Directly Deposited Cerium Phosphate Coatings for the Corrosion Protection of Al 2024-t3
Cerium phosphate coatings were directly deposited onto Al 2024-T3 substrates by precipitation from aqueous solution containing cerium citrate and phosphoric acid. These coatings were characterized and compared to post-treated, cerium-based conversion coatings (CeCCs). Directly deposited CePO4 coatings exhibited corrosion current densities of 2 - 4 µA/cm2, compared to ≈0.45 µA/cm2 for CeCCs. Analysis revealed that directly deposited CePO4 coatings did not significantly impact the electrochemical properties of bare Al 2024 T3, an indication that deposition was independent of the local galvanic activity utilized to deposit CeCCs. After salt spray exposure, cross-sectional analyses showed that directly deposited coatings acted as a static barrier to corrosion, allowing the formation of pits at crack/substrate interfaces, which were not observed in similar regions of post-treated CeCCs. Instead, an interfacial reaction layer had formed at the CeCC/substrate interface, revealing that the CeCC exhibited an active response to the salt spray environment that influenced corrosion protection.
D. K. Heller et al., "Directly Deposited Cerium Phosphate Coatings for the Corrosion Protection of Al 2024-t3," ECS Transactions, The Electrochemical Society (ECS), Jan 2010.
The definitive version is available at http://dx.doi.org/10.1149/1.3496432
Materials Science and Engineering
Keywords and Phrases
Corrosion; Passivation; Anodic Films
Article - Conference proceedings
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