Effect of the Coating Deposition Technique on the Protective Properties of Hybrid Sol-Gel on AA2024

Abstract

The deposition technique effect on the corrosion properties of thin films applied on AA2024 was evaluated. The deposition techniques were spin-dip coating and brush-spray painting. For each technique different parameters were varied in accordance with its nature of deposition. The coating was synthesized by the sol-gel method of copolymerization of 3-Glycydoxypropyltrimethoxysilane, and tetra-n-propoxyzirconium was deposited on an AA2024 substrate. Scanning electron microscopy and atomic force microscopy revealed that the spin-coating method formed a more homogenous film than the dip-coating method. The time deposition and the surface finishing significantly modified the bond strength between substrate and sol-gel coating. The corrosion properties were assessed by Electrochemical Impedance Spectroscopy. These results revealed that the spin-coating technique provides not only better corrosion properties of the sol-gel but also a marked improvement of the corrosion resistance on aluminum at longer immersion times in NaCl. The combination of ground finishing in conjunction with time deposition modifies the properties of sol-gel significantly.