I need some help on a problem - I have been attempting to do some electroless nickel plating and have come across several problems that I have overcome except one. When I submerge the substrate in the solution for approximately ten minutes the underside of the substrate nickel plates without any defects but the top turns a blotchy black in appearance and does not seem to adhere to the substrate very well.
Could you please help with this problem?John Cochrane
- Eden, New South Wales, Australia
First of two simultaneous responses -- 2001
Could be several things. First I would check for floating oil in your cleaners, rinses and acids. It also could be a bath problem with too much lead, cadmium or sulphur due to improper make up, manufacture, plating of leaded metals or drag in of sulphur containing oils.Todd Osmolski
- Charlotte, North Carolina, USA
Second of two simultaneous responses -- 2001
To solve this more information is needed,
Substrate material and pretreatments.
Temperature of nickel and if it is home brew or off the shelf.
The one thing it sounds like is a stabiliser problem but I have never seen one that just affects one area of a part.
surface treatment shop - Stroud, Glos, England
If only the top side of your part is coming out rough and dark, it means that, apart from substrates, pretreatments, etc., your problem must be "suspended particles". The most probable causes are excessive activity due to improper balance (the particles are spontaneous precipitated nickel) and improper filtration (any particle will accelerate reaction). Stabilize your reaction or lower it a little (temp, pH, load, you know) and improve filtration. Your supplier should help you. Even if you're using a home brew formula, the companies that sell the hypo normally can help.
Good luck.Guillermo Marrufo
Monterrey, NL, Mexico
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