Letter 33078

Copper stripper  

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I am looking for chemical or chemicals to strip 1 microns of copper plating from a nickel alloy material (Ni(70%), C(0.05),Si (0.15%), Mo (4.0%)) without affecting or etching the surface. I do not wish to use cyanide or a cyanide based chemical. Please recommend me the best way to solve this problem.

Fong

Fong Lean Guik
- Singapore

Immersion in ammonium hydroxide (ammonia water) will dissolve copper in short time and will not affect the nickel alloy. Odor is very strong and irritant and disposal must be done in accordance with your local laws.

Guillermo Marrufo
Monterrey, NL, Mexico

Mr. Marrufo,

Seems like it doesn't strip the copper plating even using 28% concentrated ammonia water (without adding addition water). Any other ways to strip copper on nickel alloy without using cyanide.

Thanks

Fong Lean Guik
- Singapore

Try adding about 2-4% of 35% hydrogen peroxide.

Jeffrey Holmes, CEF - Spartanburg, SC, USA

One micron of copper should be no problem to ammonia (should remove it in less than one hour). If it is not working then it is not copper or has something else on top of it. Another possibility is to use anodic treatment part is (+) stainless steel is (-), 6 volts and 30% alkali in water (sodium or potassium hydroxide) but again this may not work if ammonium didn't.

Guillermo Marrufo
Monterrey, NL, Mexico

You can use 150 gm sodium sulphide/15 gm sulphur/1 lit water solution (20 C temp.)!

Good luck!

Goran Budija
- Zagreb, Croatia

Sodium or Ammonium persulfate will work very well.

Lee Kremer Stellar Solutions, Inc. McHenry, Illinois

Your supplier can suggest a safe copper stripper. Or as Mr. Lee mentioned you can use persulphate as it ethcs copper. Or you can also go for mild hydrochloric acid with ferric chloride for slow stripping, but be careful since it is highly corrosive mixture.

Shafiuddin A. Mohammed      metal coating shop - Dubai, UAE