Formation, solution and phase change of hydration products in MgO-MgCl2-H2O system was studied with thermodynamics method, and resistance to water immersion and phase change of magnesium oxychloride cement with differ...Formation, solution and phase change of hydration products in MgO-MgCl2-H2O system was studied with thermodynamics method, and resistance to water immersion and phase change of magnesium oxychloride cement with different MgO/MgCl2 molar ratio was experimented. The results show that pH value of immersion solution of cement paste has a remarkable influence on phase stability of hydration products. A higher pH value leads to a lower solubility and a better phase stability of hydration products. When the solution pH value is higher than 10.37, the precipitation of much Mg（OH）2 crystal induces a worse phase stability of hydration products. With the increasing MgO/MgCl2 molar ratio （lower than 6）, the more amount of MgO in the hydration products enhances the alkalinity of solution and the phase stability is improved. However, when the MgO/MgCl2 molar ratio is higher than 6 and the excessive MgO exsits in the hydration products, the cement paste may be damaged by the excessive crystallization stress of a great deal of Mg（OH）2 formation.展开更多
With the worldwide rise in electric vehicles, the demand for lithium batteries is increasing day by day. In 2015, China＇s new energy vehicles developed rapidly, and the price of lithium carbonate rose from fifty or s...With the worldwide rise in electric vehicles, the demand for lithium batteries is increasing day by day. In 2015, China＇s new energy vehicles developed rapidly, and the price of lithium carbonate rose from fifty or sixty thousand yuan per ton to 150 thousand yuan. In the past, lithium was often extracted from spodumene （LiAlSi2O6）, which is time consuming, laborious and expensive. Over the past decade, abundant lithium has been discovered in brackish and salt water lakes, which is an important way to obtain lithium resources.展开更多
The microstructure and mechanical properties of extruded AZ31 magnesium at different extrusion temperature were investigated.The results show that,at 380℃,when the extrusion ratio is 23,the AZ31 magnesium alloy has a...The microstructure and mechanical properties of extruded AZ31 magnesium at different extrusion temperature were investigated.The results show that,at 380℃,when the extrusion ratio is 23,the AZ31 magnesium alloy has a dense recrystallized microstructure and good mechanical properties.On one hand,if the extrusion ratio is too small,grain crushing effect is not obvious,and part of the grain is not dynamic recrystallization.On the other hand,larger extrusion ratio can lead to grain growth and banded structure.Tensile fracture characteristics of extruded AZ31 magnesium alloy is quasi-cleavage.展开更多
Copolymerizations of L-lactide （L-LA） and ε-caprolactone （ε-CL） were conducted in bulk using magnesium octoate as a catalyst. The reactivity ratios of L-LA and ε-CL were determined to be rL=23 and rc=0.22, resp...Copolymerizations of L-lactide （L-LA） and ε-caprolactone （ε-CL） were conducted in bulk using magnesium octoate as a catalyst. The reactivity ratios of L-LA and ε-CL were determined to be rL=23 and rc=0.22, respectively. The sequence analyses of the copolymers were performed on ^13C NMR. An increase in the reaction temperature enhances the role of transesterification and the extent of randomness.展开更多
To investigate how the popular magnesium alloy AZ31 sheet(aluminum 3%,zinc 1%)behaves in cold working,deep drawing experiments at room temperature,along with finite element(FE)simulation,were performed on the cold for...To investigate how the popular magnesium alloy AZ31 sheet(aluminum 3%,zinc 1%)behaves in cold working,deep drawing experiments at room temperature,along with finite element(FE)simulation,were performed on the cold forming sheet of the AZ31 alloy after being annealed under various conditions.The activities were focused on the fracture pattern,limit drawing ratio(LDR),deformation load,thickness distribution,anisotropic effect,as well as the influences of the annealing conditions and tool configuration on them.The results display that punch shoulder radius instead of die clearance,has much influence on the thickness distribution.The anisotropy is remarkable in cold working,which adversely impacts the LDR.The fracture often happens on the side wall at an angle to axis of the deformed specimen.The results also imply that the LDR for the material under present experimental conditions is 1.72,and annealing the material at 450 ℃ for 1 h may be preferable for the cold deep drawing.展开更多
