Combustion Synthesis Co.

Numazu, Japan

Combustion Synthesis Co.

Numazu, Japan

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Zhu C.,Hokkaido University | Nobuta A.,Hokkaido University | Saito G.,Hokkaido University | Nakatsugawa I.,Combustion Synthesis Co. | Akiyama T.,Hokkaido University
Advanced Powder Technology | Year: 2014

In this work, fine powders of spinel-type LiMn2O4 as cathode materials for lithium ion batteries (LIBs) were produced by a facile solution combustion synthesis using glycine as fuel and metal nitrates as oxidizers. Single phase of LiMn2O4 products were successfully prepared by SCS with a subsequent calcination treatment at 600-1000 C. The structure and morphology of the powders were studied in detail by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The electrochemical properties were characterized by galvanostatic charge-discharge cycling and cyclic voltammetry. The crystallinity, morphology, and size of the products were greatly influenced by the calcination temperature. The sample calcined at 900 C had good crystallinity and particle sizes between 500 and 1000 nm. It showed the best performance with an initial discharge capacity of 115.6 mAh g-1 and a capacity retention of 93% after 50 cycles at a 1 C rate. In comparison, the LiMn2O4 sample prepared by the solid-state reaction showed a lower capacity of around 80 mAh g-1. © 2013 The Society of Powder Technology Japan. Published by Elsevier B.V.


Niu J.,Hokkaido University | Harada K.,Combustion Synthesis Co. | Nakatsugawa I.,Combustion Synthesis Co. | Akiyama T.,Hokkaido University
Ceramics International | Year: 2014

A facile salt-assisted combustion synthesis of β-SiAlON and systematic characterization of the endothermic effects of addition of KCl, MgCl 2, and CaCl2 were investigated under a nitrogen pressure of 1 MPa. Single-phase products containing crystals with different shapes were obtained. The results indicated that the metal chlorides act as perfect diluents that effectively absorb the reaction heat via their melting and evaporation, which occur in the same temperature ranges as the two stages of the exothermic processes. In addition, the products exhibited different morphologies when the type or amount of metal chlorides was changed. The results of this work suggest that single-phase β-SiAlON could be fabricated with the intended morphology by simply adding different kinds of metal chlorides. © 2013 Elsevier Ltd and Techna Group S.r.l.


Niu J.,Hokkaido University | Harada K.,Combustion Synthesis Co. | Suzuki S.,Hokkaido University | Nakatsugawa I.,Combustion Synthesis Co. | And 2 more authors.
Journal of Alloys and Compounds | Year: 2014

High-quality Y- and Ca-α/β-SiAlON and α-SiAlON ceramics were synthesized via salt-assisted combustion synthesis from Si, Al, and metal oxide (Y2O3 and CaO) with the addition of NaCl and MgCl2 under a nitrogen pressure of 1 MPa. NaCl and MgCl2 were employed as they act as excellent diluents that effectively absorb the reaction heat through melting and evaporation. We found that the type of metal chlorides employed significantly affected the α/β ratio and the morphology of the product, with the use of NaCl affording high α/β ratios and equiaxed morphologies, while the use of MgCl2 resulting in low α/β ratios and elongated grains. The results of this work suggest that high-purity α/β-SiAlON composite products of intended α/β ratios can be successfully fabricated by controlling the initial metal chloride content. © 2014 Elsevier B.V. All rights reserved.


Niu J.,Hokkaido University | Nakamura T.,Hokkaido University | Nakatsugawa I.,Combustion Synthesis Co. | Akiyama T.,Hokkaido University
Chemical Engineering Journal | Year: 2014

Reaction characteristics of combustion synthesis (CS) of β-SiAlON powders in a horizontal CS chamber were compared by including two types of additives (β-SiAlON and NaCl) in Si, SiO2, and Al powder raw materials. The results showed that the reaction characteristics were influenced by the additives, which exerted a strong effect on the reaction rate and the morphology of the products. At the respective maximum combustion temperatures, a relatively slow conversion rate, with a reacted fraction (η) of 58.7%, was achieved with the addition of 12mass% NaCl to the raw materials, whereas the addition of 45mass% β-SiAlON powders afforded η=88%. The NaCl additive yielded rod-like crystals, which were well developed by a long after-burn time. However, self-sintering occurred in the presence of β-SiAlON powders. The results indicate that some degree of control over the conversion rate of the reaction and the microstructures of the product can be achieved by varying the type of additives. © 2013 Elsevier B.V.


