Tunable Corrosion Behavior of Calcium Phosphate Coated Fe-Mn-Si Alloys for Bone Implant Applications

This work deals with the electrodeposition of calcium phosphate coatings on the surface of Fe-Mn-Si alloys which is designed for bone implant applications. Three different alloy compositions are considered (Fe-23Mn-5Si, Fe-26Mn-5Si and Fe-30Mn-5Si, all in wt pct). In order to explore the impact of hydrogen peroxide (H₂O₂) on the electrodeposition process, two different electrolytic solutions are studied, one that contains no H₂O₂ and the other that contains 9 vol pct H₂O₂. The physicochemical characterizations reveal that the electrodeposited coating is made of an apatite phase of low crystallinity with less porosity when hydrogen peroxide is added to the electrolyte solution. The corrosion measurements of the uncoated and coated alloys are also carried out during immersion in Hank’s solution at 310 K (37 °C), a physiological solution that simulates the inorganic composition of the body fluids. Interestingly, it was found that the manganese content in the alloy and the porosity of the coating both modify the corrosion behavior, i.e., the biodegradability of the Fe-Mn-Si alloy immersed in the physiological environment. Hence, the corrosion behavior of the calcium phosphate-coated Fe-Mn-Si alloys is tunable as a function of the experimental parameters used during the synthesis of the material.