Salt Water Exposure Effects on Single-Layer, Unidirectional Carbon-Fiber Reinforced Polymer Circuit Analog Absorbers

This paper explores the effects of extended exposure to salt water fog on the microwave absorption properties of unidirectional carbon-fiber reinforced polymer (CFRP) circuit analog absorbers (CAA). Single-layer CFRP CAAs were fabricated using a wet-layup technique and were then subjected to a controlled salt water fog chamber following B117 standards. A total of ten samples using 305 g/m2 areal-weight unidirectional CFRP were fabricated. Three samples were withdrawn from the salt water environment at ten-day intervals and tested, with the final samples being withdrawn after 30 days. The mass of each sample was measured immediately after removal to measure mass-accumulation and after a five-day interval to measure mass-loss. A free space microwave reflection measurement system was implemented to track and quantify changes to the absorption capabilities of the CAA. A physicallybased electromagnetic model was developed to characterize the changes caused by salt water absorption, and good agreement was observed with measured data.