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Flux for alumina rich hot-dip galvanizing

We are wondering whether the hot-dip galvanizing in a 5%Al and 95%Zn dip by single-dip would require special flux, as sometimes mentioned in the literature.

Norbert Rudolf Dr. Ing. Seyfert
product designer - Olpe, Germany
May 19, 2011

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May 19, 2011

Sir:

Any zinc bath over about 0.007% aluminum requires a special flux.

I have read a patent on a special flux for higher aluminum containing zinc baths. I do not wish to be accused of encouraging others to violate a patent so I am not able to give you a reference. Also I do not wish to comment on this flux for the same reason.

I think there are two ongoing researches, one with around 0.04% aluminum and the other as you have indicated 5% aluminum. Both pose interesting positive and negative likely results. White rust may be a problem and floating aluminum/iron rich dross may be a second problem.

I have gone a different direction and I am writing an article titled "Lead-Free Hot Dip Galvanizing."

Regards,

Dr. Thomas H. Cook
Galvanizing Consultant - Hot Springs, South Dakota, USA