CN1610956A - Oxide superconducting wire producing method - Google Patents

Abstract

An oxide superconducting wire producing method comprising a step of producing a wire having a form in which the material powder of an oxide superconductor is covered with a metal (S1, S2) and a step of heat-treating the wire in a pressurized atmosphere (S4, S6), wherein the total pressure of the pressurized atmosphere lies in the range from 1 to 50 MPa. In such a way, voids among the oxide superconducting crystals and bulging of the oxide superconducting wire are prevented, and the partial pressure of oxygen during the heat treatment can be easily controlled, thereby improving the critical current density.

Description

The manufacture method of oxide superconducting wire rod

Technical field

The present invention relates to the manufacture method of oxide superconducting wire rod, particularly relate to the method for making oxide superconducting wire rod by the wire rod of the form of the raw material powder that has covered oxide superconductor with metal.

Background technology

Up to now, manufacture method as oxide superconducting wire rod, known had in the metal casing pack behind the raw material powder of oxide superconductor, to heat-treating, so that the raw material powder of oxide superconductor is carried out the method that sintering obtains oxide superconducting wire rod by metal tube being carried out the wire rod that Wire Drawing or calendering processing obtains.But, in the heat treatment step of above-mentioned sintering, because the cause that in wire rod, produce to expand, have the problem of degradation under the superconducting characteristic of resulting oxide superconducting wire rod.

Therefore, open in the flat 5-101723 communique the spy, proposed the manufacture method of following a kind of oxide superconducting wire rod, it is characterized in that: the metal tube that in pressurization atmosphere the powder of filling oxide superconductor is constituted or its bluff body carry out heat treated and carry out sintering oxide superconductor is divided powder.In above-mentioned communique, put down in writing,, can obtain at wire rod good aspect the superconducting characteristic by carrying out the pressurized heat processing according to this method.

Specifically, done following test: with filling the metal tube of powder of oxide superconductor be contained in the heat-resisting withstand voltage closed container expansion the when rising by the pressure inside following temperature in the closed container to rise to increase prevents sintering.The internal pressure of this moment can be obtained by the equation of state of gas, for example, has put down in writing in above-mentioned communique, can obtain the internal pressure of about 4 air pressure under the about 900 ℃ heating-up temperature of temperature.

In addition, the manufacture method of a kind of oxide superconductor below in No. 2592846 communique of patent (spy opens flat 1-301114 communique), having proposed, it is characterized in that: among at least one side when heat treatment and after the heat treatment, will be at inner filling the metal tube of oxide superconducting powder etc. remain under the high-pressure state.In above-mentioned communique, put down in writing,,, can eliminate peeling off of part on the interface of the oxide superconductor that when sintering, produces and metal tube by placing under the high-pressure state according to this method.

Specifically, among at least one side when heat treatment and after the heat treatment, by will be at inner filling the metal tube of oxide superconducting powder remain in 500～2000kg/cm ²(under about 50～200MPa) the high-pressure state, metal tube can be crimped onto sintered body one side.Thus, partly produced at superconductor under the situation of quenching phenomenon, can utilize this quenching phenomenon promptly to remove the heat that is taken place.In addition, in addition, stripping portion becomes stress and concentrates portion, also can prevent the performance degradation that is out of shape the superconducting characteristic that causes because of producing.

But, open in the flat 5-101723 communique the spy, follow temperature in the closed container to rise and the internal pressure that obtains is about 4 air pressure (0.4MPa).Thus, when sintering, between the oxide superconducting crystallization, generated the space, the problem that exists critical current density to descend thus.

In addition, because internal pressure is about 4 air pressure (0.4MPa), so there is the problem of critical current density decline thus in the expansion of the oxide superconducting wire rod that generates can not be suppressed at sintering fully the time.

In addition, in No. 2592846 communique of patent,, reach 500～2000kg/cm because institute's applied pressure is very high ²(about 50～200MPa), the difficulty so the partial pressure of oxygen control during heat treatment becomes, critical current density has descended.

Disclosure of an invention

The object of the present invention is to provide by the generation of the expansion that suppresses space between the oxide superconducting crystallization and oxide superconducting wire rod, the partial pressure of oxygen control when making heat treatment simultaneously to become easily, thereby can improve the manufacture method of the oxide superconducting wire rod of critical current density.

The manufacture method of oxide superconducting wire rod of the present invention possesses following feature.

Making has the wire rod of form that has covered the raw material powder of oxide superconductor with metal.And, in pressurization atmosphere, wire rod is heat-treated.The total pressure of pressurization atmosphere is that 1MPa or 1MPa are above extremely less than 50MPa.

Manufacture method according to oxide superconducting wire rod of the present invention, owing to utilize the pressure of big wire rod outside such more than 1MPa or the 1MPa, cause the plastic flowing and the deformation of creep of the superconduction crystallization that when heat treatment, generates, so reduced the space between the oxide superconducting crystallization.In addition, because the gas on the oxide superconducting crystalline powder that generates in the time of can being used to gas in the gap of the oxide superconducting crystalline powder that generates or being attached to heat treatment when the pressure of metal tube outside suppresses heat treatment expands when heat treatment, so can suppress the generation of the expansion of oxide superconducting wire rod.Above result has improved critical current density.

In addition, in order to generate the stable oxide superconducting phase, must and pressurization atmosphere in the value of total pressure irrespectively partial pressure of oxygen is controlled in certain scope between often.But surpass the situation of 50MPa under in the total pressure of pressurization in the atmosphere this moment, reduced for the partial pressure of oxygen of this total pressure.Thus, because the value of the oxygen concentration of pressurization in the atmosphere is very little, be subjected to the influence of evaluated error etc. bigger, so the problem that exists the control of partial pressure of oxygen to become difficult.Manufacture method according to oxide superconducting wire rod of the present invention, owing in pressurization atmosphere, heat-treat less than 50MPa, so the partial pressure of oxygen for the total pressure in this pressurization atmosphere can be not too small, because the value height of the oxygen concentration in the pressurization atmosphere to a certain degree, so be not subjected to the influence of evaluated error etc. so, it is easy that the control of partial pressure of oxygen becomes.

