Author: Nelson Ndukwe AkwariPublisher:
ISBN:
Category :
Languages : en
Pages : 126
Book Description
Composite materials are widely used in various applications and industries around the world. In recent years, commercial airplane companies have used composite materials for critical load bearing structures such as fuselage sections. During the lifetime utilization of composite materials, they can be subjected to extreme environmental conditions such as ultraviolet light, temperature fluctuations, humidity, and moisture. Depending on the amount of exposure to a composite material, the environmental conditions can negatively affect the chemical and mechanical properties of the fibers and matrix. Companies are investing substantial amounts of money and time to prevent composite materials from deteriorating by protecting them with protective materials such as coverings or coatings specifically designed to mitigate any damage to the underlying composite material. This project focused on the effect of environmental conditions on a thermoset composite material and the evaluation of protective coatings to mitigate ultraviolet (UV) degradation of an underlying carbon fiber reinforced polymer (CFRP) composite substrate. Standardized laboratory test methods were used to replicate aerospace production in-service environments commonly seen in commercial aerospace factories. Additional considerations were given to the manufacturing processes and transport of composite parts. Tests and evaluations focused on the durability of the protective coating to environmental effects such as moisture, heat, and ultraviolet radiation. In order to evaluate the effectiveness of the coating to prevent degradation to the underlying composite substrate, mechanical and analytical evaluations of the coated composite substrate were performed. The composite substrate used throughout testing contained a co cured surfacing film with an epoxy polymer matrix chemistry. Consideration was given to the effects of environmental exposure on the surfacing film and potential subsequent effects on the composite structure as a whole. A goal of the project was to down select a non-chromate protective coating that could effectively protect the underlying composite material from UV degradation. A second goal of this project was to quantify the UV and Condensing Humidity (moisture) degradation mechanisms and kinetics of the protective coating. A kinetic model was utilized to evaluate theindependent degradation mechanisms due to UV exposure and Condensing Humidity (moisture) respectively. These independent mechanisms were evaluated for synergistic effects and compared to Outdoor exposure of protective coated composite panels with the goal of trying to determine if a cumulative model can be used to predict the overall degradation kinetics. One commercial off-the-shelf non chromate epoxy-based coating was down selected after the completion of screening tests and proved to successfully protect the underlying composite material throughout a wide range of extreme environmental conditions. The independent evaluation of the degradation mechanisms due to UV exposure and Condensing Humidity (moisture) yielded results which correlated to industry and literature results. This research was unable to accurately develop a cumulative model that could consistently predict the overall degradation kinetics of a protective coated composite panel subjected to outdoor exposure conditions.