To explore the corrosion properties of magnesium alloys, the chemical behavior of a high strength Mg_(97)Zn_(1)Y_(2)-1 wt.%Si C alloy in different corrosion environments was studied. Three solutions of 0.2 mol·L^...To explore the corrosion properties of magnesium alloys, the chemical behavior of a high strength Mg_(97)Zn_(1)Y_(2)-1 wt.%Si C alloy in different corrosion environments was studied. Three solutions of 0.2 mol·L^(-1) NaCl, Na_(2)SO_(4) and NaNO_(3) were selected as corrosion solutions. The microstructures, corrosion rate, corrosion potential, and mechanism were investigated qualitatively and quantitatively by optical microscopy(OM), scanning electron microscopy(SEM), immersion testing experiment, and electrochemical test. Microstructure observation shows that the Mg_(97) Zn_(1)Y_(2)-1 wt.%Si C alloy is composed of α-Mg matrix, LPSO(Mg_(12) ZnY) phase and Si C phase. The hydrogen evolution and electrochemical test results reflect that the Mg_(97)Zn_(1)Y_(2)-1 wt.%SiC in 0.2 mol·L^(-1) Na Cl solution has the fastest corrosion rate, followed by Na_(2)SO_(4) and NaNO_(3) solutions, and that the charge-transfer resistance presents the contrary trend and decreases in turn.展开更多
The formaidehyde-free finishing agent 4,5-di-hydroxy-1,3-dimethy1-2-imidazolidinone(DMeDHEU)was prepared by the reaction of 1,3-dimethylurea and glyoxal.The reaction rate and equilib-rium conversion in relation to pH ...The formaidehyde-free finishing agent 4,5-di-hydroxy-1,3-dimethy1-2-imidazolidinone(DMeDHEU)was prepared by the reaction of 1,3-dimethylurea and glyoxal.The reaction rate and equilib-rium conversion in relation to pH value,molar ratio,temperature and catalyst were studied.The conversionto DMeDHEU,catalyzed with citric acid/anhydrousNaAc,reached 95% in 6 hours at 40℃, pH 5.5 andmolar ratio 1.2.展开更多
The true stress-sWain relationships of Ti-5A1-2Sn-2Zr-4Mo-4Cr（TC17） alloy with a wide range of strain rates were investigated by tmiaxial quasi-static and dynamic compression tests, respectively. Quasi- static compr...The true stress-sWain relationships of Ti-5A1-2Sn-2Zr-4Mo-4Cr（TC17） alloy with a wide range of strain rates were investigated by tmiaxial quasi-static and dynamic compression tests, respectively. Quasi- static compression tests were carried out with Instron 8874 test machine, while dynamic compression tests were performed with the split Hopkinson pressure bar （SHPB） which was installed with heating device and synchro- assembly system. The dynamic mechanical behaviors tests of TC17 were carded out from room temperature to 800 ℃ at intervals of 200 ℃ and at high sWain rates （5 500-1 9200 s-l）. The stress-strain curves considering temperature-sWain rate coupling actions were obtained. The Johnson-Cook constitutive model was developed through data fitting of the stress-sWain curves. The material constants in the developed constitutive model can be determined using isothermal and adiabatic stress-strain curves at different strain rates. The Johnson-Cook constitutive model provided satisfied prediction of the plastic flow stress for TC17 alloy.展开更多
The influence of different lubricants on the deformation behaviour of IN 718 alloy was studied. The results show that, with the improvement of lubrication condition, the deformation of the alloy tends to be homogeneou...The influence of different lubricants on the deformation behaviour of IN 718 alloy was studied. The results show that, with the improvement of lubrication condition, the deformation of the alloy tends to be homogeneous, and the resistance of deformation decreases. Consequently, FR 2 glass lubricant is considered to be an ideal choice when the relationship between stress and strain of IN 718 alloy is measured by means of hot compression experiment.展开更多
