| The porous biomimetic Ti-Mg gradient composites with high strength,low elastic modulus,excellent biodegradability and excellent biocompatibility were prepared by combining the characteristics of high strength and high elastic modulus of Ti and low strength and low elastic modulus of Mg.Effect of milling,pressing,sintering parameters and Mg content on microstructure and properties of Ti-Mg composites,Optimum parameters for preparing Ti-Mg composites by microwave sintering were determined:milling time of 8 h,milling speed of 200 rpm,pressing pressure of 550 MPa,holding time of 200 s,sintering temperature of 600°C,holding time of 20 min.The properties of Ti-16Mg composite are superior,with compressive strength of 325 MPa,elastic modulus of 26.69 GPa,Vickers hardness of134.32 HV,and good corrosion resistance.The composite can induce the deposition of hydroxyapatite on its surface,indicating that it has good biocompatibility.In order to reduce the elastic modulus and improve the biocompatibility of the composites,porous Ti-16Mg composites were prepared.Porous composites with pore sizes of 100～500μm can be prepared by changing the particle sizes of NH4HCO3.When the NH4HCO3content increase from 6 wt%to 24 wt%,the porosity increase from 16.64%to33.09%,the elastic modulus decrease from 16.34 GPa to 4.7 GPa,and the compressive strength decrease from 280 MPa to 65 MPa.In order to further improve the mechanical compatibility and biocompatibility of porous Ti-16Mg composites,porous biomimetic Ti-16Mg gradient composites were prepared according to the characteristics of human bone tissue.The results show that the porosity of the three-layer and five-layer porous biomimetic Ti-16Mg gradient composites is about 33%.Their compressive strength are 255 MPa and 289 MPa,and their elastic modulus are 6.77 GPa and 6.89 GPa,respectively.The cytotoxicity of porous Ti-16Mg biomimetic gradient composites is 0 grade,and its biocompatibility is excellent.Figure 94;Table 22;Reference 70... |
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