Advanced Materials Research Vol. 699

Abstract: A sample method was developed to fabricate composite of TiO2 and graphite oxide by a liquid phase deposition method. (NH4)2TiF6 and H3BO3 were stirred in distilled deionized water to prepare TiO2 particles which were then in situ deposited on graphite oxide. The photograph of scanning electron microscope (SEM) shows that the TiO2 particles are compact and uniform on the surface of graphite oxide sheets. The composite exhibited efficient photocatalytic activity under the ultraviolet light in degrading organic dye of methylene blue. There are two steps in the dye reducing process: the first half hour of porous adsorption by graphite oxide, and the photocatalytic degradation by TiO2 particles. In this case, the methylene blue reduces sharply in the first half hour with the concentration from 10 mg L-1 to 5.8 mg/L. From then, the reduction rate comes down gradually with the concentration of 0.9 mg L-1 after 6 hours UV lighting. The synergism of TiO2 particles and graphite oxide increases the reduction of methylene blue and possesses composite of reutilization ability practically.

Abstract: In this paper, a polypyrrole (PPy)/SiO2 composite filler prepared via in situ polymerization of pyrrole (Py) on SiO2 particles was incorporated into Nafion to improve the performance of ionic polymer-metal composite (IPMC) actuators. A transmission electron microscope (TEM) was used to observe the morphology of the prepared PPy/SiO2. IPMC with 1% and 2% PPy/SiO2 was synthesized, and the elastic modulus, the electric current, the blocking force and the water retention ability were measured on the test apparatus. Results showed that IPMC with 1% PPy/SiO2 composite, synthesized with 0.5ml Py, exhibited the best mechanical property. Compared with the pure Nafion-IPMC, the blocking force of PPy/SiO2/Nafion-IPMC with the optimized filler content (34.68 mN) at the sinusoidal voltage of 3 V and 0.1Hz was 2.3 times higher. Such significantly improved performance was attributed to the PPy’s redox reaction, which facilitates the ion transport in IPMC. Furthermore, the reasonable amount of the PPy and PPy/SiO2 plays an important role in fabricating the homogeneously distributed PPy/SiO2/Nafion membrane.

Abstract: The efficiency of using in the charge of SHS-mixtures wollastonite “active” additives of micron size activated and modified by different organic compounds as a result of mechanochemical treatment(MCT) is considered. The structure, composition and morphology of modified particles of wollastonite depending on the conditions of MCT in mills-activators of dynamic action are studied. During SHS of composition metal-oxide materials, wollastonite particles play the role of the centre of the mixture combustion site, provide the local increase of temperature, change thermodynamic characteristics of the sample synthesis process as a whole and contribute to formation of nanostructurized SHS-ceramics with high strength and dielectric characteristics.

Abstract: This study investigates the activation of waste carbon fiber by microwave heating and potassium hydroxide and the adsorption of aqueous dye RB19 using said modified waste carbon fiber. Heating was performed in a microwave that was set to 900 W from 20 to 60 minutes (M20, M40, and M60). The specific surface areas of the original waste carbon fiber (WCF), M20, M40, and M60were 2 to489 m2/g. M40 had the highest specific surface area and an acceptable yield of 62%. In adsorption experiments at 57°C, the original waste carbon fiber adsorbed only 15 mg of dye/g of fiber. The results reveal that the capacity of adsorption increased when the waste carbon fibers were modified by activation with microwave and potassium hydroxide. Remarkably, M40 was the most suitable absorbent of aqueous dye RB19 and it had the highest capacity of 202 mg/g.

