Impact of voltage variation on topography, hydrophobicity, and corrosion behavior of the CeO₂-TiO₂ nanocomposite coating on AM60B Mg alloy prepared by plasma electrolyte oxidation

Abstract A superhydrophobic oxide layer on AM60B magnesium alloy was created by using a plasma electrolytic oxidation (PEO) technique and subsequent surface modification. PEO was applied in an electrolyte with/without CeO 2 -TiO 2 nanoparticles (NPs) by two different voltages of 350 and 450 V. Atomic force microscopy (AFM) and field emission scanning electron microscopy (FE-SEM) were used to evaluate the roughness and morphology of the surface. Water contact angles on the surface were measured to investigate the surface wettability. Potentiodynamic polarization tests in a 3.5 wt% NaCl solution were used to assess the corrosion resistance of the coating. Also, the FE-SEM images showed that increasing applied voltage, decreases the numbers and size of the pores on the surface. Results showed that applying PEO, increased the corrosion resistance of the bare AM60B because corrosion rate (C.R.) decreased from 1.523805 (bare AM60B) to 1.432107 mpy (PEO-450 V). Furthermore, using CeO 2 -TiO 2 NPs effectively enhanced the corrosion resistance of the bare AM60B by decreasing the corrosion rate from 1.523805 to 1.286469 mpy.