Corrosion protection properties of polyvinyl butyral/polyaniline-graphene oxide/poly (methylhydrosiloxane) composite coating for AA2024 aluminum alloy

In this study, polyaniline-graphene oxide (PANI-GO) composites with different loading amounts of GO (2 wt%, 4 wt%, 8 wt%) were successfully synthesized by a facile in-situ polymerization method. PANI-GO was added into polyvinyl butyral (PVB) primer to prepare anticorrosive coating for AA2024 aluminum alloy. Poly (methylhydrosiloxane) (PMHS) was introduced to improve the crosslinking degree and hydrophobicity of the composite coating. PANI-GO composites were characterized by UV-visible spectral, Fourier transform infrared spectroscopy and X-ray diffraction. The morphologies of different composites and coatings were characterized by scanning electron microscopy and transmission electron microscope. The anticorrosion performances of composite coatings were investigated by electrochemical impedance spectroscopy and Tafel polarization in 3.5 wt% NaCl solution under room temperature. Results showed that PVB/PANI-GO 20/PMHS coating exhibited much better protection properties to the substrate compared with PVB coating, the vertical bar Z vertical bar(0.01Hz) of the former reached 1.0 x 10(8) Omega.cm(2), which is almost 3 orders higher than PVB coating, and I-corr decreased to 5.88 x 10(-9) A.cm(2). With the hydrophobic surface formed by PMHS, the coating contact angle reached 104.52 +/- 1.52 degrees, and the long-term corrosion protection to the aluminum could last for over 70 days.