatment (SMAT) for Al-Zn-Mg alloy, a gradient structure with average grain size increased from 20nm in surface layer to about 100nm at a depth of 20μm was formed. The thermal stability of surface nanostructured layer in Al-Zn-Mg alloy samples was investigated by vacuum annealing at 100°C, 150°C, 200°C and 250°C for 1h, respectively. The microstructural evolution as well as the microhardness along the depth from top surface layer to matrix of SMATed samples was analyzed. Experimental results showed that the grain size of surface nanocrystallites remains in submicro-scale, ranging from 300nm to 400nm, when annealed at a temperature of 250°C, and the microhardness of surface nanostructured layer was still high compared with that of matrix, indicating satisfying thermal stability of nanocrystallized layer. This might be attributed to the presence of substantive trident grain boundaries and pinning effect of dispersive precipitated phases in nanocrystalline materials, which hindered the grain boundary migration that leading to grain growth.
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