Papers by Keyword: Powder Processing

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Authors: Tehreem Kanwal, Rub Nawaz Shahid, Naeem Ul Haq Tariq, Fahad Ali, M. A. Rafiq, Muhammad Iqbal, J.I. Akhter, Bin Awais Hasan
Abstract: The ceramic-metal composites that have all phases continuous throughout the structure are known as Interpenetrating Phase Composites (IPCs) and they have many applications in various fields. In this investigation ZrO2-Ni IPCs of varied compositions were synthesized using tubular furnace and microwave furnace routs. Samples were Characterized using BET surface area, Pycnometer density, dilatometry and scanning electron microscopy. The Electrical parameters of the composites were measured using impedance spectrometer. Results indicate that threshold percolation reached at 40 volume percent of Ni in both cases. Moreover, no significant difference was observed in BET surface area and CTE of composites prepared by conventional and microwave sintering processes.
293
Authors: Jun Akedo
Abstract: Aerosol deposition method (ADM) for shock-consolidation of fine ceramics powder to form dense and hard layers is reported. Submicron ceramic particles were accelerated by gas flow in the nozzle up to velocity of several hundred m/s. During interaction with substrate, these particles formed thick (10 ~ 100 µm), dense, uniform and hard ceramics layers. Depositions were fulfilled at room temperature. Every layer has polycrystalline structure with nano-meter order scale.􀀂 The results of fabrications, microstructure, mechanical and electrical properties of oxides (α-Al2O3; Pb(Zr0.52,Ti0.48)O3 etc.) and non-oxides materials are presented.
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Authors: Xu Bing, Qian Ping, Xu Cheng Qian, Yuan Fang Hong
Abstract: This paper discusses the anti-explosion control system project for the fine powder processing. To prevent explosion, safety interlock control system is brought up. The article describes the hardware configuration and software establishment of the project, and makes suggestions for the project implement about sensor installing and program debugging.
1978
Authors: Sergio Luiz Mineiro, Maria do Carmo de Andrade Nono, Carlos Kuranaga, Dailton de Freitas
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Authors: O.C. Standard, Charles C. Sorrell
251
Authors: A. Bellosi, Frédéric Monteverde, S. Botti, S. Martelli
255
Authors: Ladislav Čelko, David Jech, Karel Dvořák, Ivo Šulák, Lenka Klakurková, Karel Obrtlík
Abstract: Barium-Magnesium-Aluminium-Silicate (BMAS) powder was produced from a mixture of initial compounds BaO–MgO–Al2O3–SiO2 by means of solid state synthesis at the temperature of 1200 °C for 3 hours in a laboratory furnace. Synthetized powder was crushed into the fraction of 15-45 μm in a planetary ball mill. Thermal barrier coating system consisting of CoNiCrAlY (bond coat) and BMAS (top coat) was sprayed by atmospheric plasma spray technique onto the polycrystalline nickel-based superalloy substrate. During plasma spraying process, the BMAS underwent phase transformation and the amorphous phase within the top coat was produced. Therefore, after the spraying, several samples were crystallized via annealing in a furnace (4 hours at 1200 °C or 24 hours at 1000 °C) or by subjecting them to several passes of plasma jet. Both samples with an amorphous phase and fully-crystallized samples were subjected to the fire in a burner-rig test (propane-oxygen flame, single 3 + 3 minute cycle), where the top coat reached the temperature of 1150 °C. Top coat failure occurred during the cooling period due to the transformation of the amorphous phase into the crystalline one and/or due to the difference in thermal conductivity and expansion between the top coat and the bond coat.
383
Authors: Rub Nawaz Shahid, Bin Awais Hasan, Fahad Ali, Naeem Ul Haq Tariq
Abstract: In this work percolation range for Al2O3-Ni interpenetrating phase composite (IPC) was studied to find the optimal combination of electrical conductivity and coefficient of thermal expansion (CTE). The impedance spectroscopy and scanning electron spectroscopy were used to study the percolation limit.
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Authors: Marta López, José A. Jiménez, R. Benavente
Abstract: Composites materials consisting of pure copper reinforced with 1 vol.% of NbC were prepared by the powder metallurgy route to determine the influence of the milling process on the mechanical and electrical properties. For comparative purpose different milling times at four different rotational speeds were used. The resulting powders were consolidated by hot uniaxial pressing under 90MPa for 2h at 923K to obtain materials with a fine microstructure without residual porosity. It was found that the microstructure and properties of composite materials could be principally related to the amount of Fe, Cr, C and O incorporated as impurities during the milling process. Therefore, the rotational speeds used for milling has an important influence on the properties of the final product. A lower energy-ball milling is accompanied by a smaller amount of impurities (Fe, C and O) incorporated during milling. Composites materials combine electrical conductivity above 40% IACS with high strength. A detailed microstructural analysis by scanning and transmission electron microscopy and X ray diffraction showed that these properties are related not only to NbC particles, but also to the presence of very fine particles of carbides and oxides.
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