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在模拟高温高压H_2S/CO_2气田腐蚀环境中对镍基合金825表面钝化膜进行腐蚀试验,利用电化学方法测量其极化曲线、电化学阻抗谱(EIS)和Mott-Schottky曲线(M-S曲线),研究了温度和H_2S/CO_2分压比对其表面钝化膜电化学特性的影响。结果表明:温度和H_2S/CO_2分压比对镍基合金825表面钝化膜的电化学行为影响规律相同,温度升高或H_2S/CO_2分压比增大时,双电层电容和钝化膜电容均增大,电荷转移电阻和钝化膜电阻减小,载流子浓度增大,说明温度升高和H_2S/CO_2分压比增大时,钝化膜的致密性降低,容易遭到破坏,厚度减薄,对基体的保护性降低。
Corrosion tests were carried out on the passivation film of Ni-based alloy 825 in the simulated H_2S / CO_2 gas field. The polarization curves, electrochemical impedance spectroscopy (EIS) and Mott-Schottky curves (MS curves) were measured by electrochemical methods. , The effects of temperature and H 2 S / CO 2 partial pressure ratio on the electrochemical properties of the passivation film were studied. The results show that the influence of temperature and H 2 S / CO 2 partial pressure on the electrochemical behavior of passivation film on the surface of Ni-based alloy 825 is the same. When the temperature rises or the partial pressure ratio of H 2 S / CO 2 increases, the electric double layer capacitance and passivation film The capacitance increases, the charge transfer resistance and passivation film resistance decreases, the carrier concentration increases, indicating that the temperature rise and H2S / CO_2 partial pressure ratio increases, the densification of the passivation film to reduce susceptibility to damage , The thickness of the thinning, reducing the protection of the substrate.