2205钢在模拟深海热液区中的腐蚀行为

Corrosion Behavior of 2205 Steel in Simulated Hydrothermal Area

利用交流阻抗法、线性极化法、动电位极化法及Mott-Schottky分析法,研究了2205钢在不同温度、20 MPa静水压的3.5%Na Cl溶液中的电化学性质,通过SEM、EDS及白光干涉仪分析了电化学测试后2205钢的腐蚀形貌及腐蚀产物。结果表明,在模拟深海热液区环境中,2205钢在25℃下具有良好的耐点蚀能力;溶液温度达到65℃时,2205钢表面会出现明显的点蚀现象;溶液温度达到150和200℃时,2205钢表面会产生裂纹状点蚀坑;65℃时,点蚀坑主要发生在奥氏体相内,100~200℃时,点蚀坑主要发生在铁素体相内。随着模拟深海热液区温度的升高,2205钢的电化学阻抗及线性极化电阻先减小后增大,且在150℃的电化学阻抗及线性极化电阻最小;2205钢的点蚀电位随着温度的升高先负移后正移,其在模拟深海热液区中生成的钝化膜载流子密度随着温度的升高而增大。

Deep-sea hydrothermal area has a lot of mineral resources, and study the corrosion behavior of metal in deep-sea hydrothermal area is useful for marine resource development. Electrochemical impedance spectroscopy, linear polarization, potentiodynamic polarization and Mott-Schottky analysis were used to study the electrochemical properties of 2205 steel in 20 MPa hydrostatic pressure 3.5%Na Cl solution with different temperatures. Corrosion morphologies and corrosion products of 2205 steel after electrochemical tests were analyzed by SEM, EDS and white light interferometry. The results show that2205 steel has good pitting resistance under 25 ℃ in simulated hydrothermal area, pit occurred on the surface of 2205 steel after the solution temperature reaching 65 ℃, crack-shaped pit occurred on the surface of 2205 steel under 150 and 200 ℃. Pit occurs in austenite phase at 65 ℃, and occurs in ferritephase at 100~200 ℃. Impedance and linear polarization resistance of 2205 steel first decrease and then increase with temperature increasing in simulated hydrothermal area, and impedance and linear polarization resistance under 150 ℃ are lowest. Pitting potential of 2205 steel first negative shift and then positive shift, and carrier density of passive film formed in simulated hydrothermal area increase with temperature increasing.