In the manufacture method of above-mentioned oxide superconducting wire rod, preferably, the operation of utilizing hot isobar pressurization method (HIP:Hot Isostatic Pressing) to heat-treat.

Thus, because oxide superconducting wire rod is pressurizeed equably, so prevented the space and the expansion of wire rod.

In the manufacture method of above-mentioned oxide superconducting wire rod, preferably, oxide superconductor comprises bismuth, lead, strontium, calcium and copper, is to comprise (bismuth and lead): strontium: calcium: copper is approximately 2: 2: 2: the oxide superconductor of the 3 Bi2223 Bi-Pb-Sr-Ca-Cu-O series of recently representing as its atom mutually.

Thus, suppress to finish the generation of the expansion of the space of intergranular and oxide superconducting wire rod, its result can improve critical current density.

In the manufacture method of above-mentioned oxide superconducting wire rod, preferably, the operation of in oxygen atmosphere, heat-treating, and partial pressure of oxygen is 0.003MPa～0.02MPa.

Like this,, can generate the stable oxide superconducting phase, improve critical current density by partial pressure of oxygen being remained in the scope of 0.003MPa～0.02MPa.Have, if partial pressure of oxygen surpasses 0.02MPa, then generate out-phase, under the situation less than 0.003MPa, be difficult to generate the oxide superconducting phase, critical current density descends.

In the manufacture method of above-mentioned oxide superconducting wire rod, preferably, during intensification before the heat treatment in heat treated operation, control like this, make partial pressure of oxygen follow temperature in the pressurization atmosphere to rise and increase.

The value of best partial pressure of oxygen increases with the temperature rising in the generation of oxide superconducting phase.Thus, though since the heat treatment in heat treated operation before intensification the time also become suitable partial pressure of oxygen, so can generate the stable oxide superconducting phase, can improve critical current density.

In the manufacture method of above-mentioned oxide superconducting wire rod, preferably, when heat treatment, control like this, it is constant making the total pressure in the pressurization atmosphere.

When heat treatment, because the cause of swing during the pressure control of pressure regulator that consumes oxygen or pressure retaining valve etc. because of the oxidation of the supporter of supporting line body in the pressurizing vessel or the pressure oscillation in order to remedy the additional gas of oxygen that has been consumed and to import etc. demonstrates the trend that total pressure reduces sometimes.Thus, if produce rapid decompression in container, then the pressure height of the pressure ratio wire rod outside of wire internal so just generates the expansion of wire rod.But, of the present invention comparatively desirable aspect in total pressure when being controlled to heat treatment be constant, so the generation of the expansion of the wire rod that the rapid decompression can prevent because of heat treatment the time causes.

In the manufacture method of above-mentioned oxide superconducting wire rod, preferably, the operation of in oxygen atmosphere, heat-treating, and, control like this, the partial pressure of oxygen when making heat treatment 10% with interior mobility scale in for constant.

Thus, even, partial pressure of oxygen is in the scope of partial pressure of oxygen best in the generation of oxide superconducting phase,, can improve critical current density so can generate the stable oxide superconducting phase because the change of temperature is arranged.

In the manufacture method of above-mentioned oxide superconducting wire rod, preferably, injecting gas when lowering the temperature at once after heat treatment is so that remedy the decline of the pressure that causes because of cooling.

Cause during cooling after heat treatment that the pressure of following variations in temperature descends.If this moment is decompression sharp in heating container, then the pressure height of the pressure ratio wire rod outside of wire internal so just generates the expansion of wire rod.But, of the present invention be injecting gas aspect comparatively desirable so that remedy the decline of the pressure that causes because of cooling, so can prevent the generation of the expansion of the wire rod that the rapid decompression when lowering the temperature at once after the heat treatment causes.

In the manufacture method of above-mentioned oxide superconducting wire rod, preferably, the metal that covers raw material powder comprises silver, the area of metal in the cross section of the wire rod after heat treated operation part for the ratio of the area of oxide superconductor (below, be called silver than) be under 1.5 the situation, the decompression rate when being controlled to the cooling after the firm heat treatment is 0.05MPa/min or below the 0.05MPa/min.

Thus, than being under 1.5 the situation, prevent that the effect of generation of the expansion of the wire rod that causes because of rapid decompression from becoming more remarkable at silver.

In the manufacture method of above-mentioned oxide superconducting wire rod, preferably, the metal that covers raw material powder comprises silver, at silver than being under 1.5 the situation, in heat treated operation, under the temperature of pressurization in the atmosphere is situation more than 200 ℃ or 200 ℃, to control like this, the decompression rate that makes the total pressure in the pressurization atmosphere is 0.05MPa/min or below the 0.05MPa/min.

If the temperature in atmosphere is decompression sharp in the heating container under the situation more than 200 ℃ or 200 ℃, then the pressure height of the pressure ratio wire rod outside of wire internal so just generates the expansion of wire rod.Therefore, than being under 1.5 the situation, the effect of generation that suppresses the expansion of the wire rod that causes because of the rapid decompression in (before the heat treatment, during heat treatment, after the heat treatment) in the heat treated operation becomes more remarkable at silver.

In the manufacture method of above-mentioned oxide superconducting wire rod, preferably, the metal that covers raw material powder comprises silver, and than being under 3.0 the situation, the decompression rate when being controlled to heat treatment and lowering the temperature at once afterwards is 0.03MPa/min or below the 0.03MPa/min at silver.

Thus, than being under 3.0 the situation, prevent that the effect of generation of the expansion of the wire rod that causes because of rapid decompression from becoming more remarkable at silver.

