Satin (Pearl-Bright Nickel) Plating on the Dechromed, Bright Nickel Plated ZDC Parts
Hello, I am electroplating chief in a sanitary fitting manufacturer in Turkey. We use decorative plating on brass parts with bright nickel and decorative chromium. We have also satin (pearl bright) nickel and black (antique) nickel plating. Our plating line is suitable for only brass parts.
One of our customer want a product with satin nickel plating, but the problem is one of the part of this product is OEM , nickel - chrome plated part and made from ZDC (zinc based die cast).
We took some samples, stripped the chrome layer with NaOH under current. After de-chroming operation, we applied ultrasonic cleaning, hot degreasing, cathodic degreasing with 3A/dm2 current and acid activation with fluoride based chemical ( and also with 15% sulfuric acid instead of fluoride based acid activator) and tried to satin plating on nickel layer but we didn't get satisfied results.There were some small blisters occurred on the surface. Do you have any information about this kind of process? ! I mean, how can we activate dechromed nickel layer for another (satin) nickel layer? Thank you for your interests.KEREM TOPCU
RTEMA - Boz¸y¸k, TURKEY
Plating nickel on nickel is very complicated. Is your cathodic cleaner a cyanide one? A cathodic cyanide activation is the best way to plate nickel on nickel. But your problem might come from the stripping of the chrome layer. If your NaOH solution is highly alkaline it might attack the zinc die casting and the small blisters might be a result of this attack.
chemical process supplier
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