In order to lower the usage of expensive Cyanex 923 and increase the extraction capacity of the system of Cextrant 230,the synergistic extraction of thorium from chloride media by a mixture of Cextrant 230 and Cyanex ...In order to lower the usage of expensive Cyanex 923 and increase the extraction capacity of the system of Cextrant 230,the synergistic extraction of thorium from chloride media by a mixture of Cextrant 230 and Cyanex 923 was investigated.The maximum synergistic enhancement coefficient(R)of 1.53 is obtained at 1:1 molar ratio of Cextrant 230/Cyanex 923.The syne rgistic extracted species of Th^(4+)is determined as ThCl_(4)·2Cextrant 230·Cyanex 923.The synergistic extraction of Th^(4+)is an entropy-driven exothermic process.The loading capacity of 0.60 mol/L mixed extractant for thorium is about 17.10 g/L(calculated as ThO_(2)),and the loaded thorium in the organic phase can be effectively stripped by distilled water.For comparison,rare earth cations are barely extracted under the similar conditions,suggesting that the mixtures can be applied to separate thorium from rare earths.A cascade extraction process was developed based on the synergistic extraction system to separate thorium from the hydrochloric acid leaching of bastnaesite.The content of thorium in the leaching solution decreases obviously from 19.90 mg/L to1.4μg/L by 3 stages of extraction,which is superior to sole Cextrant 230 or Cyanex 923.The introduction of Cextrant 230 into the extraction system not only lowers the usage of Cyanex 923 but also enhances the selective extraction of thorium at low acidity,implying that the synergistic extraction system can selectively extract thorium more efficiently and economically than the sole systems.展开更多
Nickel-based superalloys(Haynes 230)fabricated by laser powder bed fusion suffer from high cracking suscepti-bility,leading to a decrease in mechanical performance.In this study,the cracking mechanism of Haynes 230 wa...Nickel-based superalloys(Haynes 230)fabricated by laser powder bed fusion suffer from high cracking suscepti-bility,leading to a decrease in mechanical performance.In this study,the cracking mechanism of Haynes 230 was investigated based on microstructural and thermodynamic calculations.It was found that C and carbide-forming elements(such as Mo and Cr)were segregated at the grain boundaries,which increased the solidification range and impeded liquid film backfalling by forming nano-carbides.Additionally,the coalescence of high-angle grain boundaries(>15°)requires a higher undercoolingΔT_(b)than that of low-angle grain boundaries(2-15°),which increases the susceptibility to hot cracking.Through gradually reducing laser energy input,the grain size is sig-nificantly decreased from 27.86μm(47.40 J/mm^(3))to 14.66μm(31.81 J/mm^(3)).Moreover,the calculated cooling rate|dT∕dt|and temperature gradient|dT∕ds|gradually increase with decreasing energy input,which reduces the duration of dendrite merging and shortens the length of the liquid film.Compared with cracked samples,the optimized sample showed superior mechanical properties,including high yield strength(678 MPa),ultimate tensile strength(943 MPa),and elongation to failure(19.2%),which increased by 16.1%,9.7%,and 77.7%,respectively.展开更多
基金Project supported by the National Key Research and Development Project of China(2022YFC2905201)the Science and Technology Service Network Initiative Program of the Chinese Academy of Sciences(KFJ-STSQYZD-2021-18-001)+3 种基金the Research Projects of Ganjiang Innovation Academy,Chinese Academy of Sciences(E055C002)Jiangxi"Double Thous and Plan"(jxsq.2020101005)Jiangxi Province Natural Science Foundation(20212BAB213033)Ganzhou Science and Technology Program(2022CXRC9671)。
文摘In order to lower the usage of expensive Cyanex 923 and increase the extraction capacity of the system of Cextrant 230,the synergistic extraction of thorium from chloride media by a mixture of Cextrant 230 and Cyanex 923 was investigated.The maximum synergistic enhancement coefficient(R)of 1.53 is obtained at 1:1 molar ratio of Cextrant 230/Cyanex 923.The syne rgistic extracted species of Th^(4+)is determined as ThCl_(4)·2Cextrant 230·Cyanex 923.The synergistic extraction of Th^(4+)is an entropy-driven exothermic process.The loading capacity of 0.60 mol/L mixed extractant for thorium is about 17.10 g/L(calculated as ThO_(2)),and the loaded thorium in the organic phase can be effectively stripped by distilled water.For comparison,rare earth cations are barely extracted under the similar conditions,suggesting that the mixtures can be applied to separate thorium from rare earths.A cascade extraction process was developed based on the synergistic extraction system to separate thorium from the hydrochloric acid leaching of bastnaesite.The content of thorium in the leaching solution decreases obviously from 19.90 mg/L to1.4μg/L by 3 stages of extraction,which is superior to sole Cextrant 230 or Cyanex 923.The introduction of Cextrant 230 into the extraction system not only lowers the usage of Cyanex 923 but also enhances the selective extraction of thorium at low acidity,implying that the synergistic extraction system can selectively extract thorium more efficiently and economically than the sole systems.
基金supported by the National Key R&D Program of China(Grant No.2022YFB3707405)National Natural Science Foun-dation of China(Grant Nos.U22A20113,52371135,52201156)+2 种基金Hei-longjiang Provincial Natural Science Foundation of China(Grant No.TD2020E001)Young Elite Scientists Sponsorship Program by CAST(Grant No.2023QNRC001)Heilongjiang Touyan Team Program.
文摘Nickel-based superalloys(Haynes 230)fabricated by laser powder bed fusion suffer from high cracking suscepti-bility,leading to a decrease in mechanical performance.In this study,the cracking mechanism of Haynes 230 was investigated based on microstructural and thermodynamic calculations.It was found that C and carbide-forming elements(such as Mo and Cr)were segregated at the grain boundaries,which increased the solidification range and impeded liquid film backfalling by forming nano-carbides.Additionally,the coalescence of high-angle grain boundaries(>15°)requires a higher undercoolingΔT_(b)than that of low-angle grain boundaries(2-15°),which increases the susceptibility to hot cracking.Through gradually reducing laser energy input,the grain size is sig-nificantly decreased from 27.86μm(47.40 J/mm^(3))to 14.66μm(31.81 J/mm^(3)).Moreover,the calculated cooling rate|dT∕dt|and temperature gradient|dT∕ds|gradually increase with decreasing energy input,which reduces the duration of dendrite merging and shortens the length of the liquid film.Compared with cracked samples,the optimized sample showed superior mechanical properties,including high yield strength(678 MPa),ultimate tensile strength(943 MPa),and elongation to failure(19.2%),which increased by 16.1%,9.7%,and 77.7%,respectively.