In the manufacture method of above-mentioned oxide superconducting wire rod, preferably, the metal that covers raw material powder comprises silver, at silver than being under 3.0 the situation, in heat treated operation, temperature in atmosphere is under the situation more than 200 ℃ or 200 ℃, to control like this, and the decompression rate that makes the total pressure in the pressurization atmosphere is 0.03MPa/min or below the 0.03MPa/min.

If the temperature in atmosphere is decompression sharp in the heating container under the situation more than 200 ℃ or 200 ℃, then the pressure height of the pressure ratio wire rod outside of wire internal just generates the expansion of wire rod thus.Therefore, than being under 3.0 the situation, the effect of generation that suppresses the expansion of the wire rod that causes because of the rapid decompression in (before the heat treatment, during heat treatment, after the heat treatment) in the heat treated operation becomes more remarkable at silver.

In the manufacture method of above-mentioned oxide superconducting wire rod, preferably, in heat treated operation, total pressure in pressurization atmosphere is under 1MPa or the situation more than the 1MPa, control like this, the decompression rate that makes the total pressure of pressurization in the atmosphere is 0.05MPa/min or below the 0.05MPa/min.

If the total pressure in atmosphere is decompression sharp in the heating container under 1MPa or the situation more than the 1MPa, then the pressure height of the pressure ratio wire rod outside of wire internal just generates the expansion of wire rod thus.Thus, the effect of generation that suppresses the expansion of the wire rod that causes because of the rapid decompression in (before the heat treatment, during heat treatment, after the heat treatment) in the heat treated operation becomes more remarkable.

In the manufacture method of above-mentioned oxide superconducting wire rod, preferably, after making the operation of wire rod and before heat treated operation, also possess the operation of utilizing roller that wire rod is rolled, the skin thickness of the wire rod after the operation of calendering is 200 μ m or more than the 200 μ m.

Pin hole mainly is to form like this, because the cause of the friction of wire rod and stack makes the surperficial destroyed roughening of wire rod, pin hole penetrates on the oxide superconductor filament from the outside.But, if after the operation of calendering, skin thickness at oxide superconducting wire rod all is to roll under 200 μ m or the state more than the 200 μ m on which part, even then the surface of wire rod is because of the destroyed roughening of calendering, pin hole can not penetrate on the oxide superconductor filament from the outside yet, therefore can not generate pin hole.Thus, utilize above-mentioned heat treated operation can suppress the generation of space or expansion, can improve critical current density.Have, so-called in this manual pin hole means to have the 100 μ m that penetrate into from the outside on the oxide superconductor filament or the hole of the diameter more than the 100 μ m again.In addition, what is called has the wire rod of pin hole, means the diameter 100 μ m that comprise in the wire rod of 4mm * 10mm more than 2 or 2 or the wire rod in the hole more than the 100 μ m.

In the manufacture method of above-mentioned oxide superconducting wire rod, preferably, after making the operation of wire rod and before heat treated operation, also possess and make silver or silver alloy be attached to operation on the wire rod.

In order to be increased in the supercurrent that can flow in the per unit area, reduce the silver ratio of oxide superconducting wire rod as far as possible.But, owing to silver lacks than the ratio of the metal part of little wire rod, so can not increase skin thickness.Particularly, form pin hole during the processing of the calendering before heat treated operation etc. easily for the wire rod of the skin thickness after heat treated operation less than 200 μ m.Even the operation of in above-mentioned pressurization atmosphere the wire rod with pin hole being heat-treated, the gas that has pressurizeed also invades wire internal from pin hole.Therefore, there is not the inside and outside pressure differential of wire rod, less by utilizing generation that pressurization suppresses space or expansion with the effect of the decline that prevents critical current density.Therefore, by after making the operation of wire rod and silver or silver alloy are attached on the surface of wire rod, pin hole is by silver or silver alloy covering and disappear from the surface.Thereby, because the operation of after making the wire rod that does not have pin hole before, heat-treating, so the gas that has pressurizeed when heat treated operation can not invade wire internal from pin hole.Thus, utilization heat treated operation in above-mentioned pressurization atmosphere suppresses the generation of space or expansion, can improve critical current density.

In the manufacture method of above-mentioned oxide superconducting wire rod, preferably, after making the operation of wire rod and before heat treated operation, also possess the operation of utilizing roller that wire rod is rolled, the surface roughness Ry of the part of joining with wire rod of roller is 320 μ m or below the 320 μ m.

Thus, because the friction of wire rod and roller is little,, can irrespectively obtain not having the wire rod of pin hole with the skin thickness of wire rod so that the surface of wire rod is difficult to is destroyed and coarse.Thereby when heat treated operation, the gas that has pressurizeed can not invade wire internal from pin hole.Thus, irrelevant with the skin thickness of wire rod, utilization heat treated operation in above-mentioned pressurization atmosphere suppresses the generation of space or expansion, can improve critical current density.Have, so-called surface roughness Ry is the maximum height that has been prescribed in JIS (Japanese Industrial Standards (JapaneseIndustrial Standard)) again.

In the manufacture method of above-mentioned oxide superconducting wire rod, preferably, during intensification before the heat treatment in heat treated operation, control like this, make pressure follow temperature in the atmosphere to rise and increase steppedly.

For the wire rod that pin hole is arranged, the operation of promptly using common pressure method to heat-treat in the atmosphere in pressurization, the gas that has pressurizeed also invades wire internal from pin hole.Therefore, do not have the inside and outside pressure differential of wire rod, utilize generation that pressurization suppresses space or expansion less with the effect of the decline that prevents critical current density.But, rising and stepped ground increase pressure by being controlled to the temperature followed in the atmosphere, external pressure is increased before the gas that has pressurizeed invades wire internal from pin hole.Thus, produce the inside and outside pressure differential of wire rod, have with wire rod before the heat treated operation that pin hole is not irrelevant, can suppress the generation of space or expansion, can improve critical current density.

In the manufacture method of above-mentioned oxide superconducting wire rod, preferably, during intensification before the heat treatment in heat treated operation, control like this, the total pressure in the atmosphere is increased with 0.05MPa/min or the speed more than the 0.05MPa/min.

