Polymethyl (hydro)/polydimethylsilazane-derived coatings applied on AA1050: effect of the dilution in butyl acetate on the structural and electrochemical properties

Abstract

Polyorganosilazane (PSZ) has been used for many years as a ceramic precursor for the preparation of silicon carbonitrides. Recently, polymethyl (hydro)/polydimethylsilazane-derived coatings that can be cured with atmospheric moisture at low temperatures have attracted interest due to their hydrophobic nature and electrochemical properties. In this work, polymethyl (hydro)/polydimethylsilazane-derived coatings have been deposited on aluminum alloy AA1050. The effect of the PSZ precursor concentration (5–40 v/v%) on the final properties of the coatings has been investigated. Butyl acetate has been employed as solvent. The layers were applied on the substrate by dipping. The experimental results showed that the concentration of the PSZ in the solvent strongly affects the dry thickness of the hybrid layer. The electrochemical impedance spectroscopy measurements revealed that the coatings derived from PSZ precursor concentration higher than 20 v/v% are protective and homogenous. Contact angle measurements evidenced that the presence of the coatings increased the hydrophobicity of the substrate as well as the oleophobicity regardless of the dilution in the organic solvent. The graffiti resistance of the coatings has been demonstrated to be acceptable regardless of the dilution of the PSZ precursor, in the investigated range.