plating, anodizing, & finishing Q&As since 1989
Electroless nickel plating of aluminum parts
I am working on a project in which our customer has specified the finish as being paint over electroless nickel plate.
The components are machined from aluminum alloy.
I have been told that the plating is very difficult because the nickel is much harder than the aluminum and when the parts deform the plating will fall off.
Its probably off subject, but can paint be successfully applied over electroless nickel plate?
While electroless nickel is much harder than aluminum, this has nothing to do with adhesion. While bending the aluminum will loosen any non-adherent coating, it is not the cause.
To obtain good adhesion on aluminum requires careful cleaning and pretreatment, typically including a double zincate procedure.
Treatment of the electroless nickel coating in a 30 g/L solution of potassium or sodium dichromate at 85 °C will usually provide sufficient adhesion of the paint to the coating. Without such a treatment, the paint will normally peel out easily.
Ron Duncan [deceased]
- LaVergne, Tennessee
It is our sad duty to note Ron's passing on Dec. 15, 2006. A brief obituary opens Episode 13 of our Podcast.
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