亚硝酸盐对含氯盐砂浆内钢筋钝化膜组成的影响

Effect of Nitrite on Passivation Film Composition of Reinforcing Bar in the Mortar Containing Chloride

关键词:  亚硝酸盐  砂浆  钝化膜  X射线光电能谱  微结构

Key words:  nitrite  mortar  passivation film  X ray photoelectron spectroscopy(XPS)  microstructure

摘要:

采用X射线光电能谱仪（XPS）研究了NaNO2对含氯盐砂浆内钢筋钝化膜微结构的影响，阐明了亚硝酸盐阻锈作用下砂浆内钢筋钝化膜的微结构变化规律及其特征.研究结果表明：NaNO2在碱性环境下与Fe元素反应生成中间产物Na2FeO2和(NaFeO2)2，进一步促进Fe3O4的生成，提高了阻锈效果；NaNO2的掺入促进了反应式向正向移动，提高了钝化膜中Fe3O4的含量；当普通碳钢钝化膜内5nm处Fe3+/Fe2+的百分比大于表层的Fe3+/Fe2+百分比时，钝化膜内部的致密性优于表面.NaNO2不参与钝化膜的组成，但参与生成钝化膜的反应过程，该反应过程为缓慢的动态平衡过程，可通过改变反应物的含量控制钝化膜厚度.

Abstract:

The effects of NaNO2 on the passivation film were studied through X ray photoelectron spectroscopy(XPS) in the chloride environment of the mortar. The microstructural variation and characteristics of the passivation film of mortar in this condition were clarified. The results show that the intermediate products Na2FeO2 and (NaFeO2)2 are formed at the reaction of NaNO2 with Fe in alkaline environment, which promote the formation of Fe3O4 and enhance the effect of rust. The increase of NaNO2 content can promote the forward reaction process so as to increase the content of Fe3O4 in the passivation film. The percentage of Fe3+/Fe2+ on the surface of the passivation film is lower than that of Fe3+/Fe2+ at 5nm. That is to say, the internal density of the passivation film of steel is denser than that of the surface.