循环冷却水含铁细菌对20碳钢管壁腐蚀行为的影响

Effect of Iron Bacteria on Corrosion Behavior of 20 Carbon Steel in Circulation Cooling System

目前,有关循环冷却水中铁细菌对常用材料20碳钢管壁的腐蚀性报道较少。采用电化学测试技术和表面分析技术,研究了循环冷却管常用材料20碳钢在有无铁细菌循环冷却水中的腐蚀行为。结果表明:在含铁细菌的水中,20碳钢自腐蚀电流密度先由2.965×10^(-4)A/cm^2减小至1.420×10^(-4)A/cm^2再增大至1.653×10^(-4)A/cm^2,浸泡第10 d自腐蚀电流密度较无菌水中增加了1.3倍;有菌水中20碳钢的极化电阻呈先增大后减小的趋势,浸泡第10 d时的极化电阻比无菌水中小111.56Ω·cm^2,与极化曲线的变化呈相同的趋势;在有菌水中20碳钢表面有一些明显的腐蚀裂缝,较无菌水中严重;循环冷却水中铁细菌的存在导致20碳钢自腐蚀电位减小、自腐蚀电流增大、极化电阻明显减小,明显影响其元素成分的含量,从而加速了腐蚀进程。

Microbe-induced corrosion behavers of 20 carbon steel in circulation cooling system with/without iron bacteria were investigated by electrochemical measurement technology and surface analysis techniques. Result showed that in the circulation cooling system with iron bacteria, the corrosion current density of 20 carbon steel decreased from 2.965× 10-4 A/cm2 to 1.420× 10-4 A/cm2 and then increased to 1.653×10-4 A/cm2. After soaking for 10 d, the corrosion current density increased by 1.3 times. The polarization resistance of 20 carbon steel in the water system with iron bacteria was smaller than that without iron bacteria by 111.56 Ω· cm2, which presented similar trend to the polarization curves results. In the water system with iron bacteria, obvious corrosion cracks were observed on the surface of 20 carbon steel, and the corro- sion phenomenon was much more serious than that in water system without iron bacteria. In circulation cooling system, the existence of iron bacteria led to decrease of corrosion potential of 20 carbon steel electrode, increase of corrosion current density, and evident decline of polariza- tion resistance, which also significantly affected the elemental composition of 20 carbon steel electrode and accelerated the corrosion process.