Letter 41040

A couple of questions about Woods Nickel Strike  

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1. What is the best ratio of anode and cathode surface in Woods nickel strike tank in order to reduce consumption of nickel?
2. When dummying the solution, can we use insoluable anode (such as Ti or carbon) to save some nickel?

Thanks

Yong

Yongzhong Liao
Aerospace Metal Finishing - Ontario, Canada

In a Woods bath nickel concentration and pH will tend to rise do to the extremely low (and desirable) eficiency of this bath. This means that far more hydrogen ions than nickel ions are reduced onto the cathode surface. On the anode, the situation is the opposite. More nickel ions are dissolved than required. Hydrogen ions need to be replenished by additions of HCl. Use a 1:1 ratio. Now, if you dummy with insoluable cathode, evolution of dangerous chlorine gas to the ambient results.

Guillermo Marrufo
Monterrey, NL, Mexico

The best ratio I have found is a 3:1 anode to cathode. In plating the rule of thumb is a minimum of 2:1. Carbon anodes are cheaper than Ti but you will generate some chlorine at the anode. In dummy plating you are still going to plate out Ni whether it be from the solution (Ni chloride) or from the anode. In a woods Ni strike the Ni metal concentration increases in the bath over time when Ni anodes are used anyway. If you want to dummy plate to remove excess Ni, insoluble anodes would make sense. If you just want to try to remove unwanted metallics and your Ni chloride is in range, using insoluble anodes would mean analyzing and adjusting the Ni metal after each dummy plate. If you figure labor time switching out anodes, analysis, adds, are you really saving money?
Regards,

Mark Baker
Process Engineer - Syracuse, New York

Thank you all for the information and suggestion.

Yongzhong Liao
- Schomberg, ON, Canada

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