Effects of environmental exposures on carbon fiber epoxy composites protected by metallic thin films

Carbon fiber epoxy composites have a wide range of applications in aerospace, construction, and automotive industries due to their good mechanical properties and lightweight characteristics. Carbon fiber epoxy composite structures are typically intended for service in corrosive and hostile environmental conditions. Therefore, development of coatings which are able to protect carbon fiber epoxy composite laminates against prolonged and harsh environmental conditions such as ultraviolet radiation and moisture deems critical. This paper offers a novel method for environmental protection of fiber-reinforced polymer composites by applying thin metallic films on composites' surface as coating materials. In order to investigate the protective properties of metallic thin films, copper and aluminum coatings were deposited on the surface of carbon fiber epoxy specimens by using direct current magnetron-sputtering technique, and then mechanical properties and surface morphology of specimens were monitored during the course of accelerated environmental exposure. Both metallic coatings showed good adhesion to carbon fiber epoxy samples during environmental aging and provided protection for the specimens' surface against environmental degradation. The correlation between flexural properties and surface morphology of carbon fiber epoxy specimens is also presented.