Faculty Profiles - OTSUBO Fumitaka

Papers - OTSUBO Fumitaka

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Characterization of Blasted Austenitic Stainless Steel and Its Corrosion Resistance Reviewed

F.Otsubo,K.Kishitake,T.Akiyama,T.Terasaki

Journal of Thermal Spray Technology 12 ( 4 ) 555 - 559 2003.12

Characterization of blasted austenitic stainless steel and its corrosion resistance Reviewed

Otsubo F., Kishitake K., Akiyama T., Terasaki T.

Journal of Thermal Spray Technology 12 ( 4 ) 555 - 559 2003.12

Language：English Publishing type：Research paper (scientific journal)

It is known that the corrosion resistance of stainless steel is deteriorated by blasting, but the reason for this deterioration is not clear. A blasted austenitic stainless steel plate (JIS-SUS304) has been characterized with comparison to the scraped and non-blasted specimens. The surface roughness of the blasted specimen is larger than that of materials finished with #180 paper. A martensite phase is formed in the surface layer of both blasted and scraped specimens. Compressive residual stress is generated in the blasted specimen and the maximum residual stress is formed at 50-100 μm from the surface. The corrosion potentials of the blasted specimen and subsequently solution treated specimen are lower than that of the non-blasted specimen. The passivation current densities of the blasted specimens are higher those of the non-blasted specimen. The blasted specimen and the subsequently solution treated specimen exhibit rust in 5% sodium chloride (NaCl) solution, while the non-blasted specimen and ground specimen do not rust in the solution. It is concluded that the deterioration of corrosion resistance of austenitic stainless steel through blasting is caused by the roughed morphology of the surface.

DOI： 10.1361/105996303772082305

Scopus

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固有ひずみ法による球状黒鉛鋳鉄溶接部の残留応力分布測定

原田浩次,大坪文隆,岸武勝彦,寺崎俊夫

日本鋳造工学会鋳鉄材料研究部会研究報告92 110 - 114 2003.11

ブラスト処理によるオーステナイトステンレス鋼の耐食性劣化 Reviewed

大坪文隆,秋山哲也,岸武勝彦,寺崎俊夫

溶射 39 ( 3 ) '108－11 - -108－112 2002.07

高速フレーム溶射したFe-Cr-Mo-８P-2C 合金非晶質溶射皮膜の耐塩酸性 Reviewed

大坪文隆,恵良秀則,岸武勝彦

溶接学会論文集 19 ( 1 ) '54－5 - -54－59 2001.02

Resistance to Hydrochloric Acid Solution of Fe-Cr-Mo-8P-2C Amorphous Coatings Sprayed by HVOF Process. Reviewed

OTSUBO Fumitaka, ERA Hidenori, KISHITAKE Katsuhiko

QUARTERLY JOURNAL OF THE JAPAN WELDING SOCIETY ( JAPAN WELDING SOCIETY ) 19 ( 1 ) 54 - 59 2001.02

Language：English Publishing type：Research paper (scientific journal)

Three kinds of Fe-8P-2C alloy powders containing 10 mass%Cr (10Cr), 20 mass%Cr (20Cr) and 10 mass%Cr-10 mass%Mo (10Mo), respectively, were thermally sprayed by a high velocity oxy-fuel (HVOF) process. The as-sprayed coatings of the 10Cr and 20Cr alloys are a mixture of an amorphous phase and a small quantity of crystalline phases, while as-sprayed coating of the 10Mo alloy is composed of only an amorphous phase. The anodic polarization curves of the coatings of the 10Cr and 20Cr alloys exhibited an activation-passivation transition in 1NHCl solution. On the other hand, the coating of the 10Mo allo, showed no active state and the lowest current density among the alloy coatings in the anodic polarization curve. The passive state of the coating of the 10Mo alloy was stable compared with the other coatings. The coating of the 10Mo alloy als, underwent no corrosion in 1NHCl solution at 0.5 and 1.0 V (vs. SCE), whereas Inconel 600 alloy plate was attacked remarkably.

DOI： 10.2207/qjjws.19.54

Scopus

CiNii Article

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Properties of Cr3C2-NiCr Cermet Coating Sprayed by High Power Plasma and High Velocity Oxy-Fuel Processes Reviewed

F.Otsubo,H.Era,T.Uchida,K.Kishitake

Journal of Thermal Spray Technology 9 ( 4 ) 499 - 504 2000.12

Formation of Amorphous Fe-Cr-Mo-8P-2C Coatings by the High Velocity Oxy-Fuel Process Reviewed

F.Otsubo,H.Era,K.Kishitake

Journal of Thermal Spray Technology 9 ( 4 ) 494 - 498 2000.12

Properties of Cr<inf>3</inf>C<inf>2</inf>-NiCr cermet coating sprayed by high power plasma and high velocity oxy-fuel processes Reviewed

Otsubo F., Era H., Uchida T., Kishitake K.

