Tunability of mechanical and biodegradation properties of zinc-based biomaterial with calcium Micronutrient alloying

Biodegradable metals are being investigated as temporary implants that dissolve safely in the body after bone regeneration. Zinc (Zn) has an intermediate biodegradation rate between magnesium and stainless steels, yet its degradation rate is too slow to function as a temporary orthopedic implant. Alloying with nutrient elements is considered a strategy to tune its mechanical properties and in vivo biodegradability. Zn/calcium (Zn/Ca) alloys (with 0.5, 1, and 2 wt% Ca) were processed by spark plasma sintering and their microstructure, mechanical, and biodegradation properties were investigated. Ca was distributed in the grain boundary regions of Zn due to its low miscibility in Zn. Furthermore, the corrosion rates of Zn/Ca alloys determined from linear polarization measurements (0.164-0.325 mm/yr) accelerated by at least 10% compared with pure sintered Zn (0.149 mm/yr) with simultaneous dissolution of Zn and Ca, as verified from X-ray diffraction analysis of the corrosion products. The alloy specimens exhibited hardness (52-58 HV) and compressive strength (93-119 MPa) comparable with those of human cortical and cancellous bones (49 HV; 90-209 MPa). This study demonstrated the tunability of the mechanical and biodegradation properties of Zn-based materials by alloying them with a nutrient element for potential application as temporary orthopedic implants.