The main issues related to the development of biodegradable Zn-Mg-Ca/Sr alloys for medical applicationsThursday (09.05.2019) 16:00 - 16:20 Part of:
Zinc-based materials are considered as a possible candidate for application in medicine like for example fixation devices for fractured bones or stents. In these cases they can substitute for a long time studied magnesium-based materials which suffer from some deficiencies like high corrosion rate and especially localized corrosion connected to micro-galvanic cells. Such issues may, unfortunately, lead to the premature loss of mechanical integrity of the implant. Another big issue of magnesium is connected to hydrogen release during corrosion. None of these known facts is so serious for zinc-based materials, which should be degraded more equally without hydrogen release and are not so prone to specific impurities in materials or localized corrosion. In presented work, Zn-Mg-Ca/Sr ternary alloys were prepared by various processing and studied by general laboratory techniques. Studies of microstructure, mechanical properties, corrosion behaviour in-vitro and cytotoxicity confirmed the competitiveness of these alloys with magnesium-based materials, although some issues related to brittleness and cytotoxicity were observed. However, presented issues were solved by appropriate adjustment of the material processing. Optimized Zn-0.8Mg-0.2Ca/Sr alloys prepared by the combination of heat treatment and extrusion were characterized by ultimate tensile strength over 400 MPa and elongation slightly above 14 %. Corrosion rates in various simulated body fluids were within 0.1 to 0.3 mm/y. No cytotoxicity on U2-OS and L929 cells were observed. Except for properties of optimized materials, relations among processing of materials and their behaviour is presented.