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| Failure Behavior of Graphene Modified Zinc-Rich Epoxy Coating in Neutral Salt Spray and Cyclic Temperature Immersion Tests |
| Received:August 29, 2021 Revised:October 19, 2021 |
| View Full Text View/Add Comment Download reader |
| DOI：10.7643/issn.1672-9242.2021.11.001 |
| KeyWord:zinc-rich epoxy coating graphene 20# steel EIS failure behavior |
| Author | Institution |
| ZHANG Han-lu |
No.92228 PLA, Beijing , China |
| CAO Jing-yi |
No.92228 PLA, Beijing , China |
| WEI Han |
Key Laboratory of Carbon Fiber and Functional Polymer, Ministry of Education, Beijing University of Chemical Technology, Beijing , China |
| CHEN Xue-ping |
Key Laboratory of Carbon Fiber and Functional Polymer, Ministry of Education, Beijing University of Chemical Technology, Beijing , China |
| XING Chao |
Key Laboratory of Carbon Fiber and Functional Polymer, Ministry of Education, Beijing University of Chemical Technology, Beijing , China |
| TANG Yu-ming |
Key Laboratory of Carbon Fiber and Functional Polymer, Ministry of Education, Beijing University of Chemical Technology, Beijing , China |
| ZHAO Xu-hui |
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: |
| This paper aims to study the failure process and behavior of the epoxy zinc-rich graphene coating on the surface of 20# steel in neutral salt spray and high and low temperature cyclic immersion (3.5% NaCl solution, 45 ℃ 12 h+RT 12 h) tests. Electrochemical impedance spectroscopy (EIS), open circuit potential (OCP), scanning electron microscopy (SEM/EDS) and infrared spectroscopy (FTIR) methods were used to study the failure behavior of graphene modified zinc-rich epoxy coating and the protection of 20# steel in neutral salt spray and cyclic temperature immersion tests (3.5wt% NaCl solution, 45 ℃ 12 h + RT 12 h). And explore the low-frequency impedance evaluation standard of coating failure. The results showed that after coating samples were immersed in neutral salt spray for 79 d and high and low temperature cycles for 160 d, rust spots began to appear on the surface and lost the protective effect on the substrate. At this time, the low-frequency impedance (|Z|0.01 Hz) value dropped to 7×104 W×cm2. Except for the shielding property, the graphene modified zinc-rich epoxy coating can also provide the cathodic protection for the steel substrate, meanwhile, the cathodic protection in the high and low temperature immersion environment has a slightly longer duration of action. In the two accelerated test environments, the gloss loss rate of the coating was “significant loss of light”, the color difference reached or approached “large discoloration”, and the characteristic functional groups in the coating presented did not change significantly. Low frequency impedance (|Z|0.01 Hz) usually is lower than 1×106 W×cm2 to measure the failure criterion of organic coating (without conductive particles), which is not suitable for evaluating epoxy zinc-rich graphene on carbon steel surface for the coating system, the failure evaluation of the system may need to be reduced by about 2 orders of magnitude, which is about 7×104 Ω.cm2. |
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