PEO layers on Mg-based metallic glass to control hydrogen evolution rate

The amorphous Mg-based alloys may be used as metallic biomaterials for resorbable orthopedic implants.The Mg-Zn-Ca metallic glasses demonstrate variable in time degradation rate in simulated body fluid.In this work the Mg 66 Zn 30 Ca 4 alloy was chosen as a substrate for coatings.This paper reports on the surface modification of a Mg 66 Zn 30 Ca 4 metallic glass by plasma electrolytic oxidation (PEO).The structure characterization of uncoated Mg 66 Zn 30 Ca 4 alloy was performed by using TEMand XRD method.The immersion tests of coated and uncoated Mg 66 Zn 30 Ca 4 alloy were carried out in Ringer's solutionat 37°C.The volume of released hydrogen by immersion tests was determined.The coatings structure and chemical composition after immersion tests by SEM/EDS were studied.Based on SEM images of surface structure samples, immersion tests results and hydrogen evolution measurement was proposed the course of corrosion process in Ringer's solution for Mg-based metallic glasses with PEO coating.Results of immersion tests in Ringer's solution allowed to determine the amount of evolved hydrogen in a function of time for Mg 66 Zn 30 Ca 4 metallic glass and sample with PEO coating.In comparison to the non-coated Mg 66 Zn 30 Ca 4 alloy, the sample with PEO layer showed a significantly decreased hydrogen evolution volume.