Abstrakt
Nowadays, implants are predominantly made of metallic materials that have two main problems. The first resides in the modulus of elasticity being higher than the one of the human bone (10-20 GPa), resulting in stress shielding and subsequent implant failure.
The second problem is the toxicity of some constitution elements of implant materials, which can lead to inflammation of the surrounding tissue due to the release of cytotoxic ions during the corrosion process and, therefore, biodegradability of the implant is not advisable. Hence, recent investigation has focused on the development of metallic materials that are at once biodegradable and biocompatible with the elasticity near human bone.
The rate of degradation by corrosion of biocompatible alloys can be controlled by surface improvement or thermal and mechanical treatment. The aim of this work was to prepare the new biodegradable alloy on the base of Mg-Ca-Zn-Mn and study the influence of thermomechanical treatment on the alloy microstructure, phase composition, microhardness and corrosion properties.
Homogenization annealing was performed at 480 °C for 24 h followed by water quenching. The material was subjected to one pass of equal channel angular pressing (ECAP) at 290 °C.
The microstructure study was performed for as-cast, heat-treated and ECAPed conditions and was accomplished by microhardness measurement. The chemical and phase composition was observed using of a scanning electron microscope and EDX analysis.
To determine the corrosion properties of the alloy, an immersion test was performed together with the measurement of the potentiodynamic polarization.