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Nickel free anodizing sealants and Ni and Zinc (Zn) contamination

2005

I am a grad student working on my master's degree in chemical engineering. I'm not a material scientist so this is not my area of expertise. I am having problems with Nickel and Zinc contaminating my experiments, and I think its coming from parts in my equipment. I need to know if all sealants used after anodizing have Nickel--are there any Nickel free ones? Do all anodized parts have to be sealed?

Also, my analization exuipment is also picking up Zinc contamination but from what I can tell Zinc is never involved in the Anodization process, is that true or am I mistaken? If so, how is it used in the anodization process. 

Thank for any information anyone can provide.     

James Patterson
Engineering - Hillsboro, OR, USA

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Anodizing is often sealed, but not always. One reason to do it is that an unsealed anodized surface is a sponge; well actually it's more of a honeycomb. It readily absorbs dirt and discoloration which is then impossible to remove. Yes, nickel acetate and nickel fluoride are often used in sealing, but they do not have to be by any means. Steam or boiling water are valid sealing processes, as is dichromate.

I don't think zinc is used in the anodizing process, but many aluminum alloys have zinc in them, so the first place I'd look is to the aluminum itself.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2005

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Cobalt acetate or cobalt fluoride can also be used for sealing.

Jeffrey Holmes, CEF
Spartanburg, South Carolina
2005