To obtain new unconventional structures with specific mechanical and physical properties is possible not only by the development of new types of materials but also by treatment of conventional materials using unconven...To obtain new unconventional structures with specific mechanical and physical properties is possible not only by the development of new types of materials but also by treatment of conventional materials using unconventional innovative technological procedures.One of these technologies is the forming in semi-solid state involving rapid solidification of miniature components from steels.Production of such components is complicated by a number of technical problems.To explain phenomena of the process and structure development,the production of miniature components from the tool steel X210Cr12 difficult to form was experimentally tested.The structure of this originally ledeburite steel consisted of 95 % of metastable austenite after the treatment.Metastable austenite was located particularly in globular and polygonal grains while the remaining interspaces were filled by lamellar network.The detected high stability of extremely high fraction of metastable austenite was tested under different conditions of thermal exposition and mechanical loading.展开更多
The grain growth behavior in reactive spray formed 7075+2.91 vol percent TiCAl alloy was studied and compared with that of spray formed 7075 Al alloy at semi-solid state. Theeffects of in-situ TiC particles on the mic...The grain growth behavior in reactive spray formed 7075+2.91 vol percent TiCAl alloy was studied and compared with that of spray formed 7075 Al alloy at semi-solid state. Theeffects of in-situ TiC particles on the microstructure of spray formed 7075 Al alloy were alsoinvestigated. The specimens were heat-treated isothermally at various temperatures between thesolidus and liquidus of 7075 Al alloy for times in the range of 10-60 min, then quenched in water.The microstructure of reheated specimens was characterized using scanning electron microscopy andoptical microscopy. The grain size was measured using a mean linear intercept method. Results showthat the in-situ TiC particles can effectively retard grain growth and refine the grain at a limitedsize. The grain growth exponent in Arrhenius equation increases from 2 to 3, which indicates thatthe in-situ TiC particles have the significant pinning effect on grain coarsening in the semi-solidstate.展开更多
The mold pressing process was applied to investigate the formability of closed-cell aluminum foam in solid–liquid–gas coexisting state.Results show that the shape formation of closed-cell aluminum foam in the solid...The mold pressing process was applied to investigate the formability of closed-cell aluminum foam in solid–liquid–gas coexisting state.Results show that the shape formation of closed-cell aluminum foam in the solid–liquid–gas coexisting state was realized through cell wall deformation and cell movement caused by primary α-Al grains that slid,rotated,deformed,and ripened within cell walls.During formation,characteristic parameters of closed-cell aluminum foam were almost unchanged.Under proper forming conditions,shaped products of closed-cell aluminum foam could be fabricated through mold pressing.展开更多
Irbesartan (IBS) is a tetrazole derivative and antihypertensive drug that has two interconvertible structures, 1H- and 2H-tautomers. The difference between them lies in the protonation of the tetrazole ring. In the so...Irbesartan (IBS) is a tetrazole derivative and antihypertensive drug that has two interconvertible structures, 1H- and 2H-tautomers. The difference between them lies in the protonation of the tetrazole ring. In the solid-state, both tautomers can be isolated as crystal forms A (1H-tautomer) and B (2H-tautomer). Studies have reported that IBS is a polymorphic system and its forms A and B are related monotropically. These reports indicate form B as the most stable and less soluble form. Therefore, the goal of this contribution is to demonstrate through a complete solid-state characterization, thermodynamic study and dissolution properties that the IBS forms are desmotropes that are not related monotropically. However, the intention is also to call attention to the importance of conducting strict chemical and in solid-state quality controls on the IBS raw materials. Hence, powder X-ray diffraction (PXRD) and Raman spectroscopy (RS) at ambient and non-ambient conditions, differential scanning calorimetry (DSC), hot stage microscopy (HSM), Fourier transform infrared (FT-IR) and scanning electron microscopy (SEM) techniques were applied. Furthermore, intrinsic dissolution rate (IDR) and structural stability studies at 98% relative humidity (RH), 25℃ and 40 ℃ were conducted as well. The results show that in fact, form A is approximately four-fold more soluble than form B. In addition, both IBS forms are stable at ambient conditions. Nevertheless, structural and/or chemical instability was observed in form B at 40℃ and 98% RH. IBS has been confirmed as a desmotropic system rather than a polymorphic one. Consequently, forms A and B are not related monotropically.展开更多
