Metal finishing Q&As since 1989



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Avoiding electroplated gold diffusion into nickel at 700° C

March 18, 2011

Hi all,

Many times in the past have my questions been answered by experts and amateurs alike here in finishing.com.
I'm doing some research on DCFC/MCFC. We are using nickel as our electrodes. To collect current, we are currently using gold wire that is spot welded onto the electrodes.

In hopes of reducing fabrication costs (when industrialised) we are looking towards electroplating gold "strips", at the same locations as the gold wire used to be.
This can be done through immersion or brush plating.

My question is that I've notice when heating the Nickel up to 700° C (In order to oxidize nickel to nickel oxide (NiO) ) the gold seems to "diffuse" into the nickel oxide, as the gold strip previously visible is no longer gold, but rather a darker shade of NiO.

I know it is commercial practise to use a nickel barrier when plating gold onto copper. however I am wondering if there are any other metals that offer better resistance to gold diffusion, and that would be able to sustain high temperatures (700° C)

Thanks!

Michael Leung
University Student, working on co-op as Reasearch Scientist - Waterloo, ON, Canada

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It seems that it is more likely that the gold is diffusing through porosity in the nickel layer, than diffusing into the nickel.

Lyle Kirman

Lyle Kirman
consultant - Cleveland Heights, Ohio
March 21, 2011