The application's inventors are in the operation that wire rod is heat-treated, and the gas of having found to pressurize invades wire internal from pin hole speed is for less than 0.05MPa/min.Thereby the total pressure that is controlled to atmosphere during by the intensification before heat treatment increases with 0.05MPa/min or the speed more than the 0.05MPa/min constantly, constantly the pressure in the atmosphere is kept between can be often than the pressure height of wire internal.Thus, owing to have with wire rod before the heat treated operation that pin hole is not irrelevant, during intensification that can be before heat treatment wire rod is applied the power of compression, so suppressed the generation of space or expansion.Its result, utilize 1MPa or more than the 1MPa to less than the heat treatment in the pressurization atmosphere of 50MPa, can suppress the decline of critical current density effectively.

In the manufacture method of above-mentioned oxide superconducting wire rod, preferably, during heat treatment in heat treated operation, so that the mode that the total pressure in the atmosphere increases is constantly controlled.

Thus, when heat treatment, the state delay that the pressure of wire internal is equated with pressure in the atmosphere can continue to keep the high state of pressure of the pressure ratio wire internal in the atmosphere more longways.Thereby, when heat treatment, suppressed the generation of space or expansion, utilize 1MPa or more than the 1MPa to less than the heat treatment in the pressurization atmosphere of 50MPa, can suppress the decline of critical current density effectively.

In the manufacture method of above-mentioned oxide superconducting wire rod, preferably, after the operation of making wire rod and before heat treated operation, also possesses the operation that wire rod is rolled, the reduction ratio of the wire rod in the operation of calendering is below 84% or 84%, is preferably below 80% or 80%.

Carry out to the pressurization atmosphere at 1MPa or more than the 1MPa under the situation of operation that wire rod is heat-treated, even oxide superconducting wire rod also is compressed when heat treated operation less than 50MPa.Thereby, the operation of promptly using the ratio low reduction ratio below 84% or 84% of reduction ratio in the past to roll wire rod, raw material powder also is compressed in heat treated operation thereafter, and therefore, the result can improve the density of filaments.On the other hand, by using the operation of rolling wire rod than in the past the low reduction ratio below 84% or 84% of reduction ratio, owing in raw material powder, be difficult to produce the space, so can be suppressed at the generation in the upwardly extending space, side vertical with the long side direction of oxide superconducting wire rod.According to above reason, can improve the critical current density of oxide superconducting wire rod.In addition, by the operation of rolling wire rod with the reduction ratio below 80% or 80%, owing in raw material powder, do not produce the space, so can further be suppressed at the generation in the side upwardly extending space vertical with the long side direction of oxide superconducting wire rod.

Have again, in this manual, define reduction ratio (%) with following formula.

Reduction ratio (%)={ 1-(thickness before the calendering of the thickness/wire rod after the calendering of wire rod) } * 100

In the manufacture method of above-mentioned oxide superconducting wire rod, preferably, wire rod is carried out repeatedly heat treatment, this repeatedly at least 1 heat treatment in the heat treatment be to be 1MPa or to pressurization atmosphere, to carry out more than the 1MPa less than 50MPa in total pressure.

The generation of the space between the oxide superconducting crystallization that takes place in the time of thus, can being suppressed at heat treatment and the expansion of oxide superconducting wire rod.

The simple declaration of accompanying drawing

Fig. 1 is the cut-away section oblique view that the structure of oxide superconducting wire rod conceptually is shown.

Fig. 2 is the figure that a manufacturing process of oxide superconducting wire rod is shown.

Fig. 3 is the summary section of hot isobar pressurization method (HIP) device.

Fig. 4 A～4D is the concept map that the situation in the space between the oxide superconducting crystallization is shown interimly.

Fig. 5 is expansion number that total pressure P (MPa) and the wire rod of the pressurization atmosphere are shown (figure of individual/10m) relation.

Fig. 6 is expression about the total pressure of the mist that nitrogen is about 80%, oxygen is about 20% ratio and the figure of partial pressure of oxygen.

Fig. 7 is that to make partial pressure of oxygen be the figure of the relation of the total pressure of constant situation and oxygen concentration value in expression.

Fig. 8 A is the figure that time of having carried out the situation of decompression rate control at once after the heat treatment and the relation of the temperature of wire rod are shown, and Fig. 8 B is the figure that the relation of the interior total pressure of time of having carried out the situation of decompression rate control at once after the heat treatment and container is shown.

Fig. 9 A is the curve chart that the wire thickness of the oxide superconducting wire rod that does not have pin hole before and after the heat treatment of pressurization in the atmosphere is shown, and Fig. 9 B is the curve chart of wire thickness that the oxide superconducting wire rod of pin hole is shown.

Figure 10 is the cut-away section oblique view of structure that the oxide superconducting wire rod of pin hole conceptually is shown.

Figure 11 is the constructed profile that the calendering process in the embodiment 2 is shown.

Figure 12 is the figure that another manufacturing process of oxide superconducting wire rod is shown.

Figure 13 is the cut-away section oblique view that conceptually illustrates the structure of the oxide superconducting wire rod after the operation of wire material electroplating silver or silver alloy.

Temperature and pressure when Figure 14 is the heat treatment that illustrates in the 4th method of embodiment 2 and the figure of time relation.

Figure 15 A illustrates silver in the embodiment 2 than the figure of relation of temperature and time that is the heat treated operation of 1.5 situation, Figure 15 B illustrates silver in the embodiment 2 than being the pressure of heat treated operation of 1.5 situation and the figure of time relation, Figure 15 C illustrates silver in the embodiment 2 than being the oxygen concentration of heat treated operation of 1.5 situation and the figure of time relation, and Figure 15 D illustrates silver in the embodiment 2 than being the partial pressure of oxygen of heat treated operation of 1.5 situation and the figure of time relation.

