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Takayuki Takasugi - One of the best experts on this subject based on the ideXlab platform.
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further investigation on phase relation and microstructures in ni3si ni3ti ni3nb pseudo ternary alloy system
Intermetallics, 2006Co-Authors: K Ohira, Yasuyuki Kaneno, Hiroshi Tsuda, Takayuki TakasugiAbstract:Abstract The isothermal phase diagram at 1323 K in the Ni3Si–Ni3Ti–Ni3Nb pseudo-ternary alloy system was re-investigated by scanning electron microscopy (attached with a wavelength dispersive spectroscope), X-ray diffraction and transmission electron microscopy (TEM), focusing on the phase relation among possible geometrically-close-packed (GCP) Ni3X phases. The prepared alloys exhibited widely different microstructures, depending on alloy compositions whether they exist in a single phase, a two- or a three-phase region, and also on the constituent GCP Ni3X phases. The L12(Ni3Si), D024(Ni3Ti) and D0a(Ni3Nb) phases were directly equilibrated one another or each other when keeping Ni content 79.5 at.%. On the other hand, the D019(Ni3Ti0.7Nb0.3) phase was identified to exist when keeping Ni content 75 at.%. The phase stability and existing region of each GCP Ni3X phase identified in the Ni3Si–Ni3Ti–Ni3Nb pseudo-ternary alloy system were discussed, based on the electron concentration (e/a) and the atomic Size Factor (Rx/RNi) of the constituent atoms.
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phase relation and microstructure in multi phase intermetallic alloys based on ni3si ni3ti ni3nb pseudo ternary alloy system
Intermetallics, 2004Co-Authors: Y Nunomura, Yasuyuki Kaneno, Hiroshi Tsuda, Takayuki TakasugiAbstract:Abstract The phase relation and microstructure of alloys based on the Ni3Al–Ni3Ti–Ni3V pseudo-ternary alloy system at 1273 and 1373 K were investigated by optical microscopy, X-ray diffraction, differential scanning calorimetry and scanning electron microscopy (attached with a wavelength dispersive spectroscope). As the constituent intermetallic phases at 1273 K, L12(Ni3Al), D024(Ni3Ti), D022(Ni3V) and rhombohedral (Ni3Ti0.7V0.3) were identified and then their phase fields were shown to depend upon the electron concentration (e/a) and the atomic Size Factor (Rx/RNi) of the constituent atoms. Among four intermetallic phases identified at 1273 K, five kinds of two-phase relations (i.e. L12–D024, D024–rhombohedral, rhombohedral–D022 D022–D024 and D022–L12) and two kinds of three-phase relations (i.e. L12–D024–D022 and D024–rhombohedral–D022) were found to exist. Also, D024 (Ni3Ti) phase extended up to concentration field in which a majority of constituent Ti elements were replaced by Al and V elements, keeping their concentrations identical. The prepared alloys exhibited widely different microstructures, depending on alloy composition and temperature. In the low Ti concentration region, dual multi-phase microstructures composed of L12+D024+A1(→L12+D022) were formed by a eutectic reaction.
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phase relation and microstructure in multi phase intermetallic alloys based on ni3al ni3nb ni3v pseudo ternary alloy system
Intermetallics, 2004Co-Authors: Y Nunomura, Yasuyuki Kaneno, Hiroshi Tsuda, Takayuki TakasugiAbstract:Abstract The phase relation and microstructure of alloys based on the Ni3Al–Ni3Ti–Ni3V pseudo-ternary alloy system at 1273 and 1373 K were investigated by optical microscopy, X-ray diffraction, differential scanning calorimetry and scanning electron microscopy (attached with a wavelength dispersive spectroscope). As the constituent intermetallic phases at 1273 K, L12(Ni3Al), D024(Ni3Ti), D022(Ni3V) and rhombohedral (Ni3Ti0.7V0.3) were identified and then their phase fields were shown to depend upon the electron concentration (e/a) and the atomic Size Factor (Rx/RNi) of the constituent atoms. Among four intermetallic phases identified at 1273 K, five kinds of two-phase relations (i.e. L12–D024, D024–rhombohedral, rhombohedral–D022 D022–D024 and D022–L12) and two kinds of three-phase relations (i.e. L12–D024–D022 and D024–rhombohedral–D022) were found to exist. Also, D024 (Ni3Ti) phase extended up to concentration field in which a majority of constituent Ti elements were replaced by Al and V elements, keeping their concentrations identical. The prepared alloys exhibited widely different microstructures, depending on alloy composition and temperature. In the low Ti concentration region, dual multi-phase microstructures composed of L12+D024+A1(→L12+D022) were formed by a eutectic reaction.
