Corrosion Resistance Improvement of Galvanised Steel by Doped Silane Pre-Treatments

Abstract

In this paper, galvanised steel substrates were pre-treated in γ-(2,3-epoxypropoxy) propytrimethoxy silane solutions containing salts ((NH4)2TiF6, K2ZrF6 and NaVO3) and SiO2. The surface microstructures of the coated substrates were evaluated by scanning electron microscopy (SEM). The anti-corrosion performance of the modified silane film applied on galvanised steel substrates was evaluated by potentiodynamic polarization (Tafel) and electrochemical impedance spectroscopy (EIS). The electrochemical results revealed that the addition of salts ( (NH4)2TiF6, K2ZrF6 and NaVO3) may produced a more stable and protective fluoride combined with their oxides in the silane layer. The results also revealed that the addition of the SiO2 nanoparticles reinforces the barrier properties of the silane films and imparts its corrosion inhibition ability.