Increasing complexity of distributed hydrological model （DHM） has lowered the efficiency of convergence.In this study,global sensitivity analysis （SA） was introduced by combining multiobjective （MO） optimization...Increasing complexity of distributed hydrological model （DHM） has lowered the efficiency of convergence.In this study,global sensitivity analysis （SA） was introduced by combining multiobjective （MO） optimization for DHM calibration.Latin Hypercube-once at a time （LH-OAT） was adopted in global parameter SA to obtain relative sensitivity of model parameter,which can be categorized into different sensitivity levels.Two comparative study cases were conducted to present the efficiency and feasibility by combining SA with MO（SA-MO）.WetSpa model with non-dominated sorting genetic algorithm-Ⅱ （NSGA-Ⅱ） algorithm and EasyDHM model with multi-objective sequential complex evolutionary metropolis-uncertainty analysis （MOSCEM-UA）algorithm were adopted to demonstrate the general feasibility of combining SA in optimization.Results showed that the LH-OAT was globally effective in selecting high sensitivity parameters.It proves that using parameter from high sensitivity groups results in higher convergence efficiency.Study case Ⅰ showed a better Pareto front distribution and convergence compared with model calibration without SA.Study case Ⅱ indicated a more efficient convergence of parameters in sequential evolution of MOSCEM-UA under the same iteration.It indicates that SA-MO is feasible and efficient for high dimensional DHM calibration.展开更多
5-（Difluoromethoxy）-2-mercapto- 1H-benzimi- dazole （DMB） was precipitated by adding acetic acid to the DMB sodium salt solution. The spherical agglomeration of DMB during the reactive crystallization in a batch cr...5-（Difluoromethoxy）-2-mercapto- 1H-benzimi- dazole （DMB） was precipitated by adding acetic acid to the DMB sodium salt solution. The spherical agglomeration of DMB during the reactive crystallization in a batch crystallizer was monitored by real-time Particle Video Microscope （PVM）. We found that the low feeding rate of acetic acid, high crystallization temperature, low agitation rate or adding seed crystal can facilitate the formation of spherical agglomerates. By using a simple model, the mean crystal agglomerate size of DMB thus predicted is generally in agreement with the experimental data. In addition, the crystallization process of DMB was optimized by a new control strategy of supersaturation to avoid disadvantages brought by agglomeration.展开更多
基金Financially supported by the National Natural Science Foundation of China (51665012)the Jiangxi Province Science Foundation for Outstanding Scholarship (20171BCB23061,2018ACB21020)the Primary Research & Development Plan of Jiangxi Province (20192BBEL50019)。
文摘To explore the corrosion properties of magnesium alloys, the chemical behavior of a high strength Mg_(97)Zn_(1)Y_(2)-1 wt.%Si C alloy in different corrosion environments was studied. Three solutions of 0.2 mol·L^(-1) NaCl, Na_(2)SO_(4) and NaNO_(3) were selected as corrosion solutions. The microstructures, corrosion rate, corrosion potential, and mechanism were investigated qualitatively and quantitatively by optical microscopy(OM), scanning electron microscopy(SEM), immersion testing experiment, and electrochemical test. Microstructure observation shows that the Mg_(97) Zn_(1)Y_(2)-1 wt.%Si C alloy is composed of α-Mg matrix, LPSO(Mg_(12) ZnY) phase and Si C phase. The hydrogen evolution and electrochemical test results reflect that the Mg_(97)Zn_(1)Y_(2)-1 wt.%SiC in 0.2 mol·L^(-1) Na Cl solution has the fastest corrosion rate, followed by Na_(2)SO_(4) and NaNO_(3) solutions, and that the charge-transfer resistance presents the contrary trend and decreases in turn.
