THERMEC 2006 Supplement

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Authors: Prakash Parasivamurthy
Abstract: The rapid Urbanization and Industrialization all over the world has resulted in large deposition of Plastic waste. This waste can be utilized under proper condition to reduce the Cement content in Concrete.M20 concrete is used for most of the constructional works, since it gives maximum strength. The strength of this concrete was compared with concrete obtained of shredded Plastic waste varying from 2-8%. Experimental investigations comprised of testing physical requirements of coarse aggregates, fine aggregates, cement and the modifier. M20 concrete was prepared as per IS SP: 23-1982. The said percentage of modifier was blended with the cement concrete mix and the optimum modifier content was found. Cubes were cast and tested for 1, 3, 7, 14 and 28 day strength. These tests revealed that by adding modifier, the strength of concrete increased. At 5% optimum modifier content, the strength of the modified concrete was found to be 1.2 times greater than the plain cement concrete. By using Plastic waste as modifier, we can reduce the quantity of cement and sand by their weight, hence decreasing the overall cost of construction .The Modified cement concrete can be used in the construction of small drainage works and rigid pavement. Which leads to decrease in the overall thickness of the pavement.
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Authors: Isabel C. Atías Adrián, Dario Vallauri, Z. Zhang, A. Chrysanthou, Bruno DeBenedetti, Ignazio Amato
Abstract: Non-oxide ceramic nanostructured powders are synthesized through metastable transformation processing based on the Self-propagating High-temperature Synthesis (SHS) process followed by quenching. Binary systems like the investigated TiC–TiB2, when quenched from the liquid state give rise to metastable structures capable of being converted into a stable, fine-grained (nanocomposite) microstructure upon recrystallization by medium temperature treatments. A necessary condition is that the combustion temperature of the SHS reaction is higher than the eutectic temperature. A previous optimisation of the reaction stoichiometry was carried out to obtain SHS products with composition approximately equal to the eutectic (i.e. 67%mol TiC0,7 – 33%mol TiB2), according to the reaction: 6Ti + B4C + 1.8C → 4TiC0.7 + 2TiB2. In this work, different amounts of sodium borate (borax) were used in order to determine the optimum amount of additive to produce nanostructured TiC0.7–TiB2 composites. The morphological evolution of the powders after thermal treatment yielding re–crystallized structures demonstrates the metastability of the SHS–quench products. Therefore, the metastability process based on SHS– quench represents an extremely attractive route suitable for the achievement of nanocomposites.
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Authors: Bong Jae Choi, Si Young Sung, Young Jig Kim
Abstract: The aim of this study is to fabricate an α-case free (TiB+TiC) hybrid titanium matrix composites (TMCs) shot sleeve for aluminum alloy diecasting by in-situ synthesis and investment casting. Granular 1.88 wt% B4C was added to a titanium matrix in a vacuum induction melting furnace. The synthesized (TiB+TiC) TMCs were examined using electron probe micro-analysis and transmission electron microscopy. The results of the in-situ synthesis and investment casting of the TMCs show that our casting route constitutes an effective approach to the economic net-shape forming of TMC sleeves.
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Authors: Masaru Morobayashi, Kenji Matsuda, T. Saeki, Susumu Ikeno, K. Nishimura, Katsunori Mori
Abstract: Superconductive MgB2/Al composite material with low and high volume fractions of particles were fabricated by our special pre-packing technique and 3-dimensional penetration casting 3DPC method. The composite material showed homogeneous distribution of MgB2 particles in the Al-matrix with neither any aggregation of particles nor defects such as cracks or cavities. The critical temperature of superconducting transition (TC) was determined by electrical resistivity and magnetization to be about 37 ~39K.
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Authors: Hua Min Kou, Yu Bai Pan, Jing Kun Guo
Abstract: Al/Al2O3 cermet composites were fabricated by hot-pressing at the temperature range of 1350~1450oC from commercial γ - Al2O3 reinforced by Al/Al2O3 core-shell particles, which were synthesized via calcining the Al/AlOOH·nH2O core-shell particles prepared by wet-chemical based method. This newly designed aluminum coated with alumina composite structure can not only reduce or resist the oxidization of Al at elevated temperature but also make it possible to control inter-particle and particle-matrix interactions, and this predesigned structure is expected to improve the following sintering ability and therefore the properties of final products.
