Confocal laser scanning microscopy as a tool for in situ monitoring of corrosion underneath organic coatings

This paper discusses the application of confocal laser scanning microscopy for the investigation of corrosion processes on aluminum alloy AA2024-T3 occurring beneath a transparent organic coating. The ability of the microscopy to monitor the topography of both the alloy surface under the coating and the surface of the coating, itself, in three dimensions, is demonstrated. The resolution limits (x, y, z), when imaging through a bulk solution, coating, and coating blister solution are better than 1 μm. The technique described has potential to clarify the roles of alloy heterogeneity and corrosion damage associated with intermetallic phases at the micrometer scale on the underpaint corrosion process and coating blister formation and growth.