Metal Finishing Guide Book

2011-2012 Surface Finishing Guidebook

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mizing hydrogen embrittlement. Stainless steels may be passivated as follows: 40% v/v of 42O 25% v/v of 42O Bé nitric acid at 75-145O F (24-63O Aqueous solutions of citric acid at 120 to 140O C). Bé nitric acid, 6 oz/gal of molybdic acid at 70-150O F (49-60O F (21-66O C). C) may also be eval- uated. Note: Comprehensive information describing electropolishing (the anodic brightening and descaling of metals) and use of the Wood's nickel strike are in the chapter titled "Surface Preparation of Various Metal Alloys Before Plating and Other Finishing Applications." ACID TREATMENT OF OTHER METALS AND ALLOYS Aluminum Bright Dipping 1. Nonetch aluminum soak cleaner. 2. Chemically polish in a special acid solution consisting of: 94% v/v of 85% phosphoric acid and 6% v/v of 42O Bé nitric acid at 180-185O until desired surface polishing is achieved. Descaling 1. Nonetch aluminum soak cleaner. 2. 3-5% sulfuric acid or phos- phoric acid dip. Neutralizes and conditions the surface. 3. Chemically polish in 15- 20% v/v sulfuric acid and 30-40% by wt. of ferric sul- fate at 100-140O F (38-60O C). Solution is wetted and spe- cially inhibited. 4. Tarnish inhibit in dip appli- cation using a soap (mechanical tarnish inhibit film) or apply on organic topcoat such as a lacquer. Conditioning for Plating Note: Comprehensive informa- tion describing aluminum alloys, castings, and suggested deoxidizer/desmutting baths is described in the chapter titled, "Surface Preparation of Various Metal Alloys Before Plating and Other Finishing Applications." F (82-85O ), AMBIENOL® C • Acid additive for scale, smut and oil removal • Enhance heat treat scale removal • Extends acid life • Reduces rejects Greatly improve the performance of your hydrochloric or sulfuric acid pickle with Ambienol® C. Used by platers nationwide. Available in 5 and 55 gallon containers. METALLINE CHEMICALS CORP. www.metallinechemicals.com www.metalfinishing.com/advertisers 262-241-3200 • Fax: 262-241-8712 Email: info@metallinechemicals.com 115 G e t O u t o f a P i c k l e W i t h

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