Contamination limits for Woods Nickel Strike
A discussion started in 2010 but continuing through 2018March 24, 2010
A. I would like to know if anyone has established metal contaminant limits for a typical woods nickel activating bath?John Tinder
plating shop employee - Milwaukee, Wisconsin, USA
March 25, 2010
A. I will not comment on "metallic contaminants" but I will state that the statistically most frequent problem is that platers do not understand that leaving S-rounds soaking all weekend (when they should be using [and removing] Rolled Depolarized) increases the nickel metal content and changes the strike from an inefficient "strike" to an efficient plating solution that does not bond.
Robert H Probert
Robert H Probert Technical Services
Garner, North Carolina
Editor's note: Mr. Probert is the author of Aluminum How-To / Aluminio El Como
and co-author of The Sulfamate Nickel How-To Guide
March 25, 2010
Q. The main thing to watch in your Wood's bath is copper. You don't want more than 80 ppm or you will start to develop adhesion problems.
Fe contamination in Woods NickelNovember 15, 2018
Q. We have been experiencing a low fail rate adhesion issue (blistering after 30 minute dwell at 300 °C) on S303 parts that are barrel plated through a Au/Ni process with Wood's strike. Our chemistry seems to be in spec with what everyone has recommended over the forum but we do have a significant level of Fe in the bath, at this point it is over 1000 ppm. Would codeposition of Fe in the Ni cause stress leading to adhesion problems? What are the standard levels of acceptability for Fe in Woods?
- Massachusetts, USA
A. Hi Tim. I'm not aware of any textbook information on that subject, but 1000 ppm sounds like a huge amount of iron contamination even for standard nickel plating, let alone a Wood's nickel strike. I can't swear that iron contamination is the cause of your adhesion or stress problem, but I do note that in Durney's troubleshooting text "Trouble in Your Tank", right after "Don't Panic" and "Identify the Problem" is his third whole chapter entitled "Obey the Letter of the Law". 1000 ppm Fe is surely nowhere near right; don't talk yourself into accepting it :-)
It seems that there are two likely causes, operating with a partially anodic cycle (which is suggested in some text books, but which some knowledgable writers question), or parts falling off the rack and dissolving. Or is there another explanation for this high amount of iron?
Ted Mooney, P.E. RET
Pine Beach, New Jersey
Striving to live "Aloha"
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