The Research On The Corrosion Inhibition Performance Of TDPA SAMs On The Surface Of2024Aluminum Alloy

As one of the environmentally friendly techniques, self-assembled monolayers(SAMs) has attracted tremendous attention due to its easy-processing, mild assembling condition and friendly to environment advantages compared with the traditional corrosion inhibition techniques. Meanwhile, SAMs with highly ordered packing structure have high corrosion inhibition performance. In recent years, the corrosion resistance of metal alloys was extensively studied as well as that of pure metal. The corrosion resistance of aluminum alloy, one of the most important metal alloy, has been studied by many researchers. One of the most popular corrosion inhibitor is silane.Based on the report that alkyl phosphinic acid self-assembly film on pure aluminum surface is more stable and corrosive resistant than silane in the corrosive environment. In this work, SAMs of1-tetradecylphosphonic acid (TDPA) prepared on2024aluminum alloy were studied with the adsorption behavior and corrosion inhibition performance.The corrosion inhibition performance was studied by potentiodynamic scanning, Electrochemical Impedance Spectrum (EIS), contact angle measurement, Fourier Transform Infrared Spectroscopy (FTIR), X-ray Photoelectron Spectroscopy (XPS) and Atomic Force Microscopy (AFM). The corrosion electrolytes are3.5%NaCl and0.1M H2SO4. Both the effects of water and assembling time period on the formation of TDPA SAMs and the inhibition performance were studied. The results of FTIR, XPS and contact angle measurement show that adding water into the assembly solution is beneficial to improve the corrosion inhibition efficiency of SAMs. Furthermore, the higher water content results in greater corrosion inhibition efficiency. Through electrochemical and AFM measurements, it was found that the optimized assembly time to reach the greatest efficiency is2-4hrs. increasing water content may aggravate the dissolution effect of oxide film which is caused by ionization of TDPA molecules. At the same time, increasing water content is beneficial to the hydration of AA2024and it enhanced the adsorption of TDPA molecules. The local corrosion is more susceptible to the dissolution of oxide film than uniform corrosion, So the effect of water on the corrosion inhibition efficiency is different for different corrosion electrolyte. In NaCl corrosion electrolyte, the corrosion inhibition performance of SAMs prepared in solution with20%water is better than that with40%water. However, in H2SO4corrosion electrolyte, the corrosion inhibition performance of SAMs prepared in solution with40%water is better than that with20%water.