The practical engineering applications of powder metallurgy (PM) Ti alloys produced through cold compaction and pressure-less sintering are impeded by poor sintering densification, embrittlement caused by excessive O ...The practical engineering applications of powder metallurgy (PM) Ti alloys produced through cold compaction and pressure-less sintering are impeded by poor sintering densification, embrittlement caused by excessive O impurities, and severe sintering deforma-tion resulting from the use of heterogeneous powder mixtures. This review presents a summary of our previous work on addressing the above challenges. Initially, we proposed a novel strategy using reaction-induced liquid phases to enhance sintering densification. Near- complete density (relative density exceeding 99%) was achieved by applying the above strategy and newly developed sintering aids. By focusing on the O-induced embrittlement issue, we determined the onset dissolution temperature of oxide films in the Ti matrix. On the basis of this finding, we established a design criterion for effective O scavengers that require reaction with oxide films before their dissol-ution. Consequently, a ductile PM Ti alloy was successfully obtained by introducing 0.3wt% NdB6 as the O scavenger. Lastly, a powder- coating strategy was adopted to address the sintering deformation issue. The ultrafine size and shell-like distribution characteristics of coating particles ensured rapid dissolution and homogeneity in the Ti matrix, thereby facilitating linear shrinkage during sintering. As a result, geometrically complex Ti alloy parts with high dimensional accuracy were fabricated by using the coated powder. Our fundament-al findings and related technical achievements enabled the development of an integrated production technology for the high-performance and accurate shaping of low-cost PM Ti alloys. Additionally, the primary engineering applications and progress in the industrialization practice of our developed technology are introduced in this review.展开更多
The separation of water isotopologues has been a“century-old”challenge,also known as“the Holy Grail”in separation science.Heavy water(D2O)is a stable non-radioactive water isotopologue that plays a critical role i...The separation of water isotopologues has been a“century-old”challenge,also known as“the Holy Grail”in separation science.Heavy water(D2O)is a stable non-radioactive water isotopologue that plays a critical role in scientific research,military,nuclear energy,and medical fields.Heavy water was first reported in 1931 when H.C.Urey discovered D2 and D2O,for which he was awarded the Nobel Prize in Chemistry in 1934.Then in 1933,G.N.Lewis et al.obtained 0.5μL of heavy water at a concentration of around 65.7%when electrolyzing 10 liters of water.In 1935,the world's first heavy water plant was built in Norway,producing 2 tons of heavy water by electrolysis,but the separation factor was merely 1.05,which was extremely energy-consuming.In 1943,the first heavy water plant employing the distillation method was built in the United States.展开更多
High-temperature stretching plays a crucial role in enhancing the performance of fibres,while a quantitative investigation into the impacts of tension and stretching duration on the microstructure and performance of h...High-temperature stretching plays a crucial role in enhancing the performance of fibres,while a quantitative investigation into the impacts of tension and stretching duration on the microstructure and performance of hexagonal boron nitride(h-BN)fibres remains absent.In this study,to elucidate the microstructural evolution of the h-BN fibres under thermal stretching,amorphous BN fibres were heated at 2000℃under tension of 30,50,and 70 N for 1,3,and 5 h in a nitrogen atmosphere.Subsequently,the grain size,pore structure,orientation degree,microscopic morphology,and mechanical properties were analysed at room temperature.The results show that high-temperature stretching enhances the orientation degree of the BN fibres,consequently elevating Young’s modulus.The maximum orientation degree of the BN fibres was 86%,aligning with a corresponding Young’s modulus of 206 GPa.Additionally,high-temperature stretching enlarged the sizes of grains and pores,a fact substantiated by the radial cracking of the fibres upon extending thermal stretching time.Owing to the expanded pore structure of the BN fibres and the inability to form a sufficiently strong“card structure”between shorter microfibre bundles,the tensile strength of the BN fibres did not increase continually,reaching a maximum of 1.0 GPa.Microstructural observations revealed that the BN fibres,composed of highly oriented lamellar h-BN grains,tend to form radial textures under high-tensile thermal stretching and onion-skin textures under prolonged thermal stretching.These findings offer a theoretical foundation for the preparation of high-performance h-BN fibres.展开更多
