Advanced Materials Research Vols. 706-708

Abstract: Nonvolatile of polycrystalline Bi4Ti3O12 thin films prepared by solgel method were studied, and the effect of annealing temperature on resistance switching behavior has been studied. The main point is accented on decrease the operation voltage. Two controllable resistance states were observed by applying voltage pulses. It was also found that the conduction mechanisms dominating the low and high resistance states are Ohmic behavior and Space Charge Limited Current(SCLC).

Abstract: The thermodynamic properties of (B1-xCx)(N1-xCx) (x=0, 0.25, 0.5) are calculated by the ultra-soft pseud-potentials within local density approximation in frame of density functional theory with virtual crystal approximation and using the quasi-harmonic Debye model. The normalized relative volume V/V0, bulk modulus, thermal expansion coefficient α and heat capacity were computed with different temperature and pressure. Meanwhile the lower limit of the thermal conductivity κmin is also examined in details.

Abstract: A new type Cu-La₂O₃ composite was fabricated by internal oxidation method using powder metallurgy. The sliding behavior of the Cu-La₂O₃ composites was studied using a pin-on-disk wear tester under different electrical currents and different applied loads. The worn surfaces were examined using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) to determine the wear mechanisms. The results showed that the wear rate and friction coefficient of the La₂O₃ composites pins increased with the increase of the applied load at low electrical current, while at high electrical current the wear rate and friction coefficient decreased firstly and then increased as the applied load increased. The main wear mechanisms of the Cu-La₂O₃ composites were found to be adhesive wear, abrasive wear, oxidation wear and arc erosion.

Abstract: Polymer matrix composites made from phenolic resin are filled with natural graphite powders. They are fabricated by compression molding technique. The density, electrical conductivity and flexural strength of composite are analyzed to determine the influences of mould pressure and mould pressing time on the physical, electrical and mechanical properties of composite. It is found that the density, electrical conductivity and flexural strength of composites increased with increasing mould pressure. Under pressure of 40 MPa for 60 min, the density, electrical conductivity and flexural strength of composites were 1.85 g/cm3, 4.35  103 S/cm and 70 MPa, respectively. The decreased gaps could be the main reason for the increasing of density, electrical conductivity and flexural strength as mould pressure increases. The results also show that the density of composites increased with increasing mould pressing time.

Abstract: Based on the principle of pore formation, geometrical model to describe open-cell cellular materials was constructed. The model is rhombus dodecahedron cell shapes with circle-strut and transitional-junction. The dependence of relative density on the microstructure of the model was analyzed; by finite elements method, the relative elastic modulus of the model was calculated, the influence of microstructure and relative density on the elastic modulus was also obtained. The results show that circle-strut radius and transitional-junction curvature radius are the primary factors on relative density increment; nonlinearity of relative density on relative elastic modulus is similar to that of circle-strut radius on relative elastic modulus, is obviously greater than that of transitional-junction curvature radius on relative elastic modulus.

Abstract: In recent years ferroelectric polymer-based nonvolatile memory devices have attracted much attention due to their flexibility, transparency and ease of production. However, their electrical stability is seldom studied. In this letter we report the observation of electric fatigue in metal/ferroelectric polymer/SiO₂/p-Si capacitor memories, which is compared with the electric fatigue obtained from metal/ferroelectric polymer/p-Si capacitors. Our experiments indicate that the existence of SiO₂ layer has greatly improved the fatigue endurance in metal/ferroelectric polymer/SiO₂/p-Si capacitors. We also discuss the possible mechanism causing this improved fatigue endurance.

Abstract: The ideal effects of mixing the short fiber-rubber composite can not be reached under current conditions. This paper built the physical model for the short fiber mixes and disperses in rubber through studying the mixing mechanism of the short fiber-rubber composite. The new 6-wing synchronous rotor was designed according to the requirement of material mixing mechanism. The mixing requirement of the ordinary material and the reasonable length-diameter ratio of the short fiber could be met through changing the clearance gap between the rotor edge peak and mixer room. Finally, verify the theory through experimental study.

Abstract: China have the biggest biogas yield in the world, but biogas quality is low and the utilizations of biogas are monotonous now, the shorting of appropriate upgrading technologies is impeding the developing and high quality using of biogas. With analog biogas as raw material, this study investigated biogas upgrading by water scrubbing with adsorption materials used for scrubber picking. Three sorts of packing-plastic hollow sphere, clay ring and zeolite pellet were chosen for the test and the experiments were operated under various pressures (0.65MPa、0.5MPa and 0.3MPa). The results showed that the adsorption packing could improve biogas upgrading effect, the removal rate of CO2 were better when use zeolite pellet( which have better adsorption) as packing compared with conventional plastic hollow sphere, and the results of clay ring(which have little adsorption) experiments were between the above two.

Abstract: In this paper, the hydroxyapatite (HA) based bioceramic materials were used in a rapid prototyping (RP) system to fabrication bioceramic bone scaffold for tissue engineering (TE) using an additive manufacturing (AM) technology. When the bioceramic slurry is sintered via the processing parameters of an 85 mm/s laser scanning speed, 24.5 W of laser power, 10 kHz of scanning frequency, and 2500 Cp of slurry viscosity, a porous bone scaffold can be fabricated under a lower laser power energy. Results indicate that the bending strength of the scaffold was 14.2 MPa, which could be improved by heat-treatment at 1200 °C for 2 hour. MTT method and SEM observations confirmed that the fabricated bone scaffolds possess suitable biocompatibility and mechanical properties, allowing smooth adhesion and proliferation of osteoblast-like cells. Therefore, the fabricated bone scaffolds have great potential for development in tissue engineering.

Abstract: We presented a novel chemical technique to prepare TiO₂ screen-printing from commercially available P25 powder to fabricate high performance and transparent porous TiO₂ electrodes for dye-sensitized solar cells (DSCs). In this new method, acetic acid was modified on TiO₂ surface as dispersant to overcome the aggregation problem and achieve efficient dispersion of P25 powder in water; The modified TiO₂ powder was configured into viscous paste by flocculating reaction with hydrochloric acid. The porous transparent films over 12μm thickness without cracking and peeling-off were fabricated on FTO substrates. A remarkably conversion efficiency of 8.1% was achieved.