文摘The formaidehyde-free finishing agent 4,5-di-hydroxy-1,3-dimethy1-2-imidazolidinone(DMeDHEU)was prepared by the reaction of 1,3-dimethylurea and glyoxal.The reaction rate and equilib-rium conversion in relation to pH value,molar ratio,temperature and catalyst were studied.The conversionto DMeDHEU,catalyzed with citric acid/anhydrousNaAc,reached 95% in 6 hours at 40℃, pH 5.5 andmolar ratio 1.2.
基金Funded by the National Basic Research Program of China(No.2009CB724401)the Major Science and Technology Program of High-end CNC Machine Tools and Basic Manufacturing Equipment(No.2012ZX04003-041)
文摘The true stress-sWain relationships of Ti-5A1-2Sn-2Zr-4Mo-4Cr（TC17） alloy with a wide range of strain rates were investigated by tmiaxial quasi-static and dynamic compression tests, respectively. Quasi- static compression tests were carried out with Instron 8874 test machine, while dynamic compression tests were performed with the split Hopkinson pressure bar （SHPB） which was installed with heating device and synchro- assembly system. The dynamic mechanical behaviors tests of TC17 were carded out from room temperature to 800 ℃ at intervals of 200 ℃ and at high sWain rates （5 500-1 9200 s-l）. The stress-strain curves considering temperature-sWain rate coupling actions were obtained. The Johnson-Cook constitutive model was developed through data fitting of the stress-sWain curves. The material constants in the developed constitutive model can be determined using isothermal and adiabatic stress-strain curves at different strain rates. The Johnson-Cook constitutive model provided satisfied prediction of the plastic flow stress for TC17 alloy.
文摘The influence of different lubricants on the deformation behaviour of IN 718 alloy was studied. The results show that, with the improvement of lubrication condition, the deformation of the alloy tends to be homogeneous, and the resistance of deformation decreases. Consequently, FR 2 glass lubricant is considered to be an ideal choice when the relationship between stress and strain of IN 718 alloy is measured by means of hot compression experiment.
基金National Basic Research Program(973)of China(No.2010CB951102)Innovative Research Groups of the National Natural Science Foundation,China(No.51021006)National Natural Science Foundation of China(No.51079028)
文摘Increasing complexity of distributed hydrological model （DHM） has lowered the efficiency of convergence.In this study,global sensitivity analysis （SA） was introduced by combining multiobjective （MO） optimization for DHM calibration.Latin Hypercube-once at a time （LH-OAT） was adopted in global parameter SA to obtain relative sensitivity of model parameter,which can be categorized into different sensitivity levels.Two comparative study cases were conducted to present the efficiency and feasibility by combining SA with MO（SA-MO）.WetSpa model with non-dominated sorting genetic algorithm-Ⅱ （NSGA-Ⅱ） algorithm and EasyDHM model with multi-objective sequential complex evolutionary metropolis-uncertainty analysis （MOSCEM-UA）algorithm were adopted to demonstrate the general feasibility of combining SA in optimization.Results showed that the LH-OAT was globally effective in selecting high sensitivity parameters.It proves that using parameter from high sensitivity groups results in higher convergence efficiency.Study case Ⅰ showed a better Pareto front distribution and convergence compared with model calibration without SA.Study case Ⅱ indicated a more efficient convergence of parameters in sequential evolution of MOSCEM-UA under the same iteration.It indicates that SA-MO is feasible and efficient for high dimensional DHM calibration.
文摘5-（Difluoromethoxy）-2-mercapto- 1H-benzimi- dazole （DMB） was precipitated by adding acetic acid to the DMB sodium salt solution. The spherical agglomeration of DMB during the reactive crystallization in a batch crystallizer was monitored by real-time Particle Video Microscope （PVM）. We found that the low feeding rate of acetic acid, high crystallization temperature, low agitation rate or adding seed crystal can facilitate the formation of spherical agglomerates. By using a simple model, the mean crystal agglomerate size of DMB thus predicted is generally in agreement with the experimental data. In addition, the crystallization process of DMB was optimized by a new control strategy of supersaturation to avoid disadvantages brought by agglomeration.
