Letter 42038

Rusting on trivalent chrome plating [India] 

August 28, 2006

Can any body tell the reason, why the metal parts getting rust after trivalent chrome plating with blue passivation? What precautions to be made to protect from rust? These parts are made at India & sent to UK.

G. Ravichandran
Molded components with assy for Electrical industries - Ahmednagar, Maharashtra, India

Passivation is not done on chrome plated parts, G., so I assume that you are not actually speaking of trivalent chrome plating, but rather of zinc plating with a trivalent chrome conversion coating? If the components are rusting it is because the parts were not dried properly, or are not properly packaged for shipping, or the plating plating process is not as robust as required. Please describe the component, the complete plating specification, and how they are packaged for shipment. Thanks.

 
Ted Mooney, P.E.
finishing.com Inc. - Brick, NJ

Mr Ravichandran

The question is very broad. You have zinc plated , trivalent blue chromated parts failing earlier in Corrosion testing than these should.

I suggest your plating vendor goes in for a proper audit first with a third party as supervisor to find out the cause first.

Therefater you can have remedial measures implemented within your reach.

For your info, properly treated , correctly applied, Trivalent Blue chromated parts withstand from 76 to 180 hours in Accelerated corrosion tests. In India not far from Ahmednagar...

Regards,

Asif Nurie Atlanta Global Limited New Delhi, India

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