Metal Finishing Guide Book

2013

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325 2.0–4.0 Zinc Metal1 Nonammonium or all-potassium chloride 1.0–1.5 1.8–2.5 3.5–4.5 10.0–12.0 10.0–12.0 10.0–12.0 10.0–14.0 16.0–20.0 Sodium Hydroxide2 1.5–2.5 3.5–6.0 11.0–14.0 Sodium Cyanide 1 All figures in oz/gal. Conversion to metric: oz/gal 7.49 = g/L Zinc metal source: Acid chloride zinc—zinc chloride. Alkaline non-cyanide zinc—zinc oxide (preferably nonleaded). Cyanide zinc—zinc oxide or zinc cyanide. 2 Sodium hydroxide source: mercury cell grade or rayon grade. 3 Ammonium and potassium chloride source: untreated is preferred. 4 Boric acid source: granular preferred, as powdered form creates a dusting problem. Low cyanide Mid cyanide High cyanide Cyanide Zinc: Low chemistry High chemistry 0.8–1.2 1.8–3.0 3.0–5.0 Low ammonium potassium chloride Alkaline Non-cyanide Zinc: 2.0–4.0 All ammonium chloride Acid Chloride Zinc: Table I. Bath Composition 4.0–6.0 16.0–20.0 Ammonium Chloride3 25.0–30.0 16.0–20.0 Potassium Chloride4 3.0–5.0 Boric Acidd 5.0–5.5 5.0–6.0 5.0–6.0 pH

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