Recently, zinc-based materials have been intensively studies as candidates for the fabrication of biodegradable implants. Application of such implants would fasten the healing proces and decrease the costs connected with it. Zinc possesses corrosion rate suitable for this kind of application; however, its mechanical properties are not sufficient for implantology. Therefore, it is neccessary to alloy zinc with suitable elements (e.g. Mg, Ca, Sr, etc.) and undergo those materials to suitable a thermomechanical treatment (extrusion, ECAP, etc.). The combination of those approaches can lead to a significant strenghtening and to an increase of the ductility of the materials. It is caused not only grain refinement but also by the formation of texture, which plays a significant role in the mechanical properties of zinc-base materials. Another approach enhancing the behaviour, especially the biocompatibility, of zinc is its reinforcement by particles of a biocompatible substance, for example by hydroxyapatite or TCP. Such composites can be prepared by powder metallurgical processes. In such cases, the powder mixtures of zinc and the reinforcement are compacted by extrusion, spark plasma sintering or by other methods. For some applications in the area of trabecular bone, porous materials possessing low moduli of elasticity are required. Preparation of porous zinc-based materials by common approaches is problematic; therefore, new methods have to be invented or the current methods have to be modified. Spark plasma sintering or thermal plasma spraying seem to be suitable for the preparation of porous zinc materials. In all cases mentioned above, the preparation method and its parameters have a significant influence on the microstructure of the material. Subsequently, the microstructure determines mechanical and corrosion properties and the corrosion properties influences the biocompatibility of the material. This means that the studied problematic is very complex and difficult. Therefore, we closely cooperate on this topic with other Czech institutes (UCT Prague and The First Faculty of Medicine of Charles University).
a) Tensile curves of the ZnMg0.8Sr0.2 alloy extruded at various conditions. b) 001 IPF map of a longitudinal section of the alloy extruded at 200 °C and at the extrusion ratio of 25:1.
