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Yi-cheng Liou - One of the best experts on this subject based on the ideXlab platform.
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Low-temperature synthesis of BiNbO4 ceramics using Reaction-Sintering process
Ceramics International, 2009Co-Authors: Yi-cheng Liou, Wen-chou Tsai, Hong-meng ChenAbstract:Abstract Low-temperature synthesis of BiNbO4 ceramics using Reaction-Sintering process was investigated. Orthorhombic BiNbO4 phase together with minor triclinic BiNbO4 phase were found in the pellets. The phase transition temperature in BiNbO4 with 0.5 wt% CuO addition was lowered from 960 °C via traditional route to 880 °C when the Reaction-Sintering process was used. After 920 °C Sintering for 4 and 6 h, densities 6.8–6.85 g/cm3 (94% of the theoretical value) were obtained. The abnormal grain growth in BiNbO4 via traditional route was not observed in this study.
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synthesis and diffused phase transition of ba0 7sr0 3tio3 ceramics by a Reaction Sintering process
Ceramics International, 2008Co-Authors: Yi-cheng LiouAbstract:Abstract Ba0.7Sr0.3TiO3 (BST) ceramics prepared by a Reaction-Sintering process were investigated. BST ceramics could be obtained after 2–6 h Sintering at 1330–1370 °C without any calcination involved. BST with density 5.68 g/cm3 (99.8% of the theoretic value) was obtained at 1350 °C for 6 h Sintering. Grains of 2–15 μm were formed after 2–6 h Sintering at 1330–1370 °C. A diffused ferroelectric–paraelectric transition was observed in pellets sintered at 1330 °C for 2 h and disappeared at a longer soak time or a higher Sintering temperature.
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preparation of columbite mgnb2o6 and znnb2o6 ceramics by Reaction Sintering
Ceramics International, 2008Co-Authors: Yi-cheng Liou, Yuehlun SungAbstract:Abstract Columbite MgNb2O6 (MN) and ZnNb2O6 (ZN) ceramics produced by the Reaction-Sintering process were investigated. Secondary phases Mg0.652Nb0.598O2.25 and Mg0.66Nb11.33O29 were found in MgNb2O6 pellets. After 1250 °C Sintering for 2 h, a density 4.85 g/cm3 (97.1% of the theoretical value) was obtained in MgNb2O6 pellets. In ZnNb2O6 pellets, no secondary phase formed. The maximum density 5.55 g/cm3 (98.7% of the theoretical value) occurs at 1200 and 1180 °C Sintering for 2 and 4 h, respectively.
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calcium doped mgtio3 mgti2o5 ceramics prepared using a Reaction Sintering process
Materials Science and Engineering B-advanced Functional Solid-state Materials, 2007Co-Authors: Yi-cheng Liou, Songling YangAbstract:Abstract Calcium-doped MgTiO3–MgTi2O5 (MCT) ceramics prepared using a Reaction-Sintering process were investigated. Without any calcination involved, the mixture of MgO, CaCO3, and TiO2 was pressed and sintered directly. MCT ceramics were obtained after 2–6 h Sintering at 1150–1250 °C. MCT containing high percentage of MgTi2O5 phase (45.6%) was observed at 1150 °C/2 h Sintering and the percentage decreased to 37.2% at 1300 °C/2 h Sintering. The maximum density 3.85 g/cm3 could be obtained at 1250 °C. Dielectric constant at 10 MHz reaches 23.7–25.9 in MCT ceramics sintered at 1150 and 1200 °C. ɛr = 22.4 and Q × f ∼ 40,400 GHz (at 9.8 GHz) and a τf value of −9.6 ppm/°C were obtained in MCT ceramic sintered at 1300 °C/2 h. The Reaction-Sintering process has been proven a simple and effective method to produce dense MCT ceramics with good dielectric properties even without the addition of Sintering aid.
