Structure and corrosion properties of Mg_(70-x)Zn_(30)Ca_x[x=0.4] alloys for biomedical applications

摘要

Purpose: The main objective of the paper was to investigate the structure and corrosion properties of amorphous and crystalline Mg-based alloys for biodegradable implants. This paper presents a preparation method and the structure, microhardness and corrosion properties characterization of Mg_(70)Zn_(30) and Mg_(66)Zn_(30)Ca_4 alloys in the form of plates. Design/methodology/approach: The studied samples were prepared by the pressure die-casting to copper mould. The structure of the both alloys was examined by X-ray diffractometry (XRD) and a scanning electron microscope (SEM). The thermal properties of the samples were examined using a differential scanning calorimeter (DSC). In addition, corrosion properties research (immersion tests) were performed in a physiological fluid. Microhardness was measured using the Vickers microtester. Findings: The results of X-ray diffraction investigations confirmed that the sample of Mg_(66)Zn_(30)Ca_4 alloy is amorphous and sample of Mg_(70)Zn_(30) alloy has crystalline structure. Immersion tests of both samples have shown homogeneous progress of corrosion. The changes of a structure caused by calcium addition resulted in an increase of microhardness for sample Mg_(66)Zn_(30)Ca_4 compared with the sample of Mg_(70)Zn_(30) alloy. Research limitations/implications: Results of immersion tests are dependent of used fluid. In this paper used physiological (multielectrolyte) fluid to corrosion studies, which composition is similar to the electrolyte composition of the blood plasma. Chemical composition of fluid used in corrosion studies could be affected to results of studies. Therefore it is appropriate to carry out comparative studies such as electrochemical corrosion studies. Practical implications: Mg-based alloys can be applied as the medical implants. The chemical composition of the samples Mg_(66)Zn_(30)Ca_4 and Mg_(70)Zn_(30) was chosen, because they meet the requirements of a biodegradable material, that is, material, which after completing their stability function will dissolve in the body of the patient without the harmful effects on health. Originality/value: Crystalline and amorphous magnesium alloys are examined as a material for biodegradable medical implants. This new concept is an alternative to previously used conventional implant materials. New concept doesn't require re-operation, and allows foreign object to remain in the human body.