The biodegradability and biocompatibility of Mg alloys have rendered them favorable for cranial reconstruction applications.However,their rapid degradation rate has limited widespread use.In this study,we developed a ...The biodegradability and biocompatibility of Mg alloys have rendered them favorable for cranial reconstruction applications.However,their rapid degradation rate has limited widespread use.In this study,we developed a Mg alloy-based mesh designed for calvarial bone defect reconstruction.We modulated the bone formation through the controlled degradation rate of the Mg alloy mesh.To achieve this,the Mg alloy mesh was coated with 2 types of coatings:Zn-d/Ca-P and Zn-d/Ca-P/P.Our findings revealed that,in comparison to the uncoated Mg alloy,both Zn-d/Ca-P and Zn-d/Ca-P/P coatings significantly reduced the degradation rate.The biocompatibility of the coated meshes improved markedly.With the Zn-d/Ca-P coating,there was not only an augmentation in the osteogenic potential of the Mg mesh but also an enhancement in angiogenic capacity.These meshed Mg samples were subsequently implanted into calvarial defects in rats.Bone regeneration was accelerated in specimens treated with Zn-d/Ca-P and Zn-d/Ca-P/P coatings compared to those with the bare Mg mesh.Furthermore,the in vivo assessments indicated that the coated meshes promoted angiogenesis.Nonetheless,the degradation rate of the Zn-d/Ca-P/P coating was slower than that of Zn-B/Ca-P.For applications requiring prolonged mechanical support,the Zn-d/Ca-P/P coating on Mg alloy is recommended,whereas the Zn-d/Ca-P coating is advisable for rapid regeneration where extended mechanical support is not critical.展开更多
The influence of pre-strain on the formation of bimodal grain structures and tensile properties of a Co-20 Cr-15 W-10 Ni alloy was investigated.The bimodal grain structures consist of fine grains(FGs;2-3μm in diamete...The influence of pre-strain on the formation of bimodal grain structures and tensile properties of a Co-20 Cr-15 W-10 Ni alloy was investigated.The bimodal grain structures consist of fine grains(FGs;2-3μm in diameter)and coarse grains(CGs;8-16μm in diameter),which can be manipulated by changing the pre-strain(ε=0.3-0.7)and annealing temperatures(1000-1100℃).High pre-strain applied in the samples can intensify the plasticity heterogeneity through increasing the total dislocation density and the local volumes of high-density dislocations.This can essentially result in finer FGs,a higher FG volume fraction,and overall grain refinement in the samples after annealing.High-temperature essentially increases both the size and volume fraction of CGs,leading to an increase in the average grain size.The tensile test suggests that the bimodal grain structured samples exhibited both high strength and ductility,yield strengths of621-877 MPa and ultimate tensile strengths of1187-1367 MPa with uniform elongations of 55.0%-71.4%.The superior strength-ductility combination of the samples arises from the specific deformation mechanisms of the bimodal grain structures.The tensile properties strongly depend on the size ratio and volume fraction of FGs/CGs in addition to the average grain size in the bimodal grain structures.The grain structures can be modified via changing the pre-strain and annealing temperature.展开更多
基金funded by the National Research Foundation of Korea (NRF) funded by the Ministry of Education,(2015R1A6A1A03032522),South Koreapartially by Soonchunhyang University,South Korea.
文摘The biodegradability and biocompatibility of Mg alloys have rendered them favorable for cranial reconstruction applications.However,their rapid degradation rate has limited widespread use.In this study,we developed a Mg alloy-based mesh designed for calvarial bone defect reconstruction.We modulated the bone formation through the controlled degradation rate of the Mg alloy mesh.To achieve this,the Mg alloy mesh was coated with 2 types of coatings:Zn-d/Ca-P and Zn-d/Ca-P/P.Our findings revealed that,in comparison to the uncoated Mg alloy,both Zn-d/Ca-P and Zn-d/Ca-P/P coatings significantly reduced the degradation rate.The biocompatibility of the coated meshes improved markedly.With the Zn-d/Ca-P coating,there was not only an augmentation in the osteogenic potential of the Mg mesh but also an enhancement in angiogenic capacity.These meshed Mg samples were subsequently implanted into calvarial defects in rats.Bone regeneration was accelerated in specimens treated with Zn-d/Ca-P and Zn-d/Ca-P/P coatings compared to those with the bare Mg mesh.Furthermore,the in vivo assessments indicated that the coated meshes promoted angiogenesis.Nonetheless,the degradation rate of the Zn-d/Ca-P/P coating was slower than that of Zn-B/Ca-P.For applications requiring prolonged mechanical support,the Zn-d/Ca-P/P coating on Mg alloy is recommended,whereas the Zn-d/Ca-P coating is advisable for rapid regeneration where extended mechanical support is not critical.
基金financially supported by the Korea Institute of Materials Science(No.PNK7140)the National Key R&D Project of Ministry of Science and Technology of China(No.2020YFC1107200)。
文摘The influence of pre-strain on the formation of bimodal grain structures and tensile properties of a Co-20 Cr-15 W-10 Ni alloy was investigated.The bimodal grain structures consist of fine grains(FGs;2-3μm in diameter)and coarse grains(CGs;8-16μm in diameter),which can be manipulated by changing the pre-strain(ε=0.3-0.7)and annealing temperatures(1000-1100℃).High pre-strain applied in the samples can intensify the plasticity heterogeneity through increasing the total dislocation density and the local volumes of high-density dislocations.This can essentially result in finer FGs,a higher FG volume fraction,and overall grain refinement in the samples after annealing.High-temperature essentially increases both the size and volume fraction of CGs,leading to an increase in the average grain size.The tensile test suggests that the bimodal grain structured samples exhibited both high strength and ductility,yield strengths of621-877 MPa and ultimate tensile strengths of1187-1367 MPa with uniform elongations of 55.0%-71.4%.The superior strength-ductility combination of the samples arises from the specific deformation mechanisms of the bimodal grain structures.The tensile properties strongly depend on the size ratio and volume fraction of FGs/CGs in addition to the average grain size in the bimodal grain structures.The grain structures can be modified via changing the pre-strain and annealing temperature.
