Corrosion Protection of Q235 Steel Using Epoxy Coatings Based on Polyaniline Loaded with Benzotriazole

Polyaniline (PANI) doped with hydrochloric acid and phytic acid are prepared as benzotriazole (BTA) inhibitor carriers, and their anticorrosion properties are studied on epoxy resin-coated Q235 steel. The structure and morphology of the prepared PANI materials are investigated by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The thermal stability of PANI and its release rate of corrosion inhibitor are measured, and the test results indicate that hydrochloric acid-doped PANI can accommodate a larger amount of corrosion inhibitor. The results of contact angle and water absorption tests show that the PANI loaded with BTA can improve the hydrophobicity and reduce the water absorption of the coating. The anticorrosion performances of epoxy coatings with 0.6 wt% PANI are investigated in 3.5 wt% NaCl solution using electrochemical tests. The experimental results reveal that PANI loaded with BTA shows a good anticorrosion effect in the epoxy coating. Particularly, phytic acid-doped PANI loaded with BTA has a better inhibition efficiency (93.6%), which is superior to hydrochloric acid-doped PANI loaded with BTA (86.4%).