It is shown that an adapted powder sintering process can successfully prepare a 24.0%-35.5% porous titanium composite using 20μm Ti powder and rice husk particles ranging in size between 250μm and600μm.The phase co...It is shown that an adapted powder sintering process can successfully prepare a 24.0%-35.5% porous titanium composite using 20μm Ti powder and rice husk particles ranging in size between 250μm and600μm.The phase constituents of the porous Ti composite samples were determined by X-ray diffraction（XRD）pattern sintered at 1250℃.The generation of silicon in the form of a TiSi2 solid solution,injected into the substrate,illustrates the solid solution strengthening effect.The average grain size of the tested sample and the grain boundary area increase along with the silicon content.This indicates that silicon is dispersed within the green compact of Ti.As the distance from a hole becomes greater,the nanohardness increases until it reaches a maximum hardness of 3.5GPa at approximately 1.5mm.This may be due to the solid solution strengthening of SiO2.However,nanohardness is 3.3GPa at a distance of approximately 0.5mm from a hole′s edge.The compressive strength is measured to be in the range of 440-938 MPa.The strain reaches 14.8%-16.6% under compression testing.A large number of cleavage steps appear following a fracture.The observed fracture is a brittle fracture.Porous Ti composites with about 36% porosity have promising potential biomaterial applications,specifically related to bone implants and biological bearings.展开更多
Let f ： M → M be a partially hyperbolic diffeomorphism on a closed Riemannian manifold with uniformly compact center foliation. We show that if the center foliation of f is of dimension one then the topological entr...Let f ： M → M be a partially hyperbolic diffeomorphism on a closed Riemannian manifold with uniformly compact center foliation. We show that if the center foliation of f is of dimension one then the topological entropy is constant on a small C1 neighborhood of f.展开更多
基金financial support from the National Natural Science Foundation of China(51601143,51641106)the Pivot Innovation Team of Shaanxi Electric Materials and Infiltration Technique(2012KCT-25)
文摘It is shown that an adapted powder sintering process can successfully prepare a 24.0%-35.5% porous titanium composite using 20μm Ti powder and rice husk particles ranging in size between 250μm and600μm.The phase constituents of the porous Ti composite samples were determined by X-ray diffraction（XRD）pattern sintered at 1250℃.The generation of silicon in the form of a TiSi2 solid solution,injected into the substrate,illustrates the solid solution strengthening effect.The average grain size of the tested sample and the grain boundary area increase along with the silicon content.This indicates that silicon is dispersed within the green compact of Ti.As the distance from a hole becomes greater,the nanohardness increases until it reaches a maximum hardness of 3.5GPa at approximately 1.5mm.This may be due to the solid solution strengthening of SiO2.However,nanohardness is 3.3GPa at a distance of approximately 0.5mm from a hole′s edge.The compressive strength is measured to be in the range of 440-938 MPa.The strain reaches 14.8%-16.6% under compression testing.A large number of cleavage steps appear following a fracture.The observed fracture is a brittle fracture.Porous Ti composites with about 36% porosity have promising potential biomaterial applications,specifically related to bone implants and biological bearings.
基金supported by NSFC(No:11371120)GCCHB(No:GCC2014052)supported by NSFHB(No:A2014205154)
文摘Let f ： M → M be a partially hyperbolic diffeomorphism on a closed Riemannian manifold with uniformly compact center foliation. We show that if the center foliation of f is of dimension one then the topological entropy is constant on a small C1 neighborhood of f.
