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Ted Mooney, P.E. RET
Pine Beach, NJ
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for Metal Finishing 1989-2024
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Activation of 304 stainless steel with acids
A. HCl 50%/vol cathodic 1- 2 minute, followed by Wood's or Sulfamate Nickel Strike give good adhesion. Let me know if you don't have pits issues.
Best Regards!
Plating Tech - potrero, California
July 6, 2022
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Q. Hi all
I am a master student in materials science and engineering and I am working on electroless nickel plating on stainless steel 304. I know that we can activate the surface of stainless steel for electroless nickel with Wood's strike, but why don't we just activate stainless steel with concentrated hydrochloric acid? I tried it and it works perfectly.
I used 35 % HCl for 5 minutes on the stainless steel 304 and it was activated
can I do any thing to reduce the concentration and time of activation with HCl?
I do think that wood's attack is more reliable but I have curiosity to know about HCl activation.
and what about using oxalic acid in activation process?
Wesam Kiwan
student - Damascus, Syria
November 10, 2010
A. Wesam-
You are correct. You activate the SS with hydrochloric acid. That step would be followed by a Wood's strike if you are going to perform subsequent plating. The purpose of the strike is not to activate, but to provide a base layer that will allow for better adhesion of the subsequent plating layers compared to plating directly onto activated SS. I hope this helps.
Jon Barrows, MSF, EHSSC
GOAD Company
Independence, Missouri
Q. Thanks Jon
Yes wood's attack helps to raise the adhesion of EN on substrate; it is also helps by providing activated nickel surface for EN plating. But for the activation process by acids I want to know if we can use oxalic acid for this process?
Oxalic acid is used as an etchant for metallography tests under microscope -- so can we use it for activation?
Thanks again Jon for your helpful comment
Wesam Kiwan [returning]
student - Damascus, Syria
November 17, 2010
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A. In this country, oxalic acid is far more expensive than mineral acids. It is possible that it might cause a waste treatment problem. Not much is written on the subject with that acid. James Watts- Navarre, Florida A. Hello, Wessam. I don't have experience with oxalic acid in this application and would guess that it is very uncommon. It may be suitable for you in place of the HCl to activate the metal, but it would not be a substitute for the strike plating which is necessary for adhesion of the subsequent plating layers. Good luck. Jon Barrows, MSF, EHSSC GOAD Company Independence, Missouri |
A. Although it is used in many places, it is well known that HCl is very bad to put on stainless steel of any kind. Other acids are good in general. Chlorides are very bad for stainless steel, forming ferric chloride in the intergranular boundaries.
Lee Kremer
Stellar Solutions, Inc.
McHenry, Illinois
Thank you all for your comments
- Damascus, Syria
November 29, 2010
A. Chlorides are accepted as bad for SS, but probably 99% of plated stainless steel uses a woods nickel strike which is extremely high in chlorides.
HCl is common for low nickel grades of SS.
Sulfuric with current is sometimes used. Sulfuric/nitric is sometimes used and sometimes it has ammonium bifluoride added which is safer than using hydrofluoric acid.
- Navarre, Florida
Q. What are the best polishing and surface activation conditions for 304 SST for electroplating with Ni and Co
mohamed ramadancairo university - giza, egypt
<January 12, 2016
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A. Hi mohamed ramadan, Wood's nickel strike is the accepted pretreatment for electroplating onto stainless steel; a sulfamate nickel strike or a gold strike might work, but golf doesn't sound appropriate if you're doing nickel or cobalt plating.
Luck & Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
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