Livestock wastewater is mainly treated with activated sludge, but ions such as phosphorus, potassium, ammonium, nitrate and sulfate remain in the effluent. In this study, the effects of residual ions on phosphorus rec...Livestock wastewater is mainly treated with activated sludge, but ions such as phosphorus, potassium, ammonium, nitrate and sulfate remain in the effluent. In this study, the effects of residual ions on phosphorus recovery using the magnesium potassium phosphate crystallization method were investigated when magnesium was added to increase the pH. If co-existing ions affect the products, the phosphorus to potassium molar ratio (K/P ratio) of the precipitate will deviate from being equimolar. Artificial wastewater test solutions containing 5.6 - 20.3 mM ammonium, 25.6 mM potassium, 6.5 mM phosphorus, 0 - 7.35 mM nitrate, and 0 - 3.06 mM sulfate were used. First, the optimum operating pH and amount of magnesium added to give a high phosphorus removal rate and recovery rate were determined. The experimental setup was a 10 L aerated and stirred reactor, and a 5 L settling tank. The K/P ratio in precipitate was approximately 1 using the optimum conditions. Continuous 2 h treatment allowed a white precipitate containing about 30 g of needle-like crystals to be obtained. Next, the effects of varying the ammonium, nitrate, and sulfate ion concentrations in the artificial effluent were investigated. Ammonium and sulfate ion concentrations of 8 mM or more and 3 mM or more, respectively, caused the K/P ratio to decrease to about 0.7 and 0.5, respectively. Varying the nitrate concentration did not affect the K/P ratio, even at a nitrate concentration of 7.35 mM.展开更多
ZE10 magnesium alloy sheets were prepared through ingot casting and the hot-rolling process. The mechanical properties, conical cup value （CCV）, bore expanding performance, and limit drawing ratio （LDR） were inves...ZE10 magnesium alloy sheets were prepared through ingot casting and the hot-rolling process. The mechanical properties, conical cup value （CCV）, bore expanding performance, and limit drawing ratio （LDR） were investigated to examine the stamping formability of ZE10 alloy sheets, at temperatures ranging from 20 to 300℃. The results showed that the tensile strength decreased, whereas, plasticity, drawing-bulging performance, bore expanding properties, and deep drawing performance increased markedly at elevated temperatures. The CCV specimens could be drawn into the conical die＇ s underside cylindrical hole from the conical cliff, without cracking, and could have the minimum CCV at 200 and 250 ℃ In the bore-expanding test, the bore （φ10 mm） could be expanded to the dimension of the punch （φ25 mm） and the maximum bore-expanding ratio could be achieved at above 150℃. The limiting drawing ratio （LDR） of 2.85 is acquired during the deep drawing test at 230 v with the punch temperature of 20 - 50℃, the punch velocity of 50 mm · min^-1, and the mixture of graphite and cylinder grease as lubricant.展开更多
基金Funded by the National Natural Science Foundation of China(No50078019)
文摘Formation, solution and phase change of hydration products in MgO-MgCl2-H2O system was studied with thermodynamics method, and resistance to water immersion and phase change of magnesium oxychloride cement with different MgO/MgCl2 molar ratio was experimented. The results show that pH value of immersion solution of cement paste has a remarkable influence on phase stability of hydration products. A higher pH value leads to a lower solubility and a better phase stability of hydration products. When the solution pH value is higher than 10.37, the precipitation of much Mg（OH）2 crystal induces a worse phase stability of hydration products. With the increasing MgO/MgCl2 molar ratio （lower than 6）, the more amount of MgO in the hydration products enhances the alkalinity of solution and the phase stability is improved. However, when the MgO/MgCl2 molar ratio is higher than 6 and the excessive MgO exsits in the hydration products, the cement paste may be damaged by the excessive crystallization stress of a great deal of Mg（OH）2 formation.
文摘With the worldwide rise in electric vehicles, the demand for lithium batteries is increasing day by day. In 2015, China＇s new energy vehicles developed rapidly, and the price of lithium carbonate rose from fifty or sixty thousand yuan per ton to 150 thousand yuan. In the past, lithium was often extracted from spodumene （LiAlSi2O6）, which is time consuming, laborious and expensive. Over the past decade, abundant lithium has been discovered in brackish and salt water lakes, which is an important way to obtain lithium resources.
