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| Degradation Behavior of Environmentally Friendly Epoxy Coatings in Salt Spray and Preliminary Study on the Correlation between Different Performance Parameters |
| Received:October 23, 2024 Revised:November 23, 2024 |
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| DOI：10.7643/issn.1672-9242.2025.02.010 |
| KeyWord:waterborne epoxy solvent-based epoxy EIS performance parameter correlation performance evaluation |
| Author | Institution |
| ZHANG Hanlu |
Unit 92228, Chinese People's Liberation Army, Beijing , China |
| LI Ziqiang |
Key Laboratory of Carbon Fiber and Functional Polymer, Ministry of Education, Beijing University of Chemical Technology, Beijing , China |
| CAO Jingyi |
Unit 92228, Chinese People's Liberation Army, Beijing , China |
| LIANG Jinglong |
Key Laboratory of Carbon Fiber and Functional Polymer, Ministry of Education, Beijing University of Chemical Technology, Beijing , China |
| ZHAO Xuhui |
Key Laboratory of Carbon Fiber and Functional Polymer, Ministry of Education, Beijing University of Chemical Technology, Beijing , China |
| TANG Yuming |
Key Laboratory of Carbon Fiber and Functional Polymer, Ministry of Education, Beijing University of Chemical Technology, Beijing , China |
| ZUO Yu |
Key Laboratory of Carbon Fiber and Functional Polymer, Ministry of Education, Beijing University of Chemical Technology, Beijing , China |
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| Abstract: |
| The work aims to study the failure processes and electrochemical behaviors of environmentally friendly waterborne epoxy coatings on Q235 carbon steel in salt spray test and explore the correlation between the main performance parameters. The changes of main performance parameters during the failure process of waterborne epoxy coatings and solvent-free epoxy coatings and their relationship with the protective properties of coatings were studied by electrochemical impedance technique (EIS), open-circuit potential (OCP), adhesion test and scanning electron microscope (SEM) and the correlation between some performance parameters was studied by Pearson correlation mathematical method. When the low-frequency impedance modulus |Z|0.01 Hz dropped to about 1×107 Ω.cm2, the OCP decreased rapidly, the break point frequency fb reached 102 Hz, the decay ratio of the adhesionwas close to 30%. At this time, corrosion products were observed on the steel substrate surface underneath the coating by SEM. When the |Z|0.01 Hz decreased to around 1×106 Ω.cm2, the OCP stabilized close to −0.45 V (vs. SCE), the adhesion decayed close to 45%, and meanwhile small rust spots were observed on the coating. There were strong correlations (correlation factor r is 0.60~0.96) between the |Z|0.01 Hz, the OCP, the adhesion and the fb. The water absorption process of waterborne epoxy coatings is different from that of solvent-based epoxy coatings, and there is no obvious water absorption saturation platform. Low-frequency impedance |Z|0.01 Hz, OCP, adhesion and characteristic frequency fb can be used as important parameters to evaluate the protective properties of coatings. |
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