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Cadmium plating over nickel plated brass

Dear Sirs,

We are having a typical job of having to plate Cadmium over nickel plated brass. The base metal is BRASS with a plating thickness of the nickel 6 microns. This is further plated CADMIUM over NICKEL, Cad plating thickness 6 microns. Then further chromated ( yellow passivated). Main problem is after 2 months in operation the parts started developing dark black spots all over their body with no particular reason. The parts do not exhibit any particular trend. Please advice if this is due to base nickel plating. Whether Cadmium plating over Nickel plated Brass is advisable. Or any other alternative is suggested.

ATUL DEDHIA
- MUMBAI, MAHARASTRA, India
2003

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Dear Mr Atul,

I would be surprised if the discoloration didn't happen. You would be damaging the nickel plating severely during the cadmium plating. Why don't you increase the nickel thickness to 10 microns without any cadmium? What is the component and where is it used ?

Khozem Vahaanwala
Saify Ind

Bengaluru, Karnataka, India

2003