Accelerated Corrosion Testing of Galvanic Couples

New materials and structural designs are required for advanced aircraft functionalities.   Long standing standardized corrosion test methods (e.g. ASTM B117) are regularly called out in procurement documents to qualify these new materials.  However, it is becoming increasingly evident that these test methods can be misleading resulting in approval of material systems that have very poor in service performance and/or the rejection of promising new technologies.   In this work, we examine critical differences in the galvanic corrosion behavior between silver and aluminum alloys under bulk immersion and simulated atmospheric exposures.  Possible cathodic reactions and their relative importance under the different exposure conditions will be described.   The effect of these reactions on the overall galvanic current will also be explained.  Finally, the implications of these findings on the selection of corrosion abatement technologies will be addressed.