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Chromate conversion coating is applied to passivate zinc (either plated zinc or zinc diecastings) to slow corrosion. To be in compliance with RoHS and ELV legislation, Eastern Plating uses Trivalent Chromates exclusively. These are less toxic to the environment than the hexavalent chromates used in the past.
Chromating is commonly used on zinc-plated parts to protect the zinc from white corrosion, which is primarily a cosmetic issue. It has additional value as a primer for subsequent organic coatings. Chromated parts retain their electrical conductivity to varying degrees, depending on coating thickness. The process may be used to add color for decorative or identification purposes.
Chromate coatings are soft and gelatinous when first applied but harden and become hydrophobic as they age. Curing can be accelerated by heating up to 70C, but higher temperatures will gradually damage the coating over time.
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