Safe, green and efficient industrial production has always been the pursuit of the chemical industry. Since thermal energy is the driving force for most of chemical reactions, an ideal reaction tank would have the cap...Safe, green and efficient industrial production has always been the pursuit of the chemical industry. Since thermal energy is the driving force for most of chemical reactions, an ideal reaction tank would have the capacity to automatically regulate heat conduction rate. In detail, this reaction tank should endow an ability that resists the heat loss when the reaction temperature is lower than the target, while accelerating the heat dissipation when the system is overheated. In this case, this smart reactor can not only minimize energy consumption but also reduce safety risks.Hollow structures are known to reduce heat conductivity. Particularly, the hollow structure with multishells can provide more interfaces and thus further inhibit heat transmission, which would be more favorable for heat isolation. Step forward, by coupling HoMSs with temperature-sensitive polymer, a smart heat isolation material has been fabricated in this work. It performs as a good heat isolator at a relatively lower temperature. A heat insulation effect of 6.5℃ can be achieved for the TSPU/3S–TiO_(2)HoMSs with a thickness of 1 mm under the temperature field of 50℃.The thermal conductivity of composite material would be raised under overheating conditions. Furthermore, this composite displays an unusual two-stage phase transformation during heating. Benefiting from the unique multishelled structure, energy is found to be gradually guided into the hollow structure and stored inside. This localized heat accumulation enables the composite to be a potential coating material for intelligent thermal-regulator and site-defined micro-reactor.展开更多
In recent years, near surface ozone pollution, has attracted more and more attention,which necessitates the development of high efficient and low cost catalysts. In this work,Cu O/Cu_(2)O heterojunctioned catalyst is ...In recent years, near surface ozone pollution, has attracted more and more attention,which necessitates the development of high efficient and low cost catalysts. In this work,Cu O/Cu_(2)O heterojunctioned catalyst is fabricated by heating Cu_(2)O at high temperature, and is adopted as ozone decomposition catalyst. The results show that after Cu_(2)O is heated at180℃conversion of ozone increases from 75.2% to 89.3% at mass space velocity 1,920,000cm^(3)/(g·hr) in dry air with 1000 ppm V ozone, which indicates that this heterojunction catalyst is one of the most efficient catalysts reported at present. Catalysts are characterized by electron paramagnetic resonance spectroscopy and ultraviolet photoelectron spectroscopy,which confirmed that the heterojunction promotes the electron transfer in the catalytic process and creates more defects and oxygen vacancies in the Cu O/Cu_(2)O interfaces. This procedure of manufacturing heterostructures would also be applicable to other metal oxide catalysts, and it is expected to be more widely applied to the synthesis of high-efficiency heterostructured catalysts in the future.展开更多
Solar thermal interfacial water evaporation is proposed as a promising route to address freshwater scarcity,which can reduce energy consumption and have unlimited application scenarios.The large semiconductor family w...Solar thermal interfacial water evaporation is proposed as a promising route to address freshwater scarcity,which can reduce energy consumption and have unlimited application scenarios.The large semiconductor family with controllable bandgap and good chemo-physical stability are considered as good candidates for photo-evaporation.However,the evaporation rate is not satisfactory because the rational control of nano/micro structure and composition is still in its infancy stage.Herein,by systemically analyzing the photo-thermal evaporation processes,we applied the hollow multishelled structure(HoMS)into this application.Benefiting from the multishelled and hierarchical porous structure,the light absorption,thermal regulation,and water transport are simultaneously optimized,resulting in a water evaporation rate of 3.2 kg·m^(-2)·h^(-1),which is among the best performance in solar-vapour generation.The collected water from different water resources meets the World Health Organization standard for drinkable water.Interestingly,by using the CuO/Cu_(2)O system,reactive oxygen species were generated for water disinfection,showing a new route for efficient solar-vapour generation and a green way to obtain safe drinking water.展开更多
基金supported by the National Natural Science Foundation of China (Nos.52074254 and 52174349)the CAS Project for Young Scientists in Basic Research,China (No.YSBR-025)+3 种基金the Shandong Provincial Science and Technology Innovation Project,China (No.2019JZZY010363)the Key Projects of International Cooperation,China (No.122111KYSB20200034)the Project of Key Laboratory of Science and Technology on Particle Materials,China (No.CXJJ-22S043)Chinese Academy of Sciences.This work was also financially supported by the Selection of Best Candidates to Undertake Key Research Projects,China (No.211110230200).
