Preventing Filiform Corrosion of Aluminum
I'm trying to find out more about Filiform corrosion.
I have the paper presented at the Estal Conference by Professor Defrancq in September 1994 which indicates that the cause is the alloy.
The interim status report of a R&D project as of March 1997 as commissioned by Alusuisse, Hydro Aluminium and Pechiney and published in April 1997 which indicates that it is nothing to do with the alloy.
A paper in English & Italian by Franz P. Theiler, on the 'Corrosion Behavior of Aluminium' which puts forward a theory based on Cl ions.
Does anybody else have their own theories or knowledge of scientific papers on the subject?
Any help or pointers would be much appreciated.Peter Hirst
Any corrosion book will help you. You can also find articles in the corrosion journal. If you have any specific question I will be happy to assist. I have a few books that mention the filiform corrosion subject.
CONTACT HENKEL TECHNOLOGIES, MADISON HTS., MI -USA. A PAST EMPLOYEE, SINCE RETIRED IS A EXPERT ON THIS SUBJECT. I'M SURE HENKEL WOULD GIVE YOU ALL THE SOURCES YOU DESIRE. THAT RETIRED EMPLOYEE IS WALTER CAVANUAGHRICH PODOLSKI
CHEMICAL PROCESSING & ACCESSORIES - LINCOLNSHIRE, ILLINOIS
Ed. note: Rich's advice is appreciated; but time flies, and it may not stay applicable forever.
March 25, 2011
I had heard that an acid bath followed by a clear anodize (for pre-treatment) will decrease (to eliminate) the chance for filiform corrosion on liquid coatings. Does anyone have any experience with this?William Keller
- Fonda, New York USA
March 25, 2011
Hi, William. I don't have experience in exactly that process, but the underlying fact is that raw aluminum is subject to filiform corrosion (some alloys more than others), but proper pretreatments like chromate conversion coating, chromic acid anodizing (and probably clear anodizing) discourage filiform corrosion on aluminum by providing an environment contrary to the environment in which it thrives.
Davis' "Corrosion of Aluminum and Aluminum Alloys" has in-depth information on this subject; and the technical articles quoted in letter 38996 should help as well. Good luck!
Ted Mooney, P.E.
Pine Beach, New Jersey
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