A theoretical model on the solvus line prediction of a film was proposed and applied to a nanogranular A1-Cu system. The calculation results show that the solvus line of solute Cu will markedly lower with the decrease...A theoretical model on the solvus line prediction of a film was proposed and applied to a nanogranular A1-Cu system. The calculation results show that the solvus line of solute Cu will markedly lower with the decrease of grain size, namely, the starting temperature of θ （Al2Cu） precipitation in a nanogranular A1-Cu film will markedly lower than that of conventional coarse grain alloy with the same Cu concentration, and the precipitation temperatures calculated are comparable with the experimental ones. The theoretical model can be simply used to calculate the starting temperature of precipitation in A1-Cu films under three states： ① films with substrate; ②films without substrate; ③ultrafine grain bulk alloy. As a result, the model is universal, moreover, can be, in principle, used to predict precipitation temperature in other systems.展开更多
To reveal the affecting mechanism of cooling rate on lamellarαprecipitation,the precipitation behaviors of lamellarαphase in IMI834 titanium alloy during isothermal and non-isothermal heat treatments were quantitati...To reveal the affecting mechanism of cooling rate on lamellarαprecipitation,the precipitation behaviors of lamellarαphase in IMI834 titanium alloy during isothermal and non-isothermal heat treatments were quantitatively characterized using experimental analysis.Critical precipitation temperatures at various cooling rates were obtained using thermal dilatation testing.Using metallographic microscopy,electron microprobe analysis,and data fitting methods,the quantitative evolution models of average width,volume fraction,and solute concentration in theαandβphases were built for different temperatures or cooling rates.A comparison between the two precipitation behaviors showed that the average width and volume fraction of lamellarαphase under non-isothermal conditions were smaller than those under isothermal conditions.With increasing cooling rate,the average width and volume fraction were decreased significantly,and the critical precipitation temperatures were reduced.This phenomenon is mainly attributed to the decreased diffusion velocity of solutes Al,Mo,and Nb with increasing cooling rate.展开更多
Vapor-liquid equilibrium （VLE） data for copolymer solutions are necessary for several chemical processes. However, VLE data for copolymer solutions in the published report are rare. In this study, experimental VLE d...Vapor-liquid equilibrium （VLE） data for copolymer solutions are necessary for several chemical processes. However, VLE data for copolymer solutions in the published report are rare. In this study, experimental VLE data for binary systems copolymer＋solvent were obtained using a gravimetric-sorption apparatus. The studied systems were hexane＋poly （21% acrylonitrile-co-butadiene）, hexane＋poly （33% acrylonitrile-co-butadiene）, hexane＋poly （51% acrylonitrile-co-butadiene）, hexane＋poly （23% styrene-co-butadiene）, hexane＋poly （45% styrene-co-butadiene）, and benzene＋poly （44% styrene-co-methyl methacrylate） in the range 50-70℃. The experimental data were correlated with the UNIFAC and Elbro-FV group contribution models for the activity coefficient. Two sets of functional groups had been used to represent the monomers in copolymers： literature groups and new proposed groups. The mean deviations between experimental and calculated mass fractions about 2.4% with Elbro- FV and 13.3% with Zhong were observed when the groups proposed in this study were used, and of 3.5% for E1- bro-FV and 13.2% for Zhong, when literature grouns were used.展开更多
A single phase of zirconium diboride （ZrB2） powder was successfully synthesized by sol-gel method in Zr-B-C-O system, using zirconium oxychloride （ZrOC12 ~ 8H20）, nano-scale boron and suerose（C12H22011）as the st...A single phase of zirconium diboride （ZrB2） powder was successfully synthesized by sol-gel method in Zr-B-C-O system, using zirconium oxychloride （ZrOC12 ~ 8H20）, nano-scale boron and suerose（C12H22011）as the starting materials and propylene oxide （PO） as complexing agent at a low temperature. Simultaneously, the experimen- tal and theoretical studies of ZrB2 synthesized by boro/carbothermal reduction from novel sol-gel technology were discussed. The results indicated that the pure rod-like ZrB2 powder without residual ZrO2 phase could be obtained with a B/Zr molar ratio of 3.5 at 1 400~C in argon atmosphere. Besides, in this study, a kinetic model for the Zr-B-C-O sys- tem producing ZrB2 by boro/carbothermal reaction was established based on thermodynamic analysis. It was also ob- served that, with the increase of reaction temperature, the reaction which produced ZrB2 powders changed from the borothermal reaction to boro/carbothermal reaction in the Zr-B-C-O system.展开更多
This paper presents formulae and explanation about the growth of a convective gas bubble in the blood and other tissues of divers who surface too quickly, concentration distribution around the growing bubble is also p...This paper presents formulae and explanation about the growth of a convective gas bubble in the blood and other tissues of divers who surface too quickly, concentration distribution around the growing bubble is also presented. The formulae are valid all over the growth stages, i.e. under variable ambient pressure while the diver is ascending, and under constant ambient pressure at diving stops or at sea level. The mathematical model is solved analytically by using the method of combined variables. The growth process is affected by tissue diffusivity, concentration constant and the initial void fraction, which is the dominant parameter. Results show that, the time of the complete growth, in the convective growth model, is shorter than those earlier presented by Mohammadein and Mohamed [Concentration distribution around a growing gas bubble in tissue, Math. Biosci. 225（1） （2010） 11-17] and Srinivasan et al. [Mathematical models of diffusion- limited gas bubble dynamics in tissue, J. Appl. Physiol. 86 （1999） 732-741] for the growth of a stationary gas bubble, this explains the effect of bubble motion on consuming the oversaturated dissolved gas from the tissue into growing bubble which leads to increment in the growth rate to be more than those presented in the previous stationary models.展开更多
基金The National Natural Science Foundation of China (No 50471014)The Science and Technology Foundation of Shanghai (No0210nm017)
文摘A theoretical model on the solvus line prediction of a film was proposed and applied to a nanogranular A1-Cu system. The calculation results show that the solvus line of solute Cu will markedly lower with the decrease of grain size, namely, the starting temperature of θ （Al2Cu） precipitation in a nanogranular A1-Cu film will markedly lower than that of conventional coarse grain alloy with the same Cu concentration, and the precipitation temperatures calculated are comparable with the experimental ones. The theoretical model can be simply used to calculate the starting temperature of precipitation in A1-Cu films under three states： ① films with substrate; ②films without substrate; ③ultrafine grain bulk alloy. As a result, the model is universal, moreover, can be, in principle, used to predict precipitation temperature in other systems.
