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中性环境下高铬铸铁电化学腐蚀阳极溶解行为研究
Anodic Dissolution Behavior of Electrochemical Corrosion of High Chromium Cast Iron in a Neutral Environment
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- DOI:
- 作者:
- 金海霓1,2隋育栋1,2蒋业华1,2周谟金1,2
JIN Haini 1,2 , SUI Yudong 1,2 , JIANG Yehua 1,2 , ZHOU Mojin 1,2
- 作者单位:
- 1. 昆明理工大学材料科学与工程学院2. 昆明理工大学金属先进凝固成形及装备技术国家地方联合工程研究中心
1. College of Materials Science and Engineering, Kunming University of Science and Technology, Kunming 650000, China; 2. National & Local Joint Engineering Research Center of Advanced Metal Solidification Forming and Equipment Technology, Kunming University of Science and Technology, Kunming 650000, China
- 关键词:
- 高铬铸铁;电化学腐蚀;腐蚀电流密度;腐蚀电位;
high chromium cast iron; electrochemical corrosion; corrosion current density; corrosion potential
- 摘要:
- 面向长期在海洋大气环境下使用的高铬铸铁材料,其晶面取向不同的表面的腐蚀行为存在差异必然会引发微观腐蚀原电池及点蚀萌生。通过明确不同取向表面的腐蚀行为,调控特定取向表面的占比及组合,可有效减弱高铬铸铁材料的电偶腐蚀敏感性,延缓腐蚀速率。本文通过第一性原理建模,计算了KmTBCr26高铬铸铁中(100)、(110)和(111)3个晶面的腐蚀电位和腐蚀电流密度,获得了该牌号铸铁在NaCl中性环境下的电化学腐蚀阳极溶解反应极化曲线。结果表明,在理想表面的情况下,3个低指数表面中(100)面的腐蚀电位最高且腐蚀电流密度最低,分别为-0.5674V和-7.858 7 log(A/cm2),表现出最优的耐蚀性。而表面空位和C1吸附则会导致3个低指数表面腐蚀电流密度的计算结果增大,即阳极溶解速率加快,且略微降低了不同表面间溶解速率的差距;同时也会导致所有表面的腐蚀电位降低,略微缩小了不同表面间的电位差。
For high chromium cast iron (HCCI) used in marine atmospheres for a long time, the different corrosion behaviors of surfaces with different crystal orientations will inevitably lead to microscopic corrosion galvanic cells and pitting initiation. By defining the corrosion behavior of different oriented surfaces and adjusting the proportion and combination of specific oriented surfaces, the galvanic corrosion sensitivity of high chromium cast iron can be effectively weakened and the corrosion rate of high chromium cast iron can be delayed. Therefore, in this paper, the corrosion potential and corrosion current density of the (100), (110) and (111) crystallographic surfaces in KmTBCr26 high chromium cast iron were calculated by first principles modelling, and the electrochemical corrosion anodic dissolution reaction polarization curves of this HCCI in a neutral NaCl environment were obtained. The results show that the surface with (100) orientation has the highest corrosion potential and the lowest corrosion current density among the three low-index surfaces, which are -0.567 4 V and -7.858 7 log(A/cm 2 ) for the ideal surfaces, respectively, showing the best corrosion resistance. However, the existence of surface vacancies and Cl adsorption can lead to an increase in the calculated results of corrosion
current density on all the three low-index surfaces, that is, the anode dissolution rate is accelerated, and the dissolution rate gap between different surfaces is slightly reduced. At the same time, it also reduces the corrosion potential of all surfaces and slightly narrows the potential difference between different surfaces.