Magnesium is an excellent material in terms of biocompatibility and its corrosion products can serve as an active source for new bone formation.However,localized corrosion and H_(2)generation limit the potential of Mg...Magnesium is an excellent material in terms of biocompatibility and its corrosion products can serve as an active source for new bone formation.However,localized corrosion and H_(2)generation limit the potential of Mg-based implants.Utilizing low-alloyed Mg-Zn wires can strongly reduce problems with large H_(2)bubbles and improve the mechanical properties considerably while maintaining excellent long-term biocompatibility.Acidic pickling and a polymer coating can be effectively used to lower the rate of in vivo degradation.In this work,microstructural,mechanical,and in vitro characterization of 250μm and 300μm extruded wires made from ultra-pure Mg,commercially pure Mg,Mg-0.15Zn,Mg-0.4Zn and Mg-1Zn was performed.Additionally,Mg-0.4Zn wires together with a variant coated with a copolymer of L-lactide andε-caprolactone were tested in vivo on artificially damaged Wistar rat femurs.Based on the observed Mg-induced osteogenesis,polymer-coated Mg wires with a small addition of Zn are a perspective material for bone-support applications,such as cerclage and fixation wires.展开更多
Mg−1Mn−0.5Al−0.5Ca−0.5Zn(wt.%)alloy was fabricated by conventional extrusion at 673 K with an extrusion ratio of 25:1,followed by aging at 473 K.The microstructure was characterized by scanning electron microscopy,ele...Mg−1Mn−0.5Al−0.5Ca−0.5Zn(wt.%)alloy was fabricated by conventional extrusion at 673 K with an extrusion ratio of 25:1,followed by aging at 473 K.The microstructure was characterized by scanning electron microscopy,electron back-scattered diffraction,and transmission electron microscopy.The mechanical properties were determined by the tensile test.The peak-aged sample shows fine recrystallized grains with an average grain size of 1.7μm.Area fraction of Al−Ca particles in the alloy increases significantly after peak aging.Meanwhile,botháañandác+añdislocations were observed to remain in the alloy after hot extrusion.Thus,the peak-aged sample exhibits simultaneously high strength and good ductility with the ultimate tensile stress,tensile yield stress,and tension fracture elongation of 320 MPa,314 MPa,and 19.0%,respectively.展开更多
Creep of squeeze-cast Mg-3Y-2Nd-1Zn-1Mn alloy was investigated at the constant load in the stress range of 30-80 MPa. Tensile creep tests were performed at 300℃up to the final fracture.Several tests at 50 MPa were in...Creep of squeeze-cast Mg-3Y-2Nd-1Zn-1Mn alloy was investigated at the constant load in the stress range of 30-80 MPa. Tensile creep tests were performed at 300℃up to the final fracture.Several tests at 50 MPa were interrupted after reaching the steady state creep;and another set of creep tests was interrupted after the onset of ternary creep.Fraction of cavitated dendritic boundaries was evaluated using optical microscopy.Measurement of grain boundary sliding by observation of the offset of marker lines was carried out on the surface of the crept specimens after the test interruption by scanning electron microscopy and by confocal laser scanning microscopy.The results show that the dominant creep mechanism in this alloy is dislocation creep with minor contribution of the grain boundary sliding.Creep failure took place by the nucleation,growth and coalescence of creep cavities on the boundaries predominantly oriented perpendicular to the applied stress.Increasing amount of cavitated boundaries with time of creep exposure supports the mechanism of continuous cavity nucleation and growth.展开更多
