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Boric Acid Depletion in Sulphamate Nickel Electroplating

 

We are currently using a Sulphamate Nickel bath as a corrosion preventative underlay for Cr. Although, we are only processing a small amount of work through the bath, our chemical analysis shows that the Boric Acid content is depleting at a greater rate than the baths other constituents. At present, we are unable to find any technical literature to explain this phenomena. The baths constituents are Nickel Sulphamate, Boric Acid & Nickel Chloride. The Baths capacity is 550 liters and is kept at a temperature of 46 - 54 °C and is air agitated.

Steve Manolitsis
Boeing, Hawker de Havilland - Melbourne, Victoria, Australia

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Many nickel baths operate near the saturation point of boric acid and the solubility of boric acid is extremely temperature-dependent. If the bath is cooled down during weekends, some of the boric acid may be crystalizing and removed in your filters. If the filters are also changed on weekends this may explain the mysterious disappearance.

Lyle Kirman
- Newbury, Ohio