Effect of pH on the structure and corrosion protection properties of sol-gel coatings

In this work, effect of pH on the structure and corrosion protection properties of sol-gel coatings were investigated, with a special focus on a broad pH range (pH = 1-10) of sol synthesis process. Viscosity, molecular weight, particle size measurements of sols and structural analysis of sol-gel coatings show the highest condensation degree in pH = 4 samples. Electrochemical, localized electrochemical techniques and morphology characterization demonstrate the best corrosion resistance of pH = 4 coatings. Results reveal that high condensation degree results in a compact and stable three-dimensional sol-gel network with high crosslinking density and less silanol content, providing highly effective corrosion protection.