Abstract
Organic coatings used in aerospace applications are the primary means of protecting structures from atmospheric corrosion in harsh environments. Corrosion often occurs in occluded areas buried within a structure, such as crevices at faying surfaces and fasteners, and may be difficult to measure directly. At the same time, conventional coating testing relies on post-test analysis of corrosion damage and does not provide continuous measures of coating performance or alloy degradation. This makes quantifying interaction effects between temperature, RH, and mechanical loading to better understand the time-dependent degradation of the coatings and corrosion of the substrate difficult. To address this, in situ atmospheric measurements of coating condition have been developed for use in laboratory and outdoor exposure tests. The purpose of this work was to demonstrate the capability of these methods to provide real-time information about coating condition in cyclic atmospheric corrosion tests. Results are presented that demonstrate detection of coating damage to test panels, including measurement of flat panel scribe and repair and measurement of the introduction of coating cracks via mechanical step loading. Results of additional testing to quantify the limitations of these measurements and progress in the development of atmospheric coating condition measurement systems are also discussed.
