Electrochemical impedance spectroscopy characteristic of degradation process for carbon fiber/vinyl ester composites in salt water

• Published in: Journal of composite materials Vol. 56; no. 8; pp. 1299 - 1312
• Main Authors: Tang, Yuming, Dun, Yuchao, Chen, Xueping, Zhou, Yong, Zhao, Xuhui, Zuo, Yu
• Format: Journal Article
• Language: English
• Published: London, England SAGE Publications 01-04-2022
• Subjects: Carbon fiber reinforced composite; T700/vinyl ester; electrochemical impedance spectroscopy; 3.5% NaCl solution; cathodic protection
• ISSN: 0021-9983; 1530-793X
• DOI: 10.1177/00219983211067700

The Electrochemical impedance spectroscopy of the T700/VE (vinyl ester) carbon fiber composite in 3.5% NaCl solution under open circuit potential (OCP) and cathodic polarization (−0.6 VSCE and −1.2 VSCE) conditions were studied, the moisture absorption was evaluated by weight gain test, and the degradation process was analyzed combined with scanning electron microscope. The T700/VE composite has very good resistance to degradation under OCP condition for long time (205 days) immersion, with about 0.38% moisture uptake and a slight decrease of low-frequency impedance (|Z|0.01 Hz). Cathodic polarization remarkably promotes the diffusion of moisture and ions in the resin matrix, the de-bonding between resin and carbon fibers, and characteristic of a porous electrode occurrence with a very quick decrease in |Z|0.01 Hz value. The variation of |Z|0.01 Hz is negatively correlated with the moisture absorption under OCP and −0.6 VSCE polarization conditions. So, |Z|0.01Hz may be used to monitor the water absorption and degradation process of the composite.