Determination of optimum concentration of cloisite in an eco-friendly silane sol-gel film to improve corrosion resistance of mild steel

• Protective ecofriendly silane sol-gel coating with nanoclay was applied on mild steel.
• Electrochemical noise method was used to evaluate performance of the silane coating.
• Optimum nanoclay content was found using electrochemical methods and surface analysis
• Effect of nanoclay on coating barrier properties was confirmed by surface analysis.
• Good trend correlation between noise resistance and low frequency impedance was seen.

In this study, the effect of cloisite concentration on the protective performance of an eco-friendly silane sol-gel coating consisting of tetraethoxysilane (TEOS), methyltriethoxysilane (MTES) and glycidyloxypropyltrimethoxysilane (GPS) applied on mild steel substrate was investigated using electrochemical techniques and surface analysis. Through taking advantage of electrochemical impedance spectroscopy, potentiodynamic polarization and electrochemical noise measurements, the optimum concentration of nanoparticles was determined. In the presence of the cloisite content, superiority of the hybrid silane film was connected to the enhanced barrier properties, confirmed by FE-SEM, FTIR and water contact angle studies. Moreover, a good trend correlation was observed between the noise resistance and low-frequency impedance modulus data.