Institute of Chemistry of Far-Eastern Branch of Russian Academy of Sciences, Vladivostok, Russia:

S. V. Gnedenkov, Professor, Deputy Director for Science, Head of Department of Electrochemical Systems and Surface Modification Processes
S. L. Sinebryukhov, Assistant Professor, Head of Laboratory of Nonsteady Surface Processes
A. V. Puz, Head of Laboratory of Composite Biomedical Purpose Coatings, e-mail: smol_shaman@mail.ru
D. V. Mashtalyar, Senior Researcher (Laboratory of Composite Biomedical Purpose Coatings)

The calcium phosphate coatings consisting of magnesium oxide and hydroxyapatite, accelerating osteogenesis, were obtained by plasma electrolytic oxidation (PEO) on the surface of the magnesium alloys (Mg – Mn – Ce, Mg – Zn – Zr systems). Phase and elemental composition, morphology and corrosion resistance of the coatings were investigated in this work. The combination of physicochemical methods was used for the definition that sealing up of PEO-coating pores with superdispersed polytetrafluoroethylene significantly decreases the defectiveness of the PEO-layer and increases the corrosion resistance of the treated Mg alloys. Polarization resistance of the MA14 and MA20 magnesium alloys with composite coatings in Hank’s solution, at the temperature of 37 °C was increased by 3–4 orders of magnitude in comparison with uncoated materials. The composite coating on the surface of MA8 Mg alloy provides the maximal increasing of the protective properties (the value of corrosion current density is <5.0.10–10 A/cm²). The volumetry method in vitro in an artificial media (Simulated Body Fluid — SBF, 37 °C) made a definition that simulation of ion composition of human blood plasma leads to significant reduction of dissolution rate of Mg alloys with composite coatings in comparison with bare alloys. Analysis of the results indicated the highest degree of the protective properties of the polymer-containing coating on the magnesium alloy MA8 surface. The hydrogen evolution was not observed during 28 days of the sample exposure in SBF-solution. Сomposite coatings on the surface of the MA20 and MA14 alloys decrease the corrosion rate of the samples in the SBF-solution in 50 and 3 times in comparison with the uncoated material, respectively. The surface of the hydroxyapatite-containing composite coating remains to be a bioactive.

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