Corrosion Behavior of Mg–Zn–Ca–Mn Alloy Coated with Nano-hydroxyapatite by Cyclic Voltammetry Method

Abstract: Coating and alloying are the two possible solutions for enhancing the corrosion resistance of magnesium. Nanostructured hydroxyapatite (n-HA) was coated on Mg–1% Zn–0.5% Ca–0.2% Mn by cyclic voltammetry method to increase its biocompatibility and bioactivity alongside corrosion resistance. XRD and EDS analyses approved the formation of hydroxyapatite. A central composite design (CCD) coupled with response surface methodology (RSM) was employed to optimize the four selected variables. Corrosion current density obtained from polarization tests in the simulated body fluid (SBF) was considered as the main response for optimization. The experimental values were fitted well by the derived model (R2 = 96.8%). The proposed optimum condition was − 1.4 V, 75 °C, 7 cycles, and 0.05 M for the start potential, temperature, cycle number and concentration of NaNO3, respectively. The corrosion current density of the sample made at the optimum condition was decreased around 90% compared with the bare one (1423 µA/cm2 to 136 µA/cm2). The FESEM images confirmed the formation of n-HA coating on magnesium alloy. The best coating adhesion among all samples was determined to be 4.52 MPa. Finally, the EIS test confirmed the results of previous corrosion experiments. The corrosion resistance of the optimized sample was measured to be about 2000 Ω cm2. Graphic Abstract: [Figure not available: see fulltext.]. © 2021, Springer Nature Switzerland AG.