Development of Ternary Hydroxyapatite-Al2O3-TiO2 Nanocomposite Coating on Mg Alloy by Electrophoretic Deposition Method.

In the present study, ternary hydroxyapatite (HA)-Al₂O_3-TiO₂ nanocomposite coating and HA nano-coating have been developed on Mg alloy by the electrophoretic deposition (EPD) method for temporary bioimplant application. Following this, a post-heat-treatment has been done at 250 °C for 2 h. Detailed microstructural studies indicate uniform deposition of coating with the presence of porosities (area fraction-16%), agglomerated particles of size range 0.3-1.8 μm and micro-cracks in composite coating. However, in HA-coated samples, the presence of porosities (area fraction-25%) and particles of size range 0.2-1.4 μm are observed. The phase evaluation shows the presence of HA, Al₂O₃, TiO₂, and Mg phases in the composite coating, whereas presence of HA and Mg phases in HA coating. The residual stress is tensile in nature with a value 88 MPa for composite coating and compressive in nature with a value − 82 MPa for HA coating. The hydrophilicity increases after applying the coating in terms of a decrease in contact angle from 66° for as received Mg alloy to 20-42°, where 42° for HA coating and 20° for composite coating. Corrosion studies reveal that the corrosion potential (Ecorr) of composite coating is marginally shifted toward the negative direction (− 1.3 V(SCE)) as compared to HA coating (− 1.2 V(SCE)). The corrosion rate decreases from 399 mpy for HA coating to 88 mpy for composite coating. [ABSTRACT FROM AUTHOR]