Abstract
Repair and replacement of exterior coating systems that no longer meet aesthetic or protective requirements generate a significant volume of environmentally hazardous waste, which includes the coating material combined with solvents and/or media used to remove the coatings, as well as the waste materials generated in surface preparation and reapplication of the coating system. There are strong economic and environmental drivers to extend the service life of aerospace coatings. However, development, selection, and use of the most durable coatings systems have often been limited by the ability to predict service performance in accelerated tests. Current accelerated test methods do not adequately employ the chemical, thermal, mechanical, or radiative stressors that produce relevant damage mechanisms in coated structures that can be used for accurate quantification of coating performance and service life. Test methodologies are being developed that employ combined environmental and mechanical loading modes to overcome this issue. The mechanisms and kinetics of damage progression are quantified continuously throughout a test using in situ measurements of coating system properties and substrate corrosion. Mechanical test fixtures and simulated structural components are being used to apply stresses to coating systems in accelerated atmospheric test chambers. The combined mechanical and environmental tests are expected to produce failure modes not achieved using traditional atmospheric test chambers. An overview is given of the test methods, in situ measurement systems, coating characterization, and combined effects atmospheric exposure testing.