The consolidation recycled AZ80 billets were successfully fabricated through the cold press and hot press sintering of the AZ80 metal chips.The consolidation recycled billets sintered at 350℃present the comparable co...The consolidation recycled AZ80 billets were successfully fabricated through the cold press and hot press sintering of the AZ80 metal chips.The consolidation recycled billets sintered at 350℃present the comparable compressive properties and inferior tensile properties compared with the initial cast billets.The defects in the consolidation recycled billet were inclined to propagate along the bond interface between the metal chips during tension,which resulted in the inferior tensile properties of the recycled billets.The recycled billets were then subjected to the integrated extrusion-shear(ES) process.The homogeneous finer dynamic recrystallization grains with an average grain size of 6 μm can be obtained in the shear deformation zone and extrusion sizing zone through integrated ES process at 300℃with an extrusion velocity of 0.6 mm/s.The recycled billets after integrated ES forming process present rival tensile properties compared with the initial cast billets after integrated ES forming with the same extrusion parameters,which can be ascribed to that the integrated ES forming can nearly eliminate the defects through the severe compressive and shear strain.The solid-state recycling process through hot press sintering and subsequent integrated ES process can fabricate the consolidation recycled AZ80 rod,which demonstrates the comparable tensile properties with the cast-extrusion rod.展开更多
为了推动脉冲功率技术的应用,研制了紧凑、可高重复频率运行的固态脉冲功率源。通过大功率固体开关及电路拓扑结构的比较,选择了基于光导开关的层叠Blumlein线型脉冲功率源这一技术路线。基于铁电陶瓷脉冲形成线和光导开关构建了大电流...为了推动脉冲功率技术的应用,研制了紧凑、可高重复频率运行的固态脉冲功率源。通过大功率固体开关及电路拓扑结构的比较,选择了基于光导开关的层叠Blumlein线型脉冲功率源这一技术路线。基于铁电陶瓷脉冲形成线和光导开关构建了大电流固态模块,光导开关通流能力超过4 k A。已经实现的应用包括:研制了200 k V/1 k A固态脉冲功率源并与反射二极管结合实现了重复频率为100 Hz或1 k Hz、脉冲宽度约40 ns的猝发X射线脉冲输出;利用基于光导开关的Blumlein线模块产生的快脉冲进行了血液病原体灭活初步研究,可得当脉冲个数为10个时,在80 k V/cm的电场作用下红细胞悬液中细菌的抑制率为57%。展开更多
基金the project 1M06032 Research Centre of Forming TechnologySlovak and Czech Project SK-CZ-0180-09
文摘To obtain new unconventional structures with specific mechanical and physical properties is possible not only by the development of new types of materials but also by treatment of conventional materials using unconventional innovative technological procedures.One of these technologies is the forming in semi-solid state involving rapid solidification of miniature components from steels.Production of such components is complicated by a number of technical problems.To explain phenomena of the process and structure development,the production of miniature components from the tool steel X210Cr12 difficult to form was experimentally tested.The structure of this originally ledeburite steel consisted of 95 % of metastable austenite after the treatment.Metastable austenite was located particularly in globular and polygonal grains while the remaining interspaces were filled by lamellar network.The detected high stability of extremely high fraction of metastable austenite was tested under different conditions of thermal exposition and mechanical loading.
基金This work was financially supported by the National Natural Science Foundation of China (No.50171010)
文摘The grain growth behavior in reactive spray formed 7075+2.91 vol percent TiCAl alloy was studied and compared with that of spray formed 7075 Al alloy at semi-solid state. Theeffects of in-situ TiC particles on the microstructure of spray formed 7075 Al alloy were alsoinvestigated. The specimens were heat-treated isothermally at various temperatures between thesolidus and liquidus of 7075 Al alloy for times in the range of 10-60 min, then quenched in water.The microstructure of reheated specimens was characterized using scanning electron microscopy andoptical microscopy. The grain size was measured using a mean linear intercept method. Results showthat the in-situ TiC particles can effectively retard grain growth and refine the grain at a limitedsize. The grain growth exponent in Arrhenius equation increases from 2 to 3, which indicates thatthe in-situ TiC particles have the significant pinning effect on grain coarsening in the semi-solidstate.
