Metal Finishing Guide Book

2011-2012 Surface Finishing Guidebook

Issue link: https://metalfinishing.epubxp.com/i/49721

Contents of this Issue

Navigation

Page 119 of 707

ammonium bifluoride, 75-90O or Chromic acid containing solution consisting of: 44-48 oz/gal chromic acid, 3- 4 oz/gal sodium nitrate, 1.5 oz/gal sodium chloride, 0.1 oz/gal sodium sulfate, 65-90O F (18-32O C). Nickel and Cobalt Alloys 1. Alkaline soak clean. 2. Cathodically condition in a highly conductive electrocleaner blended for steel. 3. Acid dip in a solution consisting of 50% v/v of 70% hydrofluoric acid and 7% v/v of 42O Bé nitric acid at 75-90O Silver and Silver Alloys 1. Alkaline soak clean. 2. Acid dip in either of the following solutions: A. 66% v/v of 42O acid at 75-160O (24-32O F (24-71O Titanium 1. Alkaline soak clean. 2. Acid treatment in solution consisting of 40% v/v of 42O 2-3% v/v of 75% hydrofluoric acid, at 120-135O F (52-57O Bé nitric acid and C). 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 90O F (24-32O and 75 to 120O F (24-49O C). C), 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 C). B. 88% v/v of 66O C). C. 22% v/v of 42O Bé nitric acid at 75-90O Bé sulfuric acid, 75-90O F (24-32O C). Bé nitric F F (24-32O C). F (24-32O C). 118

Articles in this issue

view archives of Metal Finishing Guide Book - 2011-2012 Surface Finishing Guidebook