Corrosion resistance of water-cooled rebar quenched in a novel agent

摘要

Purpose - The purpose of the investigation was to research the corrosion resistance of water-cooled rebar quenched in a novel agent (CQ) named CQ-cooled rebar. Design/methodology/approach - Water-cooled rebar was quenched in CQ about 1 s, then cooled in air. The corrosion resistance of water-cooled rebar and CQ-cooled rebar was evaluated by atmospheric exposure (AE) and wet/dry cyclic accelerated corrosion tests (CCT). The electrochemical properties of the two rebar scales were researched using electrochemical tests, and their compositions and structure were examined using XRD, SEM and FT-IR. Findings - The corrosion tests showed that the corrosion resistance of CQ-cooled rebar was better than that of water-cooled rebar. The electrochemical tests indicated that the CQ-cooled rebar scale had a higher corrosion potential, a lower corrosion current density and a higher polarization resistance. The thickness of the scale was 56μm for CQ-cooled rebar, and 29μm for water-cooled rebar. The phase constitution of the two scales comprised Fe_2O_3, Fe_3O_4, 2FeO·SiO_2 and FeO, but the mass ratio of Fe_2O_3 and Fe_3O_4 to 2FeO·SiO_2 and FeO, called protective ability index of the scale (PAIS), changed from 0.45 for water-cooled rebar to 24 for CQ-cooled rebar. Originality/value - The results clarified the role of CQ-quenching in improving the corrosion resistance of water-cooled rebar, which was to generate thick and compact Fe_3O_4 and Fe_2O_3 layers over the rebar substrate, and retard the anodic dissolution and cathodic hydrogen evolution reaction.