http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
초전도 세라믹 Y-Ba-Cu-O계의 구조적 상전이와 분해거동에 관한 연구
이민호,이민상,김양수,진영철 ( M . H . Lee,M . S . Lee,Y . S . Kim,Y . C . Jin ) 한국열처리공학회 1991 熱處理工學會誌 Vol.4 No.3
In this study, the structural phase transition and decomposition of superconducting ceramic, Y-Ba-Cu-O system was studied. The results of the study are as follows. The high Tc superconductor Y₂Ba₂Cu₃O_(7-x) is made in solid state reaction of O₂atmosphere and the valve of X in Y₂Ba₂Cu₃O_(7-x) is 0.1∼0.2. The transition temperature of tetragonal-orthorhombic phase of Y₂Ba₂Cu₃O_(7-x) appear at 790℃-900℃. In the result of measuring the electrical resistance of sample annealed in O₂atmosphere, the electrical resistance show zero at 92K and the best superconductor, Y₂Ba₂Cu₃O_(7-x)(Y123) can be mabe.
Bi-Pb-Sr-Ca-Cu-O계 산화물 고온초전도체의 특성에 관한 연구
김양수,이민상,이민호,진영철 ( Y . S . Kim,M . S . Lee,M . S . Lee,Y . C . Jin ) 한국열처리공학회 1991 熱處理工學會誌 Vol.4 No.1
The formation of high T_c phase is very sluggish and c parameter of unit cell of high T_c phase is about 37Å. High T_c oxide superconductor with a T_c above 100K has been successfully prepared by solid state reaction method in BiSrCaCuO system by Pb adding. The microstructure related to the formation of the high T_c phase has been investigated. As compared with YBCO compound, the formation reaction of the high T_c requires long time heat treatment. It is due to the transformation from the low T_c phase to high T_c phase. The sintering just below the melting point of the calcined powder mixture is effective on the formation of the high T_c phase in Pb-added BiSrCaCuO system. The growth of the high T_c superconducting phase has a thin plate shape, which is characterized by the c parameter of 37Å. The formation of the high T_c phases is delayed by the excessive addition of Pb. The lattice parameter (c) of the unit cell (both the low and high T_c phases) is increased with increase of Pb.
진영철,홍은성,김양수,이민상,유창영 ( Y . C . Jin,E . S . Hong,Y . S . Kim,M . S . Lee,C . Y . Yoo ) 한국열처리공학회 1993 熱處理工學會誌 Vol.6 No.1
To investigate the properties of diffusion bonding of 7050 Al alloy, the diffusion bonding joints have been produced in self-made diffusion bonding hot-press which admits a defined application of the bonding pressure during the heating phase and also rapid cooling after the bonding process with various bonding condition. The strength of the bond increases with increasing the bonding time and temperature. Shear test at toom temperature showed that high strength up to 70% that of parent metal (320㎫), 220㎫ for the specimen bonded 14hr at 560℃, with 3㎫. In this case, however, there is large deformation more than 20% reduction in thickness. The results were correlated with joint characteristics found by optical microstructure and by fractography by SEM. When the strengths of the bonds are more than 50% that of parent metal, a great deal of dimples stretched along the direction of shear stress are observed over the fractured surface of the bond. On the microstructure of the bond line, initial mophology of the bond line disapeared for the grain boundary migration with increasing tire bonding time.
진영철,국진선,김양수,홍은성,이민상,이민호,유창영 ( Y . C . Jin,J . S . Kook,Y . S . Kim,E . S . Lee,M . H . Lee,C . Y . Yoo ) 한국열처리공학회 1992 熱處理工學會誌 Vol.5 No.1
The effects of alloying elements on the superplastic properties of Al-Li based alloys had been investigated. The intermediate thermo-mechanical treated(ITMT) Al-2.0wt%Li, Al-2.0wt%Li-1.0wt%Mg, Al-2.0wt%Li-0.12wt%Zr and Al-2.0wt%Li-1.2wt%Cu-1.0wt%Mg-0.12wt%Zr alloys were tested in tension at various temperature (400, 450, 500 and 550℃) and strain rate(6.7×10^(-3), 1.0×10^(-2), 1.6×10^(-2) and 5.0×10^(-2)/sec). The results were as follows : The superplasticity in binary, ternary and pentanary alloys appeared at 500 to 550℃, and good strain rate for superplasticity, 1.6×10^(-2)/sec∼1.0×10^(-2)/sec for a binary alloy and 1.0×10(-2)/sec∼6.7×10^(-3)/sec for ternary and pentanary alloys. A Zr-added ternary alloy had best value of elongation (730%) in four alloys at 550℃ of tension temperature and 1.0×10^(-2)/sec of strain rate. The strain rate was greatly dependent on tension temperature and true strain rate was more than 1.0 at all test temperature and strain rate. In binary and Mg-added teranry alloys, the necks were slightly formed and their fracture surface had lips shape, but Zr-added ternary and pentanary alloy fractured along the grain boundary without necking. Their dislocations moved to grain boundary during superplasticity deformation and arranged perpendicular to grain boundary. Superplastic deformation was made by grain boundary slip of dislocation slip creep and model of core and mantle.