The Experts below are selected from a list of 19464 Experts worldwide ranked by ideXlab platform
Guanghua Liu - One of the best experts on this subject based on the ideXlab platform.
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Combustion Synthesis of α-Si3N4 with green additives
Ceramics International, 2019Co-Authors: Jie Zhang, Guanghua Liu, Zhaobo Tian, Siyuan Sun, Wei Cui, Kexin ChenAbstract:Abstract This paper reports the Combustion Synthesis of α-Si3N4 using green additives of water and alcohol. The addition of water and alcohol is demonstrated to be effective in controlling the reaction kinetics and improving the formation of α-Si3N4 by vapor reactions. With increasing proportion of additives in the starting composition, the content of α-Si3N4 in the product is clearly enhanced. In contrast to the ammonium halides usually employed as additives in the Combustion Synthesis of α-Si3N4, the green additives used here are nontoxic, noncorrosive, and thus more attractive for industrial applications.
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Combustion Synthesis: An effective tool for preparing inorganic materials
Scripta Materialia, 2018Co-Authors: Guanghua Liu, Kexin ChenAbstract:Abstract Combustion Synthesis is a fast and energy-efficient process to prepare inorganic materials from self-sustained Combustion reactions. It is widely used for preparing ceramics, metals, and their composites. The unique condition in Combustion Synthesis with high temperatures and large heating rates offers good opportunities to explore new materials and novel microstructures. This paper gives a viewpoint on recent progress in Combustion Synthesis, from fundamentals to applications. New results on theories, processings, and materials are reviewed, and perspectives on the development of Combustion Synthesis are provided.
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22 Combustion Synthesis
Handbook of Combustion, 2016Co-Authors: Guanghua Liu, Kexin ChenAbstract:Combustion Synthesis is used to synthesize useful materials via Combustion reactions. Compared to many other material Synthesis approaches, Combustion Synthesis is furnace-free and more efficient, with negligible energy consumption, short processing times, large productivities, and low costs of production. The unique conditions of Combustion Synthesis, characterized by extremely high temperatures and rapid heating/cooling rates, offers tremendous possibilities for controlling the microstructure and Synthesis of novel materials. To date, Combustion Synthesis has been used to produce a wide variety of inorganic materials, including metals, ceramics, and metal–ceramic composites, in different forms of powders, coatings, and bulks. Today, Combustion Synthesis is associated with many scientific disciplines, is applied to various industrial fields, and represents a promising branch of modern science and technology with an ever-growing influence. In this chapter, a comprehensive introduction to Combustion Synthesis, from theory to practice, is provided. Initially, some basic concepts and fundamentals of the process are elucidated, with the essential parameters of Combustion reactions, including adiabatic temperature, propagation velocity and stability of Combustion wave, being explained based on homogeneous models. Heterogeneous and discrete Combustion models are then described for heterogeneous reaction media. Finally, the reaction mechanism of Combustion Synthesis is discussed, along with improvements in experimental skills. The processing of Combustion Synthesis (and materials thus created) are also reviewed. The effects of the main parameters in routine processing of Combustion Synthesis are discussed for solid–solid and solid–gas reactions. Details of various hybrid processes based on Combustion Synthesis are then presented, with high-gravity Combustion Synthesis as a particular example. Finally, solution Combustion Synthesis and gas Combustion Synthesis are introduced, with emphasis placed on the preparation of nanosized particles. Keywords: ceramics; Combustion; high temperature; refractory compounds; reaction mechanism; Synthesis
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Combustion Synthesis of Cu2SnSe3 thermoelectric materials
Journal of the European Ceramic Society, 2016Co-Authors: Guanghua Liu, Kexin Chen, Min ZhouAbstract:Abstract Thermoelectric materials are attractive for solar thermal energy conversion and waste heat recovery. The existing methods for fabricating thermoelectric materials involve multi-step processes with considerable time and energy consumption. Here we report a fast and one-step way to prepare thermoelectric materials by gas-pressure or high-gravity assisted Combustion Synthesis. Dense Cu2SnSe3 samples with a porosity below 2% were prepared from self-sustained Combustion reaction of element powders. The electrical conductivity of the Cu2SnSe3 samples was greatly enhanced and the thermal conductivity was reduced by partial substitution of Sn with In. The ZT values of the un-doped and In-doped Cu2SnSe3 samples reached 0.51 and 0.62 at 773 K, respectively, which are comparable to the best results reported for Cu2SnSe3 produced by other methods. Combustion Synthesis offers an efficient way to prepare thermoelectric materials with reduced time and energy consumption, which may open up new possibilities for Synthesis of thermoelectric materials.
