Composite MAO-PLGA coatings with improved mechanical and corrosion properties on Mg-Zr-Zn-Ce alloy in UFG state

In recent years, there has been an increasing focus on magnesium and its alloys as potential materials for use in bioresorbable medical implants. This issue can be addressed through two primary approaches: alloying the magnesium alloy itself and modifying the alloy surface with various types of coatings. Comparative studies of the structure, mechanical properties and corrosion behavior of micro-arc coatings based on Sr-substituted hydroxyapatite and two-layer composite coatings including micro-arc and polymeric poly(lactic-co-glycolic) acid (PLGA) layers formed on MA20 magnesium alloy substrates in the ultrafine grained (UFG) state have been carried out. The morphology of the coatings, their microstructure, and phase composition were studied by scanning electron microscopy (SEM) and powder X-ray diffraction (XRD) methods. The findings of this study revealed that the presence of a PLGA layer on a MAO coating led to a substantial enhancement in adhesive strength, with an increase of approximately 2 times, an increase in microhardness by 1.2 times, a reduction in corrosion current density to 1.40 ×10−7 A / cm2, and an increase in polarization resistance to 4.48 ×105 Ω∙cm2. When maintaining the samples in a 0.9 % NaCl solution for 14 days, the mass loss for the MAO-coated and MAO-PLGA-coated samples amounted to 3.5 % and 0.9 % respectively.