| JING Chaojie,GUO Hui,ZHAO Fangchao,WU Dequan,CHEN Xueqing,LIU Jie.Preparation and Protective Performance of BI@ZIF-8/EP Coating under Deep-sea Pressure[J],53(8):93-106 |
| Preparation and Protective Performance of BI@ZIF-8/EP Coating under Deep-sea Pressure |
| Received:May 05, 2023 Revised:September 12, 2023 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2024.08.009 |
| KeyWord:hydrostatic pressure simulated deep-sea pressure failure process infrared spectrum electrochemical impedance spectroscopy adsorption film |
| Author | Institution |
| JING Chaojie |
Weathering Test and Research Center of Science Technology and Industry for National Defense, Southwest Institute of Technology and Engineering, Chongqing , China |
| GUO Hui |
School of Chemistry and Chemical Engineering, Yantai University, Shandong Yantai , China |
| ZHAO Fangchao |
Weathering Test and Research Center of Science Technology and Industry for National Defense, Southwest Institute of Technology and Engineering, Chongqing , China |
| WU Dequan |
Weathering Test and Research Center of Science Technology and Industry for National Defense, Southwest Institute of Technology and Engineering, Chongqing , China |
| CHEN Xueqing |
AVIC China Aero-Polytechnology Establishment, Beijing , China |
| LIU Jie |
School of Chemistry and Chemical Engineering, Yantai University, Shandong Yantai , China |
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| Abstract: |
| The high pressure, low temperature, low dissolved oxygen and other harsh environments in the deep sea could cause accelerated failure of organic coatings. This has seriously threatened the service safety of deep-sea equipment. ZIF-8 is a representative zeolite imidazole type MOFs material. It is widely used in metal corrosion protection field because of its small particle size, high porosity and high specific surface area. Therefore, the work aims to develop a test protocol to investigate the failure behavior of the coating containing ZIF-8 particles loaded with corrosion inhibitors under two seawater pressure. In this work, the BI@ZIF-8 functional particles were prepared by the one-pot method, and the BI@ZIF-8/EP coatings were prepared by adding BI@ZIF-8 directly to epoxy coatings at the optimal mass ratio based on the conclusions drawn from the content of the previous studies. The structural characterization of the BI@ZIF-8 functional particles was carried out by FI-IR, XRD, UV, SEM, and TG. The prepared BI@ZIF-8/EP coatings were also subject to simulated seawater (3.5 wt.% NaCl) immersion tests at atmospheric pressure (0.1 MPa) and simulated deep-sea pressure (6 MPa). A blank control group of EP coating was also set up for comparison clarity. The comparative analysis of the failure behavior of the coating was carried out from the perspective of surface morphology, light loss rate, color difference, coating adhesion, electrochemical impedance spectrum and chemical structure. The test results showed that high hydrostatic pressure could significantly accelerate the diffusion of corrosive particles to the interior of the coating and accelerate the failure process of the coating. In the test of adhesion, BI@ZIF-8/EP coating had higher adhesion, and the adhesion decreased by 21.6% and 55.7% for 1 008 h under 0.1 and 6 MPa, respectively, which was significantly higher than that of EP coating under the same conditions. This was because the imidazole group in ZIF-8 particles could increase the crosslink density of epoxy coating and reduce the permeability of corrosive particles, which made BI@ZIF-8/EP coating have a higher adhesion. The BI@ZIF-8/EP coating consistently had higher impedance values under the same pressure conditions. After 1 008 h of test under 6 MPa, the impedance value of the EP coating dropped to 3.2×104 Ω∙cm2, which meant that the protective performance of the EP coating was largely lost. At this time, the impedance value of the BI@ZIF-8/EP coating was 4.39×106 Ω∙cm2 and the coating still had a certain protection ability. The reason was that the lone electron pair of N atom in BI molecule and 2-Melm molecule and the empty orbital of Fe atom could form adsorption film on the surface of metal substrate, and Zn2+ and OH− could form deposition film on the surface of metal substrate. The area and intensity of electrochemical reactions under the coating were effectively reduced. The rust at high water pressure and high Cl− concentration were transformed into streaky corrosion products. In the FT-IR test, the intensity of the BI characteristic peak in the BI@ZIF-8/EP coating under 6 MPa was significantly weakened with increasing immersion time, indicating that the degradation mechanism of the coating was not affected by pressure conditions. |
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