Corrosion Inhibition Of Aluminum Alloys By Amino Acid Schiff Base Corrosion Inhibitor

Aluminum and its alloys are extremely susceptible to corrosion in acidic media,which can affect the material properties severely.The use of corrosion inhibitor is the most efficient and convenient way to inhibit corrosion.The amino acid corrosion inhibitor has broad prospects for its environment-friendly feature.It is harmless to the environment and can be degraded by organisms.In this work,L-lysine,L-aspartic,L-tyrosine were dehydrated and condensed with vanillin and salicylaldehyde respectively to synthesize a series of amino acid schiff base corrosion inhibitors.The inhibition effect of amino acid schiff base corrosion inhibitor for LY12 CZ aluminum and 1060 pure aluminum in 2 mol/L HCl were investigated by means of potentiodynamic polarization(PP),electrochemical impedance spectroscopy(EIS)and weight loss measurements.Scanning electron microscope(SEM)and energy dispersive spectrometer(EDS)were used to observe the surface morphology and composition of LY12 CZ aluminum and 1060 pure aluminum after being immersed in blank solution and 2 mol/L HCl solution with different inhibitors for 15 min.In addition,the mechanism of corrosion inhibition was deeply studied and discussed by calculating the adsorption thermodynamics and kinetic parameters.The results show that:(1)The synthesized amino acid schiff base corrosion inhibitors can effectively inhibit the corrosion of LY12 CZ aluminum and 1060 pure aluminum in 2 mol/L HCl solution.When the concentration of vanillin L-lysine schiff base,salicylaldehyde L-lysine schiff base,vanillin L-aspartate schiff base,salicylaldehyde L-aspartate schiff base,vanillin L-tyrosine schiff base,and salicylaldehyde L-tyrosine schiff base were 2.5 g/L,3.5 g/L,2.5 g/L,3.0 g/L,2.5 g/L,and2.5 g/L.The corrosion inhibition efficiency of LY12 CZ aluminum reached 95.20%,94.26%,68.06%,71.11%,89.77%,and 85.17%,respectively.When the concentration of amino acid schiff base corrosion inhibitors were 2.0 g/L,3.0 g/L,1.5 g/L,1.5 g/L,4.0 g/L,and 2.0 g/L.The corrosion inhibition efficiency of 1060 pure aluminum reached 91.10%,79.23%,78.41%,71.11%,89.26%,and 85.14%,respectively.(2)The SEM images showed that the synthesized amino acid schiff base corrosion inhibitors all contributed in reducing the number of corrosion pits of LY12 CZ aluminum and1060 pure aluminum in 2 mol/L HCl solution,and making the pore diameter of the corrosion pores smaller.The results of EDS,electrochemical impedance spectroscopy and kinetic parameters indicated that the electronegative atoms of O,N and ? electrons in the molecular structure of amino acid schiff base provided lone pair electrons to coordinate with aluminum to form a dense adsorption film to increased the apparent activation energy of aluminum and its alloys,which means that the charge and mass transfer reactions on the metal surface were required to overcome higher energy barriers.As a result,the occurrence of corrosion was effectively slowed down.(3)The amino acid schiff base should be considered as a mixed-type inhibitor in HCl solution.The adsorption of amino acid schiff base corrosion inhibitor on the surface of LY12 CZ aluminum and 1060 pure aluminum obeys the Langmuir adsorption isotherm,and being both physisorption and chemisorption.