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Povzetek: Zinc alloys are recognised for their excellent biocompatibility and favourable corrosion rates, making them suitable for bioabsorbable implants. However, their mechanical properties necessitate improvement to fulfil the rigorous requirements of biomedical applications. This research focuses on engineering pseudo-harmonic structures within zinc alloys through a comprehensive method combining mechanical alloying, spark plasma sintering, and hot extrusion techniques. This fabrication process results in a composite material characterised by a soft core surrounded by a continuous, three-dimensional, ultrafine-grained hard shell. The experiment involved blending pure zinc with Zn–1Mg alloy powder, leading to the formation of both ductile zinc and fine-grained Zn–1Mg regions. While the Mg2Zn11 intermetallic phase was found to enhance the alloy's mechanical strength, the presence of oxide shells adversely affected the material's properties. The elimination of these shells via hot extrusion markedly improved the alloy's tensile strength, reaching an average value of tensile strength of 333 ± 7 MPa. This study provides significant insights into the material engineering of zinc-based alloys for biodegradable implant applications, demonstrating a viable approach to optimising their mechanical performance.
Ključne besede: zinc, magnesium, biodegradable, powder metallurgy, harmonic structure
Objavljeno v DiRROS: 23.07.2024; Ogledov: 114; Prenosov: 110
Celotno besedilo (14,29 MB)
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Povzetek: Zinc alloys belong to the widely studied materials for applications like medical devices, however, they often encounter an inappropriate combination of mechanical/corrosion/biological properties. In this respect, we produced the Zn–1Mg and Zn–1Mg–1Si containing biologically friendly elements with potential strengthening effects on zinc matrix by powder metallurgy methods including mechanical alloying, spark plasma sintering, and extrusion further enabling the formation of materials with unique extremely fine-grained microstructures. The systematic study of these materials showed the possibility of reaching homogeneous nano-grain microstructure and high strength values exceeding 450 MPa in tension. Selected chemical composition and processing methods led also to slightly decreased wear and corrosion rates and rather uniform corrosion.
Ključne besede: zinc, mechanical alloying, biodegradable metals, composite, spark plasma sintering, extrusion, powder metallurgy
Objavljeno v DiRROS: 23.07.2024; Ogledov: 108; Prenosov: 106
Celotno besedilo (21,50 MB)
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Povzetek: In vitro testing is the first important step in the development of new biomaterials. The human fetal osteoblast cell line hFOB 1.19 is a very promising cell model; however, there are vast discrepancies in cultivation protocols, especially in the cultivation temperature and the presence of the selection reagent, geneticin (G418). We intended to use hFOB 1.19 for the testing of Zn-based degradable metallic materials. However, the sensitivity of hFOB 1.19 to zinc ions has not yet been studied. Therefore, we compared the toxicity of zinc towards hFOB 1.19 under different conditions and compared it with that of the L929 mouse fibroblast cell line. We also tested the cytotoxicity of three types of Zn-based biomaterials in two types of media. The presence of G418 used as a selection reagent decreased the sensitivity of hFOB 1.19 to Zn2+. hFOB 1.19 cell line was more sensitive to Zn2+ at elevated (restrictive) temperatures. hFOB 1.19 cell line was less sensitive to Zn2+ than L929 cell line (both as ZnCl2 and extracts of alloys). Therefore, the appropriate cultivation conditions of hFOB 1.19 during biomaterial testing should be chosen with caution.
Ključne besede: zinc degradable materials, in vitro cytotoxicity testing, hFOB 1.19 osteoblasts
Objavljeno v DiRROS: 28.02.2024; Ogledov: 329; Prenosov: 113
Celotno besedilo (1,81 MB)
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