Abstract
This paper reports the successful deposition of mono- and double-layer coatings of silane-Al2O3/multi-walled carbon nanotube (MWCNT) nanocomposites on magnesium alloy (AZ91) by sol-gel dip coating technique to improve the corrosion behavior. Scanning electron microscopy, atomic force microscopy, electrochemical impedance spectroscopy, and potentiodynamic polarization techniques were utilized to assess the protective performance of the coatings with various MWCNT contents (0.02, 0.05, 0.1, and 0.15 wt.%) and constant Al2O3 concentration (2 wt.%). The incorporation of an optimal amount of MWCNTs (0.1 wt.%) into the mono-layer coating led to corrosion resistance with polarization resistance and roughness of 183.4 kΩcm2 and 23.97 nm, respectively. In the case of the double-layer coatings, 0.15 wt.% MWCNT was the optimal value as it significantly increased the polarization resistance (349.6 kΩcm2) and reduced the roughness (5.58 nm), and cracking. The mentioned coating system can be a promising candidate to protect AZ91 magnesium alloy against corrosion