Oxidation protection of enamel coated Ni based superalloys: Microstructure and interfacial reaction

•A SiO2-Al2O3-CaO-BaO-MgO based enamel coating is applied Ni alloy.•The enamel coating can provide effective protection for super-alloy at 900 °C.•Crystallization of enamel coating further suppresses interfacial reaction.•Interfacial microstructure evolution during oxidation is discussed.•Elemental...

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Bibliographic Details
Published in:Corrosion science 2020-08, Vol.173, p.108760, Article 108760
Main Authors: Yan, Gaosheng, Yu, Wenshan, Shengping, Shen
Format: Article
Language:English
Subjects:
Aluminum oxide
Barium oxides
Bonding strength
Enamel
Enamel coating
evolution
High temperature oxidation
Interface reactions
Interfacial reaction
Microstructure
Ni based superalloys
Nickel base alloys
Oxidation
Silicon dioxide
Submerging
Superalloys
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Summary:•A SiO2-Al2O3-CaO-BaO-MgO based enamel coating is applied Ni alloy.•The enamel coating can provide effective protection for super-alloy at 900 °C.•Crystallization of enamel coating further suppresses interfacial reaction.•Interfacial microstructure evolution during oxidation is discussed.•Elemental reaction and diffusion(Cr Ti and Al) at interface are considered. We study the oxidation of SiO2-Al2O3-CaO-BaO-MgO based enamel coated Ni based superalloy at 900°C and find that the enamel coatings are highly capable of protecting the Ni based superalloy from oxidation. During the oxidation, the complicated composition crystals precipitated in enamel lead to two linear variation stages of oxidation weight gain. Moreover, the increased roughness of the superalloy interface due to oxidative attack and the immersion of the enamel coating in superalloy should increase the interface bonding strength. Finally, oxidations of Al, Ti and Cr from superalloy dominates the interfacial reactions.
ISSN:0010-938X
1879-0496
DOI:10.1016/j.corsci.2020.108760