Synthesis of biodegradable Zn-based scaffolds using NaCl templates: Relationship between porosity, compressive properties and degradation behavior

Recently, Zn-based alloys are attracting intensive interest as biodegradable biomaterials. Their moderate degradation rate makes them a better potential candidate for porous scaffolds than Mg-based alloys. In this study, hot press sintering (HPS) was employed to enhance the stacking density of NaCl templates. And then, pure Zn and Zn-3 wt%Cu scaffolds with different porosities were achieved by replicating the architecture of NaCl templates. The pore structure, compressive properties and degradation behavior of the scaffolds were investigated. The scaffolds with a higher porosity of about 75% showed enhanced interconnectivity and reduced surface area due to the formation of more interconnected pores and the enlarged size of them. The scaffolds with a lower porosity of about 68% exhibited higher yield strength on account of the earlier closure of the smaller interconnected pores during deformation. The corrosion rate was decreased with the increase of the porosity due to the reduction of specific surface area. The compressive properties (including yield strength and modulus) and corrosion rate of the Zn scaffolds were significantly enhanced by the addition of 3 wt% Cu because of the solution of Cu in Zn matrix and the precipitation of CuZn5 secondary phase. Moreover, the effect of porosity on corrosion was more distinguishable for Zn-3 wt%Cu scaffolds than pure Zn scaffolds due to the acceleration of galvanic corrosion effect.