Porous Ti-Mg composites were successfully fabricated through powder metallurgy processing with ammonium hydrogen carbonate （NH4HCO3） as a space-holder. The effects of NH4HCO3 on properties of porous composites were ...Porous Ti-Mg composites were successfully fabricated through powder metallurgy processing with ammonium hydrogen carbonate （NH4HCO3） as a space-holder. The effects of NH4HCO3 on properties of porous composites were comprehensively investigated. The pore characteristics and compressive properties of the specimens were characterized by X-ray diffractometry （XRD） and scanning electron microscopy （SEM）. The results show that the porosity of the porous composites can be tailored effectively by changing the amount of NH4HCO3 added, and the use of NI-I4HCO3 has no influence on the microstructure and phase constituents of the Ti-10%Mg porous composites. The open porosity and compressive strength as well as compressive elastic modulus vary with the adding amount and particle size of NHaHCO3. When the mass fraction of NHaHCO3 added is 25%, elastic modulus and compressive strength of composites with porosity of around 50% are found to be similar to those of human bone.展开更多
The flow stress features of PM Ti-47Al-2Cr-0.2Mo alloy were studied by isothermal compression in the temperature range from 1000 to 1150 °C with strain rates of 0.001-1 s-1 on Gleeble-1500 thermo-simulation machi...The flow stress features of PM Ti-47Al-2Cr-0.2Mo alloy were studied by isothermal compression in the temperature range from 1000 to 1150 °C with strain rates of 0.001-1 s-1 on Gleeble-1500 thermo-simulation machine.The results show that the deformation temperature and strain rate have obvious effects on the flow characteristic,and the flow stress increases with increasing strain rate and decreasing temperature.The processing maps under different deformation conditions were established.The processing maps of this alloy are sensitive to strains.The processing map at the strain of 0.5 exhibits two suitable deformation domains of 1000-1050 °C at 0.001-0.05 s-1 and 1050-1125 °C at 0.01-0.1 s-1.The optimum parameters for hot working of the alloy are deformation temperature of 1000 °C and strain rate of 0.001 s-1 according to the processing map and microstructure at true strain of 0.5.展开更多
The deformation behavior of hot isostatic pressing （HIP） FGH96 superalloy was characterized in the temperature range of 1000-1100 ℃ and strain rate range of 0. 001-0. 1 s^-1 using hot compression testing. The flow ...The deformation behavior of hot isostatic pressing （HIP） FGH96 superalloy was characterized in the temperature range of 1000-1100 ℃ and strain rate range of 0. 001-0. 1 s^-1 using hot compression testing. The flow curves of HIP FGH96, superalloy during hot deformation was analyzed systematically. The results show that deformation temperature, strain rate and strain are the main influence factors on flow stress of HIP FGH96 superalloy during hot deformation. The flow stress displays a peak at a critical strain and then decreases with further increase in strain. For a given strain, the flow stress decreases with the increase of deformation temperature, and increases with the increase of strain rate. A mathematical model of these flow curves was established through regression analysis and taking the strain as a modification factor. The calculated stress values agree well with the experimental values.展开更多
This work describes a study of tabletting of selected Malaysian herbs such as Eurycoma longifolia Jack, Ficus deltoidea and Morinda citrifolia. These herbs are famous for their therapeutic properties and are used as h...This work describes a study of tabletting of selected Malaysian herbs such as Eurycoma longifolia Jack, Ficus deltoidea and Morinda citrifolia. These herbs are famous for their therapeutic properties and are used as herbal medicine or as medicinal food. A cylindrical uniaxial die of 13 mm was used to compress the herb powders into tablets. Pressures ranging from 7.5 MPa to 75 MPa were applied using a universal testing machine. Two feed weights, 0.5 g and 1.0 g, were used to produce the tablets. A binder, the microcrystalline cellulose known as Avicel, was used to investigate its effect on tabletting. Properties associated with both the binder and the compounds were studied, and binary mixtures with compositions ranging from 10% to 60% were examined. The strength of the herb tablets was then tested using an indirect tensile strength test. Upon compression, the Morinda citrifolia powder showed the highest density compared to that of Avicel. However, due to its high elasticity, the tensile strength of the Morinda citrifolia tablet was the lowest. The experimental data were also verified using an established model for compression property development. The results indicated that this simple approach can be used to understand the tabletting characteristics of these herbs.展开更多
文摘Porous Ti-Mg composites were successfully fabricated through powder metallurgy processing with ammonium hydrogen carbonate （NH4HCO3） as a space-holder. The effects of NH4HCO3 on properties of porous composites were comprehensively investigated. The pore characteristics and compressive properties of the specimens were characterized by X-ray diffractometry （XRD） and scanning electron microscopy （SEM）. The results show that the porosity of the porous composites can be tailored effectively by changing the amount of NH4HCO3 added, and the use of NI-I4HCO3 has no influence on the microstructure and phase constituents of the Ti-10%Mg porous composites. The open porosity and compressive strength as well as compressive elastic modulus vary with the adding amount and particle size of NHaHCO3. When the mass fraction of NHaHCO3 added is 25%, elastic modulus and compressive strength of composites with porosity of around 50% are found to be similar to those of human bone.