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phase relation and microstructure in ni3al ni3ti ni3nb pseudo ternary alloy system
Intermetallics, 2002Co-Authors: K Tomihisa, Yasuyuki Kaneno, Takayuki TakasugiAbstract:Abstract The phase relation and microstructure of alloys based on the Ni 3 Al–Ni 3 Ti–Ni 3 Nb pseudo-ternary alloy system at 1273 K were investigated by an optical microscope, an X-ray diffraction and a scanning electron microscope (attached with a wavelength dispersive spectroscope). As the constituent intermetallic phases, L1 2 (Ni 3 Al), D0 24 (Ni 3 Ti), D0 a (Ni 3 Nb) and D0 19 (Ni 3 Ti 0.7 Nb 0.3 ) were identified and then their phase fields were shown to depend upon the electron concentration ( e/a ) and the atomic Size Factor ( R x / R Ni ) of constituent atoms. Among four intermetallic phases identified, five kinds of two-phase relations (i.e. L1 2 –D0 24 , D0 24 –D0 19 , D0 19 –D0 a , D0 a –L1 2 and D0 24 –D0 a ) and two kinds of three-phase relations (i.e. L1 2 –D0 24 –D0 a and D0 24 –D0 19 –D0 a ) were found to exist. Also, D0 24 (Ni 3 Ti) phase extended up to concentration field in which a majority of constituent Ti elements were replaced by Al and Nb elements, keeping their concentration ratios identical. The prepared alloys exhibited widely different microstructures, depending on whether their alloy compositions exist in a single phase, a two-phase or a three-phase region, and also on what kind of intermetallic phases their alloy compositions are composed of.
Shivaji Sircar - One of the best experts on this subject based on the ideXlab platform.
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experimental study of a novel rapid pressure swing adsorption based medical oxygen concentrator effect of the adsorbent selectivity of n2 over o2
Industrial & Engineering Chemistry Research, 2016Co-Authors: Rama Rao Vemula, Mayuresh V. Kothare, Shivaji SircarAbstract:It was experimentally demonstrated that the performance of a medical oxygen concentrator based on rapid pressure swing adsorption (RPSA) process using a LiLSX zeolite was improved [lower bed Size Factor (BSF) and higher oxygen recovery (RO)] when the adsorbent exhibited higher selectivity of adsorption of N2 over O2. The effects of N2 selectivity on BSF and RO as functions of the RPSA process cycle times were found to be complex and nonintuitive. The key properties of a LiLSX zeolite sample for adsorption of N2 and O2 (pure and binary gas isotherms, binary selectivity, pure gas isosteric heats, pure gas mass-transfer characteristics, and degrees of adsorbent heterogeneity), which exhibited a relatively higher selectivity of adsorption for N2 over O2 compared to a previously reported sample, were measured and used in this study.
