Synthesis and Study of Microstructure, Mechanical and Biocompatibility Properties of Mg-Zn Scaffolds

The aim of this research is to synthesize and study the microstructure and mechanical properties of biodegradable Mg-Zn scaffolds for orthopedic applications. For this purpose, Mg-Zn scaffolds containing 3 and 5 wt. % Zn were prepared using 15, 25 and 35 Vol% of urea by powder metallurgy and were subjected to heat treatment at different temperatures of 500, 550, 565, and 580 C to determine the optimum sintering temperature. Then, the chemical composition, microstructure and mechanical properties of the scaffolds were investigated. According to the results, the average diameter of macro- pores and micro- pores in the scaffolds are about 400-200 and less than 100 ?m, respectively. The results showed that the compressive strength of Mg-Zn scaffolds increases with decreasing porosity amount. In fact, the porosity in the sample reduces the mechanical strength of the scaffold due to the stress concentrating areas and the reduction of the effective surface of scaffold against external stresses. Also, by increasing the Zn content, the strength of the Mg-Zn scaffold increases through the strength of the solid solution and dispersion strengthening. However, in all of the made scaffolds, the compressive strength is in the range of compressive strength of the human body's bone. The results of the SEM micrographs also showed that, by adding Zn, the intermetallic compounds Mg7Zn3 and MgZn could be formed. The results of polarization test showed that, by adding 5 wt.% of Zn in comparison with samples containing 3 wt%, due to the formation of more intermetallic compounds, the corrosion resistance decreased. According to the results of cytotoxicity measurement, the cell viability of scaffolds containing 3 wt% Zn was higher than those containing 5 wt% Zn.