Effect of post-treatment techniques on corrosion and wettability of hydroxyapatite-coated Co–Cr–Mo Alloy

This study is a comparison between the effect of sintering and alkaline post-treatment techniques on calcium phosphate-coated Co–Cr–Mo alloy in terms of electrochemical corrosion behavior and wettability. The Co–Cr–Mo substrates were electrophoretically coated by calcium phosphate in a solution of Ca(NO3) · 4H2O and NH4H2PO4. The sintering and alkaline post-treatment techniques were then conducted to convert an as-deposited dicalcium phosphate dihydrate phase to crystalline hydroxyapatite (HA). The coated layers were characterized in terms of phase, crystallinity and composition using X-ray diffraction, Fourier transform infrared spectroscopy and energy-dispersive spectroscopy. In addition, morphology and thickness of coated layers were evaluated using a scanning electron microscope. The results indicate HA-coated samples with a sintering post-treatment technique exhibit more improvement in corrosion parameters, such as corrosion potential (Ecorr) and corrosion current density (Icorr), but lower enhancement in hydrophilicity. However, the HA-coated samples with an alkaline post-treatment technique reveal higher hydrophilicity with lower improvement in corrosion resistance