Materials Science Forum Vols. 620-622

Abstract: Flowerlike bicephalous titanium diboride (TiB2) nanowhisker clusters were fabricated by planetary ball-milling. The pure cleavage theory and crack growth mechanism were used to explain the formation process. The high-resolution transmission electron microscopy and nano electronic beam diffraction show that TiB2 superhard material always has a cleavage plane along the direction of [0001] zone axe and [10 0] zone axe because of its big interplane distance, weak bonding force between planes and low index directions. The flowerlike bicephalous TiB2 nanowhisker can be gained after repeated cleavage under high strains. The discovery could open a new path to fabricate C32 type superhard ceramic nanowhiskers.

Abstract: La doped ZnO nanorods were synthesized via solvothermal technique using Zn(AC)2 and La(NO3)3 as starting materials. The products were characterized by X-ray diffraction (XRD), field scanning electron microscopy (FESEM) equipped with an energy dispersion X–ray (EDX) spectrometer, photoluminescence spectroscopy and UV-vis spectroscopy. The results of XRD in combination with EDS indicated that La was successful doped in ZnO. The obtained La doped ZnO sample exhibited nanorod like morphology and the diameter was about 30 nm. The photocatalytic property of La doped ZnO was evaluated by the variation of the concentration of RhB.

Abstract: Silver nanoplates were prepared in the solution of sodium dodecyl benzene sulfonate (SDBS) and polyvinyl pyrrolidone (PVP) via reducing silver nitrate with hydrazine hydrate. X-ray diffraction (XRD) and Scanning electron microscope (SEM) were applied to identify phase and observe microstructure. The surface tension analysis showed that in SDBS + PVP system, the γ-C curve acted as dual-platform and the corresponding concentration turning points were C1 (0.8g/L) and C2 (6.0g/L) respectively. XRD analysis confirmed that the reduction product was element silver. SEM observation revealed that nano-plates silver were obtained when the SDBS concentration was between C1 and C2, otherwise spherical-shaped nanoparticles were synthesized.

Abstract: Chitosan grafting acrylic copolymer (CTS-g-AA) supported Nano palladium catalyst was obtained in this paper. Chitosan grafting acrylic copolymer (CTS-g-AA) was prepared firstly and palladium was supported on CTS-g-AA; then nano fibrous catalyst was gained via electrospinning technique. The title catalysts were characterized by TEM, SEM and IR, the diameter of nanofiber was about 70~200 nm, the size of metal particles were in a range of 10~40 nm, and palladium particles dispersed on nanofibers homogeneously. The catalyst was applied to catalyze α-octene hydrogenation in normal temperature and pressure. The results showed that the conversion of α-octene was 99%, and the yield of octane was 65% by double-metal catalyst.

Abstract: The present research describes a simple low-temperature synthesis route of fabricating porous YVO4:Sm nanoplates via a chemical co-precipitation method using commercially available Y2O3, NH4VO3, Sm2O3 and ethylene glycol as the reacting precursors. The as-synthesized YVO4:Sm was thermally treated at 300°C and 600°C for 2 h which is much lower than that of the conventional preparation methods. The obtained samples were characterized by FTIR, XRD, TEM and PL. The photoluminescence measurement revealed that the luminescence intensity was significantly increased with increasing annealing temperature.

Abstract: The enhancement of the fatigue strength is significant for the engineering applications of commercial pure titanium and its alloys. The paper investigated improvement of fatigue strength for commercial pure titanium by combined high-energy shot peening. Firstly, nano-crystallization in surface layer of pure titanium was carried out by high-energy shot peening, and then the shot peening with small diameter shots was introduced to degrade the surface roughness, enhancing the quality of the nano-grained surface. The fatigue limit of pure titanium by high-energy shot peening turns out to be increased by 34%, and the fatigue limit of pure titanium by compound high-energy shot peening turns out to be increased by 52.3%, according to the results. Effective factors such as surface states etc. to fatigue life, the fatigue crack initiation and propagation behaviors were also discussed in this paper.

Abstract: The self-propagating combustion reaction 0.741Mg + 0.247Fe2O3 + 0.188Ni + 0.318Cr → 0.741MgO + Fe0.494Ni0.188Cr0.318 was applied to prepare a nano-MgO reinforced Fe-Cr-Ni composite, by reactive hot pressing (RHP) under a condition of 700°C/30MPa/2h. The densification was enabled by the low temperatures produced by the exothermic reaction. According to TG-DTA and X-ray diffractometry (XRD), the highly-exothermic thermite reaction began at about 600°C and the in-situ formation of composites comprised predominantly of (FCC) Cr0.19Fe0.7Ni0.11, (FCC) Fe-Cr, (BCC) MgO and a small quantity of (BCC) MgFe2O4. The Vickers hardness was 3.67GPa, the three-point bending strength was 112.5±10MPa, and the fracture toughness was 3.28 MPa•m1/2. The microstructure of the composite was observed via scanning electron microscopy. This indicated that the distributions of in-situ-formed (BCC) MgO phases (~800 nanometers) were homogeneous into in a matrix of a fine-grained metallic alloy phases that gather together to form agglomerates in the composite.

Abstract: The modified valonian tannin was prepared through sulfonated-mannich reaction and used to adsorb Cu (II) from the aqueous solutions. The adsorption capacity rapidly reached equilibrium within 2 hours. The effect of pH on adsorption was apparent, the amount of adsorption increased significantly as the pH increased from 2.0 to 4.0 and then leveled off at pH 4.0-6.0. Equilibrium data fitted well with Freundlich isotherm model compared to Langmuir isotherm model, indicating that adsorption takes place on heterogeneous surface of the modified valonia tannin. The adsorption capacity was increased by increasing initial concentrations. The maximum adsorption capacity of cooper ion was determined to be 56.200 mg/g at 100 mg/L concentration.

Abstract: The ecological fiber is a new water treatment material that is processed by simulating the shape of wild water-borne plant. In recent years it has been applied broadly in sewerage treatment for its following advantages: big specific surface area, high capacity in removing organic matter, good microbiological adhesiveness, variable pore sizes, wonderful performance in preventing jamming, flexibility in operation and management, etc. Ceramic padding has high porosity and moderate density which is highly favorable to the growth of microorganisms. This paper discussed treating the micro-polluted water by the combination of oxidation pond and constructed wetland. The results show that some indexes of the treated water reached or exceeded band 3 national water quality standards. These indexes include TN (total nitrogen), TP (total phosphorus), TDP (total dissolved phosphorus), CODCr and so on. The research results can provide scientific basis for project design.

Abstract: The in vitro attachment, spread, and proliferation behavior of osteoblast cells on the plasma-sprayed composite coating with 70wt% zirconia and 30wt% dicalcium silicate were studied. The composite coating shows good cytocompatibility. The human osteoblast cells attached, spread and proliferate well on the surface. The cytocompatibility of the coating was attributed to the incongruent dissolution of dicalcium silicate and the large amount of Si-OH functional groups produced on the surface. The released calcium and silicon ions are also positive to the proliferation of cells. All our results show that the composite coating possesses good cytocompatibility.