Metal Finishing Guide Book

2011-2012 Surface Finishing Guidebook

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Page 279 of 707

Figure 1. C-5 Galaxy, Aircraft specification delineates three alter- native sealing processes that are approved for use: boiling deionized (DI) water, solutions containing cobalt acetate, and solutions con- taining nickel acetate. However, sufficient data to promote the use of these and other chromium-free sealing processes do not exist. To address these issues, the Air Figure 2. Main Landing Gear Force Research Laboratory (AFRL) Energy and Environment Team (RXSCP) tasked Concurrent Technologies Corporation (CTC) to identify and demonstrate/validate an alternative to sodium dichromate sealers used in anodizing operations at OO-ALC. The successful implementation of a chromium-free sealing technol- ogy will reduce environmental compliance burdens and foster enhanced worker safe- ty at OO-ALC. Under this effort, numerous interviews with OO-ALC personnel were conducted. The purpose of the interviews was to identify the technical requirements for the parts being processed and to capture the desired characteristics of an alter- native sealer. CTC then identified relevant products by conducting Internet search- es, vendor interviews, and literature reviews. This article presents the findings from the interviews with ALC personnel (requirements analysis) and product search (technology assessment) conducted during this effort. Although this activity focused on the specific needs of OO- ALC (e.g., military components and applications), the information and method- ology presented herein is useful for anyone interested in exploring alternatives to dichromate sealers for anodizing operations. ANODIZING AND SEALING REQUIREMENTS OO-ALC uses sulfuric acid (Type II and Type IIB) and hard coat (Type III) 278

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