Wear and corrosion behavior of electroless Ni-P- TiO₂- Al₂O₃ nanocomposite coatings on magnesium AZ91D alloy

In this work, the effect of electroless Ni-P- TiO₂- Al₂O₃ nanocomposite coatings on magnesium AZ91D alloy were investigated. Using Electroless coating, the Nickel phosphorus (Ni-P) were deposited on magnesium alloy with nano titania (TiO₂) and alumina (Al₂O₃) particles at different concentrations (0.5-0.5),(1-1),(1.5-1.5),( 2-2) g/L. The influence of nanocomposite deposit on surface properties of the alloy was characterized by an optical microscope (OM), scanning electron microscopy (SEM), energy dispersive x-ray dispersive (EDS). Wear and corrosion rate were determined by pin-on-disc and salts spray apparatus. The findings reveal that the increased microhardness (613VHN₁₀₀), low friction coefficient (0.22), and high wear resistance with a low specific wear rate of 1.3985x10^-5mm³/Nm at an optimum concentration ((1.5-1.5) g/L of nanoparticles. Similarly, the corrosion rate at (1.5-1.5)g/L showed the lowest rate of 0.000196 MPY compared to other nano co-deposits. This increase in microhardness, wear resistance, and corrosion resistance is significantly depended on the incorporation of nanoparticles. However, the results showed a converse trend when the concentration of nanoparticles exceeded optimum concentration (1.5-1.5)g/L due to agglomeration.