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review of melt casting of dense ceramics and glasses by high gravity Combustion Synthesis
Advances in Applied Ceramics, 2013Co-Authors: Guanghua Liu, Kexin ChenAbstract:Abstract High gravity Combustion Synthesis is a recently reported technique to prepare dense ceramics and glasses by melt casting instead of conventional powder sintering. This technique combines strong exothermic chemical reactions with a high gravity field, and offers an efficient and furnace free way for rapid production of bulk ceramic and glass materials. This article reviews major results on melt casting of dense ceramics and glasses by high gravity Combustion Synthesis. Several ceramic and glass materials prepared by high gravity Combustion Synthesis are firstly presented as examples, including single phase ceramics, multiphase eutectic or composite ceramics, glasses and glass–ceramics. Then, the reaction kinetics in high gravity Combustion Synthesis are discussed in detail, with an emphasis on phase separation, solidification and microstructure evolution. Finally, a conclusion is drawn with a perspective on further development and application of high gravity Combustion Synthesis.
Krishnan Rajeshwar - One of the best experts on this subject based on the ideXlab platform.
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Solution Combustion Synthesis of Complex Oxide Semiconductors
International Journal of Self-Propagating High-Temperature Synthesis, 2018Co-Authors: M. K. Hossain, E. Kecsenovity, A. Varga, M. Molnár, C. Janáky, Krishnan RajeshwarAbstract:This is a perspective of the role that Combustion Synthesis, specifically solution Combustion Synthesis, has played in the development of ternary and quaternary metal oxide semiconductors, and materials derived from these compounds such as composites, solid solutions, and doped samples. The attributes of materials, collectively termed ‘complex oxides’ within the context of this discussion, are discussed in terms of their applicability in the generation of solar fuels from water splitting and CO_2 reduction, and environmental pollution remediation via heterogeneous photocatalysis.
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solution Combustion Synthesis of oxide semiconductors for solar energy conversion and environmental remediation
Chemical Society Reviews, 2009Co-Authors: Krishnan Rajeshwar, Norma R De TacconiAbstract:In this tutorial review, we summarize recent research on the solution Combustion Synthesis of oxide semiconductors for applications related to photovoltaic solar energy conversion, photoelectrochemical hydrogen generation, and heterogeneous photocatalytic remediation of environmental pollutants. First, the advantages of Combustion Synthesis relative to other strategies for preparing oxide semiconductors are discussed followed by a summary of process variants in Combustion Synthesis. The possibility of in situ chemical modification of the oxide during its formation in the Combustion environment is addressed. Morphological and crystal structure aspects of the Combustion-synthesized products are discussed followed by a summary of trends in their photocatalytic activity relative to benchmark samples prepared by other methods.
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Combustion Synthesis and characterization of nanocrystalline wo3
Journal of the American Chemical Society, 2008Co-Authors: Walter Morales, Norma R De Tacconi, Michael Cason, Olawunmi Aina, Krishnan RajeshwarAbstract:The energy payback time associated with the semiconductor active material is an important parameter in a photovoltaic solar cell device. Thus lowering the energy requirements for the semiconductor Synthesis step or making it more energy-efficient is critical toward making the overall device economics more competitive relative to other nonpolluting energy options. In this communication, Combustion Synthesis is demonstrated to be a versatile and energy-efficient method for preparing inorganic oxide semiconductors such as tungsten trioxide (WO3) for photovoltaic or photocatalytic solar energy conversion. The energy efficiency of Combustion Synthesis accrues from the fact that high process temperatures are self-sustained by the exothermicity of the Combustion process, and the only external thermal energy input needed is for dehydration of the fuel/oxidizer precursor mixture and bringing it to ignition. Importantly, we show that, in this approach, it is also possible to tune the optical characteristics of the oxide semiconductor (i.e., shift its response toward the visible range of the electromagnetic spectrum) in situ by doping the host semiconductor during the formative stage itself. As a bonus, the resultant material shows enhanced surface properties such as markedly improved organic dye uptake relative to benchmark samples obtained from commercial sources. Finally, this Synthesis approach requires only very simple equipment, a feature that it shares with other "mild" inorganic semiconductor Synthesis routes such as sol-gel chemistry, chemical bath deposition, and electrodeposition. The present study constitutes the first use of Combustion Synthesis for preparing WO3 powder comprising nanosized particles.
