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Hardcoating anodization variables

2005

I would like to know the importance of the volume of air injected into the anodizing tank, and if it is crucial to the process the stability and the temperature of that flow.
In our process we use a concentration of H2O4 of 300g/l and ~6g/l of aluminium sulphate.

thank you

Vitor Guerreiro
air conditioning - Palmela, Portugal

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It is usually not possible to quantitatively answer such questions, Mr. Guerreiro, because it depends so much on size of the parts, depth of the tank, alloy of the substrate, etc. But very close temperature control is required in order for the acid to maintain consistent dissolution power. And if you run a quick calculation of how much power you are putting into the parts, and how quickly and how much it can raise the temperature of the solution immediately tangent to the parts, you will quickly appreciate why vigorous agitation is a necessity. Most shops would use a far lower concentration of sulfuric acid than you are using. 100 g/l by weight is more typical.

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