Cobaltous acetate doped sol-gel coatings for corrosion protection on aluminium alloy LY12

The aim of this study is to investigate the effect of cobaltous acetate doping on the corrosion resistance of sol-gel coatings on aluminium alloy LY12. The morphology and chemical composition of the coatings are investigated respectively by scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) are used to study the corrosion resistance mechanism of the coatings immersed in 0.05 mol/L NaCl solution. The results demonstrate that the doping of cobaltous acetate represented a remarkable improvement for the corrosion resistance of the coatings. In addition, the immersion test reveales that cobaltous acetate doping provided corrosion inhibition effect to the coatings. However, cobaltous acetate of relatively high concentration in sol-gel coatings might undermine both the stability and the corrosion resistance performance of the coatings after immersion.