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Combustion Synthesis and characterization of nanocrystalline WO3.
Journal of the American Chemical Society, 2008Co-Authors: Walter Morales, Norma R De Tacconi, Michael Cason, Olawunmi Aina, Krishnan RajeshwarAbstract:The energy payback time associated with the semiconductor active material is an important parameter in a photovoltaic solar cell device. Thus lowering the energy requirements for the semiconductor Synthesis step or making it more energy-efficient is critical toward making the overall device economics more competitive relative to other nonpolluting energy options. In this communication, Combustion Synthesis is demonstrated to be a versatile and energy-efficient method for preparing inorganic oxide semiconductors such as tungsten trioxide (WO3) for photovoltaic or photocatalytic solar energy conversion. The energy efficiency of Combustion Synthesis accrues from the fact that high process temperatures are self-sustained by the exothermicity of the Combustion process, and the only external thermal energy input needed is for dehydration of the fuel/oxidizer precursor mixture and bringing it to ignition. Importantly, we show that, in this approach, it is also possible to tune the optical characteristics of the ...
Kexin Chen - One of the best experts on this subject based on the ideXlab platform.
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Combustion Synthesis of α-Si3N4 with green additives
Ceramics International, 2019Co-Authors: Jie Zhang, Guanghua Liu, Zhaobo Tian, Siyuan Sun, Wei Cui, Kexin ChenAbstract:Abstract This paper reports the Combustion Synthesis of α-Si3N4 using green additives of water and alcohol. The addition of water and alcohol is demonstrated to be effective in controlling the reaction kinetics and improving the formation of α-Si3N4 by vapor reactions. With increasing proportion of additives in the starting composition, the content of α-Si3N4 in the product is clearly enhanced. In contrast to the ammonium halides usually employed as additives in the Combustion Synthesis of α-Si3N4, the green additives used here are nontoxic, noncorrosive, and thus more attractive for industrial applications.
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Combustion Synthesis: An effective tool for preparing inorganic materials
Scripta Materialia, 2018Co-Authors: Guanghua Liu, Kexin ChenAbstract:Abstract Combustion Synthesis is a fast and energy-efficient process to prepare inorganic materials from self-sustained Combustion reactions. It is widely used for preparing ceramics, metals, and their composites. The unique condition in Combustion Synthesis with high temperatures and large heating rates offers good opportunities to explore new materials and novel microstructures. This paper gives a viewpoint on recent progress in Combustion Synthesis, from fundamentals to applications. New results on theories, processings, and materials are reviewed, and perspectives on the development of Combustion Synthesis are provided.
