A 3D finite element model was established to investigate the temperature and stress fields during the selective laser melting process of Al−Mg−Sc−Zr alloy.By considering the powder−solid transformation,temperaturedepe...A 3D finite element model was established to investigate the temperature and stress fields during the selective laser melting process of Al−Mg−Sc−Zr alloy.By considering the powder−solid transformation,temperaturedependent thermal properties,latent heat of phase transformations and molten pool convection,the effects of laser power,point distance and hatch spacing on the temperature distribution,molten pool dimensions and residual stress distribution were investigated.Then,the effects of laser power,point distance and hatch spacing on the microstructure,density and hardness of the alloy were studied by the experimental method.The results show that the molten pool size gradually increases as the laser power increases and the point distance and hatch spacing decrease.The residual stress mainly concentrates in the middle of the first scanning track and the beginning and end of each scanning track.Experimental results demonstrate the accuracy of the model.The density of the samples tends to increase and then decrease with increasing laser power and decreasing point distance and hatch spacing.The optimum process parameters are laser power of 325−375 W,point distance of 80−100μm and hatch spacing of 80μm.展开更多
Preliminary sink-float experiments on high-sulfur coal was done in some mining areas and carried on elementary analysis, industrial analysis, and ashcontent analysis. Through the experiments, definite middlings, and g...Preliminary sink-float experiments on high-sulfur coal was done in some mining areas and carried on elementary analysis, industrial analysis, and ashcontent analysis. Through the experiments, definite middlings, and gangue, the phase analysis of sulfur was carried on, by which a good understanding of sulfur characters in raw coal was achieved.展开更多
Originated from the pore space segmentation modification of a reported metal-organic framework （MOF） （NOTT-125）, a new porous MOF ZnX was obtained and characterized by single-crystal X-ray diffraction, elemental a...Originated from the pore space segmentation modification of a reported metal-organic framework （MOF） （NOTT-125）, a new porous MOF ZnX was obtained and characterized by single-crystal X-ray diffraction, elemental analysis, X-ray powder diffraction and TGA. The ZnX exhibits remarkable selective CO2 adsorption property compared with that of the NOTT-125, which should be attributed to the enhanced gas-framework interactions induced by the fragmented pore space in ZnX.展开更多
基金financial supports from the National Natural Science Foundation of China (No.51804349)the China Postdoctoral Science Foundation (No.2018M632986)+1 种基金the Natural Science Foundation of Hunan Province,China (No.2019JJ50766)the National Key Laboratory of Science and Technology on High-strength Structural Materials,China (No.JCKY201851)。
文摘A 3D finite element model was established to investigate the temperature and stress fields during the selective laser melting process of Al−Mg−Sc−Zr alloy.By considering the powder−solid transformation,temperaturedependent thermal properties,latent heat of phase transformations and molten pool convection,the effects of laser power,point distance and hatch spacing on the temperature distribution,molten pool dimensions and residual stress distribution were investigated.Then,the effects of laser power,point distance and hatch spacing on the microstructure,density and hardness of the alloy were studied by the experimental method.The results show that the molten pool size gradually increases as the laser power increases and the point distance and hatch spacing decrease.The residual stress mainly concentrates in the middle of the first scanning track and the beginning and end of each scanning track.Experimental results demonstrate the accuracy of the model.The density of the samples tends to increase and then decrease with increasing laser power and decreasing point distance and hatch spacing.The optimum process parameters are laser power of 325−375 W,point distance of 80−100μm and hatch spacing of 80μm.
文摘Preliminary sink-float experiments on high-sulfur coal was done in some mining areas and carried on elementary analysis, industrial analysis, and ashcontent analysis. Through the experiments, definite middlings, and gangue, the phase analysis of sulfur was carried on, by which a good understanding of sulfur characters in raw coal was achieved.
基金supported by the National Natural Science Foundation of China(21531005,21421001,and 21290171)Ministry of Education Innovation Team of China(IRT13022)
文摘Originated from the pore space segmentation modification of a reported metal-organic framework （MOF） （NOTT-125）, a new porous MOF ZnX was obtained and characterized by single-crystal X-ray diffraction, elemental analysis, X-ray powder diffraction and TGA. The ZnX exhibits remarkable selective CO2 adsorption property compared with that of the NOTT-125, which should be attributed to the enhanced gas-framework interactions induced by the fragmented pore space in ZnX.
