Surface analysis of the 2-mercaptobenzothiazole corrosion inhibitor on 6082 aluminum alloy using ToF-SIMS and XPS

Abstract

This work presents a surface analytical study of a very thin surface layer of the 2-mercaptobenzothiazole (MBTH) corrosion inhibitor on 6082 aluminum alloy (automotive material) using time-of-flight secondary ion mass spectrometry (ToF-SIMS) and X-ray photoelectron spectroscopy (XPS). Both techniques confirmed the adsorption of MBTH on the AA6082 surface. A characteristic negative-ion ToF-SIMS signal at m/z 165.98 was found for the MBTH molecule, whereas positive-ion ToF-SIMS spectra were less informative for MBTH. A negative-ion SIMS fragmentation pattern of the MBTH molecule was suggested. ToF-SIMS imaging showed that MBTH forms islands of this corrosion inhibitor on the AA6082 surface with higher concentration (patchy adsorption). XPS measurements suggested that MBTH was adsorbed on the surface via an N–S-bridge configuration. In addition, surface characterization was also performed with atomic force microscopy (AFM), field emission scanning electron spectroscopy (FE-SEM), and energy dispersive X-ray spectroscopy (EDXS).