Electrophoretic deposition and corrosion behavior study of aluminum coating on AZ91D substrate

Aluminum coating was prepared on AZ91D magnesium alloy substrate using the electrophoretic deposition (EPD) method in absolute ethanol solvent. In order to determine the optimal concentration of AlCl3.6H2O additive, the zeta potential and size of particles in the suspension were measured in the presence of different concentrations of AlCl3.6H2O. The results showed that an appropriate coating is obtainable in the presence of  0.6 mM AlCl3.6H2O as an additive. The effects of applied voltage, deposition time, and additive concentration on deposition weight, deposition thickness, and coating morphology were also studied. A uniform coating with smaller pores and higher density was obtained at the additive concentration of 0.6 mM, deposition time of 18 min, and applied voltage of 70 V. The thickness of this coating was measured at about 256.91 µm. According to the results of corrosion behavior studies, the corrosion current density was measured at 29.16 and 12.85 µA/cm2 for uncoated and aluminum-coated AZ91D alloy, respectively.