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Chromate Conversion vs. Electroless Nickel Plating

Hello, I am a new mechanical engineer for a power electronics company and one of my first project is to investigate alternative coatings for an aluminum casing that cases our power converters. We currently have tested Alodined coated finishes, but are having handling issues with the Alodine being scratched and rubbed off through one of our processes.

Our product will require properties with low resistance, high hardness, high wear resistance, and high corrosion resistance.

So I have been looking into Electroless Nickel Plating which seems to have similar properties with chromate conversions (depending on phosphorous levels)

Would EN make a good alternative? Thanks

Regards,

Phu Bui
power electronics - Worcester, Massachusetts
2006

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First of two simultaneous responses --

To my mind, electroless nickel plating is rather dissimilar to chromate conversion coating. More expensive, too.

Chromate, mask over electrical contact areas, either powder coat or anodize, and then unmask. Choice of colors, too.

Ken Vlach [deceased]
- Goleta, California
Finishing.com honored Ken for his countless carefully researched responses. He passed away May 14, 2015.
Rest in peace, Ken. Thank you for your hard work which the finishing world, and we at finishing.com, continue to benefit from.
2006

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Second of two simultaneous responses --

"Our product will require properties with low resistance, high hardness, high wear resistance, and high corrosion resistance". This seems to be a direct pointing to electroless nickel, much more than your current conversion coat that which is somewhat high in resistance and low on hardness and wear.

Guillermo Marrufo
Monterrey, NL, Mexico
2006

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Electroless Nickel however oxidizes, unlike Chromate Conversion. Is this true?

If so, anyway to keep the nickel from oxidizing?

Phu Bui
power electronics - Worcester, Massachusetts
2006

Only precious metals (gold, platinum, iridium, etc.), do not oxidize or react with most anything and behave much like a noble gas. Other like zinc, iron and steel, never stop reacting and thus the oxide keeps growing. Other form very stable and protective layers of oxide (nickel, chrome and aluminum are good examples). Chromate protects by a different mechanism in which a layer of oxidized hexavalent chromium salts are formed on top of a metal protecting it like a paint.

Guillermo Marrufo
Monterrey, NL, Mexico
2006