Progress in Organic Coatings ( IF 4.469 ) Pub Date : 2019-12-10 , DOI: 10.1016/j.porgcoat.2019.105459 Ting Fu, Xiaobo Tang, Zekai Cai, Yu Zuo, Yuming Tang, Xuhui Zhao
The impedance characteristic and degradation process of two epoxy coatings in 3.5 % NaCl solution and seawater environment were studied by using electrochemical impedance spectroscopy (EIS), scanning electron microscope (SEM) and infrared spectroscopy (FTIR) methods. Pearson’s correlation coefficient (r) method was used to analyze the correlation between the phase angles in different frequencies and the impedance at low frequency end (|Z|0.01 Hz) for epoxy coatings. The results show that in a middle frequency range (about 1–100 Hz) the phase angles have a strong positive correlation with |Z|0.01 Hz (r > 0.90–0.95). Based on the good linear relationship (log (|Z|0.01 Hz) = A + B × θ) between the phase angle in middle frequency range and the |Z|0.01 Hz values, it is suggested that the phase angle at 10 Hz (θ10Hz) is a suitable parameter to rapidly evaluate the degradation degree and the protective performance of the coatings.