Analysis of Premature Degradation to High Performance Aerospace Military Coatings



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Analysis of Premature Degradation to High Performance Aerospace Military Coatings Nickolaus K. Weise, Ph.D. George Mason University, 2020 Dissertation Director: Dr. Gerald L. R. Weatherspoon High performance aerospace coatings are intended to protect the substrate from the effects of sunlight and humidity, ensuring an airframe lasts its intended lifespan. The coating systems that are applied to the airframe are intended to last for 12-15 years, with minor periodic touch ups or “rework”. However, when the applied coating system degrades prematurely, the U.S Navy is forced to spend a great deal of money and man hours repairing the defective coating. Currently, the Navy employs a coating system that is experiencing premature degradation from hot and humid environments. To explore what is causing this degradation and ways to prevent it, analogue coating systems were synthesized and exposed to accelerated weathering conditions. The study focused on manipulating three (3) separate variables: 1) the blending of poly(ether) and poly(ester) macrodiol; 2) the –NCO:-OH mole ratio; and 3) the pigment volume concentration. This work describes the results from the accelerated weathering study. Surface analysis, bulk mechanical analysis and spectroscopic analysis were used to understand how variables were affected due to accelerated weathering. When the macrodiol was blended, the mechanical properties of weathered coatings more closely resembled the T0 mechanical properties after 2000 h of weathering. When the –NCO:-OH mole ratio was manipulated, the urea linkages formed from the excess isocyanate did not adversely affect coating performance. Finally, when the PVC was manipulated, the blended polyol coating systems performed better than the single polyol coating systems. This work furthers the knowledge base contributing to the development of the next generation of high performance military coatings.