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MAKING MS PASSIVE WHILE DOING HIGH PHOSPHOROUS ENP

WE ARE SUPPOSED TO PLATE A COMPONENT WHICH HAS A MILD STEEL SHELL WITH STAINLESS STEEL PINS. WE ARE TO PLATE THE MS SHELL WITH HIGH PHOSPHOROUS ELECTROLESS NICKEL WITHOUT PLATING THE STAINLESS STEEL PINS. NOW WE WOULD LIKE YOU TO SUGGEST US AS TO HOW TO MAKE THESE PINS PASSIVE. MASKING NOT POSSIBLE AS THE PINS ARE 1 MM * 3 MM IN SIZE, AND THE QUANTITIES ARE 800,000 NOS PER MONTH PLEASE SUGGEST US AN EASY METHOD TO MAKE THE SS PINS PASSIVE.

SUSHANTH JAYANNA
- MYSORE, KARANATAKA, INDIA
2005

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2005

You may make the pins passive, but they will still plate along with the plain steel. The coating just will not be adherent.

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.

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Dear Sushant Jayantha,

I agree with Ron Duncan.

Adherence of electroless Ni-P coating on stainless steel is generally poor. So, If you passivate the stainless steel pins (nitric acid - one option) and coat the component, the adherence of electroless Ni-P coating on the stainless steel pins will be poor so that the coating on the pins can be removed easily after plating.

If you could have provide a photograph of the component, you might get some more suggestions from experts.

T.S.N. Sankara Narayanan
- Chennai, Tamilnadu, India
(ed.note Nov. 2017: The good doctor has a fascinating blog at https://advancementinscience.wordpress.com)
2005

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At our local AESF meeting Tuesday night, we had a presentation on the new lead-free and cad-free MID-phos ENs. The very knowledgable lecturer claimed that passivated stainless steel is not catalytic to them. Can't promise that he's right or that it extends to high-phosphorous, but he did say that passivated stainless doesn't catalyze them and there will be no deposit on stainless.

So maybe switching to lead-free cad-free EN will answer all your problems.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2005