Salt Fog Corrosion Testing of Al-Y-Co Based Nanocrystalline and Amorphous Coatings Produced by Atmospheric Plasma Spray


Alloys based upon the Al-Y-Co system were atmospheric plasma sprayed (APS) to produce amorphous coatings with varying amounts of nanocrystalline precipitates of aluminum. All of the coatings produced in this study were deposited on 7075-T651 plate. Al91Y4Co1 and Al91Y4Co5 alloys produced a mixed microstructure of metallic glass and nanocrystalline aluminum with grain diameters between 10 and 15 nm. In contrast, coatings of Al81Y 12Ni5Co2, Al85Y8Ni 5Co2, and Al89Y4Co 5Mo2 were almost entirely amorphous. Glass forming ability and hardness of the coatings increased in proportion to the yttrium content. Salt fog corrosion tests were performed in accordance with ASTM B117-03. Corrosion performance of the coating was limited by coating permeation and subsequent attack of the 7075-T651 substrate. Improved corrosion performance was obtained using a silicone-based sealant to reduce coating permeation. Densification of the coating, using a CO2 laser, produced a crystalline coating with poor corrosion resistance.


Materials Science and Engineering

Keywords and Phrases

Al-Based Coatings; Amorphous; Nanocrystalline; Plasma Spray

Document Type

Article - Conference proceedings

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© 2004 ASM International, All rights reserved.

Publication Date

01 Jan 2004

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