Influence of Mechanical Torsion on MgCa1 Corrosion Behavior in Simulated Body Fluid

In this paper, the influence of mechanical torsion on the corrosion of MgCa1 alloy in simulated body fluid (SBF) is presented. The corrosion behavior is examined by microstructural observations, including a scanning electron microscope equipped with an energy dispersive spectroscopy detector and electrochemical studies, mainly impedance spectroscopy measurements and polarization curves. The experiments were performed for different time durations (4 h to 8 h) with and without torsion applied (within elastic deformation range in the form of rotary movements) to assign the differences between the corrosion behavior of the samples. It is shown that mechanical torsion (rotations) promotes the leaching of calcium from the grain boundaries in the samples, which decreases the overall alloy corrosion rate. On the other hand, grain boundaries leached out of calcium compounds influence the sample microstructure by enabling cracks formation and propagation. Therefore, rotated samples corroded at a lower rate but were more susceptible to catastrophic failure. It was then concluded that MgCa1 alloy may be a promising biodegradable material for medical implants, however, its durability in SBF with torsion applied is far from being satisfactory.