Abstract

Organosilane interlayers are widely used to improve the adhesion and corrosion resistance of multilayer protective coating systems. In this work, a nitrile-functional organosilane, 3-[(3-(triethoxysilyl)propyl)amino]propanenitrile (AN), was investigated as a precursor for thin protective coatings on St20 steel and as an adhesion-promoting interlayer for acrylic paint coatings. The coating formation process was optimized, and the structure, morphology, surface properties, adhesion performance, and corrosion resistance of the resulting coatings were comprehensively characterized using spectroscopic, microscopic, and electrochemical techniques. The results demonstrated the formation of a continuous and homogeneous organosiloxane coating with an average thickness of 84 ± 5 nm. Pull-off adhesion tests showed that the AN interlayer provided the highest adhesion strength (0.85 MPa) among the investigated coating systems. Electrochemical impedance spectroscopy and potentiodynamic polarization measurements confirmed a significant improvement in the barrier properties and corrosion resistance of the coated steel in both model and formation water electrolytes. Salt spray testing further demonstrated a more than fivefold reduction in metal mass loss and a substantial decrease in corrosion propagation from an artificial defect compared with the paint-only system. These findings demonstrate that the AN coating is a promising adhesion-promoting organosilane interlayer capable of enhancing both the adhesion and corrosion protection of multilayer coating systems.

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