Effect of nano-TiO2 on the initial corrosion behavior of the acrylic polyurethane coating/carbon steel interface in NaCl solutions

The initial corrosion behavior of the acrylic polyurethane coating/carbon steel interface in a 3.5% NaCl solution was in-situ investigated by electronic speckle pattern interferometry(ESPI),electrochemical impedance spectroscopy(EIS) and scanning electrochemical microscopy(SECM). The effect of nano-TiO2 on the interfacial behavior was examined. At the beginning stage without macroscopic defects,a tiny change at the interface was successfully detected by ESPI. EIS results could reflect the change of low frequency impendence moduli,which were agreed with the electrochemical morphology obtained by SECM. In other words,the interfacial changing velocity(corrosion initiation rate) of the coating without nano-TiO2 is faster than that of the coating with nano-TiO2,indicating that the addition of nano-TiO2 slows down the corrosion of the acrylic-based polyurethane/carbon steel interface.