Abstract: Disclosed herein is a method of preparing an oxide superconducting wire comprising the steps of coating a powder material for forming an oxide superconductor with a metal, performing deformation processing on the metal-coated powder material thereby obtaining a tape-type wire material, superposing a plurality of such tape-type wire materials, performing first heat treatment on the plurality of superposed tape-type wire materials while simultaneously diffusion-bonding the metallic coats to each other, then performing deformation processing on the plurality of superposed tape-type wire materials, and performing second heat treatment on the plurality of deformation-processed tape-type wire materials. Preferably the oxide superconductor to be obtained is a bismuth oxide superconductor having a 2223 composition in a composition of Bi-Sr-Ca-Cu or (Bi,Pb)-Sr-Ca-Cu, and the powder material consists of a superconducting phase, which is mainly composed of a 2212 phase, and non-superconducting phases.

Abstract: In a method of preparing an oxide superconducting wire comprising the steps of filling up raw material powder for an oxide superconductor in a metal sheath and rolling the same in this state, frictional force on surfaces of rolls employed for rolling is increased in the rolling step in order to improve denseness of the raw material powder, thereby improving the critical current density of the oxide superconducting wire. In order to increase the frictional force, films having large frictional force are formed on the roll surfaces, a coating material is applied to the roll surfaces during rolling, or the roll surfaces are roughened, for example.

Abstract: In order to prevent expansion of a metal sheath which is heat treated in order to form an oxide high-temperature superconductor therein, the heat treatment temperature is held at a certain level in an intermediate stage of temperature rising in a step of heat treating the metal sheath after filling raw material for an oxide high-temperature superconductor into the metal sheath. After the heat treatment temperature is thus held at the certain level, the metal sheath is again heated to a target temperature. Preferably, the heat treatment temperature is held at a level which is selected in a range of at least 500.degree. C. and not more than 750.degree. C.

Abstract: Disclosed herein is a method of preparing an oxide superconducting wire comprising the steps of coating a powder material for forming an oxide superconductor with a metal, performing deformation processing on the metal-coated powder material thereby obtaining a tape-type wire material, superposing a plurality of such tape-type wire materials, performing first heat treatment on the plurality of superposed tape-type wire materials while simultaneously diffusion-bonding the metallic coats to each other, then performing deformation processing on the plurality of superposed tape-type wire materials, and performing second heat treatment on the plurality of deformation-processed tape-type wire materials. Preferably the oxide superconductor to be obtained is a bismuth oxide superconductor having a 2223 composition in a composition of Bi--Sr--Ca--Cu or (Bi,Pb)--Sr--Ca--Cu, and the powder material consists of a superconducting phase, which is mainly composed of a 2212 phase, and non-superconducting phases.

Abstract: In a method of manufacturing an oxide superconducting wire including steps of performing heat treatment and deformation processing in a state of filling up a metal sheath with powder of an oxide superconductor or raw material therefor, fine particles or gas adsorbed by the powder can be desorbed by heating the powder at least once preferably under decompression in a stage before final sintering of the powder. It is possible to further withdraw the adsorbed fine particles or gas by heating the powder under decompression at least once before the same is covered with the sheath, covering the powder with the sheath, deforming the sheath and again heating the same under decompression, for example. Thus, it is possible to prevent gas generation from the powder during heat treatment for further growing superconductive particles, thereby preventing the superconducting wire from inflation etc. caused by such gas generation.

Abstract: In a method of preparing an oxide superconducting wire comprising the steps of filling up raw material powder for an oxide superconductor in a metal sheath, performing first rolling in this state for working the metal sheath into a tape, performing first heat treatment, then performing second rolling and further performing second heat treatment, diameters of rolls employed for the second rolling are larger by at least 5 cm than those of rolls employed for the first rolling, in order to improve the critical current density of the as-formed oxide superconducting wire over its longitudinal direction.

Abstract: Disclosed herein is a method of preparing a bismuth oxide superconductor by forming a superconducting phase having a 2223 composition or a 2212 composition in a composition of Bi-Sr-Ca-Cu or (Bi,Pb)-Sr-Ca-Cu in a metal sheath. This method comprises the steps of preparing raw material powder containing a mixture of a 2212 phase having the 2212 composition and non-superconducting phases, carrying out a process of heat treating the raw material powder under a reduced pressure of not more than 1 atm. immediately before filling the same into the metal sheath and thereafter cooling the same under an oxygen atmosphere, and filling the raw material powder into the metal sheath and thereafter performing deformation processing and heat treatment on the metal sheath. This method is suitable for preparation of a long wire.