It is important to know the maximum solid solubility( C max ) of various transition metals in a metal when one designs multi component alloys. There have been several semi empirical approaches to qualitatively predict...It is important to know the maximum solid solubility( C max ) of various transition metals in a metal when one designs multi component alloys. There have been several semi empirical approaches to qualitatively predict the C max , such as Darken Gurry(D G) theorem, Miedema Chelikowsky(M C) theorem, electron concentration rule and the bond parameter rule. However, they are not particularly valid for the prediction of C max . It was developed on the basis of energetics of alloys as a new method to predict C max of different transition metals in metal Ti, which can be described as a semi empirical equation using the atomic parameters, i e, electronegativity difference, atomic diameter and electron concentration. It shows that the present method can be used to explain and deduce D G theorem, M C theorem and electron concentration rule.展开更多
Based on the principle of energy change of alloy formation, the rules for the maximum solid solubility ( C max ) of various transition metals in the metals Ti, Zr and Hf were studied. It is deduced that the C max of t...Based on the principle of energy change of alloy formation, the rules for the maximum solid solubility ( C max ) of various transition metals in the metals Ti, Zr and Hf were studied. It is deduced that the C max of transition metals in the metals Ti, Zr and Hf can be described as a semi empirical equation using three atomic parameters, i.e., electronegativity difference, atomic diameter and electron concentration. From the equation analysis by using experimental data, it shows that atomic size parameter and electronegativity difference are the main factors that affect the C max of the transition metals in the metals Ti, Zr and Hf while electron concentration parameter has the smallest effect on C max .展开更多
Gadolinia-doped ceria ceramic pastes were formulated with different solid loadings and extruded using lab-scale equipment.The force to maintain a constant ram speed of 10 mm/min was recorded.The radial shrinkage after...Gadolinia-doped ceria ceramic pastes were formulated with different solid loadings and extruded using lab-scale equipment.The force to maintain a constant ram speed of 10 mm/min was recorded.The radial shrinkage after drying was proportional to the solid loading and this allowed the determination of the maximum solid loading by an extrapolation procedure.In order to obtain the apparent viscosity of the pastes,a novel approach based on the analysis of the slope of the extrusion pressure plot versus distance covered by the ram,was formulated for the direct determination of the shear stress upon extrusion.The agreement of the determined maximum solid loading with values calculated by two existing models confirmed that the proposed approach was an alternative and reliable method to identify the upper limit of the solid loading range for the formulation of extrudable ceramic pastes.展开更多
A test device with rectangular channel is developed to study the combustion performance of solid propellant in high temperature particles erosion.The flowfields in this newdevice and a test device with circular channe...A test device with rectangular channel is developed to study the combustion performance of solid propellant in high temperature particles erosion.The flowfields in this newdevice and a test device with circular channels are simulated numerically.The particle erosion experiments in these two devices are carried out under different particle concentrations.The results showthat the test device with rectangular channel can effectively improve the clarity and precision of combustion diagnosis image and can be used for research on combustion performance of solid propellant under lowconcentration particle erosion;the circular channel device has good particle convergent effect,provides high concentration particle erosion,and can be used for research on the combustion performance of solid propellant under high concentration particle erosion.The experiment data indicates that the propellant burning rate does not change obviously in lower particle concentration;the propellant with lower static burning rate increases remarkably under particle erosion,while the propellant with high static burning rate is not sensitive to the particle erosion.展开更多
文摘It is important to know the maximum solid solubility( C max ) of various transition metals in a metal when one designs multi component alloys. There have been several semi empirical approaches to qualitatively predict the C max , such as Darken Gurry(D G) theorem, Miedema Chelikowsky(M C) theorem, electron concentration rule and the bond parameter rule. However, they are not particularly valid for the prediction of C max . It was developed on the basis of energetics of alloys as a new method to predict C max of different transition metals in metal Ti, which can be described as a semi empirical equation using the atomic parameters, i e, electronegativity difference, atomic diameter and electron concentration. It shows that the present method can be used to explain and deduce D G theorem, M C theorem and electron concentration rule.
文摘Based on the principle of energy change of alloy formation, the rules for the maximum solid solubility ( C max ) of various transition metals in the metals Ti, Zr and Hf were studied. It is deduced that the C max of transition metals in the metals Ti, Zr and Hf can be described as a semi empirical equation using three atomic parameters, i.e., electronegativity difference, atomic diameter and electron concentration. From the equation analysis by using experimental data, it shows that atomic size parameter and electronegativity difference are the main factors that affect the C max of the transition metals in the metals Ti, Zr and Hf while electron concentration parameter has the smallest effect on C max .
文摘Gadolinia-doped ceria ceramic pastes were formulated with different solid loadings and extruded using lab-scale equipment.The force to maintain a constant ram speed of 10 mm/min was recorded.The radial shrinkage after drying was proportional to the solid loading and this allowed the determination of the maximum solid loading by an extrapolation procedure.In order to obtain the apparent viscosity of the pastes,a novel approach based on the analysis of the slope of the extrusion pressure plot versus distance covered by the ram,was formulated for the direct determination of the shear stress upon extrusion.The agreement of the determined maximum solid loading with values calculated by two existing models confirmed that the proposed approach was an alternative and reliable method to identify the upper limit of the solid loading range for the formulation of extrudable ceramic pastes.
基金Sponsored by the National Nature Science Foundation of China(50976095)
文摘A test device with rectangular channel is developed to study the combustion performance of solid propellant in high temperature particles erosion.The flowfields in this newdevice and a test device with circular channels are simulated numerically.The particle erosion experiments in these two devices are carried out under different particle concentrations.The results showthat the test device with rectangular channel can effectively improve the clarity and precision of combustion diagnosis image and can be used for research on combustion performance of solid propellant under lowconcentration particle erosion;the circular channel device has good particle convergent effect,provides high concentration particle erosion,and can be used for research on the combustion performance of solid propellant under high concentration particle erosion.The experiment data indicates that the propellant burning rate does not change obviously in lower particle concentration;the propellant with lower static burning rate increases remarkably under particle erosion,while the propellant with high static burning rate is not sensitive to the particle erosion.
