Corrosion and wear behavior of AZ91D Mg alloy modified by electrophoretic deposition of TiO2-graphene composite coating

In the present study, the TiO 2 -graphene surface coating was prepared by electrophoretic deposition (EPD) on the AZ91D Mg alloy. The Taguchi method was used to optimize the parameters, including heat-treatment temperature, graphene addition, and EPD voltage. With the optimal parameter combination, the surface-treated sample exhibited a corrosion current density of 7.33 µA/cm 2 and a corrosion rate of 0.82 mpy, both significantly lower than those of the uncoated AZ91D alloy (41.30 µA/cm 2 and 2.85 mpy, respectively), indicating a substantial improvement in corrosion resistance. Furthermore, wear tests and microhardness measurements showed that the treated surface exhibited approximately a 64% reduction in friction coefficient and a 44% increase in hardness compared to the untreated base material. The results demonstrate that surface modification of AZ91D magnesium alloy via electrophoretic deposition can effectively enhance corrosion and wear resistance.