Advanced Materials Research Vol. 629

Abstract: Finite element software was used to analyze the deformation of hot extrusion technology at high temperature and high speed for super-alloy Inconel 690(IN690). It had been obtained that the temperature filed and strain filed and stress field during tube extrusion deformation at different speeds and temperatures. The results presented that deformation uniformity being fine and the temperature variety increased with increasing of extruding speed. The maximal equivalent stress decreased and the distributing was further uniformity with the increasing of deformation temperature. Extrusion force reduced at first and then increased with increasing of extruding speed. Maximal extrusion force reduced with the increasing of deformation temperature. The relative errors of extrusion force between simulating results and experiment results are less than 7.3%. Extrusion technology parameters for supper-alloy Inconel690 had been optimized which are that extrusion speed being 110 ~ 120mm / s, and extrusion temperature being 1200 °C.

Abstract: We report our finite element method (FEM) simulation study on the characteristic of the charge transport layer of the multi-layer structure for organic light emitting diodes (OLEDs). The physical model cover all the key physical processes in OLEDs, namely charge injection, transport and recombination, exciton diffusion, transfer and decay for electronic properties. We performed a numerical simulation on a multilayer structure comprising a hole transport layer (HTL), an emission layer (EML), and an electron transport layer (ETL) between both electrodes; anode and cathode. The materials of the HTL is TPD (N, N'-Bis (3- methylphenyl) - N, N'- bis (phenyl) benzidine), and the ETL includes Alq3 (Tris (8- hyroxyquinolinato) aluminium). Here, we investigated the parameters such as recombination rates which influence the efficiency of the charge transport between layers in bilayer OLEDs. We also analyzed a transient response during the turn on period and the carrier transport in accordance with the variation of the injection barrier and applied voltage. In addition, this paper revealed that the effect of the insertion of the EML in bilayer structure.

Abstract: By using first-principles methods based on density functional theory (DFT), we investigated the magnetism and work function of Fe_x-1Mn_x/Fe (001) films with different spin arrangements (parallel (PL), antiparallel (APL1) and mixed (APL2)) for Mn and Fe atoms. The calculation shows that the spin arrangement and alloying have evident impact on the work function and moment of Fe_x-1Mn_x/Fe (001) films. For Mn/Fe (001), the spin arrangement affects evidently the geometrical structure, work function and magnetism of the system. Moreover, the work function for non-magnetic (NM) state is found to be higher than that for magnetic state, and the work function of Mn/Fe (001) with PL state is less than that with APL2 state. For Fe_x-1Mn_x/Fe (001), with increased Mn doping content, the Fe moments in the second layer decrease and their values are all less than the bulk value of Fe atom, which is due to the antiferromagnetic coupling between Mn and Fe atoms. Furthermore, we found that the surface alloying can have an impact on the work function of Fe_x-1Mn_x/Fe (001), but the role of spin polarization is also quite important.

Abstract: We successfully deposited the purely c-axis oriented Fete thin film, which shows superconducting transition in electrical resistivity about 12 K, by using pulsed laser deposition method. The electrical transport measurements of the thin film are studied with magnetic fields up to 14.0 T. thermally activated energy is analyzed using simple conventional Arrhenius relation and more precise relation who is closer to experimental results. Besides, the upper critical magnetic field and the vortex glass transition temperatures for the Fete thin film are studied.

Abstract: The corrosion resistances of a weathering steel SPA-H and a carbon steel Q345 after atmospheric corrosion rests of two cities were measured. The results showed that the corrosion resistance was better for SPA-H than Q345 based on the corrosion rate. The corrosion rates of two steels at Qionghai city were lower than those of Jiangjin city. The characterization of the rusts showed the rust layer on SPA-H was denser and thinner than that of Q345. The rust layers were mainly composed of goethite (α-FeOOH) with a few of lepidocrocite (γ-FeOOH). SPA-H had better weatherability attributed to the alloying elements of copper, chromium and phosphorus enriched in the rust layer. The environment factor such as the sedimentation of SO2 has more effect on the corrosion rates than other factors such as alloy elements.