Journal of Thermal Spray Technology 9 ( 4 ) 499 - 504 2000.12

Language：English Publishing type：Research paper (scientific journal)

The structure, hardness, and shear adhesion strength have been investigated for Cr3C2-NiCr cermet coatings sprayed onto a mild steel substrate by 200 kW high power plasma spraying (HPS) and high velocity oxy-fuel (HVOF) processes. Amorphous and supersaturated nickel phases form in both as-sprayed coatings. The hardness of the HVOF coating is higher than that of the HPS coating, because the HVOF coating contains more nonmelted Cr3C2 carbide particles. On heat treating at 873 K, the amorphous phase decomposes and the supersaturated nickel phase precipitates Cr3C2 carbides so that the hardness increases in the HPS coating. The hardness measured under a great load exhibits lower values compared with that measured with a small load because of cracks generated from the indentation. The ratio of the hardnesses measured with different loads can be regarded as an index indicating the coating ductility. The ductility of the HVOF coating is higher than that of the HPS coating. Adhesion strength of the HVOF coating was high compared with the HPS coating. The adhesion of the coatings is enhanced by heat treating at 1073 K, and that of the HVOF coating is over 350 MPa.

DOI： 10.1361/105996300770349719

Scopus

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Formation of amorphous Fe-Cr-Mo-8P-2C coatings by the high velocity oxy-fuel process Reviewed

Otsubo F., Era H., Kishitake K.

Journal of Thermal Spray Technology 9 ( 4 ) 494 - 498 2000.12

Language：English Publishing type：Research paper (scientific journal)

Alloy powders of Fe-10%Cr-8%P-2%C(10Cr), Fe-20%Cr-8%P-2%C(20Cr), and Fe-10%Cr-10%Mo-8%P-2%C(10Mo) compositions (in mass%) were sprayed by the high velocity oxy-fuel (HVOF) process under different conditions. The as-sprayed coatings of 10Mo alloy were composed of only an amorphous phase under all the spray conditions, while the as-sprayed coatings of the 10Cr and 20Cr alloys consisted of an amorphous phase with a small amount of crystalline material. The volume fraction of the crystalline material increased slightly with the rise of the flame temperature. The hardnesses of the as-sprayed coatings of the 10Cr and 20Cr alloys were 600 to 700 DPN, respectively, while the 10Mo coating composed of an amorphous phase revealed 560 DPN. The corrosion resistance of the as-sprayed coating of the 10Mo alloy was the best among three amorphous coatings and also superior to the nickel-base self-fluxing alloy and SUS316L stainless steel coatings in 1N H2SO4 and 1N HCl solutions.

DOI： 10.1361/105996300770349700

Scopus

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Interface Reaction between Nickel-Base Self-Fluxing Alloy Coating and Steel Substrate Reviewed

F.Otsubo,H.Era,K.Kishitake

Journal of Thermal Spray Technology 9 ( 2 ) 259 - 263 2000.06

Interface reaction between nickel-base self-fluxing alloy coating and steel substrate Reviewed

Otsubo F., E. E., Kishitake K.

Journal of Thermal Spray Technology 9 ( 2 ) 259 - 263 2000.06

Language：English Publishing type：Research paper (scientific journal)

The interface reaction between a nickel-base, self-fluxing alloy coating and a steel substrate has been investigated to examine the formation of 'pores,' which are observed along the interface of used boiler tubes. It was found that lumpy precipitates form along the interface instead of pores after heating at high temperatures and that the precipitates are of Fe2B boride. The adhesion strength of the coating is not decreased by the formation of Fe2B precipitates along the interface because of the increase of the adhesion due to interdiffusion.

DOI： 10.1361/105996300770350014

Scopus

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Structure and Phases in Nickel-Base Self-Fluxing Alloy Coating Containing High Chromium and Boron Reviewed

F.Otsubo,H.Era,K.Kishitake

Journal of Thermal Spray Technology 9 ( 1 ) 2000.03

Structure and phases in nickel-base self-fluxing alloy coating containing high chromium and boron Reviewed

Otsubo F., Era H., Kishitake K.

Journal of Thermal Spray Technology 9 ( 1 ) 107 - 113 2000.03

Language：English Publishing type：Research paper (scientific journal)

The structure of a nickel-base, self-fluxing alloy coating, containing chromium and boron thermal sprayed and fused, was investigated by x-ray diffraction (XRD), scanning electron microscopy (SEM), electron probe microanalysis (EPMA), and transmission electron microscopy (TEM). A lumpy M6C carbide, a rodlike M3B2 boride of tetragonal structure, a rodlike M7C3 carbide of hexagonal structure, and a Ni-Ni3B eutectic phase formed in the coating after fusing. Metals of M6C, M3B2, and M7C3 phases are composed of chromium, molybdenum, and nickel; chromium and molybdenum; and mainly chromium, respectively. The nickel phase in the coating has the L12 type superlattice structure.

