Advanced Materials Research Vols. 560-561

Abstract: Mn-doped ZnO thin films were prepared on SiO₂ substrates by using a radio-frequency(rf) magnetron sputtering in order to investigate structure and optical proprieties of the films. X-ray diffraction (XRD), Atomic force microscope (AFM) and UV-VIS spectrophotometry were employed to characterize the Mn-doped ZnO films. The results showed that the shape of the XRD spectrum was remarkably similar to that of the un-doped ZnO film; the film had mainly (002) peak, and indicate that the structure of the films was not disturbed by Mn-doped. The film had rather flat surfaces with the peak-to-tail roughness of about 25nm. Mn-doping changed the band gap of the films, which increased with the increase of the Mn content.

Abstract: Green-emitting Tb3+-doped Ca-deficient hydroxyapatite phosphor was successfully prepared from natural collophanite. The effects of (Tb+Ca)/P values on the crystal phases and luminescent properties of the prepared products were discussed. XRD results revealed that Ca-deficient hydroxyapatite was a biphase compound of hydroxyapatite (HA) and β-tricalcium phosphate (β-TCP), and its crystal phase transformed to HA with the increasing values of (Tb+Ca)/P. Photoluminescence measurements showed that the products presented intensely green emission peaking at 545 nm under near-ultraviolet excitation and the luminescent intensity had great correlation with the content ratios of β-TCP to HA. When (Tb+Ca)/P=1.3, the luminescent intensity of Tb3+-doped Ca-deficient hydroxyapatite reached the maximum value, which was much stronger than that of Tb3+-doped HA. These results indicate that Tb3+-doped Ca-deficient hydroxyapatite phosphor is suitable for potential application in white light-emitting diode (LED).

Abstract: In this article, study results of the electrical resistance properties of cement/carbon fiber composite are presented. Using a normal mixing and compacting method, up to 0.85v.% short carbon fiber can be easily incorporated into the cement composite. And its electrical resistivity properties are measured. The resistivity of specimens decreases greatly with the volume fraction of fibers increasing. Moreover, it is found that there is a saturation point for fiber volume fraction. Beyond that, the change of resistivity with the variation of fiber volume fraction becomes much flat. Another interest finding is that the resistivity of the cement materials is a function of frequency of applied voltage. The microstructure associated with the electrical properties of composite is observed. It is possible to apply cement/carbon fiber composite as an electromagnetic shielding composite and so on.

Abstract: TiN/AlN nanoscale multilayer films were deposited by pulsed laser ablation on silicon, with different argon and nitrogen gas flow rates. The total thickness of the TiN/AlN multilayer film was approximately 1μm. The friction and corrosion properties were studied by tribological and corrosive tests. In tribological tests, ball-on-disc was used to determine coefficients of friction and wear rates. The coefficient of friction against a Si3N4 ball varied considerably between films, as does the wear rate. The lowest coefficient of friction μ=0.97 was shown at sample 1, whereas the other three multilayer films were ranged from 1.0 to 1.5. In corrosion test, the anodic polarization characteristics were measured in a 3.5% NaCl solution at room temperature to examine the corrosion resistance. The potentiodynamic polarization measurements showed that for all the multilayer films the corrosion potential shift to higher values, and the corrosion current density decreased with increasing of nitrogen gas flow rate, which indicate a higher nitrogen partial pressures lead to a better corrosion resistance.

Abstract: Results of development of high-pressure process of low-density polyethylene production at “Tomskneftekhim” Company have been presented. New technology allowed increasing productivity, product quality, extending polymer assortment. Comparison with designed indexes and the ones at other Russian and world companies has been done.

Abstract: Ring parts with small-hole and deep groove such as duplicate gear and double-side flange, are widely used in various engineering machineries. Three-roll cross rolling (TRCR) is a new advanced plastic forming technology for the processing of rings with small-hole and deep groove. In this paper, a 3D coupled thermo-mechanical FE model for TRCR of ring with small-hole and deep groove is established under ABAQUS software environment. By simulation and analysis, the evolution and distribution laws of strain and temperature in the forming process are revealed, and the effects of the key process parameters on the deformation uniformity are explored. The results provide valuable guideline for the technological parameter design and optimization.

Abstract: Oxygen-permeable perovskite ceramics with mixed ionic-electronic conducting properties can play an important role in the high temperature separation of oxygen from air. Such membranes are envisaged for application in catalytic membranes reactors and in oxy-fuel and pre-combustion technologies for fossil fuel power plants enabling CO2 capture. Since large-scale gas separation applications demand high membrane surface/volume ratios, membranes with capillary or hollow fiber geometry have a distinct advantage over tubular and flat sheet membranes. The fabrication and performance of Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF) capillary membranes is presented. The capillaries were made by a spinning technique based on phase inversion using a sulfur or non-sulfur containing polymer binder. Attention is given to the polymer solution and ceramic spinning suspension in order to avoid the formation of macrovoids and achieve gastight membranes. The comparison of the performance of sulfur-free and sulfur-containing BSCF capillaries with similar dimensions revealed a profound impact of the sulfur contamination on both the oxygen flux and the activation energy of the overall oxygen transport mechanism. In addition the effect of activation layers on oxygen permeation is studied.

Abstract: Li_1-xLa_xV₃O₈ cathode materials has been synthesized by pechini sol-gel method. The electrochemical performances of Li_1-xLa_xV₃O₈(x=0-0.05) have been studied by X-ray diffraction (XRD), galvanostatic charge-discharge, and cyclic voltammetric (CV). The results showed that the optimal content of the La³⁺ doping in LiV₃O₈ was x=0.01, and the first discharge capacity of Li_0.99La_0.01V₃O₈ sample in the voltage range of 2.0-4.0V was 230mAhg^-1, which was much higher than that of LiV₃O₈ (200mAhg-1). The Li_0.99La_0.01V₃O₈ cathode also showed higher discharge voltage plateau than LiV₃O₈ cathode from the CV curves.

Abstract: A series of fluorinated poly(aryl ether oxadiazole)s (FPEO) were synthesized and brominated with N-bromosuccinmide (NBS) which were then functionalized with quaternary guanidinium to get fluorinated anion exchange membranes （AEM）with pendant quaternary guanidinium Groups. The structure of resulting polymers was characterized by FTIR spectroscopy. The properties of the obtained membranes were investigated in terms of ion exchange capacity (IEC), swelling ratio, area resistance and vanadium permeability. The results showed that the novel anion exchange membranes possess much higher selectivity in VRB system. The permeation rate of vanadium ions of GFPEO is 0.21×10-7 cm2min-1 which is much lower compared with that of Nafion.

Abstract: The supported Cu/Flokite catalysts were prepared by conventional incipient wetness impregnation. The catalysis oxidation degradation of phenol was carried out in heterogeneous catalyst and H2O2 process. The results indicated that the reaction system with catalyst and hydrogen peroxide was more benefit to degradation of phenol. When the phenol initial concentration was 100 mg/L, the phenol removal over the 2.5%Cu -2.5% Fe/Flokite catalyst could reach 96%. The peroxide catalytic oxidation process over the enhanced heterogeneous catalyst would be a novel technique for the treatment of phenol wastewater.