Temperature and pressure when Figure 16 is the heat treatment that illustrates in the 5th method of embodiment 2 and the figure of time relation.

Figure 17 is the figure of the optimum combination of temperature when heat treatment is shown and partial pressure of oxygen.

Figure 18 is the cut-away section oblique view of structure that the oxide superconducting wire rod of residual clearance conceptually is shown.

Figure 19 be in the schematically illustrated oxide superconducting wire rod 1 time in the calendering reduction ratio and the figure of the relation of critical current density.

The preferred plan that is used to carry out an invention

Below, use description of drawings embodiment of the present invention.

Embodiment 1

With reference to Fig. 1, the oxide superconducting wire rod of split conductor for example is described.Oxide superconducting wire rod 1 has many oxide superconductor filaments 2 that extend and the sheath section 3 that covers this oxide superconductor filament 2 on long side direction.The material separately of many oxide superconductor filaments 2 is the composition of Bi-Pb-Sr-Ca-Cu-0 system preferably for example, and particularly comprise (bismuth and lead): strontium: calcium: the atomic ratio of copper is substantially with 2: 2: 2: the Bi2223 that 3 ratio is represented approx material mutually is best.The material of sheath section 3 for example is made of silver.

Have again, split conductor has been described in above-mentioned, but also can use the oxide superconducting wire rod that covers the single-core line structure of 1 oxide superconductor filament 2 by sheath section 3.

Secondly, the manufacture method of above-mentioned oxide superconducting wire rod is described.

With reference to Fig. 2, at first, the raw material powder of filling oxide superconductor (step S1) in metal tube.The raw material powder of this oxide superconductor for example is made of the material that comprises the Bi2223 phase.

Have again, preferably use high silver of pyroconductivity or silver alloy etc. as metal tube.Thus, partly produced under the situation of quenching, can promptly remove the heat that has taken place from metal tube at superconductor.

Secondly, utilize Wire Drawing with filling the metal tube of raw material powder make the wire rod (step S2) of desirable diameter.Thus, can obtain having the wire rod of form that has covered the raw material powder of oxide superconductor with metal.This wire rod is carried out 1 calendering (step S3), carry out the 1st heat treatment (step S4) thereafter.Utilize these operations to generate the oxide superconducting phase from raw material powder.Carry out 2 calenderings (step S5) to having carried out this heat treated wire rod.Remove the cavity that in the 1st heat treatment, produces thus.The wire rod that has carried out 2 calenderings is carried out the 2nd heat treatment (step S6).With the 2nd heat treatment, with carry out oxide superconducting sintering mutually in carry out single-phaseization of oxide superconducting phase.

Utilize above-mentioned manufacture method, but Production Example oxide superconducting wire rod as illustrated in fig. 1.

In the present embodiment, applying 1MPa or carrying out the some at least heat treatment of the 1st heat treatment (step S4) and the 2nd heat treatment (step S6) more than the 1MPa to the pressurization atmosphere of pressure as total pressure less than 50MPa.

For example, utilize hot isobar pressurization method (HIP) to carry out heat treatment in this pressurization atmosphere.This hot isobar pressurization method below is described.

With reference to Fig. 3, the device 13 that carries out hot isobar pressurization method is made of following part: pressure vessel cylinder 6; The loam cake 5 at the two ends of airtight this pressure vessel cylinder 6 and lower cover 11; For gas being imported in the pressure vessel cylinder 6 and the gas introduction port 4 that on loam cake 5, is provided with; The heater 9 of heat treated product 8; Heat insulation layer 7; And the supporter 10 that supports item for disposal 8.

In the present embodiment, in metal tube filling carried out wire drawing, calendering behind the raw material powder wire rod support by supporter 10 in pressure vessel cylinder 6 as item for disposal 8.Under this state, by importing in the pressure vessel cylinder 6 from the gas of gas introduction port 4 with regulation, make that to become 1MPa or 1MPa in the pressure vessel cylinder 6 above to the pressurization atmosphere less than 50MPa, under this pressurization atmosphere, utilize heater 9 wire rod 8 to be heated to the temperature of regulation.Be preferably in and carry out this heat treatment in the oxygen atmosphere, partial pressure of oxygen is preferably 0.003MPa～0.02MPa.By this way wire rod 8 is carried out the heat treatment undertaken by hot isobar pressurization method.

According to the present embodiment,, mainly can obtain 3 following effects by heat-treating to pressurization atmosphere at 1MPa or more than the 1MPa as mentioned above less than 50MPa.

The first, the space that between the oxide superconducting crystallization, generates in the time of can reducing heat treatment.

The application's inventor has found, by heat-treating in 1MPa or the pressurization atmosphere more than the 1MPa, compares with the situation less than 1MPa, can reduce the space between the oxide superconducting crystallization that mainly generates when heat treatment especially.

Promptly, with reference to Fig. 4 A～4D, if heat-treat in the atmosphere in pressurization, the contact area between the oxide superconducting crystallization that then generates when heat treatment increases because of plastic flowing, and (Fig. 4 A → 4B) has been reduced in the space of a few μ m～tens μ m orders of magnitude that exist at the superconducting junction intergranular.If under this state, keep, then shown in Fig. 4 C, cause the deformation of creep like that, shrink in the space that exists on joint interface, and the part of the pollution portion of simultaneous oxidation coverlay etc. is destroyed and is decomposed, and produces the diffusion of atom, carries out sintering.And final space of almost having eliminated the superconducting junction intergranular like that shown in Fig. 4 D forms stable joint interface.

At this, in superconducting line, flow through electric current, refer at the superconducting junction intergranular that constitutes superconducting wire and flow through electric current.Usually, in using the cold medium (for example liquid nitrogen or helium or refrigerator) of superconducting line, restriction can keep superconducting state (resistance does not take place) and the magnitude of current that flows through be the junction surface (superconductivity of superconduction crystallization is stronger than the superconductivity at the junction surface between crystallization) of the weak superconducting junction intergranular of superconducting state.In common atmosphere bakes, in any case the gap at the junction surface of also residual superconducting junction intergranular.Therefore,, the performance of superconducting line is become well, can prevent the decline of critical current density by reducing the gap of superconducting junction intergranular.

