The Corrosion Inhibition Effect And The Mechanism Of New Complexes As Inhibitors On Carbon Steel And Copper

It is a very economic and effective method that inhibitors are added-into solutions to inhibit the corrosion of metals, and the complexes of different inhibitors have become popular. The corrosion inhibition effects of 3-amino-1,2,4-triazole (3-ATA), the complex of 3-ATA and poly-aspartic acid (PASP),2-amino-5-mercapto-1,3,4-thiazole(5-AMT), and its complex with PASP on carbon steel (CS) and copper were respectively investigated in 5% hydrochloric acid (HCl) solution,5% sodium hydroxide (NaOH) solution and 3.5% sodium chloride (NaCl) solution. Electrochemical impedance spectroscopy (EIS), polarization curves and scanning electron microscopy (SEM) techniques were used. At the same time, the mechanism of corrosion inhibition was investigated in this paper.The experiment results show that all of these four kinds of inhibitors have corrosion inhibition effects on CS and copper in the three corrosion solutions. However, the corrosion inhibition efficiencies (η) of different inhibitors are different, so are the type and the mechanism of corrosion inhibitors.The main conclusions are as follows:(1) All of the four inhibitors have better corrosion inhibition effect on CS in 3.5%NaCl solution than in 5% HCl and 5% NaOH solutions, especially, the two kinds of complex show synergistic effect.3-ATA is an anodic inhibitor, and itsηis 93.51%; 5-AMT is a mixed inhibitor, and itsηis 92.46%; The complex of 3-ATA and PASP is an anodic inhibitor whoseηis up to 99.89% in this condition; The complex of 5-AMT and PASP is a cathodic inhibitor, and theηis 95.64%.(2) The corrosion inhibition effects of the four kinds of inhibitors on copper in 5% HCl solution are better than in 3.5% NaCl and 5% NaOH solutions, what's more, the two kinds of complex show synergistic effect on copper in 5% HCl solution.3-ATA is an anodic inhibitor, and itsηis 92.86%; 5-AMT is a mixed inhibitor with theηof 92.46%; The complex of 3-ATA and PASP is an mixed inhibitor, and theηis 95.70%; The complex of 5-AMT and PASP is a mixed inhibitor with a highη, which is 96.93%.(3) The corrosion inhibition effects of 3-ATA and its complex with PASP on CS. copper in 60% LiBr solution were investigated. It can be found that both of them have corrosion inhibition effect. Especially, the complex of 3-ATA and PASP both shows synergistic effect.