Fluorine-doped hydroxyapatite(FHA) and calcium deficient hydroxyapatite(CDHA) were coated on the surface biodegradable magnesium alloy using electrochemical deposition(ED) technique. Coating characterization was inves...Fluorine-doped hydroxyapatite(FHA) and calcium deficient hydroxyapatite(CDHA) were coated on the surface biodegradable magnesium alloy using electrochemical deposition(ED) technique. Coating characterization was investigated X-ray diffraction(XRD), Fourier-transformed infrared spectroscopy(FTIR), transmission electron microscopy(TEM), scanni electron microscopy(SEM) and energy dispersive X-ray spectroscopy(EDS). The result shows that nano-FHA coated samp presents nano needle-like structure, which is oriented perpendicular to the surface of the substrate with denser and more unifo layers compared to the nano-CDHA coated sample. The nano-FHA coating shows smaller crystallite size(65 nm) compared to t nano-CDHA coating(95 nm); however, CDHA presents thicker layer(19 μm in thickness) compared to the nano-FHA(15 μm thickness). The corrosion behaviour determined by polarization, immersion and hydrogen evolution tests indicates that the nano-FH and nano-CDHA coatings significantly decrease corrosion rate and induce passivation. The nano-FHA and nano-CDHA coatings c accelerate the formation of bone-like apatite layer and significantly decrease the dissolution rate as compared to the uncoated M alloy. The nano-FHA coating provides effective protection to Mg alloy and presents the highest corrosion resistance. Therefore, t nano-FHA coating on Mg alloy is suggested as a great candidate for orthopaedic applications.展开更多
Ternary Zn-0.5A1-0.5Mg and quatemary Zn-0.5A1-0.5Mg-xBi （x = 0.1, 0.3 and 0.5） alloys were studied to evaluate the thermal and structural characteristics, mechanical properties, cytotoxicity and in vitro degradation...Ternary Zn-0.5A1-0.5Mg and quatemary Zn-0.5A1-0.5Mg-xBi （x = 0.1, 0.3 and 0.5） alloys were studied to evaluate the thermal and structural characteristics, mechanical properties, cytotoxicity and in vitro degradation behavior. Thermal analysis and microstructural observations showed that Zn-0.5A1-0.5Mg is composed of FCC-A1 ＋ HCP- Zn ＋ Mg2（Zn,A1）ll while a new phase a-Mg3Bi2 appeared after the addition of Bi to the Zn-0.5A1-0.5Mg ternary alloy. The results revealed that the quaternary Zn-A1-Mg-Bi alloys have higher tensile strength, elongation and hardness but slightly lower corrosion resistance than those of the temary Zn-AI-Mg alloy. Based on the MTT assay, the Zn-A1-Mg and Zn-A1-Mg-Bi alloys were found to be biocompatible, and thus, they can be considered for further investigation in an in vivo environment.展开更多
文摘Fluorine-doped hydroxyapatite(FHA) and calcium deficient hydroxyapatite(CDHA) were coated on the surface biodegradable magnesium alloy using electrochemical deposition(ED) technique. Coating characterization was investigated X-ray diffraction(XRD), Fourier-transformed infrared spectroscopy(FTIR), transmission electron microscopy(TEM), scanni electron microscopy(SEM) and energy dispersive X-ray spectroscopy(EDS). The result shows that nano-FHA coated samp presents nano needle-like structure, which is oriented perpendicular to the surface of the substrate with denser and more unifo layers compared to the nano-CDHA coated sample. The nano-FHA coating shows smaller crystallite size(65 nm) compared to t nano-CDHA coating(95 nm); however, CDHA presents thicker layer(19 μm in thickness) compared to the nano-FHA(15 μm thickness). The corrosion behaviour determined by polarization, immersion and hydrogen evolution tests indicates that the nano-FH and nano-CDHA coatings significantly decrease corrosion rate and induce passivation. The nano-FHA and nano-CDHA coatings c accelerate the formation of bone-like apatite layer and significantly decrease the dissolution rate as compared to the uncoated M alloy. The nano-FHA coating provides effective protection to Mg alloy and presents the highest corrosion resistance. Therefore, t nano-FHA coating on Mg alloy is suggested as a great candidate for orthopaedic applications.
文摘Ternary Zn-0.5A1-0.5Mg and quatemary Zn-0.5A1-0.5Mg-xBi （x = 0.1, 0.3 and 0.5） alloys were studied to evaluate the thermal and structural characteristics, mechanical properties, cytotoxicity and in vitro degradation behavior. Thermal analysis and microstructural observations showed that Zn-0.5A1-0.5Mg is composed of FCC-A1 ＋ HCP- Zn ＋ Mg2（Zn,A1）ll while a new phase a-Mg3Bi2 appeared after the addition of Bi to the Zn-0.5A1-0.5Mg ternary alloy. The results revealed that the quaternary Zn-A1-Mg-Bi alloys have higher tensile strength, elongation and hardness but slightly lower corrosion resistance than those of the temary Zn-AI-Mg alloy. Based on the MTT assay, the Zn-A1-Mg and Zn-A1-Mg-Bi alloys were found to be biocompatible, and thus, they can be considered for further investigation in an in vivo environment.