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novel design and performance of a medical oxygen concentrator using a rapid pressure swing adsorption concept
Aiche Journal, 2014Co-Authors: Vemula Rama Rao, Mayuresh V. Kothare, Shivaji SircarAbstract:A novel design of a compact rapid pressure swing adsorption system consisting of a single adsorber enclosed inside a product storage tank is proposed for application as a medical oxygen concentrator (MOC). A self-contained test unit for the process is constructed which is capable of directly and continuously producing 1–3 sl/m of 90% O2 from compressed air. Pelletized LiLSX zeolite is used as the air separation adsorbent. Steady state process performance data [bed Size Factor (BSF) and O2 recovery (R) as functions of total cycle time (tc)], as well as transient, cyclic, adsorber pressure, and temperature profiles are presented. A four-step Skarstrom-like pressure swing adsorption cycle was used. Two options for column pressurization, (a) using compressed feed air cocurrently or (b) using a part of the oxygen-enriched product gas counter-currently were evaluated. Option (b) exhibited superior performance. The optimum total cycle time for option (b) was 5–6 s where the BSF was lowest (∼45 kgs/TPD O2) and the corresponding R was ∼29.3%. These numbers indicate that the adsorbent inventory of a MOC can be potentially reduced by a Factor of three while offering a ∼10–20% higher O2 recovery compared to a typical commercial unit. © 2014 American Institute of Chemical Engineers AIChE J, 60: 3330–3335, 2014
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rapid pressure swing adsorption for reduction of bed Size Factor of a medical oxygen concentrator
Industrial & Engineering Chemistry Research, 2011Co-Authors: Siew Wah Chai, Mayuresh V. Kothare, Shivaji SircarAbstract:Reduction of the adsorber Size of a medical oxygen concentrator (MOC) employing a generic pressure swing adsorption (PSA) technology is an ongoing research and development activity. The MOC typically produces a 90–93% O2-enriched product gas from ambient air at a rate of ≤10 L/minute (LPM) for individual use. A common practice is to reduce the total cycle time (tc, seconds) of the PSA process in order to decrease the bed Size Factor [BSF, pounds of adsorbent in the PSA unit per ton of contained O2 per day production rate (TPDc)]. Adsorbent columns packed with very small adsorbent particles are used to enhance the adsorption kinetics for rapid PSA cycle operation. An experimental mini-PSA set up was used to measure the performance of a simulated Skarstrom-like PSA cycle using a commercial sample of LiX zeolite as the air separation sorbent. Different adsorbent particle Sizes, adsorption pressures, and cycle times were tested. It was experimentally demonstrated that BSF cannot be indefinitely reduced by low...
Yasuyuki Kaneno - One of the best experts on this subject based on the ideXlab platform.
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further investigation on phase relation and microstructures in ni3si ni3ti ni3nb pseudo ternary alloy system
Intermetallics, 2006Co-Authors: K Ohira, Yasuyuki Kaneno, Hiroshi Tsuda, Takayuki TakasugiAbstract:Abstract The isothermal phase diagram at 1323 K in the Ni3Si–Ni3Ti–Ni3Nb pseudo-ternary alloy system was re-investigated by scanning electron microscopy (attached with a wavelength dispersive spectroscope), X-ray diffraction and transmission electron microscopy (TEM), focusing on the phase relation among possible geometrically-close-packed (GCP) Ni3X phases. The prepared alloys exhibited widely different microstructures, depending on alloy compositions whether they exist in a single phase, a two- or a three-phase region, and also on the constituent GCP Ni3X phases. The L12(Ni3Si), D024(Ni3Ti) and D0a(Ni3Nb) phases were directly equilibrated one another or each other when keeping Ni content 79.5 at.%. On the other hand, the D019(Ni3Ti0.7Nb0.3) phase was identified to exist when keeping Ni content 75 at.%. The phase stability and existing region of each GCP Ni3X phase identified in the Ni3Si–Ni3Ti–Ni3Nb pseudo-ternary alloy system were discussed, based on the electron concentration (e/a) and the atomic Size Factor (Rx/RNi) of the constituent atoms.
