Effect of Surface Roughness on Corrosion Resistance of Sol-Gel Coatings on AA2024-T3 Alloy

The effect of surface roughness on the corrosion resistance of sol-gel coatings on 2024-T3 aluminum alloy was studied. Mechanical abrasion with various grit size papers was used to produce different micro roughness on the alloy, and then the hybrid sol-gel coatings were formed. Scanning electron microscopy (SEM) and surface texture measurements were used to characterize the surface morphology. Pull-off tests were used to measure the adhesive strength of the sol-gel coatings. The corrosion protective performance of the coatings was evaluated by using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization. The adhesion strength of the sol-gel coatings on substrates with different roughness presented the similar value. The results show that the roughness of the metallic surface has significant influence on the corrosion resistance of sol-gel coating on AA2024 alloys. It indicates that the Al alloy with high roughness reduces the corrosion protection of sol-gel coatings. (C) 2015 The Electrochemical Society. All rights reserved.