Metal Finishing Guide Book

2011-2012 Surface Finishing Guidebook

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

Contents of this Issue

Navigation

Page 199 of 707

Table I. General Purpose Copper Cyanide Strike Potassium Copper cyanide Total potassium cyanide Total sodium cyanide Potassium hydroxide Sodium hydroxide Potassium carbonate Sodium carbonate Rochelle salt Free potassium cyanide by analysis Free sodium cyanide by analysis Temperature Current density Time Cathode efficiency Recommended agitation 30.0 g/L (4.0 oz/gal) 58.5 g/L (7.8 oz/gal) — 3.75-7.5 g/L (0.5-1.0 oz/gal) — 15.0 g/L (2.0 oz/gal) — 30.0 g/L (4.0 oz/gal) 11.25-15.0 g/L (1.5-2.0 oz/gal) — 24-66° 0.5-4 A/dm2 Sodium 30.0 g/L (4.0 oz/gal) — 48.0 g/L (6.4 oz/gal) — 3.75-7.5 g/L (0.5-1.0 oz/gal) — 15.0 g/L (2.0 oz/gal) 30.0 g/L (4.0 oz/gal) — C (75-140° 11.25-15.0 g/L (1.5-2.0 oz/gal) F) (5-40A/ft2 ) 30 sec to 2 min or until fully covered 30-60% None or mechanical Strike-Plate Bath The strike-plate bath (see Table II) is the one most used for the plating of zincated aluminum. It is also used for zinc die castings and other metals that are subject to attack by subsequent plating baths or finishing operations that require more than a strike deposit for protection. This formulation eliminates the need for two baths—a strike followed by a plate in a high efficiency bath. Deposits range from 3.0 to 5.0 µm (0.12-0.20 mil) in thickness for the parameters given in the formu- lation. High-Efficiency Bath The high-efficiency bath (see Table III) is used when a rapid buildup of a sig- Table II. Copper Cyanide Strike-Plate Bath Potassium Copper cyanide Total potassium cyanide Total sodium cyanide Potassium carbonate Sodium carbonate Rochelle salt Free potassium cyanide by analysis Free sodium cyanide by analysis pH Temperature Current density and time Cathode efficiency Recommended agitation 42.0 g/L (5.6 oz/gal) 66.6 g/L (8.9 oz/gal) — 30.0 g/L (4.0 oz/gal) — 60.0 g/L (8.0 oz/gal) 5.7 g/L (0.8 oz/gal) — 10.2-10.5 40-55° C (100-130° Initial (strike) 2.5-3.0 A/dm2 Final (plate)1.0-1.5 A/dm2 for 3-5 minutes. 30-50% None or mechanical Use diluted tartaric acid or acetic acid to lower the pH; hydroxide to raise it. 198 F) (25.0-30.0 A/ft2 (10.0-15.0A/ft2 ) for 2 min. ) Sodium 42.0 g/L (5.6 oz/gal) — 51.9 g/L (6.9 oz/gal) — 30.0 g/L (4.0 oz/gal) 60.0 g/L (8.0 oz/gal) — 5.7 g/L (0.8 oz/gal)

Articles in this issue

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