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phase relation and microstructure in multi phase intermetallic alloys based on ni3si ni3ti ni3nb pseudo ternary alloy system
Intermetallics, 2004Co-Authors: Y Nunomura, Yasuyuki Kaneno, Hiroshi Tsuda, Takayuki TakasugiAbstract:Abstract The phase relation and microstructure of alloys based on the Ni3Al–Ni3Ti–Ni3V pseudo-ternary alloy system at 1273 and 1373 K were investigated by optical microscopy, X-ray diffraction, differential scanning calorimetry and scanning electron microscopy (attached with a wavelength dispersive spectroscope). As the constituent intermetallic phases at 1273 K, L12(Ni3Al), D024(Ni3Ti), D022(Ni3V) and rhombohedral (Ni3Ti0.7V0.3) were identified and then their phase fields were shown to depend upon the electron concentration (e/a) and the atomic Size Factor (Rx/RNi) of the constituent atoms. Among four intermetallic phases identified at 1273 K, five kinds of two-phase relations (i.e. L12–D024, D024–rhombohedral, rhombohedral–D022 D022–D024 and D022–L12) and two kinds of three-phase relations (i.e. L12–D024–D022 and D024–rhombohedral–D022) were found to exist. Also, D024 (Ni3Ti) phase extended up to concentration field in which a majority of constituent Ti elements were replaced by Al and V elements, keeping their concentrations identical. The prepared alloys exhibited widely different microstructures, depending on alloy composition and temperature. In the low Ti concentration region, dual multi-phase microstructures composed of L12+D024+A1(→L12+D022) were formed by a eutectic reaction.
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phase relation and microstructure in multi phase intermetallic alloys based on ni3al ni3nb ni3v pseudo ternary alloy system
Intermetallics, 2004Co-Authors: Y Nunomura, Yasuyuki Kaneno, Hiroshi Tsuda, Takayuki TakasugiAbstract:Abstract The phase relation and microstructure of alloys based on the Ni3Al–Ni3Ti–Ni3V pseudo-ternary alloy system at 1273 and 1373 K were investigated by optical microscopy, X-ray diffraction, differential scanning calorimetry and scanning electron microscopy (attached with a wavelength dispersive spectroscope). As the constituent intermetallic phases at 1273 K, L12(Ni3Al), D024(Ni3Ti), D022(Ni3V) and rhombohedral (Ni3Ti0.7V0.3) were identified and then their phase fields were shown to depend upon the electron concentration (e/a) and the atomic Size Factor (Rx/RNi) of the constituent atoms. Among four intermetallic phases identified at 1273 K, five kinds of two-phase relations (i.e. L12–D024, D024–rhombohedral, rhombohedral–D022 D022–D024 and D022–L12) and two kinds of three-phase relations (i.e. L12–D024–D022 and D024–rhombohedral–D022) were found to exist. Also, D024 (Ni3Ti) phase extended up to concentration field in which a majority of constituent Ti elements were replaced by Al and V elements, keeping their concentrations identical. The prepared alloys exhibited widely different microstructures, depending on alloy composition and temperature. In the low Ti concentration region, dual multi-phase microstructures composed of L12+D024+A1(→L12+D022) were formed by a eutectic reaction.
