Metal Finishing Guide Book

2011-2012 Surface Finishing Guidebook

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DEMONSTRATION/VALIDATION TESTING Based on the findings of this activity, three candidates were selected for labora- tory testing: the COTS permanganate solution, the COTS low-nickel sealing solu- tion, and a 50 ppm sodium dichromate solution that will serve as a bench- mark. As mentioned previously, the COTS low-nickel seal will be considered with and without a warm water rinse after the sealing process. The currently used sodi- um dichromate sealer, the boiling DI water seal, and unsealed options will be eval- uated as baselines for all testing conducted for this effort. The candidate test matrix is summarized in Table 3. Efforts to test aluminum alloy test panels that have been anodized and sealed with the above processes are in progress. (2 The ideal processing temperature of the NCP process is 100°F and the opti- mum processing time is 10 minutes. 3 The solution was made up at 10% by vol- ume. Temperature was maintained at 170-180°F, pH was maintained between 5.0 and 8.0, and seal time was 12 to 15 minutes.) SUMMARY The overall objective of this effort was to identify alternatives to the sodium dichromate sealer used in anodizing operations. To this end, the requirements for the sodium dichromate sealer currently in use at OO-ALC were determined. Furthermore, extensive literature and vendor searches identified promising can- didates that may meet the requirements. The findings were then used to derive a path forward to demonstrate/validate the most-promising alternatives for the specific needs and applications of OO-ALC. FUTURE WORK Having established the test methods and acceptance criteria for replacing sodi- um dichromate sealers, as well as available candidates for testing, the effort will focus on testing and data evaluation. It is anticipated that this work will iden- tify a candidate that can meet the needs of OO-ALC with respect to an anodiz- ing seal. Once this candidate has been identified, thoroughly validated through testing, and recommended for use at OO-ALC, the process of modification of the relevant technical order (TO) for conducting anodizing and sealing operations at OO-ALC will be initiated accordingly. The replacement of sodium dichromate in this application will reduce the environmental burden and increase worker health and safety at OO-ALC. ABOUT THE AUTHORS Rob Mason is a Senior Materials and Process Scientist at Concurrent Technologies Corporation (CTC) in Largo, Fla. In this role, he provides technical support to CTC's clients in government and commercial industry. His current work includes providing sup- port to inorganic coating activities conducted by the Air Force Research Laboratory (AFRL). Mr. Mason has more than 20 years cumulative experience in surface engineering, coatings R&D, and testing and evaluation methodology development, and has co-authored over 50 technical publications and presentations on these subjects. He earned his B.S. in Chemistry from Fairleigh-Dickinson University, New Jersey. He is a member of the National Association of Surface Finishers (NASF), NACE International, and Toastmasters International. 284

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