Letter 20100

Anodic Passivation on Electroless Nickel Stainless Steel Tanks  

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Hi,

Does anyone know how the anodic passivation on Electroless Nickel (EN) bath with stainless steel tank work? What parameters should be considered? How to control it to prevent the EN bath plated out early?

I have some inconsistent results with the anodic passivation system on EN stainless steel tanks. The tanks were somtimes lasted to 8 metal turn-over (MT) without plating out (I dump the bath when it reaches 8 MT). Sometimes, the tanks were plated out within one day of using (about one MT).

The stainless steel tank has 4 cathode rods at 4 corners of the tank, which are connected to the negative post on rectifier, and the tank is connected to the positive post of rectifier (tank is made as anode). The voltage from the rectifier is controlled between 0.6 to 0.9 volts. The pH of EN baths are kept about 4.7 to 5.1 and temperature is kept about 185 to 205 oF.

I appreciate any input on this topic.

Thanks,

Dai Bac
- Oaklawn, IL, USA

Did you make this unit yourself, Mr. Bac, or did you buy it from Atotech or Palm International or another electroless nickel specialist? The commercial units come with instructions, and you should be able to get some from one of these two vendors.

Ted Mooney, P.E.  finishing.com Brick, New Jersey

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