Investigation of the corrosion behavior of phosphate coated magnesium in a Kokubo Solution

• Published in: International journal of electrochemical science 2018-06, Vol.13 (6), p.6072-6082
• Main Authors: Quintana-Camacho, H., Ramírez-Reyes, J.L., Medina-Almazán, A.L., García-Navarro, N., Galicia-Aguilar, G.
• Format: Article
• Language: English
• Subjects: Biomaterials; Magnesium; Phosphate Coating
• ISSN: 1452-3981; 1452-3981
• DOI: 10.20964/2018.06.53

Magnesium is a biocompatible element. Nevertheless, in order for it to be used as a prosthesis or implant, it is necessary that the organism is able to assimilate it. Thus, it is essential to control its degradation rate. There are two means so as to reach this objective. The former consists in looking for one element to alloy it. As for the latter, a compound precipitation could be induced by means of a chemical conversion treatment. In the present work, we focused on the induction of Mg3(PO4)2 precipitation on a Mg surface from a phosphate solution of pH 10. The obtained compound was characterized by means of Scanning Electron Microscopy (SEM), X-Ray diffraction (XRD) and ellipsometry. Corrosion rate (CR) of Mg with the obtained precipitate was measured in a Kokubo solution by means of Linear Polarization Resistance (LPR); the capacitor at the metal-electrolyte interphase was determined using Electrochemical Impedance Spectroscopy (EIS) experimental data by varying the stabilization and exposition time. Results reveal the presence of Mg3(PO4)2 and Mg(H2PO4)2 on the Mg surface. It is suggested that the presence of MgO and Mg(OH)2 favors the precipitation of Mg3(PO4)2 on the surface of pure Mg exposed to a Kokubo solution. In the presence of Mg3(PO4)2 precipitate, the CR of Mg in a Kokubo solution decreases in an order of magnitude.