Summary for nickel hydroxide deposition Discussion
Nickel hydroxide is depositing with my nickel plating, and the thread suggests the problem is likely a pH issue rather than normal nickel deposition. Chandrashekhar Pendyala asked why a green deposit appeared on the cathode during basic electroplating rate studies with two nickel plates in 0.1N nickel sulfate at 7 mA/cm2. Trevor Crichton said this is not a normal situation and suspected the pH was rising; he advised measuring it and lowering it to 4.0 if it is above 4.5, using sulfuric acid, and considering boric acid as a buffer to keep it stable. He also noted, with some humor, that the lab partner may have reversed the polarity. The practical takeaway is to control bath acidity carefully before expecting clean metal deposition.
Q. I am trying to do basic electroplating rate studies using 2 nickel plates. Initially I used 0.1N nickel sulphate solution allowing7 mA/cm2 current through the system. I see green deposit on the cathode and I think its nickel hydroxide. Is there a way to prevent this and allow metal deposition only?
Chandrashekhar Pendyala
student – Cleveland, Ohio
2004
A. This is not a normal situation, and I’m not sure exactly what’s wrong, but I suspect the pH may be rising. You should measure it, and lower it to 4.0 if it is over 4.5. Use sulfuric acid, and consider the addition of boric acid as a buffer to hold it stable.
Another possibility is that your lab partner reversed the polarity :-)
Ted Mooney, P.E.
Striving to live Aloha
finishing.com – Pine Beach, New Jersey
Need quick confidential answers? $25
Need project assistance? $100/hr.
2004
A. If you only used a solution of nickel sulphate I am not surprised you didn’t get any metallic deposit. It sounds as if your pH is too high, but without knowing the bath composition, no-one can tell. Please give more detail of your bath composition, pH, temperature etc.
Trevor Crichton
R&D practical scientist
Chesham, Bucks, UK
2004