Effect of Gelatin Additions on the Corrosion Resistance of Cerium based Conversion Coatings Spray Deposited on Al 2024-T3

Abstract

The corrosion resistance of cerium based conversion coatings on Al 2024-T3 was improved by the addition of a water soluble gelatin to the coating solution. Auger electron spectroscopy depth profiling showed that coatings deposited from solutions containing 800–3200 ppm gelatin were ~ 400 nm thick, while coatings deposited from solutions with 0–200 ppm gelatin were ~ 850 nm thick. The thinner coatings exhibited reduced surface cracking and spalling. Open circuit potential measurements during deposition showed that adding gelatin to the coating solution resulted in a more negative and stable potential with increasing gelatin concentrations. Visually, increasing gelatin concentrations promoted the formation of stable bubbles that covered panel surfaces, which limited transport of cerium species to the surface and decreased the deposition rate. X-ray diffraction analysis revealed that only coatings deposited from solutions containing 400–3200 ppm gelatin could be converted to CePO4H2O during post-treatment, potentially improving the corrosion resistance compared to coatings deposited from solutions without gelatin.

Department(s)

Materials Science and Engineering

Research Center/Lab(s)

Peaslee Steel Manufacturing Research Center

Keywords and Phrases

Cerium Conversion Coating; Corrosion; Aluminum; Gelatin

International Standard Serial Number (ISSN)

0257-8972

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2009 Elsevier, All rights reserved.

Publication Date

01 Aug 2009

Link to Full Text

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