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Yokkaichi, Japan

Li Y.,Nippon Steel and Sumikin Hardfacing Co. | Noguchi M.,Nippon Steel and Sumikin Hardfacing Co. | Akasaka H.,Tokyo Institute of Technology | Nakamura A.,Chubu Chelest Co. | Saitoh H.,Nagaoka University of Technology
Proceedings of the International Thermal Spray Conference | Year: 2013

The metal oxide coatings are widely applied in the modern industry. Up to now, the plasma thermal spray process is the main method to obtain oxide coatings, because of the high melting point of the oxides. In this paper, to obtain a thick and dense Y2O3 metal oxide coatings, powders of yttrium ethylene diamine tetra acetic acid (Y-EDTA) complexes are sprayed as feedstock materials by the conventional flame spray method. During the EDTA spray process, the metal EDTA complexes were decomposed into molecular level oxides particles, and the accelerated oxides particles impact with the subject to form a thick and dense oxides coating. The organic components in the EDTA raw material were completely decomposed and the deposited coatings contained crystalline phases of metal oxides. This paper focuses on the main EDTA thermal spray parameters which influenced the organic residue, the crystal structure and the micro-structure of the coatings. By the comparison with the conventional atmospheric plasma spray (APS) Y2O3 coating, the EDTA thermal spray Y2O3 coating shows better surface morphologies with fewer microcracks than the APS coatings. We demonstrated that the reactive flame spray process using metal-EDTA complexes is convenient for obtaining metal oxide films at a low cost.

Komatsu K.,Nagaoka University of Technology | Nakamura A.,Nagaoka University of Technology | Nakamura A.,Chubu Chelest Co. | Ohshio S.,Nagaoka University of Technology | And 3 more authors.
Journal of Solid State Chemistry | Year: 2013

Chemical stability of 6-coodinated SrO is a fundamental problem when this is used for various applications. In this study, optical and chemical stabilities of 8-coordinated SrO:Eu2+ phosphor were investigated. SrO:Eu2+ phosphor was synthesized from thermal treatment of SrO:Eu powder located on a single crystalline MgO at 1500° C under reduction atmosphere. Obtained 8-coordinated SrO:Eu2+ phosphor exhibit strong blue luminescence and chemical stability in distilled water for 3 days. Our findings prove that obtained 8-coordinated SrO:Eu2+ possesses relative optical and chemical stabilities in water. © 2013 Elsevier Inc.

Komatsu K.,Nagaoka University of Technology | Tsuchida S.,Nagaoka University of Technology | Maruyama H.,Nagaoka University of Technology | Ohshio S.,Nagaoka University of Technology | And 4 more authors.
International Journal of Applied Ceramic Technology | Year: 2014

A violet divalent europium-doped strontium aluminate (Sr-Al-O:Eu 2+) phosphor particle was synthesized from a metal- ethylenediaminetetraacetic acid (EDTA) solution of Sr, Al, Eu, and particulate alumina via spray drying and sintering in a reducing atmosphere. The emission properties, crystal structures, cross-sectional emissions, and elemental distributions of the obtained Sr-Al-O:Eu2+ phosphor particles were investigated. The product was determined to be secondary SrAl12O 19:Eu2+ particles with an average diameter of 20 μm. The violet SrAl12O19:Eu2+ emission phase was found in a 1-μm-thick coating of the particles where elemental Al diffusion occurred. These particles are anticipated to find commercial applications such as paints. © 2013 The American Ceramic Society.

Komatsu K.,Nagaoka University of Technology | Sekiya T.,Nagaoka University of Technology | Toyama A.,Nagaoka University of Technology | Hasebe Y.,Nagaoka University of Technology | And 9 more authors.
Journal of Thermal Spray Technology | Year: 2014

R2O3 (R = Y, Eu, Er) metal oxides were synthesized from metal-ethylenediaminetetraacetic acid (EDTA) complexes using a flame spray technique. As this technique enables high deposition rates, films with thickness of several tens of micrometers were obtained. Films of yttria, europia, and erbia phase were synthesized on stainless-steel substrates with reaction assistance by H2-O2 combustion gas. The oxide films consisted of the desired crystalline phase with micropores. The porosity of the films was in the range of 6-15%, varying with the metal used. These results suggest that the true density of the metal oxide obtained from metal-EDTA powder through the thermal reaction process plays an important role in achieving film with the desired porosity. © 2014 ASM International.

Komatsu K.,Nagaoka University of Technology | Nakamura A.,Nagaoka University of Technology | Nakamura A.,Chubu Chelest Co. | Kato A.,Nagaoka University of Technology | And 3 more authors.
IOP Conference Series: Materials Science and Engineering | Year: 2011

A blue Sr-Al-O:Eu2+ phosphor was obtained by the elemental diffusion of Mg. The Sr-Al-O:Eu2+ phosphor was synthesized by the sintering at 1500 °C under a reduction condition with and without a MgO substrate from Sr-Al-O:Eu powder, which was fabricated by the oxidation of metal-ethylenediaminetetraacetic(EDTA) complexes. The elemental distribution of Mg, the crystal structure and the temperature dependence of photo-emission properties were investigated for these phosphors. Mg diffused into Sr-Al-O:Eu powders from the MgO substrate by sintering, and brought changes to the crystalline structure and its emission properties. The number of crystalline phases was increased from one phase of SrAl2O4 to seven phases of Sr-Al-O by Mg addition. The emission peak at 520 nm shifted to peaks at 460 and 510 nm at 300 K owing to the addition of Mg. The blue emission observed from the powder at temperatures lower than 250 K was observed up to 300 K upon the addition of Mg. These results suggested that the diffusion of Mg into Sr-Al-O crystal affected the limitation of emission energy loss due to thermal atomic vibration. © 2011 Ceramic Society of Japan.

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