Experimental study on multi-component corrosion inhibitor for steel bar in chloride environment

Abstract

This paper investigates one type of multi-component corrosion inhibitor for steel bars in chloride environment. Triethanolamine (TEA), tri-isopropanolamine (TIPA), sodium monofluorophos-phate (MFP) and sodium molybdate (T-4) were proportioned to prepare this multi-component corrosion inhibitor. Corrosion behavior of steel bar was evaluated using the polarization curve, electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM). The polarization curves were fitted using the adsorption isotherm models. Experimental results indicated that the steel bar corrosion in chloride solution can be reduced by the addition of either organic or inorganic corrosion inhibitors. This is attributed to the fact that organic corrosion inhibitor can form an adsorption film on the steel bar surface and inorganic corrosion inhibitor abates electrochemical reaction of steel bars. Compared to single component corrosion inhibitors, the corrosion rate of steel bars in simulated pore solution was significantly restrained by the multi-component corrosion inhibitor. The adsorption of multi-component corrosion inhibitor on the surface of steel bar can significantly reinforce the passive film by means of physical (organic) or chemical (inorganic) process. For all the investigated corrosion inhibitors, the adsorption isotherms were in good agreement with experimental results. The EIS result and equivalent electrochemical circuit confirmed the chemical reaction and physical adsorption process of the multi-component corrosion inhibitor. Therefore, the chloride induced corrosion of steel bars can be effectively controlled by the multi-component corrosion inhibitor.