Letter 26211

EN won't adhere to Molybdenum

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I need electroless nickel coat on molybdenum parts. I tried several pretreatment procedures (incl. Wood's nickel strike) without success - the coats were not adherent. Please help.

Frantisek Haas
R&D engineer - Jablonec kraj, Czech republik

Molybdenum has a very tenacious oxide layer that is very difficult to remove. Its structure is extremely complex and varied. However, a description on how to electroplate onto molybdenum is given in Graham's Electroplating Engineering Handbook (most recently edited by Durney) and in Vol. 5 of the ASM Metals Handbook. I would have concerns about depositing electroless nickel onto molybdenum because of the slow rate of metal deposition, the lack of polarization and the rapid formation of molybdenum oxides. You may be better off trying to put down a protective electrolytic metal and then electroless nickel

Trevor Crichton R&D practical scientist - UK

Earl Groshart stated in the 1991 Metal Finishing Guidebook that molybdenum could be plated by the following procedure:

1. Degrease in steel soak and electrocleaners
2. Anodic treatment in 885 g/L sulfuric acid plus 720 g/L phosphoric acid at 7-8 A/dm2 for 2-3 min
3. Etch in 300 g/L potassium ferricyanide plus 100 g/L potassium hydroxide at 85 C for 1/2-1 minute
4. Strike in a standard chromium plating bath
5. Strike in chloride nickel strike The part should be rinsed between steps.

I have never tried this myself. Good luck.

Ron Duncan Palm International, Inc. - LaVergne, TN

Ed. note: It is our sad duty to alert the readers to the passing of Ron Duncan on Dec. 15, 2006. For those who would like to know more about him, a brief obituary opened Update No. 13 of our Metal Finishing Industry Update Podcast.

I am a student at a University and I am currently trying to find a way to electroplate either Nickel or Copper directly onto Molybdenum so that we can solder the plate afterwards. I have found books and articles on electroplating Nickel but they all require plating Chromium so that there is good adhesion but Chromium is not an option for me. Is there any way to plate Nickel directly onto Molybdenum with good adhesion and if not then is there any way to electroplate copper directly onto Molybdenum with good adhesion.
Thanks

Joaquin Gabriels
student - Irvine, CA, USA

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