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22 Combustion Synthesis
Handbook of Combustion, 2016Co-Authors: Guanghua Liu, Kexin ChenAbstract:Combustion Synthesis is used to synthesize useful materials via Combustion reactions. Compared to many other material Synthesis approaches, Combustion Synthesis is furnace-free and more efficient, with negligible energy consumption, short processing times, large productivities, and low costs of production. The unique conditions of Combustion Synthesis, characterized by extremely high temperatures and rapid heating/cooling rates, offers tremendous possibilities for controlling the microstructure and Synthesis of novel materials. To date, Combustion Synthesis has been used to produce a wide variety of inorganic materials, including metals, ceramics, and metal–ceramic composites, in different forms of powders, coatings, and bulks. Today, Combustion Synthesis is associated with many scientific disciplines, is applied to various industrial fields, and represents a promising branch of modern science and technology with an ever-growing influence. In this chapter, a comprehensive introduction to Combustion Synthesis, from theory to practice, is provided. Initially, some basic concepts and fundamentals of the process are elucidated, with the essential parameters of Combustion reactions, including adiabatic temperature, propagation velocity and stability of Combustion wave, being explained based on homogeneous models. Heterogeneous and discrete Combustion models are then described for heterogeneous reaction media. Finally, the reaction mechanism of Combustion Synthesis is discussed, along with improvements in experimental skills. The processing of Combustion Synthesis (and materials thus created) are also reviewed. The effects of the main parameters in routine processing of Combustion Synthesis are discussed for solid–solid and solid–gas reactions. Details of various hybrid processes based on Combustion Synthesis are then presented, with high-gravity Combustion Synthesis as a particular example. Finally, solution Combustion Synthesis and gas Combustion Synthesis are introduced, with emphasis placed on the preparation of nanosized particles. Keywords: ceramics; Combustion; high temperature; refractory compounds; reaction mechanism; Synthesis
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Combustion Synthesis of Cu2SnSe3 thermoelectric materials
Journal of the European Ceramic Society, 2016Co-Authors: Guanghua Liu, Kexin Chen, Min ZhouAbstract:Abstract Thermoelectric materials are attractive for solar thermal energy conversion and waste heat recovery. The existing methods for fabricating thermoelectric materials involve multi-step processes with considerable time and energy consumption. Here we report a fast and one-step way to prepare thermoelectric materials by gas-pressure or high-gravity assisted Combustion Synthesis. Dense Cu2SnSe3 samples with a porosity below 2% were prepared from self-sustained Combustion reaction of element powders. The electrical conductivity of the Cu2SnSe3 samples was greatly enhanced and the thermal conductivity was reduced by partial substitution of Sn with In. The ZT values of the un-doped and In-doped Cu2SnSe3 samples reached 0.51 and 0.62 at 773 K, respectively, which are comparable to the best results reported for Cu2SnSe3 produced by other methods. Combustion Synthesis offers an efficient way to prepare thermoelectric materials with reduced time and energy consumption, which may open up new possibilities for Synthesis of thermoelectric materials.
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review of melt casting of dense ceramics and glasses by high gravity Combustion Synthesis
Advances in Applied Ceramics, 2013Co-Authors: Guanghua Liu, Kexin ChenAbstract:Abstract High gravity Combustion Synthesis is a recently reported technique to prepare dense ceramics and glasses by melt casting instead of conventional powder sintering. This technique combines strong exothermic chemical reactions with a high gravity field, and offers an efficient and furnace free way for rapid production of bulk ceramic and glass materials. This article reviews major results on melt casting of dense ceramics and glasses by high gravity Combustion Synthesis. Several ceramic and glass materials prepared by high gravity Combustion Synthesis are firstly presented as examples, including single phase ceramics, multiphase eutectic or composite ceramics, glasses and glass–ceramics. Then, the reaction kinetics in high gravity Combustion Synthesis are discussed in detail, with an emphasis on phase separation, solidification and microstructure evolution. Finally, a conclusion is drawn with a perspective on further development and application of high gravity Combustion Synthesis.
Norma R De Tacconi - One of the best experts on this subject based on the ideXlab platform.
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solution Combustion Synthesis of oxide semiconductors for solar energy conversion and environmental remediation
Chemical Society Reviews, 2009Co-Authors: Krishnan Rajeshwar, Norma R De TacconiAbstract:In this tutorial review, we summarize recent research on the solution Combustion Synthesis of oxide semiconductors for applications related to photovoltaic solar energy conversion, photoelectrochemical hydrogen generation, and heterogeneous photocatalytic remediation of environmental pollutants. First, the advantages of Combustion Synthesis relative to other strategies for preparing oxide semiconductors are discussed followed by a summary of process variants in Combustion Synthesis. The possibility of in situ chemical modification of the oxide during its formation in the Combustion environment is addressed. Morphological and crystal structure aspects of the Combustion-synthesized products are discussed followed by a summary of trends in their photocatalytic activity relative to benchmark samples prepared by other methods.