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phase relation and microstructure in ni3al ni3ti ni3nb pseudo ternary alloy system
Intermetallics, 2002Co-Authors: K Tomihisa, Yasuyuki Kaneno, Takayuki TakasugiAbstract:Abstract The phase relation and microstructure of alloys based on the Ni 3 Al–Ni 3 Ti–Ni 3 Nb pseudo-ternary alloy system at 1273 K were investigated by an optical microscope, an X-ray diffraction and a scanning electron microscope (attached with a wavelength dispersive spectroscope). As the constituent intermetallic phases, L1 2 (Ni 3 Al), D0 24 (Ni 3 Ti), D0 a (Ni 3 Nb) and D0 19 (Ni 3 Ti 0.7 Nb 0.3 ) were identified and then their phase fields were shown to depend upon the electron concentration ( e/a ) and the atomic Size Factor ( R x / R Ni ) of constituent atoms. Among four intermetallic phases identified, five kinds of two-phase relations (i.e. L1 2 –D0 24 , D0 24 –D0 19 , D0 19 –D0 a , D0 a –L1 2 and D0 24 –D0 a ) and two kinds of three-phase relations (i.e. L1 2 –D0 24 –D0 a and D0 24 –D0 19 –D0 a ) were found to exist. Also, D0 24 (Ni 3 Ti) phase extended up to concentration field in which a majority of constituent Ti elements were replaced by Al and Nb elements, keeping their concentration ratios identical. The prepared alloys exhibited widely different microstructures, depending on whether their alloy compositions exist in a single phase, a two-phase or a three-phase region, and also on what kind of intermetallic phases their alloy compositions are composed of.
Hiroshi Tsuda - One of the best experts on this subject based on the ideXlab platform.
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further investigation on phase relation and microstructures in ni3si ni3ti ni3nb pseudo ternary alloy system
Intermetallics, 2006Co-Authors: K Ohira, Yasuyuki Kaneno, Hiroshi Tsuda, Takayuki TakasugiAbstract:Abstract The isothermal phase diagram at 1323 K in the Ni3Si–Ni3Ti–Ni3Nb pseudo-ternary alloy system was re-investigated by scanning electron microscopy (attached with a wavelength dispersive spectroscope), X-ray diffraction and transmission electron microscopy (TEM), focusing on the phase relation among possible geometrically-close-packed (GCP) Ni3X phases. The prepared alloys exhibited widely different microstructures, depending on alloy compositions whether they exist in a single phase, a two- or a three-phase region, and also on the constituent GCP Ni3X phases. The L12(Ni3Si), D024(Ni3Ti) and D0a(Ni3Nb) phases were directly equilibrated one another or each other when keeping Ni content 79.5 at.%. On the other hand, the D019(Ni3Ti0.7Nb0.3) phase was identified to exist when keeping Ni content 75 at.%. The phase stability and existing region of each GCP Ni3X phase identified in the Ni3Si–Ni3Ti–Ni3Nb pseudo-ternary alloy system were discussed, based on the electron concentration (e/a) and the atomic Size Factor (Rx/RNi) of the constituent atoms.
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phase relation and microstructure in multi phase intermetallic alloys based on ni3si ni3ti ni3nb pseudo ternary alloy system
Intermetallics, 2004Co-Authors: Y Nunomura, Yasuyuki Kaneno, Hiroshi Tsuda, Takayuki TakasugiAbstract:Abstract The phase relation and microstructure of alloys based on the Ni3Al–Ni3Ti–Ni3V pseudo-ternary alloy system at 1273 and 1373 K were investigated by optical microscopy, X-ray diffraction, differential scanning calorimetry and scanning electron microscopy (attached with a wavelength dispersive spectroscope). As the constituent intermetallic phases at 1273 K, L12(Ni3Al), D024(Ni3Ti), D022(Ni3V) and rhombohedral (Ni3Ti0.7V0.3) were identified and then their phase fields were shown to depend upon the electron concentration (e/a) and the atomic Size Factor (Rx/RNi) of the constituent atoms. Among four intermetallic phases identified at 1273 K, five kinds of two-phase relations (i.e. L12–D024, D024–rhombohedral, rhombohedral–D022 D022–D024 and D022–L12) and two kinds of three-phase relations (i.e. L12–D024–D022 and D024–rhombohedral–D022) were found to exist. Also, D024 (Ni3Ti) phase extended up to concentration field in which a majority of constituent Ti elements were replaced by Al and V elements, keeping their concentrations identical. The prepared alloys exhibited widely different microstructures, depending on alloy composition and temperature. In the low Ti concentration region, dual multi-phase microstructures composed of L12+D024+A1(→L12+D022) were formed by a eutectic reaction.
