Summary for nib on nip plating Discussion
NiB electroless plating on NiP electroless nickel can fail with smut and no deposit even when each bath works separately. Sinem Eraslan asked whether the NiP-coated mild steel should be chemically activated, such as with nitric acid, before entering the NiB bath. Guillermo Marrufo replied that the bath vendor should be the first source of advice because they know the commercial chemistry. T.S.N. Sankara Narayanan added a more technical possibility: the NiP layer may be contaminated with copper, or the NiB bath may contain copper or other impurities that trigger smut. He also noted that too little reducing agent, dimethyl amineboron, in the NiB solution can cause the same problem. The thread therefore points to contamination checks and bath chemistry review rather than a simple universal activation step.
Q. Hi,
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.
Sinem Eraslan
– Istanbul, Turkey
January 18, 2012
You said you use commercial baths. Your vendor should give you advise, he makes money with you. We won’t.
G. Marrufo-Mexico
Guillermo Marrufo
Monterrey, NL, Mexico
January 24, 2012
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.
Don Baudrand
Consultant – Poulsbo, Washington
(Don is co-author of “Plating on Plastics”
and “Plating ABS Plastics” eBay
or
AbeBooks
affil links])
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: The good doctor offers a fascinating blog, “Advancement in Science” )
March 28, 2012
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