The FTP200 flake tantalum powder was introduced.The microstructures of the powder with leaf-like primary particles having an average flakiness of 2 to 20 and porous agglomerated particles were observed.The chemical co...The FTP200 flake tantalum powder was introduced.The microstructures of the powder with leaf-like primary particles having an average flakiness of 2 to 20 and porous agglomerated particles were observed.The chemical composition,physical properties,and electrical properties of the FTP200 powder were compared with those of the FTW300 nodular powder.The FTP200 powder is more sinter-resistant,and the surface area of the flake tantalum powder under sintering at high temperature has less loss than that of the nodular tantalum powder.The specific capacitance of the flake tantalum powder is higher than that of the nodular tantalum powder with the same surface area when anodized at high voltage.Thus,the flake tantalum powder is suitable for manufacturing tantalum solid electrolytic capacitors in the range of median and high（20-63 V） voltages.展开更多
Relation between doping and texture and property of tantalum bar and wire was carefully investigated by optical microscope, SEM fractograph, electron microprobe analysis, density test. observation of TEM and mechanica...Relation between doping and texture and property of tantalum bar and wire was carefully investigated by optical microscope, SEM fractograph, electron microprobe analysis, density test. observation of TEM and mechanical property test at room temperature. It is illustrated that the grain of tantalum bar after sintering reduces with the increasing of dopant quantity, and the effect of dopant Ce on reduction of the grain is more obvious than that of dopant Ge, even that sintering is be- coming insufficient and the density of tantalum bar tends to be lower with the increaseing of dopant Ce The recrystallization temperature of tantalum wire increases and the grain of texture reduces with the increaseing of dopants quantity. The tensile strength of tantalum wire at room temperature increases with the increasing of dopants quantity, while its elongation decreases with the increase of dopant Ge quantity and rises with theincrease of dopant Ce quantity. And the strengthening effect of dopant Ce is clearer than that of dopant Ge.展开更多
Effect of different dopants and various dopants quantity at different annealing temperatures on microstructure of tantalum wire, bending of tantalum wire after sintering and bending after pressing into tantalum powder...Effect of different dopants and various dopants quantity at different annealing temperatures on microstructure of tantalum wire, bending of tantalum wire after sintering and bending after pressing into tantalum powder and sintering were investigated through observation of microstructure and testing of bending of tantalum wire after sintering and bending after pressing into tantalum powder and sintering. The results show that the recrystallization temperature of tantalum wire increases and the grain of microstructure can be reduced with the increase of dopants quantity. At the same time, the effect of dopant Ce on reduction of the grain is more obvious than that of dopant Ge. The bending time of tantalum wire after sintering increases with the increase of dopant Ge or Ce quantity. Under the same condition, the bending time of tantalum wire after pressing into tantalum powder and sintering worsens with the increase of oxygen content in tantalum powder. The bending time of tantalum wire doped with Ge and Ce after pressing into tantalum powder and sintering is better than that of tantalum wire doped with Ge, while that of tantalum wire doped with Ge is better than that of pure one when oxygen content in tantalum powder is not too high.展开更多
Tantalum nitride powders with particle size of 20-50 nm were prepared by the homogeneous reduction in liquid ammonia,and were treated at the temperature range from 500 ℃ to 1 170 ℃. The results of XRD analysis indic...Tantalum nitride powders with particle size of 20-50 nm were prepared by the homogeneous reduction in liquid ammonia,and were treated at the temperature range from 500 ℃ to 1 170 ℃. The results of XRD analysis indicate that the powders heated up to 500 ℃ are in the form of amorphous. The powder heated at 600 ℃ tends to transform into crystal,the powder heated to temperatures higher than 700 ℃ is clearly of crystal. The results of surface area analysis by BET show that the surface area of the powder increases as the heating temperature increases,and reaches a maximum value of 21.8 m2/g at the heating temperature around 700 ℃.展开更多
