Metal finishing Q&As since 1989

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Are chromates a poison to an Electroless Nickel bath?

2007

Hi everyone,

Does anyone over here may know what are the principal poisons for electroless nickel baths?
Someone in my company had the bad idea to introduce an electroless nickel bath in the middle of an alkaline zinc plating line which has as well many chromating baths (which contain nitric acid) and many other pickling baths (hydrochloric).

>From my own experience and chemist training, any electroless bath is very sensitive to anything and I wouldn't be surprised that chromates would be a serious poison to any nickel electroless bath since they are strong oxidants. Anyone could confirm my claims? I really suspect that drag-out from pickling and chromates baths may have contaminated (and even killed) that Ni-P electroless bath.


A fast answer would be greatly appreciated.

Daniel Picard
Chief Chemist - Montreal

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Not sure about chromates, but nitrates and silicates are well-known EN poisons � pages 104-5 in "Electroless Plating", Mallory & Hajdu (eds) [on eBay , Amazon, or AbeBooks] . Keep nitric acid solutions and rinses as far away as possible. Nitrate test strips (paper) are available from lab suppliers.

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.
2007

Conventional electroless nickel baths can become contaminated by chrome supposedly. Never had a problem with chrome contamination with conventional electroless nickel baths and we do hard chrome and EN plating. The newer lead free/ cad free electroless nickel baths SEEM to be very sensitive to contamination from chrome compounds.

Todd Osmolski
- Charlotte, North Carolina, USA
2007

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2007

Thanks for your answers Todd and Ken,


Acutally, the concerned bath is a Lead/Cadmium free bath to comply with some ROHS specs.

Usually, acidic chromates are poisons to virtually almost any chemical processes (strong oxidant, oxidize almost anything from dirt to metals). So strong that we used to use it to clean up glassware while I was still a chemistry student, hehehe. However, I was wondering to which extent chromates would spoil that electroless bath.

Anyway, at the light of your answers, and experience, it seems it could explains why that bath is now just good for waste.


Cheers!

Daniel Picard
- Montreal