Fabrication and Properties of Zn-Containing Intermetallic Compounds as Sacrificial Anodes of Zn-Based Implants.

In the field of degradable metals, Zn-based implants have gradually gained more attention. However, the relatively slow degradation rate compared with the healing rate of the damaged bone tissue, along with the excessive Zn release during the degradation process, limit the application of Zn-based implants. The use of intermetallic compounds with more negative electrode potentials as sacrificial anodes of Zn-based implants is likely to be a feasible approach to resolve this contradiction. In this work, three intermetallic compounds, MgZn, CaZn, and CaMgZn, were prepared. The phase structures, microstructures, and relevant properties, such as thermal stability, in vitro degradation properties, and cytotoxicity of the compounds, were investigated. The XRD patterns indicate that the MgZn and CaZn specimens contain single-phase MgZn and CaZn, respectively, while the CaMgZn specimen contains MgCa and CaMgZn phases. After purifying treatment in 0.9% NaCl solution, high purity CaMgZn phase was obtained. Thermal stability tests suggest that the MgZn and CaZn specimens possess good thermal stability below 773 K. However, the CaMgZn specimen melted at around 739.1 K. Polarization curve tests show that the corrosion potentials of MgZn, CaZn, and CaMgZn in simulated body fluid (SBF) were -1.063 V, -1.289 V, and -1.432 V, which were all more negative than that of the pure Zn specimen (-1.003 V). Clearly, these compounds can act as sacrificial anodes in Zn-based implants. The immersion tests indicate that these compounds were degraded according to the atomic ratio of the elements in each compound. Besides that, the compounds can efficiently induce Ca-P deposition in SBF. Cytotoxicity tests demonstrate that the 10% extracts prepared from these compounds exhibit good cell activity on MC3T3-E1 cells.