Degradation behaviour of pure magnesium in simulated body fluids with different concentrations of HCO3-

Corrosion behaviour of pure magnesium in simulated body fluids (SBF) with HCO3− concentrations of 4, 15 and 27 m mol/L is studied. Magnesium is not sensitive to pitting corrosion in all the SBFs. Higher HCO3− concentration effectively slow down the corrosion rates. Uniform and compact corrosion product layer preferentially forms in SBF with HCO3− of 27 m mol/L. Potentiodynamic polarization test indicates that HCO3− of 27 m mol/L dramatically enhance corrosion potential and induce passivation. EIS results further confirm that higher concentration of HCO3− induce more effective protection layer, especially in SBF with HCO3− of 27 m mol/L.

Research highlights
► HCO3- in SBF stimulates corrosion of magnesium by consumption of OH−.
► HCO3- suppresses dissolution of magnesium by formation insoluble carbonates.
► The multiple effects are balanced by HCO3- concentrations.
► SBF with 27 mmol/L of HCO3- is more suitable for in-vitro studies.