文摘The practical engineering applications of powder metallurgy (PM) Ti alloys produced through cold compaction and pressure-less sintering are impeded by poor sintering densification, embrittlement caused by excessive O impurities, and severe sintering deforma-tion resulting from the use of heterogeneous powder mixtures. This review presents a summary of our previous work on addressing the above challenges. Initially, we proposed a novel strategy using reaction-induced liquid phases to enhance sintering densification. Near- complete density (relative density exceeding 99%) was achieved by applying the above strategy and newly developed sintering aids. By focusing on the O-induced embrittlement issue, we determined the onset dissolution temperature of oxide films in the Ti matrix. On the basis of this finding, we established a design criterion for effective O scavengers that require reaction with oxide films before their dissol-ution. Consequently, a ductile PM Ti alloy was successfully obtained by introducing 0.3wt% NdB6 as the O scavenger. Lastly, a powder- coating strategy was adopted to address the sintering deformation issue. The ultrafine size and shell-like distribution characteristics of coating particles ensured rapid dissolution and homogeneity in the Ti matrix, thereby facilitating linear shrinkage during sintering. As a result, geometrically complex Ti alloy parts with high dimensional accuracy were fabricated by using the coated powder. Our fundament-al findings and related technical achievements enabled the development of an integrated production technology for the high-performance and accurate shaping of low-cost PM Ti alloys. Additionally, the primary engineering applications and progress in the industrialization practice of our developed technology are introduced in this review.
基金supported by the National Natural Science Foundation of China(No.52170119)the Youth Innovation Promotion Association of Chinese Academy of Sciences(No.2021044).
文摘The separation of water isotopologues has been a“century-old”challenge,also known as“the Holy Grail”in separation science.Heavy water(D2O)is a stable non-radioactive water isotopologue that plays a critical role in scientific research,military,nuclear energy,and medical fields.Heavy water was first reported in 1931 when H.C.Urey discovered D2 and D2O,for which he was awarded the Nobel Prize in Chemistry in 1934.Then in 1933,G.N.Lewis et al.obtained 0.5μL of heavy water at a concentration of around 65.7%when electrolyzing 10 liters of water.In 1935,the world's first heavy water plant was built in Norway,producing 2 tons of heavy water by electrolysis,but the separation factor was merely 1.05,which was extremely energy-consuming.In 1943,the first heavy water plant employing the distillation method was built in the United States.
基金supported by the Key Laboratory of Science and Technology on Particle Materials(Grant No.CXJJ-21S043)the Key Laboratory of Multiphase Complex Systems(Grant No.MPCS-2021-a-02)+2 种基金the Key Research Program of the Chinese Academy of Sciences(Grant Nos.ZDRW-CN-2021-2,ZDRW-CN-2021-3)Projects of Ganjiang Innovation Academy CAS(Grant Nos.E155D001,E055A002)and the Double Thousand Plan of Jiangxi Province(Grant No.JXSQ2020105012)。
文摘High-temperature stretching plays a crucial role in enhancing the performance of fibres,while a quantitative investigation into the impacts of tension and stretching duration on the microstructure and performance of hexagonal boron nitride(h-BN)fibres remains absent.In this study,to elucidate the microstructural evolution of the h-BN fibres under thermal stretching,amorphous BN fibres were heated at 2000℃under tension of 30,50,and 70 N for 1,3,and 5 h in a nitrogen atmosphere.Subsequently,the grain size,pore structure,orientation degree,microscopic morphology,and mechanical properties were analysed at room temperature.The results show that high-temperature stretching enhances the orientation degree of the BN fibres,consequently elevating Young’s modulus.The maximum orientation degree of the BN fibres was 86%,aligning with a corresponding Young’s modulus of 206 GPa.Additionally,high-temperature stretching enlarged the sizes of grains and pores,a fact substantiated by the radial cracking of the fibres upon extending thermal stretching time.Owing to the expanded pore structure of the BN fibres and the inability to form a sufficiently strong“card structure”between shorter microfibre bundles,the tensile strength of the BN fibres did not increase continually,reaching a maximum of 1.0 GPa.Microstructural observations revealed that the BN fibres,composed of highly oriented lamellar h-BN grains,tend to form radial textures under high-tensile thermal stretching and onion-skin textures under prolonged thermal stretching.These findings offer a theoretical foundation for the preparation of high-performance h-BN fibres.
