Magnesium Rich Primer for Chrome Free Protection of Aluminum Alloys (Preprint)
Abstract
Hexavalent chromium compounds used for corrosion protection are one of the top hazardous waste materials generated by the U.S. Air Force and legislation is in effect to further restrict their use. Magnesium rich primers that utilize sacrificial magnesium metal pigment to cathodically protect aerospace aluminum alloy substrates are a potential alternative to chromated primers. This material has proven to be particularly effective as part of a completely chromate-free coating system in which a non film forming surface treatment and an Advanced Performance Coating (APC) grade topcoat are utilized. Samples using the latest advanced formulations show excellent corrosion protection of scribed AA2024-T3 panels in both ASTM B 177 and outdoor exposure at Dayton Beach, FL. Despite initial concerns regarding the reactivity of the magnesium metal pigment being used, the flammability and handling characteristics have not shown any potential problems to date. Transitioning a new class of corrosion protective primer coating such as this requires more testing than normal. The current Air Force plan involves qualification to a "system level" coating specification, MIL-PRF-32239. In addition, simulated lap joints with various fasteners specific to the target aircraft will be evaluated, along with compatibility on alternative substrates and evaluation of coating reparability characteristics.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 2007
- Accession Number
- ADA476101
Entities
People
- Joel A. Johnson
Organizations
- Air Force Research Laboratory