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canb2o6 ceramics prepared by a Reaction Sintering process
Materials Science and Engineering B-advanced Functional Solid-state Materials, 2006Co-Authors: Yi-cheng Liou, Minhang Weng, Chaoyang ShiueAbstract:Abstract CaNb 2 O 6 columbite ceramics produced by a Reaction-Sintering process were investigated. CaCO 3 was mixed with Nb 2 O 5 then pressed and sintered into CaNb 2 O 6 ceramics without any calcination stage involved. Pure columbite CaNb 2 O 6 phase was obtained successfully. After 1420 °C Sintering for 2 h, a density 4.37 g/cm 3 (92% of the theoretical value) were obtained. Some sub-micron CaO particles were segregated at the surfaces of CN grains at 1350–1450 °C. Round grains formed at 1330–1400 °C and long shaped grains are found in CN pellets sintered at temperatures above 1400 °C. 3.9–8.1 μm grain sizes are formed in CN pellets sintered at 1330–1400 °C for 2 and 4 h.
P Pena - One of the best experts on this subject based on the ideXlab platform.
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cazro3 mgo structural ceramics obtained by Reaction Sintering of dolomite zirconia mixtures
Journal of The European Ceramic Society, 2016Co-Authors: P Pena, Fernando Booth, Liliana B Garrido, E F Aglietti, Abilio P Silva, Carmen BaudinAbstract:Abstract Processing and properties of two fine grain and dense CaZrO 3 -MgO based composites obtained by Reaction Sintering of pure ZrO 2 and dolomite (CaMg(CO 3 ) 2 ) are described. Two dolomites with different levels of impurities were used to fabricate the materials: high purity (impurity content ≈1.2 wt.%, material DBZ) and impure dolomite (impurity content ≈6.12 wt.%, material DNZ). Mixtures (molar 1:1) were attrition milled and the Reaction and Sintering processes were studied using dynamical techniques (DTA-TG and dilatometry). Adequate Sintering schedule was selected using the controlled Sintering technique. The role of impurities on the physical characteristics, microstructure and mechanical properties of the obtained composites was analysed. Noticeable changes in microstructure, porosity, grain size and phases, were observed as function of final Sintering temperature at 1350, 1400, 1450 °C, and impurity content. The obtained microstructures are discussed on the basis of the phase equilibrium relationships.
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Reaction Sintering of zircon dolomite mixtures
Journal of The European Ceramic Society, 2001Co-Authors: J L Rodriguez, Miguel A Rodriguez, P PenaAbstract:Abstract Dolomite–zircon mixtures have become interesting for finding alternate sources to improve the production of high magnesia refractories. To asses this option, two minerals, dolomite and zircon were selected, as economically raw materials, to produce MgO–CaZrO 3 –Ca 2 SiO 4 materials. The Reaction Sintering mechanism of zircon–dolomite mixtures were investigated using finely ground Spanish dolomite and zircon powders as starting materials. During the heat treatment decomposed dolomite (CaO+MgO) reacts with zircon, from 1000 to 1200°C, through a series of Reactions before the final stable compounds are formed. From the results obtained the Reaction occurs prior to Sintering in the presence of an amorphous transitory phase, magnesium calcium silicate phase and the limiting process during the Reaction is the formation of Ca 2 SiO 4 . The Sintering occurs after the end of the Reaction so by controlling the whole process it is possible to obtain materials with controlled porosity. In the present work it is shown that Reaction Sintering of zircon–dolomite mixtures is a feasible route to obtain MgO–CaZrO 3 –β-Ca 2 SiO 4 porous materials for refractory insulators or as filters applications.
