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Differences between adhesion of hard chrome over decorative and bright nickel

July 4, 2008

I have been doing samples of hard chrome over decorative nickel and over semi-bright nickel. we observe that the adhesion is different, is better, in the semi-bright than in the decorative; from the decorative it is usual to peel off, by the other hand from the semi-bright the adhesion is always good.

why is this happening? what leads the chromium the get a better adherence over semi-bright nickel? is that normal?

any help will be appreciated or any idea about it

thanks,

Daniel Hernandez
NIckel plater - Bucaramanga, Santander, Colombia

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July 11, 2008

Hello Daniel,

You have a different surface properties between bright and semi-bright nickel :
- The mechanical adhesion is more important with the semi-bright nickel due to the relief of the surface.
- The adhesion is less important with the bright nickel because the nickel surface is levelled and by the way the mechanical adhesion is bad.

This is not important with decorative chrome because the layer is very thinner and more flexible.

Nicolas

Nicolas DUTHIL
- Bordeaux, FRANCE

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July 12, 2008

It should not be a different adhesion between semi-bright and bright nickel. I think in your case that's is a problem with too much of additive (organic) in the nickel bright solution. I agree with Nicolas about the surface for the different types of nickel bath who the semi bright will show you a better adhesion, because the surface structure. But this is because the chromium adhesion is like small fish hooks in to the nickel surface in your case. Your problem is more than that. Pretreatment, activating and additive of organic in the bright nickel solution is the solution for you.

Regards,

Anders Sundman
4th Generation Surface Engineering
Consultant - Arvika,
Sweden