This work aims at developing a new and reliable biomaterial for implant application by fabricating calcium phosphate/Al2O3 biocomposite coating on medical titanium using a hybrid technique of anodic oxidation and hydr...This work aims at developing a new and reliable biomaterial for implant application by fabricating calcium phosphate/Al2O3 biocomposite coating on medical titanium using a hybrid technique of anodic oxidation and hydrothermal treatment. The pre- and post-anodized samples were investigated by scanning electron microscopy (SEM), energy dispersive analysis of X-ray (EDAX), transmission electron microscopy (TEM), and X-ray diffraction (XRD) techniques. The results indicated that porous anodic alumina film containing Ca and P was obtained on the as-prepared Al-Ti substrate through anodization, and the subsequent hydrothermal treatment led to the formation of calcium phosphate crystals. SEM and TEM results showed that calcium phosphate crystals were in nanometer, in-situ embedded in the walls of the cylindrical structure of anodic alumina, and finally formed a thin and porous top layer on the anodic alumina layer. The nanometer effect of calcium phosphate top layer, the porous and cylindrical microstructure of calcium phosphate/Al2O3-Ti, and the in-situ growth effect are expect to possess a very good combination of bioactivity and mechanical integrity.展开更多
Alloys with combined outstanding strength and excellent ductility are highly desirable for many structural applications.However,alloys subjected to deformation at very high strain rates and/or cryogenic temperatures u...Alloys with combined outstanding strength and excellent ductility are highly desirable for many structural applications.However,alloys subjected to deformation at very high strain rates and/or cryogenic temperatures usually suffer from very limited ductility.Here,we demonstrate that a bulk CrCoNi medium-entropy alloy presents exceptional combination of high strength and excellent ductility during deformation at high strain rates over a wide temperature range.Full tensile stress-strain curves at a high strain rate of 2000s^(-1) and temperatures down to 77 K were successfully obtained using an electromagnetic Hopkinson tension bar system attached with a cooling device,revealing high true ultimate tensile strength(σ_(UTS,T))of 1.8 GPa and true strain of~54% at σ_(UTS,T).These outstanding mechanical properties were mainly attributed to profuse deformation twinning.Both high strain rate and cryogenic temperature promoted deformation twinning.Grain refinement caused by deformation twinning,dislocation slip and dynamic recrystallisation added to work hardening and the excellent tensile strain.展开更多
The long-term safe operation of high-power equipment and integrated electronic devices requires efficient thermal management,which in turn increases the energy consumption further.Hence,the sustainable development of ...The long-term safe operation of high-power equipment and integrated electronic devices requires efficient thermal management,which in turn increases the energy consumption further.Hence,the sustainable development of our society needs advanced thermal management with low,even zero,energy consumption.Harvesting water from the atmosphere,followed by moisture desorption to dissipate heat,is an efficient and feasible approach for zero-energy-consumption thermal management.However,current methods are limited by the low absorbance of water,low water vapor transmission rate(WVTR)and low stability,thus resulting in low thermal management capability.In this study,we report an innovative electrospinning method to process hierarchically porous metal–organic framework(MOF)composite fabrics with high-efficiency and zero-energy-consumption thermal management.The composite fabrics are highly loaded with MOF(75 wt%)and their WVTR value can be up to 3138 g m^(-2) d^(-1).The composite fabrics also exhibit stable microstructure and performance.Under a conventional environment(30℃,60%relative humidity),the composite fabrics adsorb water vapor for regeneration within 1.5 h to a saturated value Wsat of 0.614 g g^(-1),and a corresponding equivalent enthalpy of 1705.6 J g^(-1).In the thermal management tests,the composite fabrics show a strong cooling capability and significantly improve the performance of thermoelectric devices,portable storage devices and wireless chargers.These results suggest that hierarchically porous MOF composite fabrics are highly promising for thermal management of intermittent-operation electronic devices.展开更多
文摘This work aims at developing a new and reliable biomaterial for implant application by fabricating calcium phosphate/Al2O3 biocomposite coating on medical titanium using a hybrid technique of anodic oxidation and hydrothermal treatment. The pre- and post-anodized samples were investigated by scanning electron microscopy (SEM), energy dispersive analysis of X-ray (EDAX), transmission electron microscopy (TEM), and X-ray diffraction (XRD) techniques. The results indicated that porous anodic alumina film containing Ca and P was obtained on the as-prepared Al-Ti substrate through anodization, and the subsequent hydrothermal treatment led to the formation of calcium phosphate crystals. SEM and TEM results showed that calcium phosphate crystals were in nanometer, in-situ embedded in the walls of the cylindrical structure of anodic alumina, and finally formed a thin and porous top layer on the anodic alumina layer. The nanometer effect of calcium phosphate top layer, the porous and cylindrical microstructure of calcium phosphate/Al2O3-Ti, and the in-situ growth effect are expect to possess a very good combination of bioactivity and mechanical integrity.
基金support from the Australian Microscopy and Microanalysis Research Facility node at the University of Sydneysupported by the Australian Research Council(DP190102243)。
文摘Alloys with combined outstanding strength and excellent ductility are highly desirable for many structural applications.However,alloys subjected to deformation at very high strain rates and/or cryogenic temperatures usually suffer from very limited ductility.Here,we demonstrate that a bulk CrCoNi medium-entropy alloy presents exceptional combination of high strength and excellent ductility during deformation at high strain rates over a wide temperature range.Full tensile stress-strain curves at a high strain rate of 2000s^(-1) and temperatures down to 77 K were successfully obtained using an electromagnetic Hopkinson tension bar system attached with a cooling device,revealing high true ultimate tensile strength(σ_(UTS,T))of 1.8 GPa and true strain of~54% at σ_(UTS,T).These outstanding mechanical properties were mainly attributed to profuse deformation twinning.Both high strain rate and cryogenic temperature promoted deformation twinning.Grain refinement caused by deformation twinning,dislocation slip and dynamic recrystallisation added to work hardening and the excellent tensile strain.
基金supported by the National Natural Science Foundation of China(51877132,U19A20105,and 52003153)the Program of Shanghai Academic Research Leader(21XD1401600)。
文摘The long-term safe operation of high-power equipment and integrated electronic devices requires efficient thermal management,which in turn increases the energy consumption further.Hence,the sustainable development of our society needs advanced thermal management with low,even zero,energy consumption.Harvesting water from the atmosphere,followed by moisture desorption to dissipate heat,is an efficient and feasible approach for zero-energy-consumption thermal management.However,current methods are limited by the low absorbance of water,low water vapor transmission rate(WVTR)and low stability,thus resulting in low thermal management capability.In this study,we report an innovative electrospinning method to process hierarchically porous metal–organic framework(MOF)composite fabrics with high-efficiency and zero-energy-consumption thermal management.The composite fabrics are highly loaded with MOF(75 wt%)and their WVTR value can be up to 3138 g m^(-2) d^(-1).The composite fabrics also exhibit stable microstructure and performance.Under a conventional environment(30℃,60%relative humidity),the composite fabrics adsorb water vapor for regeneration within 1.5 h to a saturated value Wsat of 0.614 g g^(-1),and a corresponding equivalent enthalpy of 1705.6 J g^(-1).In the thermal management tests,the composite fabrics show a strong cooling capability and significantly improve the performance of thermoelectric devices,portable storage devices and wireless chargers.These results suggest that hierarchically porous MOF composite fabrics are highly promising for thermal management of intermittent-operation electronic devices.
