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What levels of pH are a problem for anodized aluminum?

I have been told that aluminum doesn't hold up well in the low and high pH level atmospheres -- because the anodic surface cannot re-generate as quickly as it gives itself up. What is the truth in this?

Jack Ries
sell conduit - Dallas, Texas
November 6, 2009

November 9, 2009

Hi Jack

Depending on many things, you will be on the secure site with pH between 4 - 9. You say pH in the atmosphere? please specify what you mean.

The natural oxide film will recover in this pH range.

Sunny regards
Anne

Anne Deacon Juhl
- - Trustrup Denmark

We do not know what you mean by "regenerating", but acids and alkalies dissolve aluminum, aluminum oxide, and hydrated (sealed) aluminum oxide, the lower the pH or the higher the pH causes more and more dissolution.

Robert H Probert
Robert H Probert Technical Services

Garner, North Carolina

November 9, 2009

Very low pH will also attack the same way that Robert talks about, only a bit slower. Some acids are faster than others.

James Watts
- Navarre, Florida
November 10, 2009

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