Corrosion behavior of Cr/RE alloyed rebar in carbonated simulated concrete pore solutions with chloride ions

摘要

The objective of this study is to investigate the corrosion resistance of low alloy steel rebars co -modified with Cr/RE in simulated concrete pore (SCP) solution under the join t action of carbonation and chloride salts. This study investigated the effect of the addition of Cr and RE microalloying regarding the steel rebar's resistance to corrosion in the co-existence of carbonation and chloride ions using electrochemical tests, scanning electron microscopy and confocal laser scanning microscopy. The best corrosion resistance of the Cr/RE microalloying rebar was found by the reduction in corrosion rates and the diminution of the rust layer. And In chlorine -containing simulated concrete pore solutions with varying pH levels, the corrosion rate follows the regularity HRB400-Cr-RE>HRB400-Cr>HRB400. During the initial stages of localized corrosion, the depth and K value of the corrosion pits was minimized, which indicating the addition of Cr/RE improved early resistance to pitting. Additionally, XPS analysis revealed that Cr/RE microalloying rebar can change the structure of the surface oxide film with a higher Fe(II)/Fe(III) ratio, confirming an enhancement in the structure of the passive film. In conclusion, the mechanism by which Cr/RE microalloying improves corrosion resistance involves grain refinement and the formation of Cr/RE oxides, which are enriched on the surface of the rebar in the SCP solution with severe carbonation (pH=9.6). This enrichment leads to the formation of a denser passive film.