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Authors: Yu Song Wu, Jiang Li, Yu Bai Pan, Jing Kun Guo, Qian Liu
Abstract: Commercial Y2O3 powders were subjected to high energy ball milling in a planetary ball mill using high purity alumina balls and vial. The refined Y2O3 power ,with commercial high-purity Al2O3, Cr2O3 and Yb2O3 powders, were used as raw materials. Transparent ytterbium and chromium codoped yttrium aluminum garnet (Yb,Cr:YAG) ceramics were fabricated by a solid-state reaction method. The Yb,Cr:YAG ceramics exhibit a pore free structure and the average grain size is about 10 micron. The strong absorptions at 940 and 968 nm of Yb3+ are suitable for InGaAs diode laser pumping, and there is an absorption band at 1030 nm, which is suitable for passive Q-switch laser output at 1030 nm. Transparent Yb,Cr:YAG ceramics may be a potential material for compact, efficient, high-stability diode-laser-pumped passive Q-switched solid-state lasers.
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Authors: Hong Mei Wei, Lin Geng, Xue Xi Zhang
Abstract: Solidification behavior of SiCw/Al-18Si metal matrix composites (MMCs) was studied by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and differential scanning calorimeter (DSC) in order to reveal the effects of strontium addition and whisker content. The results show that the Si phase does not nucleate on SiC whisker surface. With the increasing of SiC whisker content, solidification onset and peak temperatures of primary Si decrease. Sr addition lowers solidification onset and peak temperatures of primary Si, and reduces its size. Whisker content has larger effects on solidification onset and peak temperatures of primary Si without Sr addition than that of primary Si with Sr addition.But solidification onset and peak temperatures of eutectic are barely affected by whisker content and Sr addition.
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Authors: H. Hanado, Yutaka Hiraoka
Abstract: Room-temperature deformation behavior in the localized regions of W-80vol%Cu composite was investigated in this study. Plastic strain of about 10 % was added to the specimen at room temperature using a three-point bend testing machine. Then deformation behavior in a localized region was investigated using a high-magnification SEM photograph before and after deformation. Results are summarized as follow. (1) In a localized region near a large pore, heterogeneous deformation had occurred as expected. (2) In a region apart from a pore, mostly homogeneous deformation occurred but occasionally heterogeneous deformation occurred.
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Authors: Bretislav Šmíd, Toshiyuki Mori, M. Takahashi, Ding Rong Ou, V. Matolín, Iva Matolínova
Abstract: Carbon monoxide (CO) is a significant air pollutant produced in incomplete oxidation of carbon in combustion. From the viewpoint of environmental protection, it is important that the concentration of CO gas is lowered in air. Catalysis is proving to be an effective route for removing this pollutant. Therefore, a design of nano-structured catalysts with high efficiency is required. In the present work, we focus on a development of nano-size CuOx-CeO2 catalysts for CO oxidation reaction. To prepare nano-structured Cu loaded CeO2 catalysts, a combined method of the conventional impregnation and ammonium carbonate co-precipitation was examined. Morphology, crystal phase and surface structure of prepared catalysts were characterized using High-Resolution Transmission Electron Microscopy (HRTEM), Scanning Electron Microscopy (SEM) and Powder X-ray Diffraction (XRD). Catalytic properties of CuOx-CeO2 for CO oxidation were investigated in gas flow reactor system under atmospheric pressure and compared with copper oxide loaded zinc oxide. We expected that nano-structured CuOx-CeO2 catalysts could be used for removing CO produced in a wet reforming reaction of fuel cell applications.
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Authors: Caroline R. Cloutier, Akram Alfantazi, Elod Gyenge
Abstract: The conductivity and viscosity of aqueous solutions of NaBO2 were measured as a function of concentration at 25oC. Conductivity data was analyzed with various Kohlrausch correlations and the limiting molar conductivity of the BO2 - ion at infinite dilution was estimated to be of 30.59 S.cm2/mol. From this value, the mobility, diffusion coefficients and transference number for the BO2 - ion were calculated as 3.17x10-4 cm2/s.V, 8.14x10-6 cm2/s, and 0.379 respectively. Ion-solvent and ion-ion interactions were studied with Jones-Dole type correlations, which were employed to analyze the viscosity data. A value of -0.4660 1/M was estimated for the BO2 - B- coefficient.
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