Effect of melting method on the bio-corrosion resistance of Mg₆₇Zn₂₈Ca₅ cast magnesium alloy in simulated body fluid

Abstract

In recent years, biodegradable magnesium alloys have attracted considerable attention in medical devices, such as permanent implants and stents. However, poor corrosion resistance is a major problem limiting the practical application of magnesium alloys. In this study, Mg 67 Zn 28 Ca 5 alloys were prepared via two different methods, namely, vacuum induction melting and ulfur hexafluoride shielded melting. The effect of melting method on the bio-corrosion resistance of MgZnCa cast magnesium alloy was also studied. The microstructure and phase composition of Mg 67 Zn 28 Ca 5 alloys were investigated by optical microscopy and X-ray diffraction. The element distribution and surface morphology of Mg 67 Zn 28 Ca 5 alloys were examined by scanning electron microscopy and energydispersive spectroscopy. The corrosion resistance of Mg 67 Zn 28 Ca 5 alloys was measured via electrochemical and immersion tests. Results showed uniform composition of the Mg 67 Zn 28 Ca 5 alloy melted by vacuum induction. Immersed in the simulated body fluid, the corrosion rate of Mg 67 Zn 28 Ca 5 by vacuum induction melting (0.2618 mm/a) was lower than that by ulfur hexafluoride shielded melting (0.9686 mm/a); the corrosion potential of Mg 67 Zn 28 Ca 5 melted by vacuum induction (−1313 mV) was nobler than that by ulfur hexafluoride shielded melting (−1483 mV); the corrosion current of Mg 67 Zn 28 Ca 5 by vacuum induction melting (1.202×10 −5 A) was lower than that by ulfur hexafluoride shielded melting (4.332×10 −5 A). The Mg 67 Zn 28 Ca 5 by vacuum induction melting showed uniform corrosion behavior.

Influence of Metal Processing on Microstructure and Properties: Implications for Biodegradable Metals—A Mini Review

“…The electrochemical testing of Mg 67 Zn 28 Ca 5 suggests that VIM produced more stable samples with a corrosion potential of −1313 mV and a corrosion current density of 1.202 × 10 −5 A cm −2 . While the USM sample reported a corrosion potential of −1483 mV and corrosion current density at 4.332 × 10 −5 A cm −2 [74]. The main limitation of vacuum processing of metal alloys is the high cost of the necessary specialized equipment.…”