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Zinc Iron Plating (black) Vs. Zinc Plating (black)

Hello all, I would like to post this question about platings. I know there are many different blends and processes (Barrel vs rack, etc) for performance and plating. I'm currently researching Zinc plating for an automotive component that will be exposed to the environment.

So, part of my research is to optimize the plating process. My questions are: which one performs better for long term corrosion protection?
I get mixed signals on costs of both, so anyone can give me a general idea for cost comparisons between the two? I was told Zinc Iron is much cheaper...

Also, how much would Zinc Iron affect the quality of the surface. Is black going to be black or will it be brown?

Would love some help with this research to get a better idea where I stand.

Jason Miller
Oakland University - (PhD. Student) - Rochester, Michigan, USA
2007

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2007

Zinc alloys are more corrosion resistant than plain zinc plating, primarily because the electromotive potential can be engineered by picking the right alloy content. This also makes them more expensive and somewhat more difficult to operate.

Zinc-iron offers the best black color and stability; I believe it's because the iron content offers a metal that can be blackened whereas black zinc must rely on silver (which changes color) or dyes which lack stability. I am not a chemist in this area, but have been to plating shops which solved their problems with black finishes when they switched from zinc to zinc iron.

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