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Rust on Electroless Nickel Coated Motors

I have a hydraulic motor which is electroless nickel coated. The coating thickness is about .0015". I was trying to make sure that the motor does not get rusted by having it going through a Salt spray test. To my surprise I found out that 65% of my motor has been rusted. I am just wondering if my coating thickness is not good enough or if I have to use a different coating to prevent it from having rusted.
I would appreciate any suggestions.

Santosh K. Mukka
Hydraulics - Hopkinsville, Kentucky, USA
2006

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Hello Santosh,
A high phos Ni with phosphorus content between 9-11% at a thickness of .0015 should pass 1000 hours of salt spray. The higher the Phos content, the better corrosion resistance the coating gives. Good Luck!

Mark Baker
process engineer - Malone, New York
2006

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2006

Assuming that your plater properly cleaned the steel before plating, your problem is probably pores and defects in the steel that are producing pores in the EN coating. EN will only produce perfect coatings on perfect substrates.

An alternative is that the plating bath is quite old or contaminated.

Ron Duncan [deceased]
- LaVergne, Tennessee
It is our sad duty to note Ron's passing on Dec. 15, 2006. A brief obituary opens Episode 13 of our Podcast.