Anticorrosive performance of polyaniline/aluminum tripolyphosphate/waterborne epoxy composite coatings

An organic–inorganic composite, combining polyaniline (PANI) with aluminum tripolyphosphate (ATP), was prepared by in situ polymerization. On this basis, the coatings were obtained by introducing PANI-ATP composite into waterborne epoxy resin (WEP) for anti-corrosion treatment of 304 stainless steel (304ss). Several characterization methods were carried out to test and evaluate the structure properties of the composite coating, including Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM) and contact angle (CA) tester. Through electrochemical impedance spectroscopy (EIS) results, strong evidence was found when the composite coating filled with PANI-ATP composite, compared with the uncoated bare steel, its low-frequency impedance (|Z|0.01 Hz) increased significantly, and corrosion current density (Icorr) reduced to 7.2 × 10−10 A cm−2. The coating has the best corrosion resistance ability. In the long-term immersion experiment, it still has better anti-corrosion performance than bare 304ss after 170 days. This study provided a simple way to solve the corrosion problem of industrial stainless steel by adding the inorganic–organic mixture filler to the polymer matrix.