Metal finishing Q&As since 1989

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Discoloration of Electroless Nickel on Powdered Iron

2006

I have a part that's using Powder Iron (MPIF F-00/F-0000) as the base material and has a Electroless Nickel plating of 7-10 microns (0.275 - 0.393 mils). I've found that the surface of the plating get discolored.

The iron base is needed for magnetic purpose.

Any idea why this is happening and is there anyway to prevent it?

Patrick Oon
Electronic Mfg - Georgetown, Penang, Malaysia

Discoloration may originate from the inside (lack of good preplate and postplate steps, excessive base material porosity or contamination with other metal powders) or the outside (something in the environment). Do you have other parts plated similarly not made form powder that do not discolor?

Guillermo Marrufo
Monterrey, NL, Mexico
2006

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I have other similar parts which are using the same iron powder and same plating but does not show the discoloration.

What would be the main suspect? I've tried cleaning the surface of the discoloration also but there's no effect. There is no peeling of the plating nor any signs of corrosion on or beneath the plating.

Patrick Oon
- Georgetown, Penang, Malaysia
2006

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2006

I have a part that's using Powder Iron (MPIF F-00/F-0000) as the base material and has a Electroless Nickel plating of 7-10 microns (0.275 - 0.393 mils). I've found that the surface of the plating get discolored.

The iron base is needed for magnetic purpose.

Any idea why this is happening and is there anyway to prevent it?

Patrick Oon
Electronic Mfg - Georgetown, Penang, Malaysia


Discoloration may originate from the inside (lack of good preplate and postplate steps, excessive base material porosity or contamination with other metal powders) or the outside (something in the environment). Do you have other parts plated similarly not made form powder that do not discolor?

Guillermo Marrufo


I do agree with Guillermo Marrufo.

The surface area of iron powder is very high and it is highly reactive. It might have been oxidized.

We have coated iron powder by electroless plating. We have not experienced any sort of problem of discolouration.

Coating of iron powders using electroless plating can be used to prevent the oxidation of iron powders. However, you have to optimize the coating thickness so that it would not affect the magnetic property.

What pretreatment you have adopted before electroless plating?

Store your iron powder properly.

T.S.N. Sankara Narayanan
- Chennai, Tamilnadu, India
(ed.note Nov. 2017: The good doctor has a fascinating blog at https://advancementinscience.wordpress.com)