X65钢在含超临界CO_2的NaCl溶液中腐蚀机制的讨论  

CORROSION MECHANISM DISCUSSION OF X65 STEEL IN Na Cl SOLUTION SATURATED WITH SUPERCRITICAL CO_2

作　　者：魏亮[1] 庞晓露[1] 高克玮[1] 

机构地区：[1]北京科技大学材料物理与化学系,北京100083

出　　处：《金属学报》2015年第6期701-712,共12页Acta Metallurgica Sinica

基　　金：国家自然科学基金项目51271024;北京市自然科学基金重点项目2131004资助~~

摘　　要：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.In recent years, the corrosion problem of steels under supercritical CO2/H2O system in oil/gas pro- duction has got more and more attention. The temperature and pressure of some oil wells in China usually exceed 120℃ and 100 MPa, where CO2 is in supercritical state. To transportation easier and cost reduction, the oil/gas in pipelines is usually pressured to a high pressure, normally causes CO2 in supercritical state. The supercritical CO2 corrosion environment includes CO2-saturated water and H20-saturated CO2 phases. Moreover, corrosive ions such as Cl- usually exists in CO2 corrosion environment, however the influence of Cl on corrosion of carbon steel in su- percritical CO2-saturated NaCl solution and NaCl solution-saturated supercritical CO2 are investigated limited. The corrosion behaviors and corrosion rates of X65 carbon steel exposed in supercritical CO2-saturated 3.5%NaCl solution, supercritical CO2-saturated deionized water and NaCl solution-saturated supercritical CO2 systems were investigated. SEM, EDS and XRD were used to analyze the morphology and characteristic of corrosion product scale on the steel surface. The results show that the addition of Cl in supercritical CO2- satureated water significantly in- creased the corrosion rate of X65 steel, and modified the FeCO3 grain morphology. The average corrosion rate of X65 steel in NaCl solution-saturated supercritical CO2 was much lower than in supercritical CO2-saturated NaCl solution, but in supercritical CO2 phase X65 steel suffered serious localized corrosion. The corrosion process of X65 steel in supercritical CO2-saturated NaCl solution could be divided into three stages： the first was the active dissolu- tion stage, the surface of X65 steel was corroded inhomogeneous due to the competitive adsorption between CF and H2CO3, HCO3, and Fe3C as well as some lumpish matrix were residued on steel surface; the second was the ini- tiation stage of FeCO3 precipitation, Cl-postponed the precipitation of FeCO3, the FeCO3 scale formed in this peri- od

关 键 词：CO2腐蚀 超临界CO2 X65钢 Cl- 腐蚀机制 

分 类 号：TG172.9[金属学及工艺—金属表面处理]