Niu J.,Hokkaido University | Yi X.,Northwest University, China | Nakatsugawa I.,Combustion Synthesis Co. | Akiyama T.,Hokkaido University
Intermetallics | Year: 2013

A novel method of producing submicron-size β-SiAlON powders by combustion synthesis using NaCl as a diluent was proposed. The combustion synthesis was carried out with the raw materials Si, SiO2, and Al powders, and varying amounts of NaCl under a nitrogen pressure of 1 MPa. Phase compositions and particle morphologies of the synthesized powders were analyzed. The results revealed that as the z-values increased, the amount of NaCl needed to complete the reaction increased, which in turn decreased the particle size of the product. With small z-values, single-phase products were obtained; however, with large z-values, NaCl and unreacted Si remained in the products due to the large amount of liquid phase. NaCl acted not only as a diluent by absorbing the heat generated by the reaction but also as a diffusion barrier between β-SiAlON particles, which greatly limited the growth of β-SiAlON crystals.©2012 Elsevier Ltd. All rights reserved.


Zhu C.,Hokkaido University | Nobuta A.,Hokkaido University | Nakatsugawa I.,Combustion Synthesis Co. | Akiyama T.,Hokkaido University
International Journal of Hydrogen Energy | Year: 2013

In this work, nanoparticles of LaMO3 (M = Fe, Co, Mn) perovskite oxide catalysts were produced by facile solution combustion synthesis with glycine as the fuel and metal nitrates as the oxidizers. The electrocatalytic activities of the catalysts for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) were evaluated using a three-electrode half-cell design and a full rechargeable Zn-air battery with a 6 M KOH electrolyte. Comprehensive study of combustion synthesis and characterization of synthesized products showed that LaFeO3 had been successfully prepared in a single step of combustion synthesis, while the synthesis of LaCoO3 and LaMnO3 required an extra calcination step. The effects of the glycine/nitrate ratio and the calcination temperature and duration on the particle size and crystallinity of the final products were evaluated. Electrochemical characterization showed that LaMnO3 exhibited the best catalytic activity for both ORR and OER during the initial discharge-charge cycles, especially for the ORR corresponding to the discharge of the Zn-air battery. The order of activity is as follows: LaMnO3 > LaCoO3 > LaFeO3 > CB (carbon black). However, cycling performance measurements showed that the LaMnO3 catalyzed air electrode degraded very quickly, whereas the LaCoO3 catalyzed electrode exhibited the best rechargeability and stability. © 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.


Niu J.,Hokkaido University | Yi X.,Hokkaido University | Yi X.,Northwest Agriculture and Forestry University | Harada K.,Combustion Synthesis Co. | Akiyama T.,Hokkaido University
Journal of Alloys and Compounds | Year: 2016

This paper describes the spark plasma sintering (SPS) of Y- and Ca-α/β-SiAlON powders synthesized by salt-assisted combustion at temperatures of 1600 °C with different holding times. X-ray diffraction reveals that with increasing holding time, the α to β transformation ratio of Y-α-SiAlON becomes greater than that of Ca-α-SiAlON. Nevertheless, all samples effectively reach their theoretical density after sintering. The Vickers hardness measured with an applied load of 19.614 (2.0 kg) decreases with a decreasing amount of α-SiAlON, with a maximum value of 19.4 GPa being achieved in Ca-α/β-SiAlON with an α-SiAlON content of 55%. © 2016


Niu J.,Hokkaido University | Akiyama T.,Hokkaido University | Yi X.,Northwest University, China | Nakatsugawa I.,Combustion Synthesis Co.
AIChE Journal | Year: 2013

Significance: Single-phase β-SiAlON particles with submicron size were prepared via combustion synthesis (CS) using natural kaolin, Si, and Al as raw materials under a nitrogen atmosphere of 1 MPa. Kaolin could not only act as the raw material to provide the source of oxygen, but also act as the diluent to reduce the reaction temperature by eliminating the structural water during reaction process. © 2012 American Institute of Chemical Engineers (AIChE).

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