Design and Optimisation of Corrosion Behaviour of Mg-Zn-Ca Alloy System Using Thermodynamic and Statistical Simulation

In recent years, Mg- based alloys have been considered as a biodegradable biomaterial for implant applications. However, the high corrosion rate and hydrogen gas evolution in an aqueous environment are the most important challenges for these alloys. This study has focused on optimizing the biocorrosion properties of  bioalloys in Mg-Zn-Ca system, using a combined approach of thermodynamic simulations, and response surface methodology (RSM). In, Mg۲Ca and CaxMgyZnz precipitates have a significant effect on corrosion mechanisms. It is believed that, in the Mg-Zn-Ca alloy system, the Mg۲Ca secondary phase usually enhances corrosion rate with microgalvanic coupling mechanisms. The ternary phases CaxMgyZnz have less detrimental effects on corrosion resistance. To minimize harmful phases, CompuTherm’s PANDAT software was utilized for phase evolution prediction, with outputs directly validated against experimental measurements. Potentiodynamic tafel polarization experiments and long-term immersion tests were conducted to evaluate the corrosion rate. In order to design an alloy with the least detrimental phase, a statistical model (RSM) was developed based on predicted results from thermodynamic model. The results showed that the ZX۳۱ (Mg-۲.۶Zn-۱Ca) exhibited the highest corrosion potential (-۱.۶۳۳۶ VAg/AgCl) and the lowest corrosion current density (۲۱۶ µA/cm۲), showing higher biocorrosion resistance compared to ZX۲۴ (Mg-۲.۳Zn-۴.۰Ca) and ZX۱۵ (Mg-۱.۳Zn-۴.۸Ca).

کلیدواژه ها:

Magnesium bioalloy ، Orthopedic implants ، Biocorrosion ، Corrosion optimization ، Response surface methodology (RSM).