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96 hour black chromate conversion coating

My company currently makes a part for a customer that is required to be zinc plated with a yellow chromate conversion coating per ASTM B633 Type II Fe/Zn8. After the plating the part is coated with a sealer to protect the part so that there is no white corrosion after 96 hours of salt spray exposure (salt spray test per ASTM ASTM B117 ). The appearance of these parts is very critical to our customer and since a design change has made these parts more visible in their assembly, they would like the parts to be colored black. Is there a black chromate process that is available that will meet last 96 hours of salt spray exposure with no white corrosion visible?

Raymond R [last name deleted for privacy by Editor]
motion control products supplier - Erie, Pennsylvania, USA
2003

I would go with Zinc-iron plating and black chromate, Raymond. It is not only more corrosion resistant, but the black color does not rely on silver and will be more stable.

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

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