Ca-P conversion coating on AZ60 magnesium alloy for biomedical application

To improve the anti-corrosion behaviors of magnesium alloy in the inner environment of human body, a bioactive Ca-P coating was deposited on the AZ60 magnesium alloy by a novel simple method. The morphologies of the Ca-P coatings formed under different treatment time were studied by scanning electron microscopy(SEM). The corrosion behaviors of Ca-P coating were investigated by electrochemical polarization test and electrochemical impedance spectroscopy in both 3%(mass fraction) NaCl solution and simulated body fluid(SBF). Immersion test in SBF was performed to evaluate the corrosion rate of Ca-P coated magnesium alloy. X-Ray diffraction(XRD) analysis result shows that the coating mentioned above mainly consists of dicalcium phosphate dehydrate(CaHPO4·2H2O, DCPD) and β-tricalcium phosphate dehydrate[β-TCP, Ca3(PO4)2], which exhibits good corrosion resistance. After magnesium alloy was immersed in 1 mol/L NaOH solution at 80 °C for 2 h, hydroxyapatite [Ca10(PO4)6(OH)2, HA] appeared on the magnesium alloy substrate, which can further decrease the corrosion rate of AZ60 magnesium alloy in SBF.