Corrosion and Wear Resistance Characterization of Environmentally Friendly Sol–gel Hybrid Nanocomposite Coating on AA5083

Abstract

Environmentally friendly organic–inorganic hybrid nanocomposite films have been developed by sol–gel method for corrosion protection of AA5083 alloy. The hybrid nanocomposite coatings have been synthesized from tetraethylorthosilicate (TEOS) and 3-glycidoxypropyltrimethoxysilane (GPTMS) precursors. The multilayer coatings were prepared by dip-coating technique. Attenuated total reflectance–Fourier transform infrared (ATR–FTIR) spectroscopy was carried out to show the formation of the Si–O–Si structural backbone of the hybrid coatings. Structure and surface morphology of the coatings were studied by optical microscopy (OM), scanning electron microscopy (SEM) and atomic force microscopy (AFM). Characterization of the coatings with respect to pencil scratch hardness, adhesive and abrasion resistance was performed. The corrosion protection performance of these coatings was examined by using cyclic potentiodynamic polarization technique in Persian Gulf water. The results revealed that crack-free films with smooth surface were obtained. With increasing the number of sol–gel coated layers, corrosion resistance increased from 81 to 419 kΩ cm 2 , while the abrasion wear resistance did not change significantly. However, the triple sol–gel coated layer offered excellent protection against corrosion.