Hybrid sol-gel coatings doped with non-toxic corrosion inhibitors for corrosion protection on AZ61 magnesium alloy

Abstract

Physiological human fluid is a natural corrosive environment and can lead to serious corrosion and mechanical damages to light Mg-Al alloys used in prosthetics for biomedical applications. In this work, organic-inorganic hybrid coatings doped with various environmentally friendly and non-toxic corrosion inhibitors have been prepared by the sol-gel process for the corrosion protection of AZ61 magnesium alloys. Effectiveness has been evaluated by pH measurements, optical microscopy, and SEM during a standard corrosion test in a Hanks' Balanced Salt Solution. The results showed that the addition of an inhibitor to the sol-gel coating can improve significantly the corrosion performance, being an excellent barrier for the L-cysteine-doped hybrid sol-gel films. The incorporation of TiO2 nanoparticles, 2-Aminopyridine and quinine organic molecules slowed down the corrosion rate of the Mg-Al alloy. Graphene oxide seemed to have the same response to corrosion as the hybrid sol-gel coating without inhibitors.