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Combustion Synthesis and characterization of nanocrystalline wo3
Journal of the American Chemical Society, 2008Co-Authors: Walter Morales, Norma R De Tacconi, Michael Cason, Olawunmi Aina, Krishnan RajeshwarAbstract:The energy payback time associated with the semiconductor active material is an important parameter in a photovoltaic solar cell device. Thus lowering the energy requirements for the semiconductor Synthesis step or making it more energy-efficient is critical toward making the overall device economics more competitive relative to other nonpolluting energy options. In this communication, Combustion Synthesis is demonstrated to be a versatile and energy-efficient method for preparing inorganic oxide semiconductors such as tungsten trioxide (WO3) for photovoltaic or photocatalytic solar energy conversion. The energy efficiency of Combustion Synthesis accrues from the fact that high process temperatures are self-sustained by the exothermicity of the Combustion process, and the only external thermal energy input needed is for dehydration of the fuel/oxidizer precursor mixture and bringing it to ignition. Importantly, we show that, in this approach, it is also possible to tune the optical characteristics of the oxide semiconductor (i.e., shift its response toward the visible range of the electromagnetic spectrum) in situ by doping the host semiconductor during the formative stage itself. As a bonus, the resultant material shows enhanced surface properties such as markedly improved organic dye uptake relative to benchmark samples obtained from commercial sources. Finally, this Synthesis approach requires only very simple equipment, a feature that it shares with other "mild" inorganic semiconductor Synthesis routes such as sol-gel chemistry, chemical bath deposition, and electrodeposition. The present study constitutes the first use of Combustion Synthesis for preparing WO3 powder comprising nanosized particles.
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Combustion Synthesis and characterization of nanocrystalline WO3.
Journal of the American Chemical Society, 2008Co-Authors: Walter Morales, Norma R De Tacconi, Michael Cason, Olawunmi Aina, Krishnan RajeshwarAbstract:The energy payback time associated with the semiconductor active material is an important parameter in a photovoltaic solar cell device. Thus lowering the energy requirements for the semiconductor Synthesis step or making it more energy-efficient is critical toward making the overall device economics more competitive relative to other nonpolluting energy options. In this communication, Combustion Synthesis is demonstrated to be a versatile and energy-efficient method for preparing inorganic oxide semiconductors such as tungsten trioxide (WO3) for photovoltaic or photocatalytic solar energy conversion. The energy efficiency of Combustion Synthesis accrues from the fact that high process temperatures are self-sustained by the exothermicity of the Combustion process, and the only external thermal energy input needed is for dehydration of the fuel/oxidizer precursor mixture and bringing it to ignition. Importantly, we show that, in this approach, it is also possible to tune the optical characteristics of the ...
Jun-ichiro Yagi - One of the best experts on this subject based on the ideXlab platform.
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Recent Development of Combustion Synthesis
2016Co-Authors: Jun-ichiro Yagi, Tomohiro AkiyamaAbstract:This paper describes recent developments in Combustion Synthesis (CS) for producing hydrides, nitrides, oxide and alloys during the last two decades which basically uses exothermic heat efficiently among powders and gas. It is mainly characterized by self-propagation of a high temperature Synthesis (SHS) wave, minimization of productive energy, short processing time, non-equilibrium phase, high purity product, simple equipment and high productivity. In particular, Combustion Synthesis of hydrides1-3) (Mg2NiH4, LaNi5H6, FeTiH2, MgH2), nitrides4) (Si3N4, AlN, SiAlON), oxides (TiOx, FexO, MnxO, ABO3) and alloy (Fe2VAl) under the control of atmosphere has been recently reported. Synthesis of a non-stoichiometric compound such as TiOx by control of powder mixing ratio is also attractive from the viewpoint of defect design. The survey on major database revealed that the products reported covers many state-of-the-art energy conversion materials such as photo-catalyst, catalyst for the diesel engine, semiconductor, dielectrics, battery-related material, hydrogen storage alloy, thermoelectric device, refractory, hard material, and sinter for ironmaking. In conclusion, Combustion Synthesis will be reviewed from three viewpoints