Refractory metal niobium(Nb) incorporated with a small amount of silver(Ag),the resulting Nb-Ag twophase alloys,were fabricated by mechanical alloying and spark plasma sintering.The microstructure,mechanical propertie...Refractory metal niobium(Nb) incorporated with a small amount of silver(Ag),the resulting Nb-Ag twophase alloys,were fabricated by mechanical alloying and spark plasma sintering.The microstructure,mechanical properties,wear resistance,corrosion behavior,in vitro and in vivo antibacterial properties and biocompatibility of the Nb-Ag alloys were systematically investigated.The results show that the mechanical properties,wear resistance,corrosion resistance and antibacterial ability were significantly enhanced after addition of 5 at.% Ag.The fabricated Nb-5 at.% Ag alloy demonstrates high yield strength of up to ~1486 MPa and fracture strain of ~35 %.The precipitated Ag particles could reduce friction and wear.The enhanced corrosion resistance was attributed to the higher relative density of the sintered alloys and the formation of a stable and dense passive film of niobium and silver oxides.In vitro and in vivo evaluations show that the Nb-5 at.% Ag alloy also has strong antibacterial activity and good biocompatibility and osteointegration ability.These results demonstrate great potential of the nanostructured Nb-Ag alloys for dental and orthopedic implants.展开更多
Dental enamel is the most mineralised hard tissue with a complex hierarchically organised anisotropic structure and it protects human teeth from mechanical damage during the dental function.Due to the sample size cons...Dental enamel is the most mineralised hard tissue with a complex hierarchically organised anisotropic structure and it protects human teeth from mechanical damage during the dental function.Due to the sample size constraints,the available data for quantitative evaluation of the fracture toughness of human enamel is very limited.Here,on the basis of microstructural characterisation,the fracture toughness of human dental enamel at small scale with respect to orientation was measured using notched microcantilever beams fabricated by focussed ion beam.The fracture toughness of human enamel with perpendicular orientation was measured to be 1.244±0.12 MPa·m^(1/2),80%tougher than that of in-plane parallel orientation(0.698±0.18 MPa·m^(1/2)).The present results are expected to provide deep insights into cusp fractures and the synthesis of enamel-like restorative materials.展开更多
基金financially supported by the Natural Science Foundation of Guangdong(Grant No.2019A1515011755)the Fundamental Research Program of Shenzhen(Grant Nos.JCYJ20170412153039309 and JCYJ20170307110418960)the Natural Science Foundation of Tianjin(General Program,No.18JCYBJC19500),China。
文摘Refractory metal niobium(Nb) incorporated with a small amount of silver(Ag),the resulting Nb-Ag twophase alloys,were fabricated by mechanical alloying and spark plasma sintering.The microstructure,mechanical properties,wear resistance,corrosion behavior,in vitro and in vivo antibacterial properties and biocompatibility of the Nb-Ag alloys were systematically investigated.The results show that the mechanical properties,wear resistance,corrosion resistance and antibacterial ability were significantly enhanced after addition of 5 at.% Ag.The fabricated Nb-5 at.% Ag alloy demonstrates high yield strength of up to ~1486 MPa and fracture strain of ~35 %.The precipitated Ag particles could reduce friction and wear.The enhanced corrosion resistance was attributed to the higher relative density of the sintered alloys and the formation of a stable and dense passive film of niobium and silver oxides.In vitro and in vivo evaluations show that the Nb-5 at.% Ag alloy also has strong antibacterial activity and good biocompatibility and osteointegration ability.These results demonstrate great potential of the nanostructured Nb-Ag alloys for dental and orthopedic implants.
基金Natural Science Foundation of Guangdong Province,Grant/Award Number:2019A1515011755National Key Research and Development Program of China,Grant/Award Number:2016YFB0700803。
文摘Dental enamel is the most mineralised hard tissue with a complex hierarchically organised anisotropic structure and it protects human teeth from mechanical damage during the dental function.Due to the sample size constraints,the available data for quantitative evaluation of the fracture toughness of human enamel is very limited.Here,on the basis of microstructural characterisation,the fracture toughness of human dental enamel at small scale with respect to orientation was measured using notched microcantilever beams fabricated by focussed ion beam.The fracture toughness of human enamel with perpendicular orientation was measured to be 1.244±0.12 MPa·m^(1/2),80%tougher than that of in-plane parallel orientation(0.698±0.18 MPa·m^(1/2)).The present results are expected to provide deep insights into cusp fractures and the synthesis of enamel-like restorative materials.