Abstract: The enormous carbon footprint associated with the global cement production (5-7%) asks for a radical change in the use of sustainable replacement materials in concrete. Replacement of cement by pozzolanic waste materials, being a by-product from industrial processes, has been widely recognized as the most promising route towards sustainable construction materials. This paper presents experimental study on hydration of commercial Portland cement blended with silica fume in replacement ratio of 15 mass %. Isothermal calorimetry was employed to monitor the hydration kinetics. Thermogravimetric analysis coupled by differential scanning calorimeter (TG/DSC) was used to investigate the formed hydration products at 1, 3, 7, and 28 days of hydration. Two different approaches for a dispersion of silica fume in cement paste were compared: ultrasound bath and addition of superplasticizer (polycarboxylic ether based).

Abstract: This paper presents an image based numerical method proposed to obtain information regarding pore structure and organization of pores within materials based on 3D digital image input. The output of the numerical algorithm is a pore size distribution of materials. The algorithm is based on the combination of the two digital image processing algorithms: 1) a medial axis thinning algorithm to obtain 3D skeleton of the pore structure, and 2) the distance transform of an image. The method is tested on simple 2D and 3D microstructures of packed spheres, demonstrating the performance of the proposed method.

Abstract: In this paper, the electricalcharacteristics of Ergermanideschottkyjunction werestudied for source / drain of n-typeschottky barrier Ge MOSFET.Ergermanideshowed the lowest ideality factor at RTP temperature of 600°C among the applied temperature range. When RTP temperature was increased, barrier height and work function of Ergermanidebecame similar to those of Er2Ge3. From the analysis of the leakage current, it is shown that the Poole-Frenkel barrier lowering was dominant at RTP 600°C and the influence of the Schottky barrier lowering was decreased as RTP temperature increased. The electrical characteristics of Ergermanideare very sensitive to the RTP temperature andclosely related tothe trapsites which are generated by germanidation.

Abstract: Different corrosion resistant stainless steels, nickel-based alloys, pure nickel, Ta-coated stainless steel (AISI 316L), niobium, platinum and gold rods were evaluated as possible materials for use in the intermediate temperature (200-400 °C) acidic water electrolysers. The corrosion resistance was measured under simulated conditions (molten KH2PO4) corresponding to the proton-conducting solid acids or transition metal phosphates as electrolytes. It was shown that, unlike at temperatures below 200 °C, gold is unstable with respect to corrosion in molten KH2PO4. Platinum demonstrated high corrosion resistance and the anodic and cathodic limits were for the first time found for the electrolyte. Nickel, niobium, Inconel®625, Hastelloy®C-276 and Ta-coated stainless steel (AISI 316L) demonstrated high corrosion stability and can be recommended as construction materials for bipolar plates.

Abstract: CdZnS thinfims have been prepared on mineral glass substrate by spray pyrolysis method at different deposition temperature using the optimized coating parameters. The XRD profile of the films confirms hexagonal wurtizite structure with preferred orientation along the (101) pane. The different crystallographic parameters viz., lattice constant, c/a ratio, mean grain size, number of reflections per unit area, lattice strain, dislocation density, texture coefficient and standard deviation have been calculated from the experimentally observed XRD data and the effect of deposition temperature on these parameters have been elaborately discussed. The maximum optical transmittance of 84.5% (at λ= 650 nm ) has been observed for the CdZnS thin film spray deposited at the temperature 450 °C. The direct band gap energy calculated from the transmittance measurements lies between 2.82 eV and 3.4 eV. The electrical resistivity has been found to be low with the value 50 x 103 Ω - cm for the film deposited at the temperature 450 °C. The SEM micrographs of the films show uniform surface pattern associated with large accumulation of fine grains. The grain size estimated from the SEM analysis lies between 100 nm and 350 nm.

Abstract: Nano-multilayered, crystalline CrAlSiN thin films were deposited on either steel or WC-10%Co substrates by the cathodic arc plasma deposition. Their oxidation characteristics were studied at 800-1000°C for 50 h in air. The film deposited on steel displayed good oxidation resistance, due mainly to formation of Cr2O3 and α-Al2O3. The film deposited on WC-10%Co displayed poor oxidation resistance, due mainly to the oxidation of the substrate.