The unique crystallographic lamellar microstructure(CLM) Ni-based superalloys fabricated by laser powder bed fusion(LPBF) exhibits excellent tensile properties.This study aims to investigate CLM's high-temperature...The unique crystallographic lamellar microstructure(CLM) Ni-based superalloys fabricated by laser powder bed fusion(LPBF) exhibits excellent tensile properties.This study aims to investigate CLM's high-temperature stress rupture behavior and use these findings to improve the additive manufacturing process.The result shows that the high temperature-induced intergranular fracture in <110> grain region is responsible for stress rupture failure under both conditions of 760 ℃/780 MPa and 980 ℃/260 MPa.Among them,the sub-grain boundary fracture occurs only under high temperature and low stress,980 ℃/260 MPa.Due to the severe intergranular fracture induced by stray grains,the stress rupture life is very low under both conditions.According to the finite element simulation,the formation of stray grains stems from the unstable heat flow within the melt pool during the process.In addition,the shorter stress rupture lifetime does not excite a more pronounced dislocation network around the γ′ phase.However,the deformation twins can still be activated inside the <110> grains,so it has excellent plasticity under both test conditions.Finally,this work indicates that the future optimization of CLM by LPBF should focus on eliminating of high-angle grain boundaries in <110> grains.展开更多
The excessive concentration of NO_(2) in the atmosphere has gained considerable attention due to its damage to the environment and human health. Gas sensor technology has important application prospects in detecting a...The excessive concentration of NO_(2) in the atmosphere has gained considerable attention due to its damage to the environment and human health. Gas sensor technology has important application prospects in detecting atmospheric NO_(2) concentration. Restricted by its wide bandgap, pristine ZnO needs additional energy to power the electronic transition as a gas sensing material.展开更多
Yttria-stabilized zirconia（ YSZ） coatings were deposited by low pressure plasma spray（ LPPS） in 1.0× 10^4 Pa,1.5 × 10^4 Pa,and 2.5 × 10^4 Pa. Both in-flight particle diagnostic detected by DPV-2000 ...Yttria-stabilized zirconia（ YSZ） coatings were deposited by low pressure plasma spray（ LPPS） in 1.0× 10^4 Pa,1.5 × 10^4 Pa,and 2.5 × 10^4 Pa. Both in-flight particle diagnostic detected by DPV-2000 system and ANSYS-FLUENT software were used to study the connection between the parameters of flying particles and the coating formation,which might help to recognize the relationship between the operation parameters and the coatings quality. The results of simulation showed that particles in a lower spray pressure could achieve a higher velocity. The particle velocity was around 380 m/s at a distance of 35 cm from the nozzle at 1.0 × 10^4 Pa while only 300 m/s at 2.5 × 10^4 Pa in actual measurement.The results showed that the velocity of particles increased with decreasing the spray pressure,which might enhance the flattening rate of coatings and thereby decreased the porosity. The deposited YSZ coating with the lowest porosity can be gained under 1.0 × 10^4 Pa condition.展开更多
Detecting methanol is of great importance in the organic synthesis industry.Herein,the effective utilization of ZnSnO_(3)-based microstructures for room-temperature methanol monitoring was realized through a template-...Detecting methanol is of great importance in the organic synthesis industry.Herein,the effective utilization of ZnSnO_(3)-based microstructures for room-temperature methanol monitoring was realized through a template-free approach.ZnSnO_(3)-based heterojunctions with different structures and morphologies were successfully synthesized via regulating the molar ratio of Zn2+and Sn4+sources.And room-temperature sensing properties towards methanol were investigated.Among them,ZnO/ZnSnO_(3) hollow microcubes exhibited an outstanding sensing performance including a high sensitivity(10.16)and a response/recovery time(14/75 s)and a limit of detection(490×10^(-9))towards 5×10^(-6)methanol.Additionally,the synergistic effects of hollow structure with larger specific surface areas(42.277 m^(2)·g^(-1)),the construction of n-n heterojunctions formed at ZnSnO_(3) and ZnO interfaces,the high percentage of dissociative and chemisorbed oxygen are the main causes of the elevated sensing characteristics.Besides,the practical experiment demonstrated that ZnO/ZnSnO_(3) was capable of on-field monitoring methanol in the chemical reaction utilizing H_(2) and CO_(2) as raw materials.Moreover,with the help of density functional theory calculations,the enhanced sensing properties of ZnO/ZnSnO_(3) are due to the special tuning effects of Zn ionic sites on methanol adsorption.展开更多
基金the financial support by the Project of Taihang Laboratory (No. A3023)Science Center for Gas Turbine Project (Grant No. P2022-CIV-002-001)。
文摘The unique crystallographic lamellar microstructure(CLM) Ni-based superalloys fabricated by laser powder bed fusion(LPBF) exhibits excellent tensile properties.This study aims to investigate CLM's high-temperature stress rupture behavior and use these findings to improve the additive manufacturing process.The result shows that the high temperature-induced intergranular fracture in <110> grain region is responsible for stress rupture failure under both conditions of 760 ℃/780 MPa and 980 ℃/260 MPa.Among them,the sub-grain boundary fracture occurs only under high temperature and low stress,980 ℃/260 MPa.Due to the severe intergranular fracture induced by stray grains,the stress rupture life is very low under both conditions.According to the finite element simulation,the formation of stray grains stems from the unstable heat flow within the melt pool during the process.In addition,the shorter stress rupture lifetime does not excite a more pronounced dislocation network around the γ′ phase.However,the deformation twins can still be activated inside the <110> grains,so it has excellent plasticity under both test conditions.Finally,this work indicates that the future optimization of CLM by LPBF should focus on eliminating of high-angle grain boundaries in <110> grains.
