The influence of Ce(NO3)3·6H2O on the inhibitive effect of Ca(NO2)2 in simulated concrete pore solution

Abstract

The effects of cerium nitrite on corrosion behaviors of carbon steel in simulated concrete pore solutions were studied with the methods of linear polarization, electrochemical impedance spectroscopy and surface analysis. In pore solutions in the presence of Ce(NO3)3·6H2O, the corrosion potential, polarization resistance and impedance of carbon steel obviously increased in contrast to the situation in the absence of cerium salts. The pore solution with [NO2 −] / [Cl−] = 0.3 and 0.1% Ce(NO3)3·6H2O, carbon steel shows better corrosion resistance than that in the pore solution with [NO2 −] / [Cl−] = 0.6, which indicates that a small amount of Ce(NO3)3·6H2O in pore solutions can effectively promote passivation of the steel and reduce the threshold [NO2 −] / [Cl−] ratio for corrosion control. The surface layer formed in cerium salt containing pore solutions is more compact and smooth and 1.36%Ce is examined on the sample surface. The addition of 0.1% Ce(NO3)3· 6H2O in pore solutions can decrease the corrosion rate of steel in pore solutions and has little influence on pH change of the solutions. However, more cerium nitrate addition above 0.1% may result in pH decrease of the solution.