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topic 7103

Electroless Nickel Plating Anodic Protection Problem


(2001)

We are doing Electroless Nickel Plating on Aluminium with a few SS Cathodes for anodic protection. Seems like some tanks are worse than others in terms of plate out. Appreciate any help in these matters.

1. Some times when the anodic current goes up, when we check there is no plate out in the tanks nor at the cathode. Any idea why?

2. When the current goes up, if we increase the flow rate of the nickel in the tank, the current decreases again. Why please?

3. As I'm new to this, could anybody enlighten me what's the difference between tank stripping and passivation. We put in the tank Nitric acid for 12 hours after about every 3 days of plating. If there is a difference, how to passivate?

4. Why only some tanks gives this anodic problem while others don't?

Any help is greatly appreciated. Thanks.

Kalaiarasan K
- Bayan Baru, Penang, Malaysia


(2001)

PASSIVATION IS A TERM APPLIED TO SURFACES WHICH ON THE CONTRARY COULD BE ACTIVE, LIKE METALS. IF YOUR TANKS ARE MADE OF THE SUITABLE PLASTICS (E.G. POLYPROPILENE, KYNAR, ETC.) YOU WILL STRIP THEM, NOT PASSIVATE THEM, AS PLASTICS ARE BASICALY INNERT TO E-N CATALISYS.

WHEN VERY FINE PARTICULATE ADHERES TO THE SURFACE OF PLASTICS WE USE THE TERM SEEDING WHICH IS NOT EXACTLY ACTIVATING BUT IMPLANTING METAL PARTICLES THAT COULD BE ACTIVE AND INITIATE REACTION.

WHY SOME TANKS REACT AND OTHERS DO NOT COULD BE RELATED TO DIFFERENT ACTIVITY IN THEIR SOLUTION, PRESENCE OF MAGNETIC EQUIPMENT NEAR THE TANK, HOT SPOTS, AND A NUMBER OF THINGS THAT WOULD BE IMPOSSIBLE TO DEAL WITH THRU THIS VIA.

GOOD LUCK.

Guillermo Marrufo
Monterrey, NL, Mexico



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