CO2分压对20#钢在CO2/H2O气液两相塞状流中腐蚀行为的影响

摘要

利用失重法、SEM、EDS、XRD和 XPS等分析方法在自主设计的动态腐蚀实验装置上研究了 CO2分压对20#钢在CO2/H2O 气液两相塞状流中腐蚀行为的影响,对腐蚀试样进行了腐蚀速率分析、腐蚀形貌特征观察以及腐蚀产物成分与膜层结构特征分析.结果表明:随CO2分压的增加腐蚀速率增加,0.04 MPa、0.28 MPa下分别达到腐蚀速率最小值(1.1609 mm/a)和最大值(1.8988 mm/a);上管壁腐蚀产物随着CO2分压的增加最终形成颗粒较大的节瘤状产物,下管壁腐蚀产物由球形颗粒形成初始致密的单层膜逐渐转变为由致密的内层膜和具有网状连通裂纹的片状疏松外层膜构成;经 EDS元素分析可知上下壁面的腐蚀产物均由Fe、C、O 三种元素构成,XPS分峰图谱显示C 1 s、O 1 s和Fe 2 p均出现了三个拟合峰位,结合XRD分析可知腐蚀产物的主要组成相有 Fe3C、FeCO3、Fe2O3、Fe3O4、FeOOH.%The effects of CO2partial pressure on the corrosion behavior of 20# steel in CO2/H2O gas liquid two phase slug flow was studied by means of SEM,EDS,XRD,XPS and so on.The corrosion rate,corrosion appearance,the composition of corro-sion products and the structure characteristics of corrosion film were analyzed respectively.The results manifested that the corrosion rate increased with the increasing CO2partial pressure,and the minimum and maximum value of corrosion rate are 1.160 9 mm/a and 1.898 8 mm/a at 0.04 MPa and 0.28 MPa,respectively.With the increasing CO2partial pressure,the corrosion products of the upper wall formed a larger of nodular product.The corrosion products at the bottom pipe wall formed by the initial dense monolayer film consisted of the spherical particle,and gradually transformed into a dense inner layer film and a sheet loose outer layer with a net con-nected crack composed of sheet shape products.EDS element analysis demonstrated the corrosion products on the upper and bottom walls were composed of three kinds of elements including Fe,C and O.XPS peak pattern showed that C 1s,O 1s and Fe 2p presen-ted three fitting peaks.Combined with XRD analysis,the main compositions of corrosion products were Fe3C,FeCO3,Fe2O3, Fe3O4,FeOOH.