Treat a Fuel Tank with Alodine?

[MarshMarlowe196]

I recently went through a class at work on the application of Alodine to Aluminum parts on the aircraft.  The purpose of applying Alodine is to extend the life of the Aluminum parts by preventing corrosion.  Has anyone ever heard of this being done to Aluminum Fuel Tanks for boats??

I know there's some other products available that etch the surface of aluminum prior to painting, and Alodine has the same effect, but do they add a corrosion-resistant coating as well?

There's also a form of Alodine that increases the conductivity of Aluminum to prevent the build-up of static electricity, made especially for fuel tank applications in aircraft.

My understanding is the Alodining process actually forces the aluminum to oxidize (rust), then it turns the surface oxidation into a chromate, which extends the life of the part by 1/3.  Kinda like starting an intentional brush fire in a forest to prevent a wildfire in the future.  Could we do this on our Aluminum tanks? Or is there already a rust preventative coating on aftermarket tanks (clad surface)?  I asked the instructor this question and couldn't get a solid answer.

 

[wingtime]

Good question.  I thought anodizing aluminum caused it to turn into aluminum oxide and alodine is a chromate conversion process.    I wondered about the same idea but alodine is usually applied to alclad aluminum which has a thin pure aluminum coating on it.  I don't think it will work on the typical marine alloys we use.  I've tried it on 6000 series aluminum and it didn't work that well.

[fitz73222]

Alodine is similar to the passivation process for stainless steel; it is a light etch that will eventually form the oxide layer. In our business, alodine is normally the prep bath for anodizing. The best process for keeping Aluminum from corroding is to use the Hard Anodize process; I'm at home so I dont have the ASTM spec in front of me. but I can send it Monday if anyone is interested.