The process to obtain high T(110K)phase quickly,the microstructure and properties of Ag-sheathed Bi(Pb)-Sr-Ca-Cu-O superconductor tapes have been studied.It was found that the formation time of the high T_c phase was ...The process to obtain high T(110K)phase quickly,the microstructure and properties of Ag-sheathed Bi(Pb)-Sr-Ca-Cu-O superconductor tapes have been studied.It was found that the formation time of the high T_c phase was greatly shortened by the addition of more Ca and Cu to the nominal composition of Bi(Pb):Sr :Ca:Cu=2:2:2:3 and the adoption of appropriate sintering temperature and cooling rate. Superconductor powder with predominant high T,phase was prepared after a 840 C/50 h treatment.The J of the Ag-sheathed tapes and the magnetic field dependence of Jwere obviously improved by repeatedly pres- sing and sintering.The maximum transport current density at 77K in a zero magnetic field was 12,200 A/cm^2. The magnetic dependence of Jwas summarized as follows:6.450 A/cm^(2)(B⊥1.B∥S.0.1T)1,810 A/cm^2 (B⊥1.B∥S,1T),390 A/cm^2(B⊥1.B∥S,2T)(B:magnetic field.1:electric current.S:surface of tapes).The improvement of Jwas attributed to the formation of the plate-like structure with homogeneous composition distribution and the strong c-axis texture.展开更多
The silver-sheathed Bi-Pb-Sr-Ca-Cu-O(Bi-2223) superconducting tapes have been fabricated by the powder-in-tube method. In the process,we investigated the effects of the particle size, rolling and pressing on Jc and fo...The silver-sheathed Bi-Pb-Sr-Ca-Cu-O(Bi-2223) superconducting tapes have been fabricated by the powder-in-tube method. In the process,we investigated the effects of the particle size, rolling and pressing on Jc and found that the Jc value can be a ffected greatly by the three factors.展开更多
Ag-sheathed(Bi,Pb)_2Sr_2Ca_2Cu_3O_x tapes were fabricated by a powder-in-tube method.A high critical current density of 2.8×10~4 A/cm^2 at 77K,0T and 4×10~4 A/cm^2 at 4.2K,5T(H⊥ab),6.3× 10~4 A/cm^2 at ...Ag-sheathed(Bi,Pb)_2Sr_2Ca_2Cu_3O_x tapes were fabricated by a powder-in-tube method.A high critical current density of 2.8×10~4 A/cm^2 at 77K,0T and 4×10~4 A/cm^2 at 4.2K,5T(H⊥ab),6.3× 10~4 A/cm^2 at 4.2K,7T(H∥ab)is obtained.The microstructure of the tapes with high J_c values was in- vestigated by transmission electron microscope(TEM)and X-ray energy dispersive spectrum system(EDS). For comparison,a tape fabricated by a different procedure with a low J_c of about 1×10~4 A/cm^2 at 77K,0T was also studied.The relationship between J_c and microstructure of the tapes and the effect of the processing on the microstructure and J_c were elucidated.展开更多
本研究旨在探究高密度聚乙烯(high density polyethylene,HDPE)护套的老化机理及其在自然环境下的服役寿命。对HDPE护套在湿热气候(海南琼海市)和干热气候(新疆吐鲁番市)下进行了3a的自然老化试验和在干热气候(美国凤凰城)下进行1a的太...本研究旨在探究高密度聚乙烯(high density polyethylene,HDPE)护套的老化机理及其在自然环境下的服役寿命。对HDPE护套在湿热气候(海南琼海市)和干热气候(新疆吐鲁番市)下进行了3a的自然老化试验和在干热气候(美国凤凰城)下进行1a的太阳跟踪聚光加速老化试验,对HDPE老化试验中的力学性能、分子结构、热性能、反应动力学、反应级数进行分析。结果表明,黑色HDPE护套在自然老化和太阳跟踪聚光加速老化过程中产生的特征官能团相似,热分解活化能基本相同,反应机理也一致;基于试验数据,提出了HDPE护套服役寿命模型,得出HDPE护套在中东特殊干热地区的服役寿命为15~28a,东南亚特殊湿热地区为14~20a,气候环境温和地区超过40a。本研究为预测HDPE护套在各种环境下的服役寿命提供了理论依据,也为HDPE护套材料的研发与应用提供了参考。展开更多
Iron-based superconductor,a promising candidate for high-field applications,has attracted significant attentions.For practical utilization,the superconducting tapes should have high transport critical current density(...Iron-based superconductor,a promising candidate for high-field applications,has attracted significant attentions.For practical utilization,the superconducting tapes should have high transport critical current density(J_(c)),low production cost,larger mechanical strength and good homogeneity.In this study,seven-filament Cu/Agsheathed(Ba,K)Fe_(2)As_(2)tapes were fabricated from round and square wires.It is found that the tapes rolled from square wires have a desirable uniformity of filament deformation and distribution,compared with the ones rolled from round wires.Moreover,the J_c of tape was obviously improved by using square drawing dies instead of traditional round ones.For the tapes rolled from square wires annealed under ambient and 2 MPa by hot pressing,the transport J_c values reached 1.51×10^(4) A·cm^(-2)and 4.86×10^(4) A.cm^(-2)(4.2K,10T),respectively.The deformation process on the cross section of the tapes during rolling was analyzed by using the powder-flow model.These results indicate a potential application of Cu/Ag(Ba,K)Fe_(2)As_(2)tapes in high-magnetic-field region.展开更多
