Abstract
The inhibiting action of 3-(trimethoxysilyl) propanethiol-(l) (TMSPT) polymer film on steel corrosion in 3·5%NaCl solutions has been studied. The TMSPTlayer was obtained by direct polymerisation of the TMSPToligomer at different temperatures (60, 70, 80, 90, and 100°C). Free corrosion tests with exposure times in the range 120–360 h and electrochemical tests (potentiodynamic polarisation and electrode impedance measurement) were carried out at 25°C. Surface analysis of the polymer layer and the metal surface (before and after free corrosion tests) was carried out using X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy (with total reflection). It was found that TMSPT acts as a passivating cathodic and anodic inhibitor, owing to the barrier effect of its polymer layer formed on the steel surface, and as an active inhibitor because of the formation of a chemisorbed methoxysilane compound which modifies the metal surface, thus shifting the free corrosion potential to higher values.
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