Abstract: To improve the energy efficiency of refrigeration systems, carbon nanopowders, such as fullerene (C60) and carbon nanotubes (CNTs), are used widely because of their remarkable lubrication and heat transfer capacities. In this work, the dispersion stabilities of mineral oil with added C60, CNTs, and compound C60/CNTs nanopowders were investigated, respectively, by means of sedimentation observation and UV–visible scanning spectrophotometry. The results show that the two methods correspond well. C60 is more stable than CNTs with increasing time; the absorbency of fullerene nanorefrigeration oil displays increasing order with increased concentration, whereby 2 g/L is the inflection point; but a similar pattern appears in CNTs–oil only when the concentration is below 0.5 g/L, after which the concentration of the suspension cannot be measured by the absorbency because their values are alike. The agglomeration of CNTs in mineral refrigeration oil can be restored and it may not create any problems when employed in operational refrigeration systems. The different preparation procedures of compound C60/CNTs–oil exert a large influence on dispersion stability; by grinding fullerene first, one obtains the best dispersion stability of the complex nanorefrigeration oil, in comparison with other methods.

Abstract: This study was conducted to investigate the efficiency of TiO2 photocatalytic nanomaterial as a novel environment-friendly disinfectant to control plant fungal diseases (Sphaerothecaf uliginea) by its photochemical sterilization ability in cucumber plants. Anatase nano-TiO2 sol, a neutral, viscous aqueous colloid of 1.4% TiO2, was synthesized by sol-gel method. Control efficiencies of nano-TiO2 sol in preventing from powdery mildew were measured by field experimental method with cucumber seedling naturally infected Sphaerothecaf uliginea. Results showed that spraying certain content of nano-TiO2 sol could form continuous and stable antibacterial films on blade surfaces which could not only significantly reduce lesion areas, disease incidences and disease indexes of powdery mildew but also make the leaves turn much greener. It was initially confirmed that nano-TiO2 sol could effectively delay and inhibit the development and pervasion of cucumber powdery mildew. These results indicate that nano-TiO2 sol can be developed as environment-friendly fungicide in preventing from plant disease developments.

Abstract: The microwave absorbing properties of multi-walled carbon nanotubes-reinforced cement-based composites (MWCNTs/CC) in the range of 2–18 GHz were investigated in this paper. MWCNTs with the addition of 0.08% by mass of cement were incorporated to cement mortar. It is shown that MWCNTs which act as microwave absorber reinforce the microwave absorbing properties of MWCNTs/CC. Two absorbing peaks of MWCNTs/CC appear in the range of 4–8 GHz, one lies in 4.9 GHz with the reflectivity of -29.1 dB and the other lies in 6.8 GHz with the reflectivity of - 19.2 dB, indicating that the absorbing properties of the composites are improved greatly.

Abstract: High-quality β-Ga2O3 films andβ-Ga2O3 /ZnO/β-Ga2O3 nano composite thin films were fabricated on the sapphire substrates in the high vacuum atmosphere by laser molecular beam epitaxy (LMBE). The lattice structure and optical properties of these films were characterized.With the increase of the sputtering time of ZnO target ,Photoluminescence spectrums and Raman spectrums of the β-Ga2O3 /ZnO/β-Ga2O3 nano composite films were shifted regularly . When the ZnO target was sputtered 30min , the stronggest peak of Raman spectrum was appeared at 267nm . Besides,the composition ofβ-Ga2O3 /ZnO/β-Ga2O3 nano composite film was described .

Abstract: Zinc oxide has been used for many applications, for example optoelectronic devices, ceramics, catalysts, pigments, varistors and many other important applications. In this study, ZnO nanoparticles were synthesized by mixture of fuel approach in solution chemical combustion method. Mixtures of Urea and Zinc salts were mixed at room temperature resulting in spontaneous ignition because these are hypergolic materials resulting in production of ZnO nanopowder. The crystal structure and size of the synthesized powder were determined by X- ray diffractometer (XRD), which revealed that the synthesized ZnO nanopowder has the pure wurtzite structure having average crystallite size of 30nm. Morphological studies were carried out by scanning electron microscopy (SEM), Energy Dispersive X-ray analysis (EDAX) was carried out by Scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDAX), Optical studies were examined by FT-IR and UV-Visible absorption spectrum and the particle size was estimated from Nanoparticle size analyzer.