Preparaion And Inhibition Property Of Layered Double Hydroxides Films On Copper Surface

The hydrotalcite compounds or layered double hydroxides(LDHs) are a class ofinorganic laminar compound, and have shown a very broad application prospects incatalysis, adsorption, separation, corrosion, photochemistry, electrochemistry,medicine, magnetic, environmental protection and pesticides. In this paper, we attemptto prepare LDHs film on copper surface by colloidal deposition method, hydrothermalmethod and electrochemical deposition, the its structure, morphology and corrosionperformance also had been investigated, the main conclusions are as follows:(1) LDHs precursor was synthesized by coprecipitation method, the surface ofcopper was modificatied by cysteine(Cys) film, and then prepared LDHs film bycolloid deposition method, finally we obtained Cys/LDHs films on copper surface. Inthe the electrochemical impedance spectroscopy, the Cys/LDHs films exhibit bettercorrosion performance than Cys film and LDHs film. When the LDHs soaking timewas0.5h, Cys soaking time was3h, the surface coverage of Cys/LDHs film reachedto94.4%. In the polarization curve, the corrosion potential and corrosion currentdensity of Cys/LDHs had been shifted significantly reduced. When the LDHs soakingfor0.5h, Cys soaking time was3h, the inhibition efficiency of Cys/LDHs filmreached to94.8%.(2) We prepared CuZnAl-LDHs film on copper surface by hydrothermal method,and studied its structure, morphology and corrosion protection performance. XRDresults show CuZnAl-LDHs film has obvious characteristic structure and absorptionpeaks, but the crystal form is not complete; SEM results showed CuZnAl-LDHs filmis lamellar. By polarization curves for CuZnAl-LDHs films showed thatCuZnAl-LDHs film have an inhibition efficiency for copper in3.5%NaCl solution. (3) The ZnAl-LDHs films was prepared on copper surface by electrochemicalmethod. XRD results showd the optimal preparation conditions is E=-1.6V, pH=3.8,Zn2+/Al3+=1:0.33. XRD results also showed that the ZnAl-LDHs film has the samediffraction peaks characteristic of ZnAl-LDHs powder; SEM results showed theZnAl-LDHs film was uniform and compact; The EIS and polarization curves showedthat ZnAl-LDHs film have an inhibition efficiency for copper in3.5%NaCl solution.When the deposition time is120s, the inhibition efficiency up to84.49%. Immersionexperiments showed that the ZnAl-LDHs film surface morphology was not changedafter immersed in3.5%NaCl solution for24h, it still had an inhibition efficiency forcopper.