环境介质对动态直流干扰下X80钢腐蚀行为的影响

Effect of Environmental Medium on Corrosion Behavior of X80 Steel under Dynamic DC Interference

采用腐蚀失重法、电化学阻抗谱等研究了动态直流干扰下X80钢在土壤、石英砂+土壤模拟液、土壤模拟液和土壤浸出液等4种环境介质中的腐蚀行为。结果表明:在对称动态直流干扰下X80钢在固体介质中发生局部腐蚀,在液体介质中则发生全面腐蚀。当负半周的干扰电流密度大于正半周的干扰电流密度时,X80钢在固、液体环境介质中的腐蚀形貌分别为全面腐蚀和局部腐蚀,X80钢在不同环境介质中的腐蚀速率和电流腐蚀效率均降低。4种环境介质,按X80钢的腐蚀速率和电流腐蚀效率从低到高依次为土壤、石英砂+土壤模拟液、土壤模拟液和土壤浸出液。腐蚀产物膜层电容和双电层电容的充放电效应与阴极过程的参与,是导致X80钢在环境介质中的电流腐蚀效率较低的主要原因。阴极过程的参与促使更多Fe^(2+)还原成Fe以及生成带有Fe^(3+)的腐蚀产物,可能是导致相同干扰条件下X80钢在固态介质中的腐蚀质量损失较在液体介质中减少的重要原因。

The corrosion behavior of X80 steel in soil,quartz sand+soil simulation solution,soil simulation solution and soil extract under dynamic DC interference was studied by weight loss method and electrochemical impedance spectroscopy.The results showed that the corrosion morphology of X80 steel was localized corrosion in solid environment medium and general corrosion in liquid environmental medium under symmetric dynamic DC interference.When the interference current density in the negative half cycle was greater than that in the positive half cycle,the corrosion morphology of X80 steel in solid and liquid environmental mediums was general corrosion and localized corrosion respectively,and the corrosion rate and current corrosion efficiency of X80 steel in different environmental mediums were reduced.Among the four environmental mediums,the order from low to high corrosion rate and current corrosion efficiency of X80 steel was in soil,quartz sand+soil simulation solution,soil simulation solution and soil extract.The main reason for the low current corrosion efficiency of X80 steel in environmental mediums was the charge-discharge effect on capacitance elements of corrosion product film and electric double layer,and the participation of cathodic process.The participation of cathodic process promoted the reduction of more Fe^(2+) to Fe and the formation of Fe_(3)O_(4),Fe_(2)O_(3) and Fe(OH)_(3) with Fe^(3+),which might be an important reason for the reduction of weight loss of X80 steel in solid medium compared with that in liquid medium under the same interference condition.