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Time between passivation and water rinse in zinc-nickel plating

hi,

My question is regarding Automated Zinc Nickel Electroplating process with black passivation.

In the automated process there is time delay of 17 seconds for transporting the Jig from the passivation tank to subsequent water rinse. The product looks brown in colour instead of Black. Whereas when after passivation the Jigs were removed manually and rinsed in water within 2 or 3 second the colour looks perfectly black.

Can anyone explain why this variation is happening? and also suggest how the colour can be achieved in automated process itself?

Regards

Sridhar

Sridhar Ramanujam
Plating shop owner - Chennai, India
April 2, 2011

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Sridhar,

While going for automation to do passivation process, the passivation tank should have mechanical agitation system. Then the passivation timing to be increased to achieve the required colour.

Karthikeyan
- Coimbatore, TamilNadu, India
April 6, 2011

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April 11, 2011

Dear Sridar,

May be due to too active chromate. Please check the conc., pH and dip time. Lower conc/increased pH/ increased dip time may help.

P. Gurumoorthi
electroplating process chemicals - Chennai, Tamilnadu, India