Inhibiting effects of some Schiff bases on the corrosion of bronze exposed to artificial acidic rain

摘要

Within an M-ERA.NET project named B-IMPACT, some polydentate Schiff bases were synthetized and studied as corrosion inhibitors for a copper alloy, reproducing the composition and microstructure of a Renaissance bronze. The aggressive environment consisted in a concentrated artificial acidic rain (ARX10) solution. In all cases, the substances were tested under saturated conditions (<10~(-3) M). Excellent inhibiting properties were exhibited by 2-(salicylideneimino)thiophenol (SITP) and good results were obtained with 2-(2-thiophenyl)imino-1,2-diphenylethanone (TPIE) and 2-(3-methoxy-salicylideneimino)thiophenol (MSITP) during 20 days of immersion, as evidenced by electrochemical impedance spectroscopy (EIS) monitoring. Surface analyses, such as Scanning Electron Microscope (SEM) observations, Raman and X-Ray Photoelectron Spectroscopy (XPS), were also performed to clarify the inhibition mechanism of the most effective substance.