SO2对海洋大气环境中含铬耐候钢腐蚀行为的影响

Effect of SO2 on corrosion behavior of Cr-containing weathering steel in simulated marine atmosphere

为了研究工业大气污染对含铬耐候钢腐蚀行为的影响,经真空感应熔炼、轧制含铬和无铬两组耐候钢,以NaCl、NaHSO3为腐蚀介质,通过干湿循环加速腐蚀试验、腐蚀失重分析并结合XRD、SEM等方法,分析对比了含铬耐候钢在含SO2以及不含SO2海洋大气环境中的腐蚀行为。结果表明,在Cl^-1、Cl^-1+SO2环境下,铬均降低了钢的腐蚀深度,SO2加重了钢的腐蚀。试验钢锈层均主要由α-FeOOH,β-FeOOH,γ-FeOOH和Fe3O4构成,质量分数有所区别;在Cl^-1+SO2环境下,合金铬对α-FeOOH的形成有促进作用;SO2明显抑制了含铬钢中β-FeOOH的形成,降低了γ-FeOOH和Fe3O4的质量分数,并促进了含铬钢中α-FeOOH的形成。单一Cl^-环境中,含铬钢锈层有明显分层现象,外锈层疏松,内层致密;在Cl^-1+SO2环境下,含铬钢锈层无明显分层现象。在Cl^-1+SO2环境下,无铬钢中硫、氯元素富集于内锈层;含铬钢中铬在试验钢内锈层出现一定的富集,氯元素均匀分布于锈层中,硫元素在外锈层处富集。

In order to study the effect of industrial air pollution on the corrosion behavior of Cr-containing weathering steel in marine atmosphere,the alternative wet/dry cyclic accelerated corrosion tests,using NaCl and NaHSO3 solutions as corrosive medium,and XRD,SEM were employed in tested steels with and without Cr which were vacuum induction melted and rolled,comparing the corrosion behavior in simulated marine atmosphere which contains and does not contain SO2.The results showed that the corrosion depth was decreased by the addition of Cr while was increased by the presence of SO2.The rust of two samples was both mainly composed of α-FeOOH,β-FeOOH,γ-FeOOH and Fe3O4.The transformation of Fe3O4 to α-FeOOH was promoted by the addition of Cr.The formation of β-FeOOH was hindered by SO2.Meanwhile,the transformation from γ-FeOOH and Fe3O4 to α-FeOOH in Cr-containing tested steel was promoted by the existence of SO2.Cr enriched in the inner rust layer which could help to increase the weather resistant performance.When there is no Cr in the steel sample,S and Cl enriched in the inner rust layer.However,0.43% Cr had shown the trend of cation selectivity since S enriched in the outer layer and Cl distributed evenly in both Cl^-1 and Cl^-1+SO2 containing environment.