基金supported by the Technical Project of Guangdong Province, China (Nos. 2020B090923002, 2021A1515011756)GDAS’ Project of Science and Technology Development, China (No. 2021GDASYL20210302006)+3 种基金Sciences Platform Environment and Capacity Building Projects of GDAS, China (No. 2021GDASYL-20210102005)Key R&D Program of Guangdong Province, China (No. 2020B090923002)Guangdong Special Support Program, China (No. 2019BT02C629)Guangdong Basic and Applied Basic Research Fund, China (Nos. 2020A1515111031, 2021A1515010939)。
基金financially supported by the National Natural Science Foundation of China (No. 51872254)the National Key Research & Development Program of China (No. 2017YFE0115900)the Outstanding Youth Foundation of Jiangsu Province of China (No. BK20210027)。
文摘The excessive concentration of NO_(2) in the atmosphere has gained considerable attention due to its damage to the environment and human health. Gas sensor technology has important application prospects in detecting atmospheric NO_(2) concentration. Restricted by its wide bandgap, pristine ZnO needs additional energy to power the electronic transition as a gas sensing material.
基金financially supported by the National Natural Science Foundation of China(No.51301112, No.51401129)Natural Science Foundation of Liaoning Province of China(No.201602553 )+1 种基金China Postdoctoral Science Foundation(2015M571327)The Science Research Program of Education Department in Liaoning Province(No.L2014048)
文摘Yttria-stabilized zirconia（ YSZ） coatings were deposited by low pressure plasma spray（ LPPS） in 1.0× 10^4 Pa,1.5 × 10^4 Pa,and 2.5 × 10^4 Pa. Both in-flight particle diagnostic detected by DPV-2000 system and ANSYS-FLUENT software were used to study the connection between the parameters of flying particles and the coating formation,which might help to recognize the relationship between the operation parameters and the coatings quality. The results of simulation showed that particles in a lower spray pressure could achieve a higher velocity. The particle velocity was around 380 m/s at a distance of 35 cm from the nozzle at 1.0 × 10^4 Pa while only 300 m/s at 2.5 × 10^4 Pa in actual measurement.The results showed that the velocity of particles increased with decreasing the spray pressure,which might enhance the flattening rate of coatings and thereby decreased the porosity. The deposited YSZ coating with the lowest porosity can be gained under 1.0 × 10^4 Pa condition.
基金financially supported by the Outstanding Youth of Jiangsu Province of China (No.BK20211548)the China Scholarship Council (No.202108320264)the Excellent Doctoral Dissertation Fund of Yangzhou University (2022)。
文摘Detecting methanol is of great importance in the organic synthesis industry.Herein,the effective utilization of ZnSnO_(3)-based microstructures for room-temperature methanol monitoring was realized through a template-free approach.ZnSnO_(3)-based heterojunctions with different structures and morphologies were successfully synthesized via regulating the molar ratio of Zn2+and Sn4+sources.And room-temperature sensing properties towards methanol were investigated.Among them,ZnO/ZnSnO_(3) hollow microcubes exhibited an outstanding sensing performance including a high sensitivity(10.16)and a response/recovery time(14/75 s)and a limit of detection(490×10^(-9))towards 5×10^(-6)methanol.Additionally,the synergistic effects of hollow structure with larger specific surface areas(42.277 m^(2)·g^(-1)),the construction of n-n heterojunctions formed at ZnSnO_(3) and ZnO interfaces,the high percentage of dissociative and chemisorbed oxygen are the main causes of the elevated sensing characteristics.Besides,the practical experiment demonstrated that ZnO/ZnSnO_(3) was capable of on-field monitoring methanol in the chemical reaction utilizing H_(2) and CO_(2) as raw materials.Moreover,with the help of density functional theory calculations,the enhanced sensing properties of ZnO/ZnSnO_(3) are due to the special tuning effects of Zn ionic sites on methanol adsorption.
