Studies of Substituted Trialkoxysilanes as Corrosion Inhibitors

Issue 3(69) 2013
Pages 4-16
Ivanov E.S., Lar’kov A.P., Kluyev A.L.
Keywords: pipe steel 09gsf, acidic and neutral chloride media, corrosion inhibitors, substituted trialkoxysilanes

Organofunctional trialkoxysilanes with the overall formula of Х-R1Si(OR)3, where X is an organic functional group, R1 is a carbon bridge, OR is an alkoxy group, are studied as corrosion inhibitors for pipe steel 09GSF in acidic and neutral chloride media. Corrosion tests showed that the studied trialkoxysilanes are weak inhibitors in 1 М and 4 М HCl and are rather efficient in neutral 3% NaCl (Z≥90%). The performance of trialkoxysilanes depends on the nature of substituent Х. The most efficient inhibitors in neutral chloride media are γ-glycidooxypropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, and γ-isocyanatopropyltriethoxysilane (Z=93…95%). The EIS technique is used to study the mechanism of corrosion protection by trialkoxysilanes. It is shown that the most efficient of these form on the steel surface multilayer adsorption layers of siloxanes (Me-O-Si-O-Si-O-Si-), oligomerization products with a network structure, and adsorption layers bound to the metal via organofunctional group Х: [Ме-Х-R 1(OR) 3-n], where n is the number of hydrolyzed alkoxy groups.