文摘The process to obtain high T(110K)phase quickly,the microstructure and properties of Ag-sheathed Bi(Pb)-Sr-Ca-Cu-O superconductor tapes have been studied.It was found that the formation time of the high T_c phase was greatly shortened by the addition of more Ca and Cu to the nominal composition of Bi(Pb):Sr :Ca:Cu=2:2:2:3 and the adoption of appropriate sintering temperature and cooling rate. Superconductor powder with predominant high T,phase was prepared after a 840 C/50 h treatment.The J of the Ag-sheathed tapes and the magnetic field dependence of Jwere obviously improved by repeatedly pres- sing and sintering.The maximum transport current density at 77K in a zero magnetic field was 12,200 A/cm^2. The magnetic dependence of Jwas summarized as follows:6.450 A/cm^(2)(B⊥1.B∥S.0.1T)1,810 A/cm^2 (B⊥1.B∥S,1T),390 A/cm^2(B⊥1.B∥S,2T)(B:magnetic field.1:electric current.S:surface of tapes).The improvement of Jwas attributed to the formation of the plate-like structure with homogeneous composition distribution and the strong c-axis texture.
文摘The silver-sheathed Bi-Pb-Sr-Ca-Cu-O(Bi-2223) superconducting tapes have been fabricated by the powder-in-tube method. In the process,we investigated the effects of the particle size, rolling and pressing on Jc and found that the Jc value can be a ffected greatly by the three factors.
文摘Ag-sheathed(Bi,Pb)_2Sr_2Ca_2Cu_3O_x tapes were fabricated by a powder-in-tube method.A high critical current density of 2.8×10~4 A/cm^2 at 77K,0T and 4×10~4 A/cm^2 at 4.2K,5T(H⊥ab),6.3× 10~4 A/cm^2 at 4.2K,7T(H∥ab)is obtained.The microstructure of the tapes with high J_c values was in- vestigated by transmission electron microscope(TEM)and X-ray energy dispersive spectrum system(EDS). For comparison,a tape fabricated by a different procedure with a low J_c of about 1×10~4 A/cm^2 at 77K,0T was also studied.The relationship between J_c and microstructure of the tapes and the effect of the processing on the microstructure and J_c were elucidated.
文摘本研究旨在探究高密度聚乙烯(high density polyethylene,HDPE)护套的老化机理及其在自然环境下的服役寿命。对HDPE护套在湿热气候(海南琼海市)和干热气候(新疆吐鲁番市)下进行了3a的自然老化试验和在干热气候(美国凤凰城)下进行1a的太阳跟踪聚光加速老化试验,对HDPE老化试验中的力学性能、分子结构、热性能、反应动力学、反应级数进行分析。结果表明,黑色HDPE护套在自然老化和太阳跟踪聚光加速老化过程中产生的特征官能团相似,热分解活化能基本相同,反应机理也一致;基于试验数据,提出了HDPE护套服役寿命模型,得出HDPE护套在中东特殊干热地区的服役寿命为15~28a,东南亚特殊湿热地区为14~20a,气候环境温和地区超过40a。本研究为预测HDPE护套在各种环境下的服役寿命提供了理论依据,也为HDPE护套材料的研发与应用提供了参考。
基金financially supported by the National Natural Science Foundation of China(Nos.U1832213,51721005 and 51861135311)the National Key R&D Program of China(Nos.2018YFA0704200 and 2017YFE0129500)+1 种基金the Key Research Program of Frontier Sciences,Chinese Academy of Sciences(No.QYZDJ-SSW-JSC026)the Strategic Priority Research Program of Chinese Academy of Sciences(No.XDB25000000)。
文摘Iron-based superconductor,a promising candidate for high-field applications,has attracted significant attentions.For practical utilization,the superconducting tapes should have high transport critical current density(J_(c)),low production cost,larger mechanical strength and good homogeneity.In this study,seven-filament Cu/Agsheathed(Ba,K)Fe_(2)As_(2)tapes were fabricated from round and square wires.It is found that the tapes rolled from square wires have a desirable uniformity of filament deformation and distribution,compared with the ones rolled from round wires.Moreover,the J_c of tape was obviously improved by using square drawing dies instead of traditional round ones.For the tapes rolled from square wires annealed under ambient and 2 MPa by hot pressing,the transport J_c values reached 1.51×10^(4) A·cm^(-2)and 4.86×10^(4) A.cm^(-2)(4.2K,10T),respectively.The deformation process on the cross section of the tapes during rolling was analyzed by using the powder-flow model.These results indicate a potential application of Cu/Ag(Ba,K)Fe_(2)As_(2)tapes in high-magnetic-field region.