Specifically, for the oxide superconducting wire rod that comprises the Bi2223 phase, the sintered density of having carried out the oxide superconductor of heat treated situation in atmospheric pressure is 80～90%, and be decided to be 10MPa in the total pressure of the atmosphere of will pressurizeing, utilize the sintered density of the oxide superconductor of the situation that manufacture method of the present invention makes is 93～96%, can see the minimizing in the space that generates between the oxide superconductor crystallization.

The second, can prevent the expansion of the oxide superconducting wire rod that when heat treatment, generates.

The application's inventor has studied the expansion number that produces in the wire rod after the heat treatment when having changed total pressure when in pressurization atmosphere oxide superconducting wire rod being heat-treated.With reference to Fig. 5, if the total pressure of pressurization atmosphere surpasses 0.5MPa, then the expansion in the oxide superconducting wire rod reduces significantly, and then, if be 1MPa or more than the 1MPa, then almost eliminated the expansion in the oxide superconducting wire rod as can be known.Can think and to obtain the former of such result because as described below.

Because the oxide superconductor in the metal tube solid density before sintering usually is about 80% pack completeness, so have gas in the gap of powder.If become high temperature when heat treatment, the then volumetric expansion of the gas in the gap of this powder produces wire rod and expands.But, in the present embodiment, owing in 1MPa or the pressurization atmosphere more than the 1MPa, heat-treat, so the pressure ratio metal tube pressure inside of metal tube outside is big.Therefore, can think the expansion that has prevented the wire rod that causes by the gas in the gap of powder.

In addition, the application's inventor learns when the reason of the further expansion of research wire rod, is attached to carbon (C), water (H on the raw material powder of oxide superconductor ₂O), oxygen (O ₂) adsorbate that waits gasifies in sintering, because the cause of this gas, the expansion of wire rod takes place in the volumetric expansion in the metal tube.But, by in 1MPa or the pressurization atmosphere more than the 1MPa, heat-treating,, make it bigger, so can think the expansion of the wire rod that can prevent that also the gasification by the adsorbate of this powder from causing than intermetallic pressure inside owing to can increase the pressure of outside.

According to the above, by being decided to be 1MPa or more than the 1MPa, can think and to eliminate the expansion that the gas that exists in the gap by the raw material powder of such oxide superconductor causes, and can eliminate the expansion that the gasification of the adsorbate that adheres on the surface by this particle causes.Because the expansion of oxide superconducting wire rod becomes critical current density is descended, so, can prevent the decline of critical current density by preventing the expansion of wire rod.

The 3rd, it is easy that the control of the partial pressure of oxygen in the time of can making heat treatment becomes.

The application's inventor has found that by partial pressure of oxygen and total pressure irrespectively are controlled at 0.003MPa～0.02MPa, can stably generate Bi is 2223 phases of oxide superconductor.That is,, then generated Ca if partial pressure of oxygen surpasses 0.02MPa ₂PbO ₄If such out-phase less than 0.003MPa, then is difficult to generate the Bi2223 phase, and critical current density has reduced.

With reference to Fig. 6, for example, the pressurization atmosphere total pressure be under the situation of 1 atmospheric pressure (0.1MPa), even do not carry out the control of partial pressure of oxygen, because partial pressure of oxygen is equal with the level of 0.2 atmospheric pressure (0.02MPa) that is dotted line shows, so stably generate the Bi2223 phase.But, along with the total pressure of pressurization atmosphere be increased to 2 air pressure, 3 air pressure ..., because partial pressure of oxygen also increases, so surpassed the level of 0.2 air pressure that is dotted line shows.Its result can not stably generate the Bi2223 phase.Therefore, must by changing the mixed proportion of the oxygen in the mist, partial pressure of oxygen be controlled at 0.003MPa～0.02MPa as shown in Figure 7.Have, the dotted line of Fig. 7 and the dotted line of Fig. 6 similarly show the level of 0.2 atmospheric pressure (0.02MPa) again.

Carry out actual partial pressure of oxygen control by detecting total pressure and oxygen concentration.That is, multiply each other by value and calculate partial pressure of oxygen oxygen concentration and total pressure.

Therefore, for example when total pressure was 50MPa, under the situation of heat-treating with the partial pressure of oxygen of 0.005MPa, oxygen concentration was 0.01%.Thereby, must measure 0.01% oxygen concentration and control the mist that is injected.But, because 0.01% oxygen concentration and evaluated error are equal extent, so be difficult to measure exactly the oxygen that this oxygen concentration is controlled the mist that is injected.In the present embodiment, by making the total pressure of pressurization in the atmosphere, can reduce the influence of the evaluated error of oxygen concentration for less than 50MPa, the concentration of oxygen of the mist that injects can be remained high level to a certain degree, so can easily control partial pressure of oxygen.

But, preferred when in 1MPa or the pressurization atmosphere more than the 1MPa, heat-treating, do not control decompression rate when the heat treatment and after the heat treatment, in pressurization atmosphere, not cause the mode of rapid decompression.

That is, when in 1MPa or the pressurization atmosphere more than the 1MPa, heat-treating, can think that outside gas enters wire internal from the fine hole of wire surface, makes pressure inside identical with the pressure of outside.In the atmosphere of such high pressure, the application's inventor found, if outside pressure descends because of rapid decompression, then do not catch up with the minimizing of external pressure from emitting of gas inside, and then internal pressure uprises and generates expansion.

