Electrochemical corrosion behavior of magnetron-sputtered aluminum films on carbon fiber reinforced polymer surfaces in 3.5 % NaCl solution

This study aimed to investigate the magnetron sputtering process of Al films on epoxy-based composite materials, assess the influence of outgassing from the epoxy resin, a key matrix component, on the film performance, and establish the relationship between film crystalline structure, micro-morphology, and corrosion resistance. The results reveal that the Al film was primarily characterized by the Al (220) plane peak at lower sputtering currents. As the sputtering current increased, the peak intensity of the Al (111) plane and grain size grew, and grain boundaries became more distinct. Nonetheless, the release of impurity gases from the epoxy resin led to a general presence of amorphous Al 2 O 3 structures in the film. Excessive sputtering currents or prolonged coating times brought about an increase in the Al 2 O 3 phase and a reduction in Al crystallinity. Additionally, Electrochemical impedance and Potentiodynamic polarization curves were conducted in a 3.5 wt.% NaCl solution suggests that processes with higher Al crystallinity and stronger Al (111) plane peaks demonstrated better corrosion resistance, processes with finer grains or predominantly Al (220) plane peaks were prone to pitting initiation, and processes with low Al crystallinity and enriched Al 2 O 3 phases exhibited severe pitting. The film with a thickness of 10-15 μm made by current intensity of 5-6 A has the strongest corrosion resistance. • In our investigation on the surface metallization process of carbon fiber composites, we observed that the magnetron sputtering surface treatment induces outgassing phenomena in the composite materials. The released gases react with Al atoms, resulting in the formation of Al₂O₃ phase. • There is a competitive relationship between the Al (111) and Al (220) crystal planes in the Al layer. • The excessive current intensity and heat accumulation reduce the crystallinity of the film and lead to an increase in the Al 2 O 3 phase • The film with low crystallinity and serious oxidation has poor resistance to electrochemical corrosion