V. É. Gunther - One of the best experts on this subject based on the ideXlab platform.
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Reaction Sintering of porous shape memory titanium nickelide based alloys
Russian Physics Journal, 2015Co-Authors: N. V. Artyukhova, Yu. F. Yasenchuk, Kim Jisoon, V. É. GuntherAbstract:The problems of Reaction Sintering of porous shape-memory Ti−Ni-based alloys are examined. An analysis of the structure and parameters of shape-memory materials produced with the use of different Reaction Sintering modes is performed. The temperature and time intervals are determined over which liquid-phase Sintering points responsible for a qualitative change in the TiNi phase of the Reaction-sintered Ti−Ni system are observed. The morphological structure and properties of the porous materials are investigated. Models for interactions between phases and phase transformations in the sintered alloys are built. It has been found that changes in the deformation parameters of the porous titanium nickelide-based alloys correlate with an increase in the volume fraction of the TiNi phase and with its wholeness as the Sintering time is increased.
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Reaction Sintering of Porous Shape-Memory Titanium−Nickelide-Based Alloys
Russian Physics Journal, 2015Co-Authors: N. V. Artyukhova, Yu. F. Yasenchuk, Kim Ji-soon, V. É. GuntherAbstract:The problems of Reaction Sintering of porous shape-memory Ti−Ni-based alloys are examined. An analysis of the structure and parameters of shape-memory materials produced with the use of different Reaction Sintering modes is performed. The temperature and time intervals are determined over which liquid-phase Sintering points responsible for a qualitative change in the TiNi phase of the Reaction-sintered Ti−Ni system are observed. The morphological structure and properties of the porous materials are investigated. Models for interactions between phases and phase transformations in the sintered alloys are built. It has been found that changes in the deformation parameters of the porous titanium nickelide-based alloys correlate with an increase in the volume fraction of the TiNi phase and with its wholeness as the Sintering time is increased.
Mohamed N. Rahaman - One of the best experts on this subject based on the ideXlab platform.
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Reaction Sintering of ZnO‐AI2O3
Journal of the American Ceramic Society, 1995Co-Authors: Wan‐shick Hong, Lutgard C. De Jonghe, Xi Yang, Mohamed N. RahamanAbstract:The Reaction Sintering of equimolar mixtures of ZnO and Al{sub 2}O{sub 3} powders was investigated as a function of primary processing parameters such as the temperature, heating rate, green density, and particle size. The powder mixtures were prepared by two different methods. In one method, the ZnO and Al{sub 2}O{sub 3} powders were ball-milled. In the other method, the ZnO powder was chemically precipitated onto the Al{sub 2}O{sub 3} particles dispersed in a solution of zinc chloride. The Sintering characteristics of the compacted powders prepared by each method were compared with those for a pre-reacted single-phase powder of zinc aluminate, ZnAl{sub 2}O{sub 4}. The chemical Reaction between ZnO and Al{sub 2}O{sub 3} occurred prior to densification of the powder compact and was accompanied by fairly large expansion. The mixing procedure had a significant effect on the densification rate during Reaction Sintering. The densification rate of the compact formed from the ball-milled powder was strongly inhibited compared to that for the single-phase ZnAl{sub 2}O{sub 4} powder. However, the densification rate of the compact formed from the chemically precipitated mixture was almost identical to that for the ZnAl{sub 2}O{sub 4} powder. The difference in Sintering between the ball-milled mixture and the chemicallymore » precipitated mixture is interpreted in terms of differences i the microstructural uniformity of the initial powder compacts resulting from the different preparation procedures.« less
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Reaction Sintering of zno ai2o3
