Metal finishing Q&As since 1989

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Chromate Coating for 200 Hrs Salt Spray

2001

Dear sir

We have a coating shop and we have some problem with chromate coating on the automobile parts for outstanding 200 hours in the salt spray .

Please help us.

Mansour - Kashiha
- Tehran, Iran

Dear Mr.Mansour,

Special formulated yellow passivations after zinc plating will allow you to obtain 200h salt spray test. Check it again with your supplier.

Best regards,

FREDI YARCAN
- Istanbul, Turkey
2001

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Since you are in the automotive industry, you should be aware that the hexavalent chromate coatings you are talking about are going to be banned very soon. You should be trying to handle this problem with a trivalent chromate, possibly with an additional topcoat. You should draw upon the technical expertise of your plating chemical suppliers to help you through this.

Tim Neveau
Rochester Hills, Michigan
2001

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2001

Sir,

Zinc -Cobalt alloy coating with an iridescent yellow passivation may be able to give 200 hrs salt spray corrosion resistance. Bath maintenance may require a little more attention than the conventional cyanide bath. You may check-up this with your chemical suppliers. This may also be a little more expensive.

Subramanian Ramajayam
consultant - Bangalore, India