A new idea is proposed by the PKU group to improve the magnetic properties of the Type-Ⅱ superconductor niobium. Rare earth elements like scandium and yttrium are doped into ingot niobium during the smelting processe...A new idea is proposed by the PKU group to improve the magnetic properties of the Type-Ⅱ superconductor niobium. Rare earth elements like scandium and yttrium are doped into ingot niobium during the smelting processes. A series of experiments have been done since 2010. The preliminary testing results show that the magnetic properties of niobium materials have changed with different doping elements and proportions while the superconductive transition temperature does not change very much. This method may increase the superheating magnetic field of niobium so as to improve the performance of the niobium cavity, which is a key component of SRF accelerators. A Tesla-type single-cell cavity made of scandium-doped niobium is being fabricated.展开更多
As part of the international research program on the superconducting cavity for the International Linear Collider （ILC） R＆D on the 1.3 GHz low loss superconducting cavities has been carried out at the Institute of ...As part of the international research program on the superconducting cavity for the International Linear Collider （ILC） R＆D on the 1.3 GHz low loss superconducting cavities has been carried out at the Institute of High Energy Physics （IHEP） since 2005. A design of 1.3 GHz low loss cavity shape was proposed and six single-cell cavities of different niobium material were successfully fabricated with standard technology. In this study our priority was on large grain （LG） cavities. The two LG cavities were treated with complete procedures of surface treatments based on chemical polishing （CP） without electro polishing （EP） at IHEP. The two LG cavities and a fine grain cavity were sent to KEK for vertical testing. All the three cavities reached accelerating gradients higher than 35 MV/m and the maximum gradient of 40.27 MV/m was achieved in the LG cavity. This paper presents the process of the vertical RF tests and the comparison of the LG and fine grain cavities＇s performance.展开更多
Niobium is widely used in SRF （Superconducting Radio Frequency） cavities due to its excellent superconductivity and workability. With the continuous development of technology, higher demands of material are raised. ...Niobium is widely used in SRF （Superconducting Radio Frequency） cavities due to its excellent superconductivity and workability. With the continuous development of technology, higher demands of material are raised. One of the key issues is that RRR （Residual Resistance Ratio） of the Nb material should be more than 300, which requires that the Nb ingot have even higher RRR. This article introduces the development and the experimental results of high purity niobium in OTIC in Ningxia （Ningxia Orient Tantalum Industry Co. Ltd.）, and the test results of the single cell TESLA （Tera Electron volt energy Superconducting Linear Accelerator） shaped cavity manufactured by Peking University using Nb material from OTIC.展开更多
文摘The FTP200 flake tantalum powder was introduced.The microstructures of the powder with leaf-like primary particles having an average flakiness of 2 to 20 and porous agglomerated particles were observed.The chemical composition,physical properties,and electrical properties of the FTP200 powder were compared with those of the FTW300 nodular powder.The FTP200 powder is more sinter-resistant,and the surface area of the flake tantalum powder under sintering at high temperature has less loss than that of the nodular tantalum powder.The specific capacitance of the flake tantalum powder is higher than that of the nodular tantalum powder with the same surface area when anodized at high voltage.Thus,the flake tantalum powder is suitable for manufacturing tantalum solid electrolytic capacitors in the range of median and high（20-63 V） voltages.
文摘Relation between doping and texture and property of tantalum bar and wire was carefully investigated by optical microscope, SEM fractograph, electron microprobe analysis, density test. observation of TEM and mechanical property test at room temperature. It is illustrated that the grain of tantalum bar after sintering reduces with the increasing of dopant quantity, and the effect of dopant Ce on reduction of the grain is more obvious than that of dopant Ge, even that sintering is be- coming insufficient and the density of tantalum bar tends to be lower with the increaseing of dopant Ce The recrystallization temperature of tantalum wire increases and the grain of texture reduces with the increaseing of dopants quantity. The tensile strength of tantalum wire at room temperature increases with the increasing of dopants quantity, while its elongation decreases with the increase of dopant Ge quantity and rises with theincrease of dopant Ce quantity. And the strengthening effect of dopant Ce is clearer than that of dopant Ge.
