Aerospace Coating Aging Method Investigation

Abstract Artificial aging techniques are often used to approximate the in-field conditions of aerospace coatings. The effects of commonly used artificial aging methods on the mechanical and chemical properties of United States Air Force (USAF) coating systems is generally unknown. During this investigation, anodized aluminum and free film paint specimens painted with a USAF standard epoxy primer and polyurethane topcoat were prepared and then aged with four aging methods regularly utilized for technology transition efforts. The anodized layer of the aged aluminum specimens was characterized for cracking via optical microscopy. Relative hardness of the aged free film specimens was measured via thermomechanical analysis (TMA) and changes in chemical composition were determined with Fourier Transform Infrared Spectroscopy. Tensile properties of the aged free film coating specimens were measured and compared to unexposed control specimens. Cracking of the anodized layer was observed in the control specimens, however the phenomena increased in frequency and depth after exposure to all aging methods. AMS(1) MA48721 Method A resulted in test specimens with significant degradation in hardness and tensile strength. These findings will provide future USAF technology transition efforts with the means to make technically informed decisions regarding coating aging method selection.