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Letter 42010 Electrode corrosion in anodizing bath [Greece]August 25, 2006 After a period of two weeks off (as a service period), i found out
that in one of the two anodizing baths, the cathode electrodes were
oxidized and dissolved. The concentration was 120g/l H2SO4 and
4-4.5g/l Al. The working concendration is 180-190g/l H2SO4 and
5-5.5g/l Al. I'm thinking of a ÄE change or short-circuit at the
rectifier or both. There was no positive work electrode (aluminium)
attached to the bath, but there was a water leak into the bath from
the positive head's cooling spiral. what do you think happened? Vasilis K. Makkas
August 25, 2006 Hello Vasilas. Are you using aluminum cathodes or lead cathodes (or something else)? Sorry, I don't know what you mean by "AE change". Why do you call the cooling spiral, "the positive head's". Is this cooling coil metallic, and is it not electrically isolated?
August 29, 2006 Hello Ted,
Thank you very much for your time and I hope that I made you understand of the parameters Vasilis K. Makkas
September 7, 2006 I strongly suspect that an electrical leakage current was the problem. It is possible that although the cathode is negative when the line is running, when there is no work in the tank the cathode is actually positive to a cooling coil or some other item in the tank. I don't think I'd suspect any chemical leaking from the cooling system to corrode aluminum.
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