Ion Implantation of Calcium and Zinc in Magnesium for Biodegradable Implant Applications

Abstract

Abstract:In this study, magnesium was implanted with calcium-ion and zinc-ion at fluences of 10 15 , 10 16 , and 10 17 ion·cm −2 , and its in vitro degradation behaviour was evaluated using electrochemical techniques in simulated body fluid (SBF). Rutherford backscattering spectrometry (RBS) revealed that the implanted ions formed layers within the passive magnesium-oxide/hydroxide layers. Electrochemical impedance spectroscopy (EIS) results demonstrated that calcium-ion implantation at a fluence of 10 15 ions·cm −2 increased the polarisation resistance by 24%, but higher fluences showed no appreciable improvement. In the case of zinc-ion implantation, increase in the fluence decreased the polarisation resistance. A fluence of 10 17 ion·cm −2 decreased the polarisation resistance by 65%, and fluences of 10 15 and 10 16 showed only marginal effect. Similarly, potentiodynamic polarisation results also suggested that low fluence of calcium-ion decreased the degradation rate by 38% and high fluence of zinc-ion increased the degradation rate by 61%. All the post-polarized ion-implanted samples and the bare metal revealed phosphate and carbonate formation. However, the improved degradative behaviour in calcium-ion implanted samples can be due to a relatively better passivation, whereas the reduction in degradation resistance in zinc-ion implanted samples can be attributed to the micro-galvanic effect.

In vitro and in vivo degradation assessment and preventive measures of biodegradable Mg alloys for biomedical applications

“…180 A recent study showed that the Ca ion implantation improved the corrosion resistance, whereas the Zn ion implantation with pure Mg reduced the corrosion resistance. 181 Further, the microstructure near the surface region of Mg alloy can be modified using high density laser beam to improve corrosion resistance. 182,183 Dispersion of hard particles such as titanium carbide (TiC) and silicon carbide (SiC) by laser melting can significantly improve the surface properties of AZ91 alloy.…”

“…In contrast to this result, another study found that Zn ion implantation on Mg–Ca alloy surface improved corrosion resistance along with higher hardness and elastic modulus 180 . A recent study showed that the Ca ion implantation improved the corrosion resistance, whereas the Zn ion implantation with pure Mg reduced the corrosion resistance 181 . Further, the microstructure near the surface region of Mg alloy can be modified using high density laser beam to improve corrosion resistance 182,183 .…”

PEO/Mg–Zn–Al LDH Composite Coating on Mg Alloy as a Zn/Mg Ion-Release Platform with Multifunctions: Enhanced Corrosion Resistance, Osteogenic, and Antibacterial Activities

“…Magnesium (Mg) and its alloys are widely regarded as the next generation of biomedical materials for its complete degradation in vivo, favorable mechanical strength, and elastic modulus close to natural bone. − However, its clinical applications are hampered by its fast corrosion rate, which would lead to the accumulation of hydrogen bubbles and the violent changes of local pH value . Surface modification is the most widely used method to improve its cytocompatibility and corrosion resistance, including electroless plating, , plasma electrolytic oxidation (PEO), , electrodeposition, , hydrothermal treatment, − polymer coating, ion implantation, − and so on. However, the improved corrosion resistance and cytocompatibility of Mg implants are not sufficient enough to meet the requirement of different clinical application, such as bone implants.…”

Progress in bioactive surface coatings on biodegradable Mg alloys: A critical review towards clinical translation

“…The primary advantages like selective surface modification, low temperature, and reproducibility are significant for coating Mg alloys [ 180 , 181 ]. However, amorphization caused during ion implantation causes surface devoid of grain boundaries, resulting in enhanced corrosion [ 182 ]. As ion implantation is a non-thermodynamic process, studies have reported the generation of compressive residual stresses and increased surface roughness of the ion-implanted surface.…”