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Corrosion Improvement Properties of Anodized Aluminum

2003

I have a engine component that is failing corrosion testing made of aluminum. The component part supplier has stated that a 20 times improvement for corrosion protection can be made by anodizing the aluminum seal that failing.

That seems a bit high and since it is a holiday and I do not have access to material properties technical information AND I need to make a decision immediately, I was hoping you could supply me with a sanity check for this suppliers claim.

Thank you very much,

Scott R. Diamond
Design Engineer for Auto Manufacturer - Dearborn, Michigan, USA

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It is difficult to respond in terms like '20 times improvement', and it depends on the alloy, the type of anodizing, the thickness, etc. But in answer to your 'sanity check', yes, anodizing can tremendously improve the corrosion resistance.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2003

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Anodized aluminum should have significantly more corrosion resistance than bare metal. However, aluminum die-castings are much more difficult to anodize without special techniques. Normal anodizing procedures can result in a coating with poor corrosion resistance.

Chris Jurey, Past-President IHAA
Luke Engineering & Mfg. Co. Inc.

Wadsworth, Ohio

2003

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2004

Scott,

Generally speaking anodized aluminum will have much greater corrosion resistance. The things to keep in mind are the following, anodizing can change dimensions therefore caution should be taken to make sure the parts still "fit" . As stated by several commentators alloy can cause difficulty in getting the correct anodize oxide buildup, and the type of anodizing - II or III will have a big effect on the abrasion resistance if it is a moving part. I suggest you slow down and make an educated decision.

Drew Nosti, CEF
Anodize USA

Ladson, South Carolina