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phase relation and microstructure in multi phase intermetallic alloys based on ni3al ni3nb ni3v pseudo ternary alloy system
Intermetallics, 2004Co-Authors: Y Nunomura, Yasuyuki Kaneno, Hiroshi Tsuda, Takayuki TakasugiAbstract:Abstract The phase relation and microstructure of alloys based on the Ni3Al–Ni3Ti–Ni3V pseudo-ternary alloy system at 1273 and 1373 K were investigated by optical microscopy, X-ray diffraction, differential scanning calorimetry and scanning electron microscopy (attached with a wavelength dispersive spectroscope). As the constituent intermetallic phases at 1273 K, L12(Ni3Al), D024(Ni3Ti), D022(Ni3V) and rhombohedral (Ni3Ti0.7V0.3) were identified and then their phase fields were shown to depend upon the electron concentration (e/a) and the atomic Size Factor (Rx/RNi) of the constituent atoms. Among four intermetallic phases identified at 1273 K, five kinds of two-phase relations (i.e. L12–D024, D024–rhombohedral, rhombohedral–D022 D022–D024 and D022–L12) and two kinds of three-phase relations (i.e. L12–D024–D022 and D024–rhombohedral–D022) were found to exist. Also, D024 (Ni3Ti) phase extended up to concentration field in which a majority of constituent Ti elements were replaced by Al and V elements, keeping their concentrations identical. The prepared alloys exhibited widely different microstructures, depending on alloy composition and temperature. In the low Ti concentration region, dual multi-phase microstructures composed of L12+D024+A1(→L12+D022) were formed by a eutectic reaction.
Rama Rao Vemula - One of the best experts on this subject based on the ideXlab platform.
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experimental study of a novel rapid pressure swing adsorption based medical oxygen concentrator effect of the adsorbent selectivity of n2 over o2
Industrial & Engineering Chemistry Research, 2016Co-Authors: Rama Rao Vemula, Mayuresh V. Kothare, Shivaji SircarAbstract:It was experimentally demonstrated that the performance of a medical oxygen concentrator based on rapid pressure swing adsorption (RPSA) process using a LiLSX zeolite was improved [lower bed Size Factor (BSF) and higher oxygen recovery (RO)] when the adsorbent exhibited higher selectivity of adsorption of N2 over O2. The effects of N2 selectivity on BSF and RO as functions of the RPSA process cycle times were found to be complex and nonintuitive. The key properties of a LiLSX zeolite sample for adsorption of N2 and O2 (pure and binary gas isotherms, binary selectivity, pure gas isosteric heats, pure gas mass-transfer characteristics, and degrees of adsorbent heterogeneity), which exhibited a relatively higher selectivity of adsorption for N2 over O2 compared to a previously reported sample, were measured and used in this study.
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anatomy of a rapid pressure swing adsorption process performance
Aiche Journal, 2015Co-Authors: Rama Rao VemulaAbstract:A detailed numerical study of the individual and cumulative effects of various mass, heat, and momentum transfer resistances, which are generally present inside a practical adiabatic adsorber, on the overall separation performance of a rapid pressure swing adsorption (RPSA) process is performed for production of nearly pure helium gas from an equimolar binary (N2 +He) gas mixture using 5 A zeolite. Column bed Size Factor (BSF) and helium recovery (R) from the feed gas are used to characterize the separation performances. All practical impediments like column pressure drop, finite gas-solid mass and heat transfer resistances, mass and heat axial dispersions in the gas phase, and heats of ad(de)sorption causing nonisothermal operation have detrimental impacts on the overall process performance, which are significantly accentuated when the total cycle time of a RPSA process is small and the product gas helium purity is high. These impediments also prohibit indefinite lowering of BSF (desired performance) by decreasing process cycle time alone. © 2015 American Institute of Chemical Engineers AIChE J, 61: 2008–2015, 2015
