Investigation of corrosion performance of transition metal ions doped vinyltriethoxysilane films on steel

A film was formed on the metal surface after hydrolysis of vinyl triethoxy silane (VTES) compound to be used as a protective organic coating against corrosion. For this purpose, as a result of studies with different VTES concentrations, more homogeneous and stable films were obtained with 5% concentration. The relationship of the physical properties of the final silane film with the hydrolysis time was studied at different times, 24, 48 and 72 hours. The silanol functional groups formed during hydrolysis provide chemical bonding to the surface by polymerization, depending on the curing time and temperature. For this reason, different curing times and temperatures were studied, the curing temperature was 120°C and the curing time was determined as 1 hour. These coatings were produced on clean galvanized steel plate surfaces, the oil was removed from the surface, and they were characterized by scanning electron microscopy (SEM – EDS) techniques, and their corrosion performance was examined by electrochemical impedance spectroscopy test technique (EIS). The highest corrosion resistance was obtained in the coating with silane solution hydrolyzed for 72 hours. 20 mg/l cobalt (II) chloride hexahydrate and yttrium (III) oxide were added separately into this coating. An increase was observed in the corrosion resistance of galvanized steels coated after addition, and the highest corrosion resistance was obtained with cobalt additives.