采用高温高压反应釜、失重法、X射线衍射法、扫描电镜观察及能谱分析等方法研究了N80钢在CO2与O2共存环境中不同温度下的腐蚀行为。结果表明, 在CO2与O2共存环境中, N80钢的腐蚀速率随温度的升高呈现先急剧增大后缓慢减小的趋势, 在90 ℃时腐蚀速率最大。XRD结果表明, 三个温度条件下腐蚀产物均由FeCO3, Fe3O4和Fe2O3多种腐蚀产物共同组成。在低温时, N80钢表面主要由FeCO3紧密地覆盖在试样表面, 阻碍腐蚀过程的进行; 随着温度的升高, 腐蚀产物中氧化物逐渐增多, 且疏松多孔, 保护作用减弱; 温度达到120 ℃时, 高温氧化铁产物逐渐变得致密, 具有一定保护作用。

The corrosion behavior of N80 steel in CO2/O2 co-existing environment at different temperatures was studied using high temperature and pressure autoclave, weight loss method, X-ray diffraction, scanning electron microscopy and energy dispersive spectrometer. The results showed that the corrosion rate of N80 steel increased rapidly first and then decreased slowly with temperature increasing in CO2/O2 co-existing environment. The maximum corrosion rate arrived when temperature was 90 ℃. From the results of XRD, the corrosion products formed in CO2/O2 co-existing environment were composed of FeCO3, Fe2O3 and Fe3O4 at three temperatures. The surface of N80 steel was closely covered by corrosion products mainly composed of FeCO3 which can prevent the corrosion process at low temperature. With temperature increasing, the oxide content of the corrosion products increased gradually which produced a loose film with weak protection. When the temperature reached 120 ℃, the iron oxide products became dense gradually, so the film had certain protective effect.