Corrosion Inhibition Effect of Tungstate on Fine-Grain High- Strength Reinforcement in Simulated Concrete Pore Solutions Containing Chloride Ions

摘要

Tungstate and tungstate/tartrate inhibitors were used to mitigate the corrosion of fine-grain high-strength (FGHS) reinforcement in simulated concrete pore solutions containing 3.5% NaCl. Thephysical laws governing the inhibition were investigated using potentiodynamic polarization andelectrochemical impedance spectroscopy. The semiconductor characteristics of the corrosion productswere analyzed by plotting the Mott–Schottky curves and the corrosion morphology was observed usingSEM. A comparison with conventional carbon steel reinforcement (HPB300 steel) was also performed.The results indicated that tungstate is an anodic corrosion inhibitor. Sodium tungstate at concentrationsbetween 0.1 and 0.3 g/L provided good corrosion inhibition, decreasing the corrosion current densityfrom 12.3 μA·cm ?2 to 0.326 μA·cm ?2 . The carrier density of the corrosion product layer and theelectric double-layer capacitance decreased dramatically, while the charge transfer resistance improvedsignificantly. Furthermore, only a few pits formed on the FGHS reinforcement. The tungstate/tartratemixed inhibitor was found to display the advantages of a single inhibitor, although no synergistic effectwas observed. When the inhibitor was absent, the corrosion resistance properties of FGHSreinforcement were clearly inferior to those of HPB300 steel. However, the addition of tungstate ortungstate/tartrate mixed inhibitor led to improved indicators of corrosion resistance for the FGHSsample relative to HPB300 steel.