plating, anodizing, & finishing Q&As since 1989
How to do NiB electroless plating on top of NiP electroless nickel plating
January 18, 2012
We want to obtain a double layered electroless NiP/NiB coating. We use commercial baths and when we do individual NiP and NiB coatings we have a good surface. But when I put the NiP coated sample (mild steel) in to NiB bath I get smut formation, and no NiB plating is seen on the surface.
Do you have any information about what should I do for obtaining a NiB layer on the NiP coated steel. Should I activate the surface with a chemical such as nitric acid or etc.
- Istanbul, Turkey
January 24, 2012
You said you use commercial baths. Your vendor should give you advise, he makes money with you. We won't.
Monterrey, NL, Mexico
March 10, 2012
EN phos could be contaminated with copper, or the ENB could have copper or other contaminants that cause a smut. Test for impurities (suppliers can help). Also, low reducing agent (dimethyl amineboron) in the NiB solution can cause smut.
Consultant - Poulsbo, Washington
(Don is co-author of "Plating on Plastics" [affil link to the book on: Amazon or AbeBooks ])
March 28, 2012
While depositing the Ni-B layer over Ni-P layer, formation of a passive layer on Ni-P might interfere the Ni-B coating.
A nickel strike would help solve this problem.
I did not understand what you mean by SMUT formation.
T.S.N. Sankara Narayanan
- Chennai, Tamilnadu, India
(ed.note Nov. 2017: The good doctor has a fascinating blog at https://advancementinscience.wordpress.com)