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Fluorine Residue Cleaning

We are trying to extend the life of some expensive aluminum parts, and have tried to re-anodize them. the process the parts are in uses fluorine, and the shop we tried indicated that fluorine had soaked into the aluminum, making it impossible to re-anodize. I am hoping someone has experience with re-anodization and can recommend either a process or job shop that can handle this.

Paul Ingalls
- Richardson, Texas USA
2000

Anodized aluminum are stripped of anodic coating prior to re-anodization. Etching solution can accomplish this. Stripping solutions--like a mixture of Chromic acid/Phosphoric Acid--can also be used. Any anodizing shop is able to re-anodize.

Dado Macapagal
- Toronto, Ont. Can
2000

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From what I could learn from the internet, Fluoride will complex with Al(+++). If the aluminum is exposed o fluorine gas, I don't know if the fluorine is first converted to fluoride and then reacts, or if the fluorine gas takes up residence in the spaces in the aluminum metal lattice. If it is still a gas, can you bake it out?

If it is a fluoride, can you break the complex with a stronger complex? Can immersion in a hot calcium carbonate solution remove the fluoride? Good Luck! Tom

  
Tom Pullizzi
Falls Township, Pennsylvania
2000