文摘Effect of different dopants and various dopants quantity at different annealing temperatures on microstructure of tantalum wire, bending of tantalum wire after sintering and bending after pressing into tantalum powder and sintering were investigated through observation of microstructure and testing of bending of tantalum wire after sintering and bending after pressing into tantalum powder and sintering. The results show that the recrystallization temperature of tantalum wire increases and the grain of microstructure can be reduced with the increase of dopants quantity. At the same time, the effect of dopant Ce on reduction of the grain is more obvious than that of dopant Ge. The bending time of tantalum wire after sintering increases with the increase of dopant Ge or Ce quantity. Under the same condition, the bending time of tantalum wire after pressing into tantalum powder and sintering worsens with the increase of oxygen content in tantalum powder. The bending time of tantalum wire doped with Ge and Ce after pressing into tantalum powder and sintering is better than that of tantalum wire doped with Ge, while that of tantalum wire doped with Ge is better than that of pure one when oxygen content in tantalum powder is not too high.
基金Project(2003AA302430) supported by the National Hi-tech Research and Development Program of Chinaproject(50374007) supported by the National Natural Science Foundation of China
文摘Tantalum nitride powders with particle size of 20-50 nm were prepared by the homogeneous reduction in liquid ammonia,and were treated at the temperature range from 500 ℃ to 1 170 ℃. The results of XRD analysis indicate that the powders heated up to 500 ℃ are in the form of amorphous. The powder heated at 600 ℃ tends to transform into crystal,the powder heated to temperatures higher than 700 ℃ is clearly of crystal. The results of surface area analysis by BET show that the surface area of the powder increases as the heating temperature increases,and reaches a maximum value of 21.8 m2/g at the heating temperature around 700 ℃.
基金Project supported by the National Natural Science Foundation of China(Grant No.11175008)
文摘A new idea is proposed by the PKU group to improve the magnetic properties of the Type-Ⅱ superconductor niobium. Rare earth elements like scandium and yttrium are doped into ingot niobium during the smelting processes. A series of experiments have been done since 2010. The preliminary testing results show that the magnetic properties of niobium materials have changed with different doping elements and proportions while the superconductive transition temperature does not change very much. This method may increase the superheating magnetic field of niobium so as to improve the performance of the niobium cavity, which is a key component of SRF accelerators. A Tesla-type single-cell cavity made of scandium-doped niobium is being fabricated.
基金Supported by National Natural Science Foundation of China (10525525)
文摘As part of the international research program on the superconducting cavity for the International Linear Collider （ILC） R＆D on the 1.3 GHz low loss superconducting cavities has been carried out at the Institute of High Energy Physics （IHEP） since 2005. A design of 1.3 GHz low loss cavity shape was proposed and six single-cell cavities of different niobium material were successfully fabricated with standard technology. In this study our priority was on large grain （LG） cavities. The two LG cavities were treated with complete procedures of surface treatments based on chemical polishing （CP） without electro polishing （EP） at IHEP. The two LG cavities and a fine grain cavity were sent to KEK for vertical testing. All the three cavities reached accelerating gradients higher than 35 MV/m and the maximum gradient of 40.27 MV/m was achieved in the LG cavity. This paper presents the process of the vertical RF tests and the comparison of the LG and fine grain cavities＇s performance.
基金Supported by National Basic Research Program of China (2002CB713600)
文摘Niobium is widely used in SRF （Superconducting Radio Frequency） cavities due to its excellent superconductivity and workability. With the continuous development of technology, higher demands of material are raised. One of the key issues is that RRR （Residual Resistance Ratio） of the Nb material should be more than 300, which requires that the Nb ingot have even higher RRR. This article introduces the development and the experimental results of high purity niobium in OTIC in Ningxia （Ningxia Orient Tantalum Industry Co. Ltd.）, and the test results of the single cell TESLA （Tera Electron volt energy Superconducting Linear Accelerator） shaped cavity manufactured by Peking University using Nb material from OTIC.
