X65管线钢在沉积物下腐蚀与缓蚀剂作用效果

Corrosion of X65 Pipeline Steel Under Deposit and Effect of Corrosion Inhibitor

通过电化学阻抗谱和动电位扫描法研究X65管线钢在含氧氯化钠溶液中沉积物对电化学参数的影响。采用电阻法(ER)结合零电阻电流计(ZRA)研究X65钢在沉积物覆盖下的电偶腐蚀行为与不同浓度有机膦缓蚀剂的作用效果。结果表明:X65钢在SiO_2沉积物覆盖时腐蚀电位负移,腐蚀速率降低。当有沉积物覆盖与无沉积物覆盖的电偶试片相连时,X65钢在沉积物下发生阳极极化,阳极电偶电流密度在18h内由120μA/cm^2衰减到50μA/cm^2并保持稳定。依次加入5×10^(-5),8×10^(-5)和3×10^(-4)浓度的PBTCA后,电偶电流在最高升至1300μA/cm^2后逐渐下降并稳定在610μA/cm^2附近,沉积物下X65钢腐蚀速率达到6.11mm/a,PBTCA加速了X65钢在含氧溶液中沉积物下的腐蚀。通过对试片表面进行观察,沉积物下X65钢表面发生了严重的局部腐蚀。

Effect of the deposit on the electrochemical parameters of X65 pipeline steel in oxygen contained sodium chloride solution was studied by EIS and PDS methods. The galvanic corrosion behavior under deposit and effect of different concentration of corrosion inhibitor PBTCA were studied by elec-trical resistance （ER） method combined with ZRA. The results show that the corrosion potential of X65 steel shifts negatively as Si02 covering its surface and the corrosion rate becomes lower. When the galvanic couple specimen with deposit is electrically connected with the specimen without deposit, anodic polarization occurs on X65 steel under deposit and the galvanic current density decreases from A/cm2 to 50jLtA/cm2and keeps stable. As 5X10-5 , 8 X 1 0-5 and 3 X 10-4 P B T C A were introduced into the solution, the galvanic current density reaches the highest 1300μA/cm^2 and then decreases to 610μA/cm^2 keeping stable around 610μA/cm^2, corrosion rate of X65 steel under deposit reaches 6. 11mm/a. PBTCA accelerates the corrosion of X65 steel under deposit in oxygen contained solution. Through the investigation on the surface of the specimens, serious local corrosion occurs on the X65 steel surface under deposit.