preparation of oxidation-resistant coating having diffusion barrier by molten salt electrodeposition and self-organization

Research Project

Project/Area Number	26420695
Research Category	Grant-in-Aid for Scientific Research (C)
Allocation Type	Multi-year Fund
Section	一般
Research Field	Composite materials/Surface and interface engineering
Research Institution	Akita University
Principal Investigator	HARA Motoi 秋田大学, 理工学研究科, 教授 (50156494)
Co-Investigator(Kenkyū-buntansha)	福本倫久秋田大学, 理工学研究科, 准教授 (20343064)
Research Collaborator	SATO Naka
Project Period (FY)	2014-04-01 – 2018-03-31
Project Status	Completed (Fiscal Year 2017)
Budget Amount *help	¥5,070,000 (Direct Cost: ¥3,900,000、Indirect Cost: ¥1,170,000) Fiscal Year 2016: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000) Fiscal Year 2015: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000) Fiscal Year 2014: ¥2,600,000 (Direct Cost: ¥2,000,000、Indirect Cost: ¥600,000)
Keywords	コーティング / 耐酸化性 / 電析 / 溶融塩 / ニッケルアルミナイド / 拡散障壁 / 自己組織化 / 高温酸化 / 酸化皮膜 / サイクル酸化 / ニッケルーハフニウム合金 / アルミニウム / アルミナ皮膜
Outline of Final Research Achievements	A bilayer coating consisting of Ni-aluminide and Ni-Hf alloy layers was prepared on Ni-Cr-Al alloy in four electrodeposition steps of Ni, Hf, Ni and Al. The cyclic oxidation resistance of the bilayer coating sample at 1373 K was examined with that of a single Ni-aluminide coating sample. The oxidation rate of the bilayer coating sample was lower than that of the single coating sample. A decrease in Al concentration in the Ni-aluminide layer for the bilayer coating sample during the cyclic oxidation was smaller than that for the single coating sample. This seems to result from a barrier effect of the Ni-Hf alloy layer against Al diffusion. An alumina scale formed on the bilayer coating showed a pegging morphology. This morphology led to improvement of the adherence of the scale.