First-principles and experimental study on the inhibition efficiency of BTA for 20SiMn steel in chloride-containing solutions

Abstract

The inhibition effect of benzotriazole (BTA) with the increase of concentration for 20SiMn steel in 3.5 wt% NaCl solutions was investigated by electrochemical methods, Scanning Electron Microscope (SEM), X-ray Photoelectron Spectroscopy (XPS) and Density Functional Theories(DFT). Results indicate that BTA could suppress the corrosion of 20SiMn steel through chemisorption but with a limited inhibition efficiency (around 60%). DFT calculated results show that the chemisorption of BTA has noticeable effects on the charge distribution of the whole BTA molecule, as well as that of N atom which bonds with Fe atom, but has little influence on those of Fe atom in N-Fe bond and Fe(110) surface where BTA molecules adsorb. The DFT calculated Density of States (DOS) peaks of N atom in N-Fe and those of BTA molecule become lower after the adsorption, and the location of DOS peaks move far away from the Femi surface, implying a more stable structure. As to Fe atom in N-Fe bond and Fe(110) surface, neither height nor locations of the DOS peaks change,which is crucial for losing electrons of metallic matrix and thus responsible for the limitation of BTA inhibition effect.