Metal Finishing Guide Book


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Page 87 of 843

2. Acid dip in either of the following solutions: A. 66% v/v of 42OBé nitric acid at 75-160OF (24-71OC). B. 88% v/v of 66OBé sulfuric acid, 75-90OF (2432OC). C. 22% v/v of 42OBé nitric acid at 75-90OF (24-32OC). Titanium 1. Alkaline soak clean. 2. Acid treatment in solution consisting of 40% v/v of 42OBé nitric acid and 2-3% v/v of 75% hydrofluoric acid, at 120-135OF (52-57OC). Zinc and Zinc Alloys Comprehensive information describing zinc alloys, castings, and suggested acid baths is described in the chapter titled "Surface Preparation of Various Metal Alloys Before Plating and Other Finishing Applications." Activation of Bright Nickel Electroplate There are two effective acid solutions for activating passive nickel deposits and to salvage reject parts. Their application is recommended for sulfur bearing electrolytic nickel deposits. The immersion dip consists of 5 to 10% v/v sulfuric acid and 2 to 4 oz/gal of potassium iodide at 75 to 90OF (24-32OC), 1 to 5 minutes or as required. A cathodic activation of nickel consists of 5 to 11% v/v sulfuric acid, 1 to 3 oz/gal fluoride, 2 to 4 oz/gal chloride at 5 to 7 V for 1 to 2 minutes (as required) at 20 to 40 A/ft2 and 75 to 120OF (24-49OC). 84

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