of exergy engineering, process engineering, and material science, together with companies established in Japan. Keywords; Combustion, process, energy, hydrogen, nitrogen, oxidation, industry Reference) 1) Hydriding Combustion Synthesis for the Production of Hydrogen Storage Alloy, T. Akiyama, H. Isogai and J. Yagi, Journal of Alloys and Compounds, 252(1997), pp.1-4. [I.F. 1.035] 2) Hydriding Combustion Synthesis of TiFe, I. Saita, M. Sato, H.Uesugi, T. Akiyama, Journal of Alloys and Compounds, 446-447(2007), pp.195-199. [I.F. 1.455] 3) Self-ignition Combustion Synthesis of LaNi5 utilizing hydrogenation heat of metallic calcium, N. Yasuda, S. Sasaki, N. Okinaka, T. Akiyama, International Journal of Hydrogen Energy, 35(2010), pp.11035�11041. [I.F. 3.945] 4) A New Route to Synthesize beta-Si6-zAlzOzN8-z Powders, K. Aoyagi, T. Hiraki, R, Sivakumar, T, Waranabe, T. Akiyama, Journal of Alloys and Compounds, 441(2007), pp.236-244. [I.F. 1.455]
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Activation behaviors of Mg2NiH4 at different hydrogen pressures in hydriding Combustion Synthesis
International Journal of Hydrogen Energy, 2001Co-Authors: Liquan Li, Tomohiro Akiyama, Jun-ichiro YagiAbstract:Abstract For the industrialization of the process of hydriding Combustion Synthesis of Mg2NiH4, the activation behaviors of Mg2NiH4 at different hydrogen pressures were measured by means of DSC (differential scanning calorimeter) and XRD (X-ray diffraction). The profiles of heat flow of DSC were very different at 0.5, 1.0, 2.0 and 4.0MPa hydrogen pressures within three cycles of temperature scanning at a rate of 0.1 K / s in hydriding Combustion Synthesis of Mg2NiH4. It is apparent that an activation behavior existed in the hydriding Combustion Synthesis since the height of DSC peak from the hydriding reaction of Mg2NiH4 increased with the cycling of temperature scanning. The pressure of hydrogen strongly affected this kind of an activation. The peak height increased as hydrogen pressure increased. It reached maximum values after the second cycle of temperature scanning at 4.0MPa of hydrogen pressure and after the third cycle at 2.0MPa. The patterns of XRD revealed that pure products of Mg2NiH4 were obtained after the third cycle of temperature scanning at 2.0MPa of hydrogen pressure and after the second cycle at 4.0MPa. These results are significant for developing the industrial process of hydriding Combustion Synthesis of hydrogen storage alloy Mg2NiH4 within only one temperature scanning without any activation process.
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Effect of hydrogen pressure on the Combustion Synthesis of Mg2NiH4
Intermetallics, 1999Co-Authors: Liquan Li, Jun-ichiro YagiAbstract:Abstract The aim of this work is to study the experimental production of a hydrogen storage alloy (Mg 2 NiH 4 ) directly from a magnesium and nickel mixture without activation treatment by Combustion Synthesis in hydrogen. In this paper, the effect of hydrogen pressure on the hydriding Combustion Synthesis of Mg 2 NiH 4 at 0.5, 1.0, 2.0 and 4.0 MPa has been studied by differential scanning calorimeter (DSC) and by X-ray diffraction (XRD). The XRD results showed that the Combustion products of all samples were composed mainly of Mg 2 NiH 0.3 and Mg 2 NiH 4 in spite of a slight remainder of Ni, in which the amount of Mg 2 NiH 4 increased with increasing hydrogen pressure, but not very drastically. In addition, the DSC results showed several sharp heat-flow peaks during heating and cooling periods between room temperature and 850 K. It is suggested that the reaction mechanism of the hydriding Combustion Synthesis is not simple, but complicated with several endothermic and exothermic reactions with pressure dependence.
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Reaction rate of Combustion Synthesis of an intermetallic compound
Powder Technology, 1998Co-Authors: Tomohiro Akiyama, Hiromichi Isogai, Jun-ichiro YagiAbstract:Abstract The reaction kinetics of the Combustion Synthesis of Mg 2 Ni from a powder mixture of magnesium and nickel has been investigated. The physical and chemical changes of the samples during the Combustion Synthesis were followed by scanning electron microscopy (SEM), electron probe X-ray microanalysis (EPMA), X-ray diffraction (XRD), and differential scanning calorimetry (DSC) to derive a suitable rate equation. The observations revealed that the Synthesis of Mg 2 Ni progresses homogeneously rather than topochemically, and not through an intermediate phase, with acceleration by liquid generation of the eutectoid phase. The result was that the most reasonable expression is a second-order irreversible equation, k (1− f ) 2 , with an activation energy of 165 kJ/mol.