Metal Finishing Guide Book

2011-2012 Surface Finishing Guidebook

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Page 484 of 707

Analytical Grade chemicals should be used in preparing analytical reagents (Table VI) and Reagent Grade acids should be used (Table VII). When chemicals of lesser purity are used, the accuracy of the results will be diminished. Tables VIII through XII provide specific methods for testing the constituents of electroplating, electroless, and anodizing baths, as well as acid dips and alka- line cleaners. SAFETY As with any laboratory procedure, the accepted safety rules for handling acids, bases, and other solutions should be followed. Acids are always added to water, not the reverse. Mouth pipettes should not be used for pipetting plating solutions. Safety glasses should always be worn, and care should be exercised to avoid skin and eye contact when handling chemicals. A fume hood should be used when an analytical method involves the liberation of hazardous or annoying fumes. Laboratory staff should be well versed in the first-aid procedures required for var- ious chemical accidents. DETERMINATION OF CATHODE EFFICIENCY The procedure for determining cathode efficiency, using the setup pictured in Fig. 1, is as follows: 1. Connect the copper coulometer in series with the test cell. 2. The copper coulometer solution should contain 30 oz/gal copper sulfate pen- tahydrate and 8 oz/gal sulfuric acid. 3. Use the same anodes, temperature, and agitation in the test solution that are used in the plating bath. 4. Plate at 0.4 A (30 A/ft2 ) for a minimum of 10 minutes. 5. Rinse both cathodes, dry in acetone, and weigh. % Cathode Efficiency = weight in grams of testmetal X valence of testmetal in bath X 3177 weight in grams of copper metal atomic weight of test metal *Editor's note: To view this article in its entirety, including corresponding tables, please consult the online Guidebook archive. 483

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