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Do we get a better adhesion of nickel plating on steel than on copper ?

2005

Hello , I am Geert working in a plating shop for the decorative industries as for example modern barhandles with an inox look. In fact these handles are made of 20 µ nickel plated steel witch get a high bright varnish as top finish after brushing nickel -1,-2µ
To reduce costs and improve corrosion resistance we( I ) decided to give the steel bars
a copper layer of 12-18 µ and a top layer of nickel of about 6 - 10 µ.

During brushing 10%of the parts is waste due to the fact that the nickel seems not to have enough adherence on copper around the bore holes M4 and a small nickel specimen of 1 until 2 mm2 is leaving the part. When we increase again the nickel thickness until 10-12 µ the problems does not occur any more. (THE GOAL WAS TO REDUCE NICKEL CONSUMPTION - 50 % )

   

Process : Ultrasonic degreasing , anodic degreasing , pickling , rinsing 3 x => 10' CuCN at 1 amp/dm2 => activation => 20' CuSO4 bath at 3 amp/dm2 ==> Actane 371 activation 1' ==> Nickel 35 ' 3amps/dm2 ==> rinsing 5 x and drying. Next is brushing where the problems
occurs.

Please , what can be done ? Is it true that the adherence of nickel on copper is less powerful than directly on steel ?

My best regards and thank you,

Geert Vandenweghe
- Kortrijk, Belgium

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2005

Geert

It is correct to reduce Nickel by adding a thickness of acid copper. So far you are correct in approach..

The mark looks like a spot mark left by a jigging fault. Are you hanging the parts from the hole in the component ?

If this is not the case , are you draining all the liquids out of the pipe before each stage. ?
Remember that preceeding solutions interfere with subsequent stages..

The peel off is due to localised poor adhesion and indicates nothing wrong with sequence. BUT indicates something wrong in the way you run the sequences.

Check all rinses and acid dips for oil contamination too.

Regards

Asif Nurie [deceased]
- New Delhi, India
With deep regret we sadly advise that Asif passed away on Jan 24, 2016

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2005

Dear Geert,

The problem which you have described, is it only around the holes? On the picures and how you have described it, seems, that you do not really have an adhesion problem, I think the problem occurs b/c of a bad racking design.

Regards,

Dominik Michalek
- Mexico City, Mexico