Study Of Inhibitors Of Aluminum Anode In NaCl Solution

This dissertation took aluminum anode of the aluminum air battery as the research object, inhibition behavior of mixed CeCl₃ with LaCl₃ co-inhibitors and mixed CeCl₃ with adipic acid co-inhibitors in 3.5mass% NaCl solutions for aluminum anode were studied respectively.Mixed CeCl₃ with LaCl₃ was chose by potential-time (OCP)curves as co-inhibitors for aluminum with total concentration of 500mg/L. With Electrochemical Impedance Spectroscopy (EIS), effect of these two inhibitors proportion, pH and temperature of solution with mixed CeCl₃ with LaCl₃ on inhibition of aluminum was studied. The optimum inhibition condition of aluminum anode was determined as: the proportion of CeCl₃ and LaCl₃ was 3:2 with total concentration of 500mg/L in 3.5mass% NaCl solution, solution temperature was chose between 20℃and 30℃,pH value was chose between 5 and 6. 94 hours effective period of this co-inhibitors was determined by EIS tests of aluminum anodes with immerging time in 3.5mass% NaCl solution with this co-inhibitors. Charge and discharge curve indicated that the performance of aluminum anode in 3.5mass% NaCl solution with this co-inhibitors was better than that in 3.5mass% NaCl solution without inhibitors. potentiodynamic polarization curves showed that this co-inhibitors were cathodic inhibitors, that means the hydroxides or oxides of Ce and La deposit in some small cathodic areas on aluminum anode, thus, Inhibition effect was derived by blocking oxygen reduce reaction, And the result has been confirmed by Scanning Electronic Microscopy(SEM) and Energy Disperse Spectroscopy(EDS) tests. X-ray Photoelectron Spectroscopy(XPS) spectra indicated that rare-earth oxides or hydroxides were formed by rare-earth ions with OH- introduced by corrosion reaction of aluminum anode.In study of mixed hexylic acid with CeCl₃ in 3.5mass% NaCl solution, adipic acid inhibition effect has been confirmed by OCP. Mixed hexylic acid with rare earth cation Ce3+ not only further decrease corrosion rate, but also last long inhibition time. The proportion of hexylic acid and CeCl₃ had been studied by EIS, It showed that 400mg/L CeCl₃ and 250mg/L hexylic acid had good inhibition effect on aluminum anode in 3.5mass% NaCl solution. Temperature effect of 3.5mass% NaCl solution with 400mg/L CeCl₃ and 250mg/L hexylic acid on aluminum anode was studied by EIS, and inhibition temperature was confirmed between 22℃and 30℃.Potentiadynamic polarization curves indicated that hexylic acid was cathodic inhibitor. Mixed hexylic acid with CeCl₃ had good inhibition effect on small cathode areas. Impedance-time test indicated that effective period of this kind co-inhibitors for aluminum anode was 88 hours. SEM tests were taken for aluminum anode immersing in solution with this co-inhibitors for four days, SEM photos showed that surface of aluminum anode could hardly see any corroded holes. XPS spectrum indicated that adipic acid was attracted to aluminum anode surface by hydrobond, good inhibition effect was gotten by forming a thin orgnic film.