Anti-corrosion properties of oligoaniline modified silica hybrid coatings for low-carbon steel

Novel electroactive silica-based hybrid coatings were synthesized on the surface of Q235 low carbon steel via one-step electrodeposition and were analyzed by FTIR, UV-vis, SEM, OCA20 contact angle (CA) analyzer and CHI-660E electrochemical workstation, respectively. The CA test indicated, in comparison with bare Q235 substrate, the silica hybrid material modified by N, N’-Bis(4′-(3-triethoxysilylpropylureido)-phenyl)-1,4- quinonenediimine (TSUPQD) exhibited an excellent hydrophobic properties. More importantly, the deposition potential significantly affected the corrosion resistance of TSUPQD modified silica hybrid material. By comparing with various deposition potentials (−1.1, −1.3, −1.5, −1.7 V) under the deposition time of 500 s, the coating prepared under the potential of −1.5 V presented the best anti-corrosion performance for Q235 steel in 3.5 wt.% NaCl solution. The XRD and SEM analysis of corrosion product beneath the hybrid coatings showed that the redox catalytic capability of aniline trimer unit induced the Q235 substrate to form the passive films which mainly consisted of α-Fe₂O₃ and Fe₃O₄.