Inhibition of brass corrosion in sodium chloride solutions by self-assembled silane films

Self-assembled monolayers (SAMs) of 3-mercaptopropyltrimethoxysilane (PropS-SH), dodecyltrimethoxysilane (DTMS), 3-aminopropyl(trimethoxy)silane (APS), and chloropropyl(trimethoxy)silane (CPTMS) were investigated to evaluate the influence of the silane molecule structure towards brass corrosion protection. The results indicated that SAMs of PropS-SH, CPTMS and DTMS inhibited the corrosion of brass in 0.2 M NaCl showing a mixed type behavior, while APS was not a good inhibitor. The inhibitive action of the PropS-SH and DTMS can be explained by chemisorption which obeys the Langmuir adsorption isotherm. The thiolate bond allows a better anchorage of the silane layer to the brass surface than the oxane bond.

► SAMs of PropS-SH, DTMS and CPTMS suppress corrosion of brass in 0.2 M NaCl.
► The inhibition efficiency of SAMs follows the sequence of PropS-SH > CPTMS > DTMS.
► Adsorption processes of PropS-SH and DTMS follow the Langmuir adsorption isotherm.
► Thiolate allows a better anchorage of silane layer to brass surface than oxane.