Characterization and Corrosion Resistance of the Twin-Wire Arc Spray Al-5Mg Alloy Coating Applied on a Carbon Steel Substrate

The Al-5Mg alloy coatings were fabricated by the twin-wire arc thermal spray on the SS400 steel substrate using various spraying parameters. The surface morphology of the coatings was examined using field emission scanning electron microscopy (FE-SEM). The porosity of the coatings was investigated by image analysis according to ASTM E2109-01 standard. The corrosion behavior of the coatings immersed in 3.5 wt. NaCl solution was investigated by electrochemical polarization scanning and electrochemical impedance spectroscopy measurement. The study results showed that the coating deposited with a spray mode consisting of current of 300 A, pneumatic pressure of 5.5 bar, and standoff distance of 160 mm has higher Al and Mg elemental content than the coating fabricated with other spray parameters. The porosity of the coating varies from 7.38 to 11.82, depending on the spray mode. The corrosion mitigation of the Al-Mg alloy coating was considerably enhanced due to higher contents of Al and Mg, a homogeneous surface, and low porosity. © 2023, ASM International.