Construction and utilization of rare earth complexes as efficient corrosion inhibitor in epoxy coating
Qian Zhang, Mengyi Shen, Xingcai Liu, Hao Fu, Wenbo Yang, Jinyuan Zhao, Jian Wang, Yaping Du, Chunjie Ma
Abstract
Rare earth elements raised a lot of attention in many specialized applications. In this contribution, rare earth-containing corrosion inhibitors , 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP)-La, Ce and Pr are successfully synthesized and added as active fillers into epoxy coatings for the anti-corrosion of steel materials. In the immersion (NaCl aq. for 180 h) experiment, the EIS results show that low frequencies impedance (|Z| 0.01 Hz ) of the coatings follow the order of EP/H-Ce > EP/H-La > EP/H-Pr > EP blank. The |Z| 0.01 Hz of EPH-Ce is found to be 10 6.60 Ω at 180 h with almost little change with immersion time. Similarly, the results of Tafel polarization experiments show that the HEDP-Ce-containing coating has the highest corrosion potential (−0.16 V) and the lowest corrosion current density (0.01 μA). The difference in anti-corrosion property is discussed and explained by the inherent properties of rare earth element, including electron configuration, solubility product and redox property.