Improvement of corrosion resistance and opticalproperties of formed, sulfuric acid anodized ENAW-2219 parts

Due to aircraft storage caused by the COVID-19 pandemic, several corrosion finding were reported on the leading edge of the engine, the Air Inlet Lipskin. Increasing the thickness ofthe protective oxide layer, which is created on this part by sulfuric acid anodizing, is a potential way to increase the corrosion resistance of the component. However, it is reported that such an increase of the oxide layer thickness can also have negative effects on its important optical properties. Therefore, improving the corrosion resistance while maintaining a high optical quality of the Air Inlet Lipskin presents a challenge to the anodizing process. This thesis investigates the possibility of meeting these two requirements by dyeing of the oxide layer.For this purpose, experiments are carried out with specimens from original lipskins with the aim of correlating the microstructure determined by the applied manufacturing process, the produced oxide layer, and the optical properties of the specimens influence by the dyeing parameters. To achieve this aim, the following test methods were applied: scanning electron microscopy, metallography, hardness and electrical conductivity measurements, salt spraytests, and accelerated weathering tests.