Letter 40003

Electroless nickel over babbitt alloy  

++++++

I need do this electrodeposition. But I don't know if this alloy is autocatalytic respect to nickel.

L. Medeiros
brass products - Belo Horizonte, Minas Gerais, Brazil

Babbitt is an antique bearing surface, but it still has applications where it is the one of choice. IF, you EN over the top of it you are going to kill almost all of the reason for using it. Bad choice from my distant perspective.
Activating it is going to be more of a problem because of the alloy ingredients are significantly different.
The EN start is less of a problem as you can impose a negative charge on the parts for a few seconds, which should be enough to start the electroless deposition. (you will need a temporary anode, like SS). Alternative would be a short nickel strike.

James Watts
- Navarre, Florida

Babbitt metal can be anything between 90% Pb and 90% Sn, with Sb and Cu. None of these metals are catalytic to regular acid or neutral EN plating solutions and will also poison them.

However, there is an ammonicial, nickel sulfamate and pyrophosphate based solution, that operates at pH 10 and 185F that will plate directly on babbitt metal, at least as a tie coat before regular EN.

Ron Duncan Palm International, Inc. - LaVergne, TN

Ed. note: It is our sad duty to alert the readers to the passing of Ron Duncan on Dec. 15, 2006. For those who would like to know more about him, a brief obituary opened Update No. 13 of our Metal Finishing Industry Update Podcast.

You need a Nickel Strike layer prior to the EN.

Sara Michaeli     chemical process supplier Israel