基金financially supported by the National Natural Science Foundations of China (No.51371104)
文摘The mold pressing process was applied to investigate the formability of closed-cell aluminum foam in solid–liquid–gas coexisting state.Results show that the shape formation of closed-cell aluminum foam in the solid–liquid–gas coexisting state was realized through cell wall deformation and cell movement caused by primary α-Al grains that slid,rotated,deformed,and ripened within cell walls.During formation,characteristic parameters of closed-cell aluminum foam were almost unchanged.Under proper forming conditions,shaped products of closed-cell aluminum foam could be fabricated through mold pressing.
基金financial support of FEES-CONARE (Ref 115B5662)the University of Costa Rica (UCR)+1 种基金the Costa Rica Institute of Technology (TEC)the National Laboratory of Nanotechnology (LANOTEC)
文摘Irbesartan (IBS) is a tetrazole derivative and antihypertensive drug that has two interconvertible structures, 1H- and 2H-tautomers. The difference between them lies in the protonation of the tetrazole ring. In the solid-state, both tautomers can be isolated as crystal forms A (1H-tautomer) and B (2H-tautomer). Studies have reported that IBS is a polymorphic system and its forms A and B are related monotropically. These reports indicate form B as the most stable and less soluble form. Therefore, the goal of this contribution is to demonstrate through a complete solid-state characterization, thermodynamic study and dissolution properties that the IBS forms are desmotropes that are not related monotropically. However, the intention is also to call attention to the importance of conducting strict chemical and in solid-state quality controls on the IBS raw materials. Hence, powder X-ray diffraction (PXRD) and Raman spectroscopy (RS) at ambient and non-ambient conditions, differential scanning calorimetry (DSC), hot stage microscopy (HSM), Fourier transform infrared (FT-IR) and scanning electron microscopy (SEM) techniques were applied. Furthermore, intrinsic dissolution rate (IDR) and structural stability studies at 98% relative humidity (RH), 25℃ and 40 ℃ were conducted as well. The results show that in fact, form A is approximately four-fold more soluble than form B. In addition, both IBS forms are stable at ambient conditions. Nevertheless, structural and/or chemical instability was observed in form B at 40℃ and 98% RH. IBS has been confirmed as a desmotropic system rather than a polymorphic one. Consequently, forms A and B are not related monotropically.
基金financially supported by the National Natural Science Foundation of China (No. 51875127).
文摘The consolidation recycled AZ80 billets were successfully fabricated through the cold press and hot press sintering of the AZ80 metal chips.The consolidation recycled billets sintered at 350℃present the comparable compressive properties and inferior tensile properties compared with the initial cast billets.The defects in the consolidation recycled billet were inclined to propagate along the bond interface between the metal chips during tension,which resulted in the inferior tensile properties of the recycled billets.The recycled billets were then subjected to the integrated extrusion-shear(ES) process.The homogeneous finer dynamic recrystallization grains with an average grain size of 6 μm can be obtained in the shear deformation zone and extrusion sizing zone through integrated ES process at 300℃with an extrusion velocity of 0.6 mm/s.The recycled billets after integrated ES forming process present rival tensile properties compared with the initial cast billets after integrated ES forming with the same extrusion parameters,which can be ascribed to that the integrated ES forming can nearly eliminate the defects through the severe compressive and shear strain.The solid-state recycling process through hot press sintering and subsequent integrated ES process can fabricate the consolidation recycled AZ80 rod,which demonstrates the comparable tensile properties with the cast-extrusion rod.
文摘为了推动脉冲功率技术的应用,研制了紧凑、可高重复频率运行的固态脉冲功率源。通过大功率固体开关及电路拓扑结构的比较,选择了基于光导开关的层叠Blumlein线型脉冲功率源这一技术路线。基于铁电陶瓷脉冲形成线和光导开关构建了大电流固态模块,光导开关通流能力超过4 k A。已经实现的应用包括:研制了200 k V/1 k A固态脉冲功率源并与反射二极管结合实现了重复频率为100 Hz或1 k Hz、脉冲宽度约40 ns的猝发X射线脉冲输出;利用基于光导开关的Blumlein线模块产生的快脉冲进行了血液病原体灭活初步研究,可得当脉冲个数为10个时,在80 k V/cm的电场作用下红细胞悬液中细菌的抑制率为57%。
