Study On The Evaluation And The Mechanism Of Corrosion Inhibitors In Pit Corrosion

Study on the corrosion of reinforced concrete has attracted wide international attention. Many scholars engaged in this field. However, the research about the organic corrosion inhibitors is still in its infancy. Meanwhile, the process of the organic inhibiting pitting corrosion is not mature. Therefore, we discuss the mechanism on the pitting corrosion of 16Mn carbon steel in simulated pore solution and test for the effect of amine inhibitors in order to find common characteristics of corrosion inhibitors on the amine to guide the practical application of organic corrosion inhibitor.The electrochemical noise resistance decreases in the exponential form if 16Mn steel is developing in the process of pitting, and the nucleation rate first increased and then decreased. The pitting events will be reduced. But the peak amplitude of the current will increase in the active process (corrosion product covering the eclipse point).Low concentrations of nitrite cannot enter the pit, so there is little effect on the pitting. But it will replace the adsorbed chloride ions on the corrosion products .When the concentration increased to a certain amount, the ion diffusion is mainly affected by concentration impacts, nitrite ion soon spread to the inside of the pitting.The pitting charge can respond to the nitrite ion on the role of pitting electrochemical noise process effectively. Electrochemical result indicates that TEPA can inhibit the process of pitting on 16Mn carbon steel. The synergy research on the molybdate ion and TEPA have shown that TEPA can absorb the film on metal surface to prevent erosion of chloride ions while MoO42- ions can make the passive film become more dense. Electrochemical noise tests illustrate that the current changes in the peak width can be effective response to the efficiency of inorganic corrosion inhibitors, which is not an accurate evaluation of TEPA on the inhibition ability of pitting corrosion process.