Nickel Coating is Brittle

The facility you are working at was plating 27% nickel with indefinite bath life 20 years ago. I know because I ran the operation then. Apparently personnel changes have caused the procedure to be lost. Make sure you have enough anode area and keep the operating temperature down. The problem isn't ammonia, it is sulphate from sulfamate decomposition.

A. You do not say what your pH is or how hard it is to control. My guess is that you do not have enough anode area or it is passivating. High speed requires extreme agitation, how is yours?

A. Hi Kurt,
You share a problem that many high speed Ni Sulfamate platers have in common. The secret I have found is to reach the proper halogen level (chloride). It's really a catch 22 because too much chloride can raise tensile stress, and too little polarizes the anode, causing ammonia to form. The formation of ammonia in the bath will make the deposit brittle. You are using sulfurized anodes, so the low concentration of Ni chloride seems to be the norm. I know of a few high speed plating customers that went to magnesium chloride for a halogen. It is less likely to increase tensile stress, and it can be maintained at a slightly higher level than Ni chloride helping with anode corrosion. You could check with your supplier to see if they concur on using magnesium chloride, or maybe they would suggest raising the Ni chloride a little bit in the bath. Also consider the use of a stress reducer. Good Luck!

A. I'll bet you have more than 600 ppm ammonia. ammonia causes brittleness and is caused by, high anode current density, low pH, high current density, high temperature and 140 is worse 5than 120 F, and sulfamic acid that contains ammonia to start with. Do a distillation on the incoming sulfamic acid. It is very difficult to find ammonia free sulfamic acid on the open commercial market. Also, your chloride is too high.

A. pH 3.6 - 4.0, Temperature 105 °F, 1.5 oz/gal nickel bromide, no chloride.

A. S-Rounds are far better for sulfamate than rolled depolarized because they dissolve with less current and hence make less ammonia. Your pH is too low, low pH makes ammonia, let it rise to 4.0 and hold 3.9 to 4.2. High temp also makes ammonia, try to run at 120 F. High anode current density makes ammonia.

A. I have studied it but never ran a high speed sulfamate bath, only conventional and brush. Also, you already have good and educated answers. But in my opinion you should have your defective plated wire analyzed by a a well equipped and professional lab, not just the bath. There are too many things that can go wrong and raise the stress, from operating conditions to dragged in or by-product substances. Fortunately, most will leave a track to follow in the plating. Good luck.