Anticorrosion Performance of Epoxy Coating Containing Polyaniline Modified by Montmorillonite in Marine Environment

In order to improve the long-term anticorrosion performance of epoxy (EP) coating in marine environment, montmorillonite (Mt) and polyaniline (PANI) compounds were applied to modify epoxy resin coatings (EP), and the corrosion properties and mechanism of the compounds were studied. PANI and 4 kinds of PANI conpounds with different contents of Mt were prepared by chemical oxidation method. Composite coatings of EP with different contents of PANI-Mt100:7 were coated on Q235 steel substrate. Microstructure and morphology of PANI and PANI-Mt products were characterized by fourier transform infrared spectroscopy (FTIR), X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM) respectively. The corrosion performance of Q235 steel with different composite EP coatings in 3.5% sodium chloride (NaCl) solution was studied by electrochemical methods. The results indicated that the impedance values of the modifield EP coating after immersion for 0.5 h and 360 h were 8.7×106 Ω·cm2 and 6.3×104 Ω·cm2 respectively. The impedance values of the modifield EP after immersion for 0.5 h and 360 h increased obviously after adding PANI-Mt100:7, which reached the maximal value of 2.7×108 Ω·cm2 and 1.1×107 Ω·cm2, as the content of PANI-Mt100:7 was 5%.