Metal Finishing Guide Book

2012 Organic Finishing Guidebook Issue

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service and more corrosive environments. This test meets the challenges of pro- viding a simulated service evaluation to test product specifications in research and development and provide manufacturing controls for environmental changes caused by human intervention. The B 368 Standard is a variation on the basic ASTM B 117 Salt Spray (Fog) Test. For this variation adjust the pH of the 5% salt solution into the range 6.0 to 7.0, then add 0.25 grams of reagent-grade copper chloride per liter of salt so- lution. The test is not considered to start until the temperature within the exposure zone has reached 49°C + 1.1 or - 1.7°C (120° + 2 or - 3°F) and is then run con- tinuously for 6 to 170 hours as agreed upon between purchaser and seller. It is required that the temperature within the exposure zone be checked twice a day only on regular business days when the chamber may be periodically opened for "short" durations (preferably less than 5 min) to work with test pieces and/or replenish solution. Another variation from the standard salt spray (fog) test is in the verification for consis- tency of test exposure condi- tions. In ASTM B 368 Standard using Nickel Mass Loss Coupons rather than steel (as used in the B 117 Practice). The B 368 Standard uses cor- rosion test chamber apparatus that meets the requirements for the ASTM B 117 Standard and will withstand the increased tem- perature and stronger electrolyte solution used for this test. ASTM G 85—Modified Salt Spray (Fog) Testing Five variations of this standard have been developed to accom- modate its use to different pur- poses. The variation that a sup- plier uses in any situation must be agreed upon with the purchaser. Following are brief explanations of each of the variations. Fig. 5. Typical cyclic-type corrosion test chamber with PLC control for automatic operation of changeable atmospheres, temperatures, and durations of various steps in cycle. Annex 1—Acetic-Salt Spray (Fog) Testing. The Acetic Acid-Salt Spray (Fog) Test is used to test ferrous and nonferrous met- als and inorganic and organic coatings for resistance to additional and more corrosive environments than the ASTM B 117 Standard. This test is designed as a continuous exposure test without interruptions. It uses a 5 ±1 part by mass so- lution of sodium chloride in 95 parts of ASTM D 1193 Type IV water. The pH of the solution is adjusted with the addition of glacial acetic acid to be within the range of 3.1 to 3.3. This solution is then atomized into the exposure zone to create a fog that has a condensate collection rate of 1.0 to2.0 ml/hr per 80 cm2 of horizontal collection area while the temperature of the exposure zone is be- ing held at a constant 35° + 1.1 or - 1.7°C (95° + 2 or - 3°F). This variation is particularly useful in research when evaluating the effect 298

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