The density, microstructure and magnetic properties of non-doped Mn-Zn ferrite nanoparticles sintered compacts were investigated. The compacts of non-doped Mn-Zn ferrite nanoparticles were sintered by segmented-sinter...The density, microstructure and magnetic properties of non-doped Mn-Zn ferrite nanoparticles sintered compacts were investigated. The compacts of non-doped Mn-Zn ferrite nanoparticles were sintered by segmented-sintering process at lower sintering temperature. The density of sintered samples was measured by Archimedes method, and the phase composition and microstructure were examined by XRD and SEM. The sintered Mn-Zn ferrite magnetic measurements were carried out with Vibrating Sample. The results show that the density of sintered compacts increases with the rising of sintering temperature, achieving 4.8245 g·cm-3 when sintered at 900 ℃, which is the optimal density of Mn-Zn functional ferrite needed and from the fractured surface of sintered samples, it can be seen that the grain grows well with small grain size and homogeneous distribution.展开更多
The Li-rich Zn-doped LiNbO 3 (LN) crystals were grown by the Czochralski method. The structure of the crystals was measured by ultraviolet-visible absorption spectra. The results indicated that the Li-rich Zn-doped LN...The Li-rich Zn-doped LiNbO 3 (LN) crystals were grown by the Czochralski method. The structure of the crystals was measured by ultraviolet-visible absorption spectra. The results indicated that the Li-rich Zn-doped LN crystals had the same characteristics as the pure LN crystal. After Zn 2+ entered into the lattice of Li-rich Zn-doped LN crystal, it replaced Nb Li firstly. When there was no Nb Li , Zn 2+ replaced Li + then. The second harmonic generation (SHG) property of Li-rich Zn-doped LiNbO 3 crystal was measured. The results showed that the SHG conversation efficiency of Li-rich Zn-doped LiNbO 3 crystals was higher than that of Zn-doped LiNbO 3 crystals.展开更多
基金supported by the Jiangsu Province Industry–University–Research Project,China(No.BY20221160)the Postgraduate Research and Practice Innovation Program of Jiangsu Province,China(No.KYCX22_3798)+2 种基金the National Natural Science Foundation of China(No.52275339)the Key Research and Development Plan of the Ministry of Science and Technology,China(No.2023YFE0200400)the Science and Technology Project of Jiangsu Province,China(No.BZ2021053)。
基金the project Ferr Mion of the Ministry of Education,Youth and Sports,Czech Republic,co-funded by the European Union(CZ.02.01.01/00/22_008/0004591)the support of The Charles University Grant Agency in the frame of the project No.121724 and the project Cooperatio No.207030 Dental Medicine/LF1 of the Charles University+4 种基金financial support from the Ministry of Education,Youth and Sport of the Czech Republic under the grant No.RVO 14000supported by the Ministry of Health of the Czech Republic-RVO project VFN64165the support of the project GAMA 2 of the Technology Agency of the Czech Republic No.TP01010055the project of the Czech Academy of Sciences,Czech Republic(Praemium Academiae grant No.AP2202)the support of the Ministry of Health of the Czech Republic,grant project No.NU20-08-00150。
文摘Magnesium is an excellent material in terms of biocompatibility and its corrosion products can serve as an active source for new bone formation.However,localized corrosion and H_(2)generation limit the potential of Mg-based implants.Utilizing low-alloyed Mg-Zn wires can strongly reduce problems with large H_(2)bubbles and improve the mechanical properties considerably while maintaining excellent long-term biocompatibility.Acidic pickling and a polymer coating can be effectively used to lower the rate of in vivo degradation.In this work,microstructural,mechanical,and in vitro characterization of 250μm and 300μm extruded wires made from ultra-pure Mg,commercially pure Mg,Mg-0.15Zn,Mg-0.4Zn and Mg-1Zn was performed.Additionally,Mg-0.4Zn wires together with a variant coated with a copolymer of L-lactide andε-caprolactone were tested in vivo on artificially damaged Wistar rat femurs.Based on the observed Mg-induced osteogenesis,polymer-coated Mg wires with a small addition of Zn are a perspective material for bone-support applications,such as cerclage and fixation wires.
