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利用高温高压反应釜研究了X65管线钢在含有超临界CO2(supercritical CO2,SC CO2)的3.5%NaCl溶液、去离子水以及溶解有NaCl溶液的超临界CO2相中的腐蚀行为.结果表明,Cl-的存在导致X65钢在含有饱和SCCO2的NaCl溶液中的腐蚀速率显著升高,腐蚀产物膜的晶粒形貌发生改变.X65钢在超临界CO2相中的腐蚀速率远远低于在NaCl溶液中的腐蚀速率,但出现局部腐蚀.X65钢在含有SC CO2的NaCl溶液中的腐蚀分为3个阶段:第一个阶段为基体快速溶解阶段,表面没有FeCO3生成;第二阶段为FeCO3开始沉积阶段,形成的FeCO3腐蚀产物膜不完整,增大了阴极还原反应面积,导致腐蚀加速;第三阶段为腐蚀产物膜保护阶段,形成的腐蚀产物膜致密性逐渐提高,保护性好,但Cl-仍然可以穿过腐蚀产物膜到达膜基界面,从而加速钢的腐蚀.建立了普通管线钢在含Cl-溶液中的超临界CO2腐蚀模型.
The corrosion behavior of X65 pipeline steel in 3.5% NaCl solution containing supercritical CO2 (SCCO2), deionized water and supercritical CO2 solution with NaCl solution was investigated by using a high-temperature and high-pressure reactor. The results showed that Cl -, the corrosion rate of X65 steel in NaCl solution containing saturated SCCO2 significantly increased and the grain morphology of the corrosion product film changed.The corrosion rate of X65 steel in supercritical CO2 phase was far lower than that in NaCl solution In the corrosion of X65 steel in NaCl solution containing SCCO2 is divided into three stages: the first stage is the rapid dissolution of the matrix stage, the surface without FeCO3 formation; the second stage is the deposition of FeCO3 Stage, the formation of FeCO3 corrosion film is not complete, increasing the area of the cathode reduction reaction, leading to accelerated corrosion; the third stage is the corrosion product film protection stage, the formation of the corrosion product membrane gradually increased density, good protection, but Cl- Can still pass through the film of corrosion products to reach the membrane-based interface, so as to accelerate the corrosion of steel.The supercritical CO2 corrosion model of common pipeline steel in Cl-containing solution was established.