| DING Qing-miao,LIU Rui-yang,HOU Wen-liang.Influence of Extracellular Polymeric Substances on Corrosion Behavior of 2024 Aluminum Alloy in Aircraft Fuel Tank[J],51(12):197-207 |
| Influence of Extracellular Polymeric Substances on Corrosion Behavior of 2024 Aluminum Alloy in Aircraft Fuel Tank |
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| DOI：10.16490/j.cnki.issn.1001-3660.2022.12.020 |
| KeyWord:2024 aluminum alloy extracellular polymeric substances (EPS) simulated jetting water solution electrochemical tests corrosion morphology corrosion law |
| Author | Institution |
| DING Qing-miao |
Civil Aviation University of China, Tianjin , China |
| LIU Rui-yang |
Civil Aviation University of China, Tianjin , China |
| HOU Wen-liang |
The Third Engineering Branch of China Petroleum Pipeline Bureau Engineering Co., Ltd., Zhengzhou , China |
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| Abstract: |
| This paper aims to explore the effect of extracellular polymeric substances (EPS) secreted by sulfate-reducing bacteria in the environment where there is water in the aircraft fuel tank on the corrosion behavior of 2024 aluminum alloy and provide a theoretical basis for microbial corrosion and protection in aircraft fuel tanks. The growth of microorganisms in aviation coal caused the corrosion failure of the aircraft fuel tank material 2024 aluminum alloy. Sulfate-reducing bacteria EPS was isolated and extracted by high-speed centrifugation. Different experimental groups were formed by adding different contents of EPS to the simulated jetting water solution. Cut the 2024 aluminum alloy into long squares of 10 mm×10 mm×3 mm as the materials and smooth them by sandpaper and cleaned. After placing the experimental groups for 11 days, Fourier transform infrared spectroscopy (FT-IR) was used to analyze the composition of EPS. The corrosion behavior of aircraft fuel tanks 2024 aluminum alloy induced by EPS of sulfate-reducing bacteria was investigated with surface analysis method and electrochemical method in a simulated aircraft fuel tank water environment. Results showed that compared with the medium condition without EPS, under the same experimental conditions, the corrosion current density of 2024 aluminum alloy decreased under the action of the EPS. The corrosion product film showed a loose and porous morphology. The corrosion morphology was dominated by pitting corrosion. Within 11 days of the experiment, the corrosion behavior was divided into three stages when the EPS concentration in the solution was 100 mg/L and 200 mg/L. In the first stage, within 3 days of the experiment, it hindered the diffusion of dissolved oxygen and inhibited corrosion to a certain extent since the EPS coated on the surface of the aluminum alloy acted as a protective layer. The second stage was in the 3-7 days of the experiment, the non-uniformity of the EPS film became larger, and the corrosive ions accelerated metal corrosion. The third stage was after 7 days of the experiment, EPS formed a stable protective film on the metal surface. It connected with various substances in the protective film to hinder the diffusion of corrosion ions and dissolved oxygen and inhibit the oxygen absorption reaction of the cathode, resulting in the corrosion rate to slow down. The EPS-metal complex produced by the complexation of EPS and Al3+ promoted the anodic dissolution rate of 2024 aluminum alloy samples, but the main influence was to inhibit the diffusion of dissolved oxygen to slow down the cathodic oxygen absorption reaction. The effect of inhibiting corrosion was still proportional to the EPS concentration. The corrosion behavior of aluminum alloy was influenced by EPS in the simulated jetting water solution. The corrosion current density of 2024 aluminum alloy in a solution with EPS concentration of 200 mg/L was roughly 1/10 times that of no EPS. When the EPS concentration was 200 mg/L, the effect of inhibiting the corrosion of aluminum alloy was the best. With 300 mg/L EPS concentration in the solution, the EPS-metal complex lost its effect in isolating dissolved oxygen and accelerated the corrosion rate of the sample. |
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