基金Project (51174233) supported by the National Natural Science Foundation of ChinaProject (2011CB605500) supported by National Basic Research program of China
文摘The flow stress features of PM Ti-47Al-2Cr-0.2Mo alloy were studied by isothermal compression in the temperature range from 1000 to 1150 °C with strain rates of 0.001-1 s-1 on Gleeble-1500 thermo-simulation machine.The results show that the deformation temperature and strain rate have obvious effects on the flow characteristic,and the flow stress increases with increasing strain rate and decreasing temperature.The processing maps under different deformation conditions were established.The processing maps of this alloy are sensitive to strains.The processing map at the strain of 0.5 exhibits two suitable deformation domains of 1000-1050 °C at 0.001-0.05 s-1 and 1050-1125 °C at 0.01-0.1 s-1.The optimum parameters for hot working of the alloy are deformation temperature of 1000 °C and strain rate of 0.001 s-1 according to the processing map and microstructure at true strain of 0.5.
基金Supported by Young Teacher Foundation of Tianjin University (5110105) and Aeronautic Science Foundation (03H53048).
文摘The deformation behavior of hot isostatic pressing （HIP） FGH96 superalloy was characterized in the temperature range of 1000-1100 ℃ and strain rate range of 0. 001-0. 1 s^-1 using hot compression testing. The flow curves of HIP FGH96, superalloy during hot deformation was analyzed systematically. The results show that deformation temperature, strain rate and strain are the main influence factors on flow stress of HIP FGH96 superalloy during hot deformation. The flow stress displays a peak at a critical strain and then decreases with further increase in strain. For a given strain, the flow stress decreases with the increase of deformation temperature, and increases with the increase of strain rate. A mathematical model of these flow curves was established through regression analysis and taking the strain as a modification factor. The calculated stress values agree well with the experimental values.
文摘This work describes a study of tabletting of selected Malaysian herbs such as Eurycoma longifolia Jack, Ficus deltoidea and Morinda citrifolia. These herbs are famous for their therapeutic properties and are used as herbal medicine or as medicinal food. A cylindrical uniaxial die of 13 mm was used to compress the herb powders into tablets. Pressures ranging from 7.5 MPa to 75 MPa were applied using a universal testing machine. Two feed weights, 0.5 g and 1.0 g, were used to produce the tablets. A binder, the microcrystalline cellulose known as Avicel, was used to investigate its effect on tabletting. Properties associated with both the binder and the compounds were studied, and binary mixtures with compositions ranging from 10% to 60% were examined. The strength of the herb tablets was then tested using an indirect tensile strength test. Upon compression, the Morinda citrifolia powder showed the highest density compared to that of Avicel. However, due to its high elasticity, the tensile strength of the Morinda citrifolia tablet was the lowest. The experimental data were also verified using an established model for compression property development. The results indicated that this simple approach can be used to understand the tabletting characteristics of these herbs.
