The influence of cooling processes on the corrosion performance of the rebar scale

摘要

The corrosion performance of rebar cooled by a chemical reagent (FM) was compared with water-cooled and air-cooled rebar. The influence of compositions and structure of the three scales on the corrosion resistance was analyzed. Furthermore, the reasons causing the structural difference between three scales were discussed. The results show that corrosion resistance of scale is improved through optimizing the compositions and structure of the scale. When cooled by FM, the anodic current density of the rebar electrode is less than that cooled by water or air, and the scale resistance and the charge transfer resistance is larger than that cooled by water or air. The Fe_3O_4 content in the scale is near 60% for FM-cooled rebar; however, the Fe_3O_4 content is only about 40% for water-cooled and air-cooled rebar. The FM-cooling produces a more compact outer Fe_3O_4 layer and a thicker Fe_3O_4 layer at the wustite/steel interface. Moreover, the FM-cooled scale presents the best adhesiveness of three kinds of scale. Therefore, the FM-cooled scale provides better protection to the matrix against rust.