基金financially supported by the National Natural Science Foundation of China (Nos.21931012,21971244,92163209,and 52174387)the Education Department of Henan Province (No.20A430024)。
文摘Safe, green and efficient industrial production has always been the pursuit of the chemical industry. Since thermal energy is the driving force for most of chemical reactions, an ideal reaction tank would have the capacity to automatically regulate heat conduction rate. In detail, this reaction tank should endow an ability that resists the heat loss when the reaction temperature is lower than the target, while accelerating the heat dissipation when the system is overheated. In this case, this smart reactor can not only minimize energy consumption but also reduce safety risks.Hollow structures are known to reduce heat conductivity. Particularly, the hollow structure with multishells can provide more interfaces and thus further inhibit heat transmission, which would be more favorable for heat isolation. Step forward, by coupling HoMSs with temperature-sensitive polymer, a smart heat isolation material has been fabricated in this work. It performs as a good heat isolator at a relatively lower temperature. A heat insulation effect of 6.5℃ can be achieved for the TSPU/3S–TiO_(2)HoMSs with a thickness of 1 mm under the temperature field of 50℃.The thermal conductivity of composite material would be raised under overheating conditions. Furthermore, this composite displays an unusual two-stage phase transformation during heating. Benefiting from the unique multishelled structure, energy is found to be gradually guided into the hollow structure and stored inside. This localized heat accumulation enables the composite to be a potential coating material for intelligent thermal-regulator and site-defined micro-reactor.
基金Chengdu Science and Technology Program (No.2019YF05-01833-SN)。
文摘In recent years, near surface ozone pollution, has attracted more and more attention,which necessitates the development of high efficient and low cost catalysts. In this work,Cu O/Cu_(2)O heterojunctioned catalyst is fabricated by heating Cu_(2)O at high temperature, and is adopted as ozone decomposition catalyst. The results show that after Cu_(2)O is heated at180℃conversion of ozone increases from 75.2% to 89.3% at mass space velocity 1,920,000cm^(3)/(g·hr) in dry air with 1000 ppm V ozone, which indicates that this heterojunction catalyst is one of the most efficient catalysts reported at present. Catalysts are characterized by electron paramagnetic resonance spectroscopy and ultraviolet photoelectron spectroscopy,which confirmed that the heterojunction promotes the electron transfer in the catalytic process and creates more defects and oxygen vacancies in the Cu O/Cu_(2)O interfaces. This procedure of manufacturing heterostructures would also be applicable to other metal oxide catalysts, and it is expected to be more widely applied to the synthesis of high-efficiency heterostructured catalysts in the future.
基金This work was financially supported by the National Natural Science Foundation of China(Nos.92163209,21931012,21971244,51872024,and 51932001)Talent Team of Taishan Scholar’s Advantageous and Characteristic Disciplines of Shandong Province.Prof.Lin thanks the Taishan Scholarship Project of Shandong Province(No.tsqn201909115).
文摘Solar thermal interfacial water evaporation is proposed as a promising route to address freshwater scarcity,which can reduce energy consumption and have unlimited application scenarios.The large semiconductor family with controllable bandgap and good chemo-physical stability are considered as good candidates for photo-evaporation.However,the evaporation rate is not satisfactory because the rational control of nano/micro structure and composition is still in its infancy stage.Herein,by systemically analyzing the photo-thermal evaporation processes,we applied the hollow multishelled structure(HoMS)into this application.Benefiting from the multishelled and hierarchical porous structure,the light absorption,thermal regulation,and water transport are simultaneously optimized,resulting in a water evaporation rate of 3.2 kg·m^(-2)·h^(-1),which is among the best performance in solar-vapour generation.The collected water from different water resources meets the World Health Organization standard for drinkable water.Interestingly,by using the CuO/Cu_(2)O system,reactive oxygen species were generated for water disinfection,showing a new route for efficient solar-vapour generation and a green way to obtain safe drinking water.