The Mg-6%Zn-5%Hydroxyapatite (HA) biomaterial had been prepared through powder metallurgy method in this investigation. The mechanical properties and biodegradable behaviors of the Mg-Zn-HA composite in simulated body fluid were studied. The Mg-Zn-HA specimens obtained appropriate density, adjustable elastic modulus and compatible strength to natural bones. Immersion corrosion experiments revealed that 5wt% addition of HA in Mg-6%Zn alloy exhibited acceptable corrosion rates in simulated body fluid. The Mg matrix, Mg 7 Zn 3 phase and HA are identified in the experimental composite. The Mg(OH) 2 and Hydroxyapatite were found on the corrosion products in the simulated body fluid.
The porous Mg-based scaffolds have been extensively investigated as novel biodegradable scaffolds for bone and cartilage tissue implant applications. The properties of Mg-based scaffolds are affected by pore structure and matrix composition. In order to meet the specific property requirements of different bone tissue in clinical practice, it is extremely necessary to study the relationship between microstructure and properties of Mg-based scaffolds and prepare the appropriate implants. In this study, series of β-TCP /Mg-Zn scaffolds prepared by powder metallurgy were studied via electron microscopy scan, X-ray diffraction, bending test, immersion test and cytotoxicity test. The effects of Zn content, β-TCP content, spacer agent content and spacer agent particle size on the mechanical properties and in vitro biodegradation were analyzed through signal-to-noise ratio analysis and gray relational analysis. And two function models of Zn content, β-TCP content, porosity and mean pore size for mechanical strength and corrosion rate was further obtained. The results showed Mg-3%Zn-5%β-TCP (wt.%) could be as potential matrix to ideal Mg-based scaffolds for bone tissue engineering, and 10% spacer agent and 150-250 μm spacer agent particle size are suitable synthesis parameters. In addition, a power function model was more appropriately fitted with the mechanical properties and corrosion resistance of Mg-based scaffolds, and the simulation results showed that the Mg-based scaffolds with porosities between 10-20% and mean pore sizes between 100-150 μm were more likely to be develop to ideal implants on bone tissue engineering.
The hot compression simulation of an experimental Mg-Zn-Nd alloy at different temperatures is studied by the Gleebe-1500 equipment. The deformation is performed with the strain rates 0.1s-1, 0.01s-1 and 0.002s-1. The plastic deformation behavior is analyzed at different temperatures and the deformation activation energy is calculated. The microstructures of experimental alloy during the deformation process are observed. The results show that the working hardening, dynamic recovery and dynamic recrystallization (DRX) operate under different temperatures and strain rate. The DRX starts when the temperature is over 473K and the DRX grain size after hot deformation is only 5~10μm. So the refined grains improve both the tensile strength and elongation of alloys at room temperature. The precipitate phase Mg12Nd impede the movement of dislocations, it benefit to the mechanical properties and grain refining of magnesium alloy.
Abstract In this work, a novel Zn-0.5%Li-(Ag) alloys were successfully prepared by molten casting technology, and the microstructure, mechanical properties and the biodegradation behavior of Zn-based alloys in a Dulbecco’s modified Eagle’s medium (fetal bovine serum) were assessed. Additionally, their antibacterial properties were investigated by assaying the cell viability of bone marrow mesenchymal stem cells and by disc diffusion antibiotic sensitivity testing. The alloys had a reduced corrosion rate due a grain refinement effect (through more readily passivation) provided by nano-LiZn 4 precipitates and Zn(OH) 2 /ZnO and ZnCO 3 spontaneous precipitation on the surface. The Zn-0.5%Li-0.2%Ag alloy has no cytotoxicity, and which achieved highest mechanical properties ( tensile strengths of 278.3MPa and percentage elongation ( ε ) of 96.2%) and excellent antibacterial properties.
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