文摘The microstructure and mechanical properties of extruded AZ31 magnesium at different extrusion temperature were investigated.The results show that,at 380℃,when the extrusion ratio is 23,the AZ31 magnesium alloy has a dense recrystallized microstructure and good mechanical properties.On one hand,if the extrusion ratio is too small,grain crushing effect is not obvious,and part of the grain is not dynamic recrystallization.On the other hand,larger extrusion ratio can lead to grain growth and banded structure.Tensile fracture characteristics of extruded AZ31 magnesium alloy is quasi-cleavage.
文摘Copolymerizations of L-lactide （L-LA） and ε-caprolactone （ε-CL） were conducted in bulk using magnesium octoate as a catalyst. The reactivity ratios of L-LA and ε-CL were determined to be rL=23 and rc=0.22, respectively. The sequence analyses of the copolymers were performed on ^13C NMR. An increase in the reaction temperature enhances the role of transesterification and the extent of randomness.
文摘To investigate how the popular magnesium alloy AZ31 sheet(aluminum 3%,zinc 1%)behaves in cold working,deep drawing experiments at room temperature,along with finite element(FE)simulation,were performed on the cold forming sheet of the AZ31 alloy after being annealed under various conditions.The activities were focused on the fracture pattern,limit drawing ratio(LDR),deformation load,thickness distribution,anisotropic effect,as well as the influences of the annealing conditions and tool configuration on them.The results display that punch shoulder radius instead of die clearance,has much influence on the thickness distribution.The anisotropy is remarkable in cold working,which adversely impacts the LDR.The fracture often happens on the side wall at an angle to axis of the deformed specimen.The results also imply that the LDR for the material under present experimental conditions is 1.72,and annealing the material at 450 ℃ for 1 h may be preferable for the cold deep drawing.
文摘Livestock wastewater is mainly treated with activated sludge, but ions such as phosphorus, potassium, ammonium, nitrate and sulfate remain in the effluent. In this study, the effects of residual ions on phosphorus recovery using the magnesium potassium phosphate crystallization method were investigated when magnesium was added to increase the pH. If co-existing ions affect the products, the phosphorus to potassium molar ratio (K/P ratio) of the precipitate will deviate from being equimolar. Artificial wastewater test solutions containing 5.6 - 20.3 mM ammonium, 25.6 mM potassium, 6.5 mM phosphorus, 0 - 7.35 mM nitrate, and 0 - 3.06 mM sulfate were used. First, the optimum operating pH and amount of magnesium added to give a high phosphorus removal rate and recovery rate were determined. The experimental setup was a 10 L aerated and stirred reactor, and a 5 L settling tank. The K/P ratio in precipitate was approximately 1 using the optimum conditions. Continuous 2 h treatment allowed a white precipitate containing about 30 g of needle-like crystals to be obtained. Next, the effects of varying the ammonium, nitrate, and sulfate ion concentrations in the artificial effluent were investigated. Ammonium and sulfate ion concentrations of 8 mM or more and 3 mM or more, respectively, caused the K/P ratio to decrease to about 0.7 and 0.5, respectively. Varying the nitrate concentration did not affect the K/P ratio, even at a nitrate concentration of 7.35 mM.
基金Project supported by the Foundation (2005002) from Key Laboratory for Advanced Metallic Materials Processing and Forming of Guangdong Province
文摘ZE10 magnesium alloy sheets were prepared through ingot casting and the hot-rolling process. The mechanical properties, conical cup value （CCV）, bore expanding performance, and limit drawing ratio （LDR） were investigated to examine the stamping formability of ZE10 alloy sheets, at temperatures ranging from 20 to 300℃. The results showed that the tensile strength decreased, whereas, plasticity, drawing-bulging performance, bore expanding properties, and deep drawing performance increased markedly at elevated temperatures. The CCV specimens could be drawn into the conical die＇ s underside cylindrical hole from the conical cliff, without cracking, and could have the minimum CCV at 200 and 250 ℃ In the bore-expanding test, the bore （φ10 mm） could be expanded to the dimension of the punch （φ25 mm） and the maximum bore-expanding ratio could be achieved at above 150℃. The limiting drawing ratio （LDR） of 2.85 is acquired during the deep drawing test at 230 v with the punch temperature of 20 - 50℃, the punch velocity of 50 mm · min^-1, and the mixture of graphite and cylinder grease as lubricant.
