Prepared And Inhibition Property Of Layered Double Hydroxides Films On Copper

Layered double hydroxides (LDHs) are one of the useful classes of inorganic layered compounds and have recently received considerable attention in the field of catalysts, optical, and thin-film material. LDHs are generally prepared in powder, but in order to be used as materials for functional coatings they must be fabricated into film. Reports about the use of LDHs film as inhibitors in metal corrosion have appeared recently. Normally, LDHs as a kind inorganic material, the interaction between LDHs and metal substrate is relatively weak and thus the properties of resulting films are restricted. In this paper, we attempt to prepare the new LDHs film to improve the protection performance of LDHs on copper.(1) Zn-Al LDHs were prepared by co-precipitation method and then modified with cysteine(Cys), designated as Cys/LDHs. The XRD and FT-IR results suggest that after modification no evident difference in the d-spacing of LDHs structural layers, and existed the characteristic groups of Cys, that indicating surface modification rather than intercalation into gallery. Thin films of LDHs on copper surface were prepared by colloid deposition technique. The corrosion protection performance of LDHs films in 3.5% NaCl solution was evaluated by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization curve. The surface films of both pristine LDHs and Cys/LDHs could restrain the corrosion of copper substrate markedly, and the latter showed significantly higher inhibition efficiency. The inhibition efficiency of Cys/LDHs film reached to 94.22 %.(2) CuZnAl-LDHs powder were prepared by co-precipitation method, the XRD and FT-IR results indicated that the CuZnAl-LDHs with high crystallinity can be prepared by a solution of∑(M²⁺)/Al3+= 2 and Cu²⁺/∑(M²⁺) = 0.25 at pH = 5.5. Then the CuZnAl-LDHs were deposited on copper by colloid deposition method. The results of EIS and potentiodynamic polarization curves demonstrated that CuZnAl-LDHs films have the inhibition efficiency on copper in 3.5 % NaCl solution, and the highest inhibition efficiency could reach 90.12 %.(3) CuZnAl-LDHs films were prepared by in-situ growth technique on copper surface, the structure and morphology of the CuZnAl-LDHs films were characterized by XRD, FT-IR, XPS and SEM, the corrosion inhibition of the resulted films were evaluated by potentiodynamic polarization curve. These results indicated that the CuZnAl-LDHs films were successfully prepared by in-situ growth technique on copper, and the films have an inhibition efficiency for copper in 3.5 % NaCl solution, the inhibition efficiency could reach 80.42 %.