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Does anodizing solution become oxygen-poor after successive uses?

2003

Hi all,

I am anodizing aluminium thin film (about 10nm of thickness) in acid solution of amount 0.5l, but after few uses my samples during anodizing are affronted to the erosion problem (dissolution of aluminum). To find an answer to this problem I would like to know, does the electrolyte (acid solution) used few times for anodizing of aluminum become poor in oxygen? if so, what are the consequences of this effect (poor solution in oxygen) on the next anodizing steps on the aluminium material surface?

Thank you in advance.

BR Mouss
Student - Suwon, Suwon, S-Korea

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Oxygen is not your problem. Commercial anodizers will use the same solution for months and then go into a bleed & feed to hold down impurities. My guess, you are not maintaining your temperature. As you use the tank, the temp rises. As the temp rises, the acid eats more of the formed oxide layer and gets softer and spongier to the point of virtually no layer.

You should not be having a problem with impurities with only a few days use, unless you are getting copper or iron into it in large amounts. Use aluminum hangers, not copper. Use new wires each time or strip the old ones between use. The oxide is an insulator, so current will not flow. Lesson- watch both the voltage and the amperage when you anodize. If it is not exactly the same as when you had a good one, (for the same type part) then, something is wrong.

James Watts
- Navarre, Florida
2003