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Nickel strike diffusing into tin plating

2005

Presently we are having a 300 series SS tube plated on the OD w/.0008" - .001" thickness of Electroless Nickel. We then cas tin 3/4" thickness on the plating. The purpose of the nickel is for adhesion of the Tin to the SS tube.

We have done chemical testing on the tin after casting and found that there is a high contamination of nickel in the Tin. Upwards of .15%

The tin has been tested before and after casting to confirm that it is happening at this final cast.

I understand the nickel is being put on via a sulfuric dip not the conventional chloride strike. Could this be the problem?

Has anyone heard of this happening before?

Jeffrey Rissala
- Biddeford, ME, USA

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First of two simultaneous responses --

Once the nickel is deposited, it doesn't know what sort of bath it came from. Try reducing the nickel thickness. .00005" (50 millionths) may be plenty.

Jeffrey Holmes, CEF
Spartanburg, South Carolina
2005

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Second of two simultaneous responses --

It is impossible for the nickel to diffuse through this unusually thick layer of 3/4" at the relatively low casting temperature of tin. Besides, there's not enough nickel available to reach that percentage. 0.001" / 0.750" = 0.13% (you mention 0.15%) There should be another via for this contamination.

Guillermo Marrufo
Monterrey, NL, Mexico
2005