纯铁在流动海水中的电化学腐蚀行为

Electrochemical Corrosion Behavior of Pure Iron in Flowing Seawater

为了探究纯铁在天然海水中的腐蚀机理以及流速对其腐蚀行为的影响,进而对铁合金腐蚀研究提供理论基础,采用自行制造的水槽式流体流动装置,模拟流动海水对纯铁的腐蚀状况,利用电化学测试手段(自腐蚀电位监测,动电位极化)并结合表面与截面形貌分析,研究了纯铁在静止和选取流速(0.2,0.3,0.4m/s)下的海水中的腐蚀行为。结果表明:纯铁在流动海水中的耐蚀性比静止时差,且流速越大耐蚀性越差,其腐蚀过程仍主要受阴极氧扩散控制;纯铁在海水中的自腐蚀电位随流速的提高而负移。纯铁在静止海水中的腐蚀产生突起状形貌,在流动海水中腐蚀产生具有明显方向性的腐蚀坑。

The corrosion mechanism of pure iron in natural seawater and effect of flowing velocity on the corrosion behavior were investigated, aiming at providing theoretical basis for the research of corrosion of ferroalloys. Thus electrochemical tests such as monitoring of potential electrochemical corrosion and measuring of kinetic potential polarization were conducted on a sink-like fluid flowing device to investigate the corrosion behavior of pure iron in still seawater and seawater flowing at a velocity of 0.2,0.3 m/s, and 0.4 m/s. The morphologies of the corroded surfaces and crosssections were observed using a scanning electron microscope. Results show that pure iron in the flowing seawater had poorer corrosion resistance than that in still seawater, and its corrosion resistance became increasingly worsened with increasing flowing velocity. At the same time, the corrosion process of pure iron in seawater was still mainly controlled by diffusion of oxygen at cathode. Moreover, the corrosion potential of pure iron shifted negatively as the flowing velocity rose. And protrusions were formed on the corroded surface of pure iron in still seawater, while corrosion pits with obvious orientation were formed on the corroded surface in flowing seawater.