Study of the effect of nanoclay incorporation on the rheological properties and corrosion protection by a silane layer

The corrosion protection properties offered to galvanized steel by an aqueous based silane layer are studied after incorporation of different amounts of sodium montmorillonite nanoclays (Na MMT). The rheological behaviour of Na + nanoclays in aqueous suspensions was determined in order to select the appropriate sonication time and concentration for incorporation in the silane matrix. The effect of sonication on the disaggregation/exfoliation of platelets was evaluated by using different characterization methods such as using the methylene blue (MB) dye as a spectrophotometric probe (UV–vis), zeta potential and hydrodynamic diameter measurements. The corrosion protection conferred to galvanized steel substrate by the modified silane layer was evaluated by electrochemical impedance spectroscopy (EIS) in 0.1 M aerated sodium chloride solution. The barrier properties of the silane layer are significantly increased by addition of 2 wt.% of clay sonicated for 1 and 2 h.