Optimization of process factors for the synthesis of advanced chrome-free nanocomposite sol–gel coatings for corrosion protection of marine aluminum alloy AA5083 by design of experiment

Nanocomposite sol–gel coatings based on tetraethylorthosilicate (TEOS) and 3-glycidoxypropyltrimethoxisilane (GPTMS) have been prepared for corrosion protection of AA5083. Statistical design of experimental methodology based on Taguchi orthogonal design has been used to study and optimize various parameters using multifactor analysis of variance (ANOVA). The corrosion current density has been used as a response. Structure, surface morphology and composition of the hybrid coatings were studied by using SEM, AFM and ATR/FTIR, respectively. Corrosion performance of coatings was examined using potentiodynamic polarization and EIS. The results show that by proper choice of parameters, adherent, dense and protective hybrid coatings can be obtained.

► The sol–gel films with optimum conditions provided a physical barrier on AA5083.
► Taguchi method has been found to be an effective tool in optimization of parameters.
► Hydrolysis water content among other factors is the most significant one.
► Film with higher inorganic and hydrolysis water content shows best corrosion resistance.