DOI： 10.1361/105996300770350131

Scopus

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ニッケル基自溶合金溶射皮膜の組織と生成相 Reviewed

岸武勝彦,恵良秀則,大坪文隆

溶接学会論文集 18 ( 1 ) 126 - 132 2000.02

Structure and Phases in Nickel-Base Self Fluxing Alloy Coating. Reviewed

KISHITAKE Katsuhiko, ERA Hidenori, OTSUBO Fumitaka

QUARTERLY JOURNAL OF THE JAPAN WELDING SOCIETY ( JAPAN WELDING SOCIETY ) 18 ( 1 ) 126 - 132 2000.02

Language：English Publishing type：Research paper (scientific journal)

The structure and constituents in two types of nickel-base self fluxing alloy coatings thermal sprayed and subsequently fused were precisely investigated by use of X-ray diffraction analysis, electron probe microanalysis, scanning electron microscopy and transmission electron microscopy. JIS-MSFNi1 alloy coating was composed of primary nickel solid solution and Ni3B phase between primary nickel grains with a small amount of Ni-Ni3B eutectic. In case of JIS-MSFNi4 alloy coating, lumpy crystals and two kinds of rod-like crystals appeared in addition to Ni-Ni3B eutectic. It was found that the lumpy crystal is M6C carbide containing chromium, molybdenum and nickel. The rod-like crystals are M3B2 boride of tetragonal structure and M7C3 carbide of hexagonal structure. Metal constitution of M3B2 are chromium and molybdenum and M7C3 contains mainly chromium. The nickel phase in the Ni-Ni3B eutectic of MSFNi4 alloy coating has the superlattice structure.

DOI： 10.2207/qjjws.18.126

Scopus

CiNii Article

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Improvement of adhesion strength and formation of veined structure in alumina coating Reviewed

Era H., Otsubo F., Kishitake K.

Proceedings of the International Thermal Spray Conference 1 711 - 716 1998.12

Language：English Publishing type：Research paper (international conference proceedings)

Alumina coatings plasma-sprayed on alumina substrate with metallic bond coating (50Ni-50Cr) and on metal (Ni) substrate have been investigated in terms of adhesion strength and a veined structure formed in alumina coating. The veined structure is formed to heal up cracks and pores in sprayed alumina and substrate alumina after heat-treatment in air. The veined structure consists of oxides of NiAl2O4 (spinel-type) and NiO (NaCl-type). This indicates that the metallic elements in the bond coating or the metallic substrate diffuse along the cracks and pores in alumina and react with alumina. The alumina coating with veined structure shows high strength due to the mechanical anchoring of veined oxide and chemical bonding.

Scopus

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High corrosion resistant iron-based amorphous coatings obtained by thermal spraying Reviewed

Otsubo F., Era H., Kishitake K., Matsumoto H.

Proceedings of the International Thermal Spray Conference 1 659 - 664 1998.12

Language：English Publishing type：Research paper (international conference proceedings)

Fe-Cr(-Mo)-metaloids alloy coatings were thermal sprayed by different processes of LPPS, HVOF and HPS. The as-sprayed coating by LPPS is perfectly amorphous and coatings by other processes contain partly crystalline phases. The amorphous phases crystallize at 773 K or more and shows a high hardness of about 1000 to 1400 DPN just after crystallization. The anodic polarization curves of the coatings shift from active to passive state in 1N H 2SO 4 and 1N HCl solutions. The coatings obtained by LPPS indicate the lowest active and passive current densities and possess the best corrosion resistance. The corrosion resistance of the coatings obtained by other processes are better than a SUS316L stainless steel coating. The LPPS coating of Fe-Cr-C-P alloy is not attacked on immersion test in 6% FeCl 3·6H 2O + 0.05N HCl solution at corrosion potential, while large pit corrosion is developed in a SUS316L stainless steel sheet.

Scopus

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A Modified Shear Test for Adhesion Evaluation of Thermal Sprayed Coating Reviewed

H.Era,F.Otsubo,T.Uchida,S.Fukuda,K.Kishitake

Materials Science and Engineering A251 '166 - 166 1998.04

Improvement of the Adhesion of a Ceramic Coating on a Ceramic Substrate Reviewed

K.Kishitake,H.Era,F.Otsubo,T.Sonoda

Journal of Thermal Spray Technology 7 ( 1 ) 64 - 70 1998.03

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