Investigating the effects of chitosan solution and chitosan modified TiO2 nanotubes on the corrosion protection performance of epoxy coatings

Abstract

In this research, TiO2 nanotubes (TNT) are hydrothermally synthesized and modified by chitosan (named as TCS). The structures of the prepared nanomaterials are investigated by X-ray diffraction and X-ray photoelectron spectroscopy, while transmission electron microscopy is used for characterizing the morphology of the nanopowders. Moreover, epoxy coatings loaded with different wt.% of TCS (0.1, 0.5, and 1.0 wt%), aqueous chitosan solution (1 and 2.5 wt%), and both aqueous chitosan solution (2.5 wt%) and TCS (0.1, 0.25, 0.5, and 1.0 wt% TCS) are prepared which are abbreviated as E-TCS, ECS, and ECS-TCS coating systems, respectively. The corrosion behavior of the coated samples are considered by using salt spray and electrochemical impedance spectroscopy. Pull-off test is used to evaluate the adhesion strength of the prepared coatings to the substrate, and field emission scanning electron microscopy is used for considering the fracture surface of the coated steel panels. The results clearly show that the corrosion resistance increases in the following order: pure epoxy < E-TCS0.1% < ECS2.5% < ECS-TCS0.5%, revealing that modifying the epoxy matrix with chitosan and loading the TCS in the epoxy coating increase the corrosion resistance more effectively through an eco-friendly approach and provide good anti-corrosion stability which is related to the chemical compatibility between the nanofiller and the matrix.