基金financial supports from the National Natural Science Foundation of China(No.51675433)the Natural Science Foundation for Distinguished Young Scholars of Shaanxi Province,China(No.2019JC-09)。
文摘To reveal the affecting mechanism of cooling rate on lamellarαprecipitation,the precipitation behaviors of lamellarαphase in IMI834 titanium alloy during isothermal and non-isothermal heat treatments were quantitatively characterized using experimental analysis.Critical precipitation temperatures at various cooling rates were obtained using thermal dilatation testing.Using metallographic microscopy,electron microprobe analysis,and data fitting methods,the quantitative evolution models of average width,volume fraction,and solute concentration in theαandβphases were built for different temperatures or cooling rates.A comparison between the two precipitation behaviors showed that the average width and volume fraction of lamellarαphase under non-isothermal conditions were smaller than those under isothermal conditions.With increasing cooling rate,the average width and volume fraction were decreased significantly,and the critical precipitation temperatures were reduced.This phenomenon is mainly attributed to the decreased diffusion velocity of solutes Al,Mo,and Nb with increasing cooling rate.
基金Fundao de Amparo à Pesquisa do Estado de So Paulo(FAPESP)
文摘Vapor-liquid equilibrium （VLE） data for copolymer solutions are necessary for several chemical processes. However, VLE data for copolymer solutions in the published report are rare. In this study, experimental VLE data for binary systems copolymer＋solvent were obtained using a gravimetric-sorption apparatus. The studied systems were hexane＋poly （21% acrylonitrile-co-butadiene）, hexane＋poly （33% acrylonitrile-co-butadiene）, hexane＋poly （51% acrylonitrile-co-butadiene）, hexane＋poly （23% styrene-co-butadiene）, hexane＋poly （45% styrene-co-butadiene）, and benzene＋poly （44% styrene-co-methyl methacrylate） in the range 50-70℃. The experimental data were correlated with the UNIFAC and Elbro-FV group contribution models for the activity coefficient. Two sets of functional groups had been used to represent the monomers in copolymers： literature groups and new proposed groups. The mean deviations between experimental and calculated mass fractions about 2.4% with Elbro- FV and 13.3% with Zhong were observed when the groups proposed in this study were used, and of 3.5% for E1- bro-FV and 13.2% for Zhong, when literature grouns were used.
基金Supported by the Fund for the Self-dependent Innovation of Tianjin University(2014)
文摘A single phase of zirconium diboride （ZrB2） powder was successfully synthesized by sol-gel method in Zr-B-C-O system, using zirconium oxychloride （ZrOC12 ~ 8H20）, nano-scale boron and suerose（C12H22011）as the starting materials and propylene oxide （PO） as complexing agent at a low temperature. Simultaneously, the experimen- tal and theoretical studies of ZrB2 synthesized by boro/carbothermal reduction from novel sol-gel technology were discussed. The results indicated that the pure rod-like ZrB2 powder without residual ZrO2 phase could be obtained with a B/Zr molar ratio of 3.5 at 1 400~C in argon atmosphere. Besides, in this study, a kinetic model for the Zr-B-C-O sys- tem producing ZrB2 by boro/carbothermal reaction was established based on thermodynamic analysis. It was also ob- served that, with the increase of reaction temperature, the reaction which produced ZrB2 powders changed from the borothermal reaction to boro/carbothermal reaction in the Zr-B-C-O system.
文摘This paper presents formulae and explanation about the growth of a convective gas bubble in the blood and other tissues of divers who surface too quickly, concentration distribution around the growing bubble is also presented. The formulae are valid all over the growth stages, i.e. under variable ambient pressure while the diver is ascending, and under constant ambient pressure at diving stops or at sea level. The mathematical model is solved analytically by using the method of combined variables. The growth process is affected by tissue diffusivity, concentration constant and the initial void fraction, which is the dominant parameter. Results show that, the time of the complete growth, in the convective growth model, is shorter than those earlier presented by Mohammadein and Mohamed [Concentration distribution around a growing gas bubble in tissue, Math. Biosci. 225（1） （2010） 11-17] and Srinivasan et al. [Mathematical models of diffusion- limited gas bubble dynamics in tissue, J. Appl. Physiol. 86 （1999） 732-741] for the growth of a stationary gas bubble, this explains the effect of bubble motion on consuming the oversaturated dissolved gas from the tissue into growing bubble which leads to increment in the growth rate to be more than those presented in the previous stationary models.