基金the financial supports from the Fundamental Research Funds for the Central Universities,China(Nos.2019CDCGCL316,2020CDJDPT001)Chongqing Research Program of Basic Research and Frontier Technology,China(No.cstc2019jcjy-msxmX0539)。
文摘Mg−1Mn−0.5Al−0.5Ca−0.5Zn(wt.%)alloy was fabricated by conventional extrusion at 673 K with an extrusion ratio of 25:1,followed by aging at 473 K.The microstructure was characterized by scanning electron microscopy,electron back-scattered diffraction,and transmission electron microscopy.The mechanical properties were determined by the tensile test.The peak-aged sample shows fine recrystallized grains with an average grain size of 1.7μm.Area fraction of Al−Ca particles in the alloy increases significantly after peak aging.Meanwhile,botháañandác+añdislocations were observed to remain in the alloy after hot extrusion.Thus,the peak-aged sample exhibits simultaneously high strength and good ductility with the ultimate tensile stress,tensile yield stress,and tension fracture elongation of 320 MPa,314 MPa,and 19.0%,respectively.
基金Project(106/06/0252)supported by the Czech Science FoundationProject(CTU0810412)supported by the Grant Agency of the CzechTechnical University in Prague
文摘Creep of squeeze-cast Mg-3Y-2Nd-1Zn-1Mn alloy was investigated at the constant load in the stress range of 30-80 MPa. Tensile creep tests were performed at 300℃up to the final fracture.Several tests at 50 MPa were interrupted after reaching the steady state creep;and another set of creep tests was interrupted after the onset of ternary creep.Fraction of cavitated dendritic boundaries was evaluated using optical microscopy.Measurement of grain boundary sliding by observation of the offset of marker lines was carried out on the surface of the crept specimens after the test interruption by scanning electron microscopy and by confocal laser scanning microscopy.The results show that the dominant creep mechanism in this alloy is dislocation creep with minor contribution of the grain boundary sliding.Creep failure took place by the nucleation,growth and coalescence of creep cavities on the boundaries predominantly oriented perpendicular to the applied stress.Increasing amount of cavitated boundaries with time of creep exposure supports the mechanism of continuous cavity nucleation and growth.
基金This work was financially supported by the Natural Science Fund of Hebei Province, China (No.E2005000027), and the Natural Science Foundation of Tianjin, China (No.06YFJMJC02400).
文摘The density, microstructure and magnetic properties of non-doped Mn-Zn ferrite nanoparticles sintered compacts were investigated. The compacts of non-doped Mn-Zn ferrite nanoparticles were sintered by segmented-sintering process at lower sintering temperature. The density of sintered samples was measured by Archimedes method, and the phase composition and microstructure were examined by XRD and SEM. The sintered Mn-Zn ferrite magnetic measurements were carried out with Vibrating Sample. The results show that the density of sintered compacts increases with the rising of sintering temperature, achieving 4.8245 g·cm-3 when sintered at 900 ℃, which is the optimal density of Mn-Zn functional ferrite needed and from the fractured surface of sintered samples, it can be seen that the grain grows well with small grain size and homogeneous distribution.
基金Project(ZR2021QE136)supported by the Natural Science Foundation of Shandong Province,ChinaProject(2020B010186002)supported by the Key Research and Development Program of Guangdong Province,China。
文摘The Li-rich Zn-doped LiNbO 3 (LN) crystals were grown by the Czochralski method. The structure of the crystals was measured by ultraviolet-visible absorption spectra. The results indicated that the Li-rich Zn-doped LN crystals had the same characteristics as the pure LN crystal. After Zn 2+ entered into the lattice of Li-rich Zn-doped LN crystal, it replaced Nb Li firstly. When there was no Nb Li , Zn 2+ replaced Li + then. The second harmonic generation (SHG) property of Li-rich Zn-doped LiNbO 3 crystal was measured. The results showed that the SHG conversation efficiency of Li-rich Zn-doped LiNbO 3 crystals was higher than that of Zn-doped LiNbO 3 crystals.