Journal of the American Ceramic Society, 1995Co-Authors: Wanshick Hong, Lutgard C. De Jonghe, Xi Yang, Mohamed N. RahamanAbstract:The Reaction Sintering of equimolar mixtures of ZnO and Al{sub 2}O{sub 3} powders was investigated as a function of primary processing parameters such as the temperature, heating rate, green density, and particle size. The powder mixtures were prepared by two different methods. In one method, the ZnO and Al{sub 2}O{sub 3} powders were ball-milled. In the other method, the ZnO powder was chemically precipitated onto the Al{sub 2}O{sub 3} particles dispersed in a solution of zinc chloride. The Sintering characteristics of the compacted powders prepared by each method were compared with those for a pre-reacted single-phase powder of zinc aluminate, ZnAl{sub 2}O{sub 4}. The chemical Reaction between ZnO and Al{sub 2}O{sub 3} occurred prior to densification of the powder compact and was accompanied by fairly large expansion. The mixing procedure had a significant effect on the densification rate during Reaction Sintering. The densification rate of the compact formed from the ball-milled powder was strongly inhibited compared to that for the single-phase ZnAl{sub 2}O{sub 4} powder. However, the densification rate of the compact formed from the chemically precipitated mixture was almost identical to that for the ZnAl{sub 2}O{sub 4} powder. The difference in Sintering between the ball-milled mixture and the chemicallymore » precipitated mixture is interpreted in terms of differences i the microstructural uniformity of the initial powder compacts resulting from the different preparation procedures.« less
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Reaction Sintering of Zinc Ferrite during Constant Rates of Heating
Journal of the American Ceramic Society, 1993Co-Authors: Mohamed N. Rahaman, Lutgard C. De JongheAbstract:The Reaction Sintering of equimolar quantities of zinc oxide and ferric oxide was investigated under conditions of constant rates of heating (1–10°C/min from room temperature to 1350°C) and the data were compared with those for a calcined, single-phase zinc ferrite powder. For the heating rate of 1°C/min, the densifications of the Reaction-sintered sample and the calcined sample were approximately the same. However, as the heating rate increased, the density at any temperature increased slightly for the Reaction-sintered sample but decreased slightly for the calcined powder. The factors responsible for this slight difference in Sintering between the Reaction-sintered sample and the calcined sample are discussed. For the constant heating rates used, the Reaction was completed prior to any significant densification. Relative densities of >95% were obtained for both the Reaction-sintered sample and the calcined sample under identical Sintering conditions (1–10°C/min to 1350°C). Reaction Sintering in a steep temperature gradient produced a nearly fully dense body prior to complete Reaction; a composite microstructure consisting of fine zinc oxide grains in a matrix of zinc ferrite was obtained.
Chungyu Shih - One of the best experts on this subject based on the ideXlab platform.
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microwave ceramics ba5nb4o15 and sr5nb4o15 prepared by a Reaction Sintering process
Materials Science and Engineering B-advanced Functional Solid-state Materials, 2006Co-Authors: Yi-cheng Liou, Wenhau Shiu, Chungyu ShihAbstract:Abstract Ba 5 Nb 4 O 15 (BN) and Sr 5 Nb 4 O 15 (SN) microwave ceramics prepared by a Reaction-Sintering process were investigated. Without any calcination involved, the Nb 2 O 5 mixture of BaCO 3 and SrCO 3 was pressed and sintered directly. BN and SN ceramics could be obtained after 2–6 h Sintering at 1350–1500 °C. A density 6.13 g/cm 3 (97.3% of theoretical value) was obtained in BN for 4 and 6 h Sintering at 1450 °C. The Sintering temperature was 200 °C lowered with the addition of 1 wt.% CuO. For SN, low densification 86.9% was obtained at 1500 °C and became dense with 96% of the theoretical density at 1430 °C after 1 wt.% CuO was added. Dielectric constants 39.5 and 38.1 could be obtained in BN and SN. Q × f values 22,700 GHz at 7.2 GHz and 10,500 GHz at 7.47 GHz are observed in BN and SN.
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stoichiometric pb fe1 2nb1 2 o3 perovskite ceramics produced by Reaction Sintering process
Materials Letters, 2003Co-Authors: Yi-cheng Liou, Chungyu ShihAbstract:Abstract Stoichiometric Pb(Fe 1/2 Nb 1/2 )O 3 (PFN) perovskite ceramics produced by Reaction-Sintering process were investigated. Without calcination, a mixture of PbO, Nb 2 O 5 , and Fe(NO 3 ) 3 was pressed and sintered directly. Stoichiometric PFN ceramics of 100% perovskite phase were obtained for 2 and 4 h Sintering at 1120 and 1210 °C. PFN ceramics with density 8.25 g/cm 3 were obtained.
