二氧化碳腐蚀机理及影响因素

A STUDY OF MECHANISM AND INFLUENCING FACYORS OF CARBON DIOXIDE CORROSION

利用自制高温、高压腐蚀试验及电化学测试试验装置，用失重法、电化学极化曲线、扫描电镜及Ｘ射线衍射分析，研究了碳钢在ＣＯ＿２饱和的３％ＮａＣｌ溶液中ＣＯ＿２分压、温度对碳钢腐蚀的影响，结果表明，在较低温度（７０℃）时，碳钢腐蚀速率对数与ＣＯ＿２分压对数成线性关系，与ＤｅＷａａｒｄ等人的研究结果相符；７０℃时，腐蚀产物的附着力及耐蚀性很差，此时增大ＣＯ＿２分压加速腐蚀反应的阴极过程；１１０℃时碳钢腐蚀产物为致密的碳酸亚铁膜，此膜对金属基体的附着力较强、保护性好，温度对ＣＯ＿２腐蚀产物有明显的影响。文中还探讨了缓蚀剂抑制ＣＯ＿２腐蚀。

Using a self-made apparatus for corrosion test anddectroch6mic8l measurement tec卜nique underhightemperature andhighpressure,the enects Qf temperature and山epartia1pressure of carbon dioxide on the corrosion of carbon steel in CO_2 saturated 3% NaCl solu-tion is studied by weight-loss method, electrochemical polarization technique, scanning elec- tron microscope, and X-ray diffraction. Experimental resuIts show that the logarithm of cor-rosion rate of carbOn steel is linear with CO_2 partial pressure at lower temperature (70℃),which isconsistent with the results of De Ward and Milliams.The adhesivity and protectivi-ty of corrosion product formed at 70℃ are poor, and the cathodic process of the corrosion re- action accelerates with rising of CO_2 partial pressure. Dense iron carbonate film is formed onthe surface of steel, which exhibits good adhesivity and protectivity. Thus,temperature hasobvious effect on CO_2 corrosion product. In addition, inhibition of CO_2 and corrosion by in-hibitor is discussed also.