Effects of Oxygen Pressure and Chloride Ion Concentration on Corrosion of Iron in Mortar Exposed to Pressurized Humid Oxygen Gas
Effects of Oxygen Pressure and Chloride Ion Concentration on Corrosion of Iron in Mortar Exposed to Pressurized Humid Oxygen Gas
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DOI：
10.1149/2.1421809jes
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发表时间：
2018-01-01
影响因子：
3.9
通讯作者：
Akiyama, Eiji
中科院分区：
文献类型：
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作者：
Doi, Kotaro;Hiromoto, Sachiko;Akiyama, Eiji
采用一种新的高压氧加速腐蚀试验（HOACT），研究了氧分压对不同Cl-含量砂浆中铁腐蚀的影响。在HOACT条件下，在加压100%氧气和相对湿度为95%的条件下，对埋置在砂浆中的纯铁样品进行暴露和电化学测试，砂浆的覆盖厚度为5 mm。为了进行比较，这些测试也在具有相同相对湿度的环境空气中进行。氧还原电流密度的铁嵌入砂浆中的增加与氧气压力的增加，这表明嵌入铁的腐蚀，预计将加速与氧气压力假设的氧还原限制腐蚀电流密度。铁腐蚀砂浆没有Cl-是最小的，无论氧气压力。与此相反，铁在砂浆中的腐蚀与Cl-的增加，氧气压力到一定的压力，如预期的那样加速，并在铁表面上形成的锈的厚度增加与Cl-浓度下的每个氧气压力，表明Cl-是必要的启动腐蚀，这是加强在加压氧气。然而，当氧气压力超过一定水平时，腐蚀被抑制。电化学阻抗谱测量使用的传感器组成的一对碳钢电极在砂浆中显示，在过高的氧气压力下的碳钢的电荷转移电阻变得更高，相比于在较低的氧气压力，这表明腐蚀引发的抑制是由于在过量的氧气供应下的保护钝化膜的形成。因此，加压氧气加速了砂浆中的铁与Cl-的腐蚀;然而，过量的氧气抑制腐蚀。评价了有效加速砂浆中铁腐蚀的最佳条件。(C)作者（S）2018由ECS发布。
The effects of oxygen pressure on the corrosion of iron embedded in mortar with various Cl- contents were examined by using a novel hyperbaric-oxygen accelerated corrosion test (HOACT). Exposure and electrochemical tests of a pure iron sample embedded in mortar with a cover thickness of 5 mm were performed in HOACT condition with pressurized 100% oxygen gas and with relative humidity of 95%. For comparison, these tests were also performed in ambient air with the same relative humidity. Oxygen reduction current density of iron embedded in mortar increased with an increase in oxygen pressure, suggesting that the corrosion of the embedded iron is expected to be accelerated with oxygen gas pressure assuming an oxygen reduction limited corrosion current density. Iron corrosion in mortar without Cl- was minimal regardless of oxygen gas pressure. In contrast, the corrosion of iron in mortar with Cl- was accelerated with increasing the oxygen gas pressure up to a certain pressure as expected, and the thickness of the rust formed on the iron surface increased with Cl- concentration under each oxygen gas pressure, indicating that Cl- is necessary to initiate corrosion which is enhanced in the pressurized oxygen gas. However, when the oxygen pressure exceeded a certain level, the corrosion was suppressed. Electrochemical impedance spectroscopy measurement using a sensor consisting of a pair of carbon steel electrodes in mortar showed that the charge transfer resistance of the carbon steel under excessively high oxygen gas pressure became high in comparison to that at lower oxygen pressure, indicating the suppression of corrosion initiation is due to formation of a protective passive film under the excessive supply of oxygen. Consequently, the pressurized oxygen gas accelerates the corrosion of iron in mortar with Cl- ; however, excess oxygen suppresses corrosion. The optimum condition to efficiently accelerate corrosion of iron in mortar was evaluated. (C) The Author(s) 2018. Published by ECS.