硫酸
腐蚀
硫酸盐
氯化物
点蚀
材料科学
离解(化学)
冶金
电化学
无机化学
化学
电极
物理化学
作者
Elina Huttunen‐Saarivirta,Elisa Isotahdon,Mari Lindgren,A. Mardoukhi,Petra Močnik,Tadeja Kosec,Jean-Baptiste Jorcin,S. Hägg Mameng,Y. El Ouazari,L. Wegrelius
出处
期刊:Corrosion
[NACE International]
日期:2022-08-02
卷期号:78 (10): 943-962
被引量:5
摘要
This study investigates the corrosion behavior of three stainless steel grades at two H2SO4 concentrations, namely 1 wt% and 10 wt%, with varying NaCl concentrations in the range from 500 mg/L to 10,000 mg/L. Dissociation of sulfuric acid yields the hydrogen (H+) and sulfate () ions, the former of which lowers the pH value of a solution while the latter increases the concentration of sulfate ions that act as a corrosion inhibitor. The equilibrium chemistry of the solutions was defined at the test temperatures of 22°C, 50°C, 90°C, and 130°C, and correlated with the observations on the electrochemical and microstructural examination of the materials. The results showed clear differences in the main corrosion form between the two H2SO4 concentrations. In 1 wt% H2SO4, pitting was the major form of corrosion attack in the presence of chlorides, whereas uniform corrosion dominated in 10 wt% H2SO4. The pitting corrosion tendency for the three stainless steel grades under various test conditions was consistent, but there were differences in their resistance to uniform corrosion. The chloride-to-sulfate activity ratio, , was found to be the key parameter in defining the occurrence of pitting corrosion for all three alloys. In H2SO4-NaCl systems, no pitting occurred at the activity ratio below 10, with higher values inducing pitting attack, particularly in 1 wt% H2SO4. The described novel results are presented and discussed in this paper.
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