Concentration-Dependent Modification of Steam-Formed Coatings on Mg-Li Alloys Via Cysteine and Corrosion Resistance Optimization
摘要
This study employed an in-situ steam method to modify the surface of LA103Z magnesium–lithium alloy using the corrosion inhibitor cysteine, thereby forming a Cys-SC composite film. The microstructure of the films was characterized using a variety of analytical techniques, including SEM, EDS, XRD, and FT-IR. Its corrosion resistance was evaluated through EIS and hydrogen evolution tests. The results indicate that, at a cysteine concentration of 0.04 M, the films consist of sheet-like structures. Additionally, the charge transfer resistance of the film was determined to be 1477 ohm cm−2, which is approximately two orders of magnitude higher than that of the substrate. Following a 216-h immersion period, the film demonstrated the lowest hydrogen evolution rate of approximately 0.013 ml cm−2 h−1, accompanied by a hydrogen evolution volume of approximately 2.68 ml cm−2. This value represents approximately 21% of the volume for the LA103Z substrate (12.75 ml cm−2) and approximately 27% of that for SC (9.79 ml cm−2). Cysteine has been demonstrated to enhance the active protection behavior of the metal substrate by regulating its concentration. This regulation enhances the orientation of layered double hydroxide (LDH) sheets within the layer, facilitates ion exchange with Cl− in the corrosive solution, and promotes the recrystallization of cations released from damaged layers.