Thereby, in order to prevent such expansion, preferably, when heat treatment, in container, inject Ar (argon) or N ₂The inert gas and the O of (nitrogen) etc. ₂The mist of gas etc. is so that total pressure is constant.In addition, when after heat treatment, lowering the temperature at once, inert gas injecting and O in container ₂The mist of gas etc. is to remedy the decline of the pressure that causes because of cooling.Carry out the control of these decompression rates when when the heat treatment and after the heat treatment, lowering the temperature at once, can prevent the generation of the expansion that causes because of rapid decompression.

With reference to Fig. 8 A, 8B, when the heat treatment of Fig. 8 A (about 800 ℃ temperature), as shown in Fig. 8 B, it is constant being controlled to total pressure.That is and since when heat treatment because of heating container in oxygen in the cause container of oxidation etc. of supporter of supporting line body be consumed, so the interior pressure of container has reduced.In order to prevent this point, in container, inject mist, pressure is remained constant.And, during cooling after the firm heat treatment of Fig. 8 A (about 800 ℃～about 300 ℃ temperature range), as shown in Fig. 8 B, in container, inject mist, to remedy the decline of the pressure that causes because of cooling, decompression rate is controlled to be below certain speed.That is, when cooling, the cause of the rapid decline of Yin Wendu, according to the equation of state of gas, the pressure of gas also descends sharp, therefore, must inject mist, makes cooling become mild.Have, below 300 ℃ or 300 ℃, owing to compare with about 800 ℃～about 300 ℃ situation, temperature is lower, so the pressure of wire internal is enough low again.Thereby, even can not think and control decompression rate, do not generate the expansion of wire rod yet.

In addition, the application's inventor found, for the area of the metal part in the cross section of the scope of the necessary decompression rate of generation of the expansion that the prevents oxide superconducting wire rod wire rod after according to heat treatment for the difference of the ratio of the area of oxide superconducting body portion (silver than) and difference.Promptly, preferably, at silver than being under 1.5 the situation, the decompression rate of (800 ℃～300 ℃ temperature ranges) is 0.05MPa/min or below the 0.05MPa/min when lowering the temperature at once after the heat treatment, than being under 3.0 the situation, the decompression rate of (800 ℃～300 ℃ temperature ranges) is 0.03MPa/min or below the 0.03MPa/min when lowering the temperature at once after the heat treatment at silver.

Embodiment 2

The heat treated condition of Fig. 9 A, 9B is 825 ℃ of the temperature in total pressure 20MPa, partial pressure of oxygen 0.008MPa, the atmosphere, heat treatment time 50 hours.With reference to Fig. 9 A, there is not oxide superconducting wire rod thickness after heat treatment of pin hole to reduce about 0.006mm～0.01mm.This is because by heat-treating, suppressed the generation of the expansion of space between the oxide superconducting crystallization and oxide superconducting wire rod in the pressurization atmosphere of total pressure 20MPa.On the other hand,, there is oxide superconducting wire rod thickness after heat treatment of pin hole only to reduce about 0.002mm～0.005mm, do not suppress the generation of the expansion of space between the oxide superconducting crystallization and oxide superconducting wire rod fully with reference to Fig. 9 B.In addition, for the part that pin hole is arranged in the wire rod (A part), the thickness of the thickness after the heat treatment before than heat treatment is thick.

According to the above, do not having under the situation of pin hole, if in the pressure limit of embodiment 1 (1MPa or more than the 1MPa to less than 50MPa), heat-treat, then can suppress the generation of space and expansion effectively, but having under the situation of pin hole, in the pressure limit of embodiment 1, only can not suppress the generation of space and expansion as can be known fully by heat treatment.

In the heat treatment in pressurization atmosphere of the present invention, owing to utilize the pressure of wire rod outside big like that more than 1MPa or the 1MPa to cause the plastic flowing and the deformation of creep of the superconduction crystallization that when heat treatment, generates, so the space between the oxide superconducting crystallization that has suppressed when heat treatment, to generate.In addition, because the gas on the oxide superconducting crystalline powder that generates in the time of can being used to gas in the gap of the oxide superconducting crystalline powder that generates or being attached to heat treatment when the pressure of metal tube outside suppresses heat treatment expands when heat treatment, so suppressed the generation of the expansion of oxide superconducting wire rod.Above result has prevented the decline of the critical current density that causes because of space or expansion.

But, for the wire rod that pin hole is arranged, even owing to carry out heat treatment in the above-mentioned pressurization atmosphere, the gas that has pressurizeed also invades wire internal from pin hole, so eliminated the inside and outside pressure differential of wire rod, can not utilize pressurization to suppress the generation of space or expansion fully.Its result prevents that the effect of decline of critical current density is less.

Therefore, the application's inventors have carried out deep research, found that by make the wire rod that does not have pin hole before heat treatment then to suppress the method for the generation of space or expansion fully.

The 1st method is to be decided to be 200 μ m or more than the 200 μ m in the calendering (step S3 or S5) of Fig. 2 back and at the skin thickness ω of the preceding oxide superconducting wire rod of heat treatment (step S4 or step S6).

The 2nd method is that the surface roughness Ry of the wire rod of the roller that uses in will the calendering of Fig. 2 (step S3 or the S5) part of joining is decided to be 320 μ m or below the 320 μ m.

The 3rd method be at Fig. 2 calendering (step S3 or S5) back and heat treatment (step S4 or step S6) preceding on oxide superconducting wire rod electrosilvering or silver alloy.

Below, specifically describe these methods.

As the 1st method, the application's inventor has found, by making calendering (step S3 or S5) back and all being 200 μ m or more than the 200 μ m, when calendering (step S3 or S5), do not generate pin hole on which part at the skin thickness W of the preceding oxide superconducting wire rod of heat treatment (step S4 or step S6) at Fig. 2.At this, so-called skin thickness W as shown in Figure 10, means in the section of wire rod 1 distance W after side by side the calendering of oxide superconductor filament 2 and the outer surface of wire rod 1 on the peripheral part.Can think that by making skin thickness W be 200 μ m or more than the 200 μ m and do not generate the former because as described below of pin hole.

