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Passivation of electroless nickel -- theory and practice

WE ARE AN ELECTROLESS NICKEL SHOP, EXPANDING PLATING CAPABILITY AND USING BIGGER EQUIPMENT.THAT'S WHY WE ARE LOOKING FOR INFO ON PASSIVATION THEORY AND APPLICATIONS ON E-Ni PROCESS. THANKS FOR YOUR HELP.

EDUARDO FIDEL LINENBERG
MAINTENANCE - BUENOS AIRES, ARGENTINA
November 26, 2008

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Passivation theory is simple. Electroless nickel, as well as many other alloys composed of, or containing nickel, chrome and other less common metals, when exposed to air or oxidizing media tend to oxidize very fast forming a thin, invisible but tenacious layer which is helpful to extend the coating's resistance in some environments. It also prevents further adherent deposits.
Practice may vary from very simple to highly specialized depending on what you want. If you need to produce a passive layer you may bake the plated parts in an oven that has an oxidizing atmosphere or immerse them in a diluted oxidizing acid, or just to let them dry for a time. If you need to prevent the passivity to plate something else on top, make sure the fresh EN plated surface does not become dry. If you cannot do this, you will first need to eliminate the passive layer in an acidic bath known as Woods. Good luck (Buena suerte)

Guillermo Marrufo
Monterrey, NL, Mexico
December 1, 2008