利用EIS高频区参数评价两种环氧涂层的性能

利用10 kHz下的相位角、10 kHz下的相对介电常数和对应于45°相位角的特征频率这3种EIS高频区的参数对两种环氧涂层体系在盐水浸泡+紫外照射的腐蚀条件下的失效过程进行了表征，并与涂层阻抗值进行了对比。测量结果表明，上述3种高频区参数的结果一致，都能够反映涂层性能的变化及相对优劣。当频率10 kHz处的相位角下降到40°，相对介电常数增大到40，或特征频率接近10 kHz时，所研究的两种环氧涂层体系的阻抗值都对应降低到10⁶ Ω•cm²左右，涂层保护性能接近失效。由于这几种EIS高频区参数能够很快测得，因此可以利用这些参数快速评价该涂层的保护性能与失效程度。

Evaluation of protective performance of organic coatings by EIS parameters at high frequency zone

The failure processes of two epoxy coatings exposed in 3.5% NaCl solution and violet light were studied by electrochemical impedance spectrum (EIS) technology.The work was focused on the variations of phase angle at 10 kHz, relative dielectric constant and breakpoint frequency with the decline of coating performance.The results showed that the three parameters from high frequency range of EIS gave similar results and might reflect the variation of coating performance.When the phase angle at 10 kHz decreased to 40°, relative dielectric constant increased to 40, or the breakpoint frequency approached about 10 kHz, the coating resistances of the two epoxy coatings studied decreased to about 10⁶Ω•cm², and the coating performance was very low.Therefore, the parameters may be used as quick methods to evaluate the protective performance of the coatings.