Effect of MgF2 coating on stress corrosion cracking behavior of Mg−Zn−Ca alloy in simulated body fluid

The stress corrosion cracking behavior of Mg−3wt.%Zn−0.2wt.%Ca (MZC) alloy and fluoride (MgF2) coated Mg−3wt.%Zn−0.2wt.%Ca alloy (MZC-MF) for bone implant applications was investigated using slow strain- rate tensile (SSRT) tests in simulated body fluid (SBF). The results show that MgF2 coating could significantly improve the corrosion resistance and prolonged fracture failure time of MZC alloy. MgF2 coating also greatly reduced the stress corrosion cracking sensitivity of MZC alloy in SBF. Compared to MZC alloy, stress corrosion cracking sensitivity index (Iscc) of MZC-MF alloy decreased by 21% (ultimate tensile strength, UTS), 22% (time to failure, tf), 23% (elongation after fracture, δ), 7% (reduction ratio of cross-sectional area after fracture, ϕ) and 15% (inner product work, A), respectively.