Pin hole 14 mainly destroys the surface of wire rod 1, penetrates into from the outside and form on the oxide superconductor filament 2 by friction by wire rod 1 and stack.But, if the skin thickness W at calendering rear oxidation thing superconducting wire 1 is to roll under 200 μ m or the state more than the 200 μ m on which part, even then destroyed the surface of wire rod 1 because of calendering, the hole can not penetrate on the oxide superconductor filament 2 from the outside yet, therefore can not think can generate pin hole 14.Have again, because the above-mentioned structure in addition of Figure 10 is identical substantially with the structure shown in Fig. 1, thus attached to same member with prosign, and omit its explanation.

In addition, even the skin thickness W of the oxide superconducting wire rod after the calendering is less than 200 μ m, if use the 2nd, the 3rd above-mentioned method, then also can before heat treatment, obtain not having the wire rod of pin hole 14, its result, the application's inventors have found, utilize in pressurization atmosphere and heat-treat the generation that has suppressed space or expansion, have prevented the decline of critical current density effectively.

With reference to Figure 11, calendering is with a plurality of (being generally 2) 15 on roller by rotation of tabular or bar-shaped material, reduces its thickness or the area of section, section is configured as the processing method of the shape of wanting simultaneously.In when calendering, be used to oxide superconducting wire rod 1 be introduced 15 on a plurality of rollers from the frictional force of roller 15, be subjected at this place being out of shape from the compression stress of the surperficial 15a of roller 15.

In the 2nd method, using the surface roughness Ry among the surperficial 15a of the part that conduct contacts with wire rod 1 among a certain at least side of 1 calendering (step S3) shown in figure 2 and 2 calenderings (step S5) is 320 μ m or the roller 15 below the 320 μ m.

Promptly, if the surface roughness Ry of the surperficial 15a of the roller 15 that uses in when calendering is 320 μ m or below the 320 μ m, then because the less traction of wire rod 1 and the surperficial 15a of roller 15,, can irrespectively obtain not having the wire rod 1 of pin hole with the skin thickness of wire rod 1 so that the surface of wire rod 1 is difficult to is destroyed.Thereby in the operation of heat-treating, the gas that has pressurizeed is difficult to invade the inside of wire rod 1.Thus, can irrespectively utilize the operation of in above-mentioned pressurization atmosphere, heat-treating to suppress the generation of space or expansion with the skin thickness W of wire rod 1, prevent the decline of critical current density effectively.

In addition, in the 3rd method, as shown in Figure 12,, carry out the operation (step S11 or S12) of on the surface of wire rod electrosilvering or silver alloy in calendering (step S3 or S5) back and preceding in heat treatment (step S4 or S6).Have again, because the method with Fig. 2 is identical substantially except the operation (step S11 or S12) of additional plated, thus attached with corresponding symbol in the operation of correspondence, and omit its explanation.

With reference to Figure 13, on the outer peripheral portion of sheath section 3, electroplated silver or silver alloy 16, utilize silver or silver alloy 16 to be blocked in the pin hole 14 that mouth has been opened in the outside thus.Have again, because structure in addition is identical substantially with the structure shown in Fig. 1, thus attached to same member with prosign, and omit its explanation.

Usually, in order to be increased in the supercurrent that can flow through in the per unit area, reduce the silver ratio of oxide superconducting wire rod 1 as much as possible.But, because silver is littler than the ratio of the metal part of little wire rod 1, so can not increase skin thickness W.Thereby silver less than 200 μ m, easily forms pin hole 14 in the processing before heat treated operation (for example calendering etc.) than the skin thickness of little wire rod 1.The wire rod 1 that pin hole 14 is arranged as mentioned above, can not utilize pressurization to suppress the generation of space or expansion fully, and its result prevents that the effect of decline of critical current density is less.Therefore, by before heat treated operation on the surface of wire rod 1 electrosilvering or silver alloy 16, stop up pin holes 14 with silver or silver alloy 16, it is disappeared from the surface.Thereby, owing to removing the operation of heat-treating after the pin hole 14 from wire rod 1, so when heat treated operation, the gas that has pressurizeed can not invade the inside of wire rod 1.Thus, with the value of the surface roughness Ry of the roller 15 that uses in the value of the skin thickness W of wire rod 1 and the calendering irrespectively, utilize the operation of in above-mentioned pressurization atmosphere, heat-treating to suppress the generation of space or expansion, prevent the decline of critical current density effectively.

In addition, the application's inventors have found, if use the 4th method or the 5th method of following explanation, even have the wire rod 1 of pin hole 14, also can suppress the generation of space or expansion, can prevent the decline of critical current density effectively.In the 4th method, shown in figure 2 among a certain at least side of the heat treatment (step S6) of the 1st time heat treatment (step S4) and the 2nd time, during intensification before heat treatment, control like this, make pressure follow temperature to rise and increase steppedly.In addition, in the 5th method, shown in figure 2 among a certain at least side of the heat treatment (step S6) of the 1st time heat treatment (step S4) and the 2nd time, during intensification before heat treatment, control like this, the total pressure of atmosphere is increased with 0.05MPa/min or the speed more than the 0.05MPa/min.And, when heat treatment, control like this, the total pressure in the atmosphere is increased constantly.Moreover, when after heat treatment, lowering the temperature at once, control like this, make it to remedy the decline (additonal pressure) of the pressure that causes because of cooling.At first, the 4th method is described.

With reference to Figure 14, under the condition of 800 ℃ of heat treatment temperatures, pressure 20MPa, carried out heat treatment.At this moment, control like this, make pressure follow temperature to rise and increase steppedly.That is, come controlled pressure like this, repeatedly carry out following technology: promptly, when pressure increases, pressure is increased, keep the regular hour once more with the pressure after increasing.Specifically, in pressure increase process, in the regular hour, keep-up pressure with about 7MPa, 10MPa, 12.5MPa, 15MPa and 17MPa.In addition, the sequential that makes it to increase after carrying out in the regular hour, keep-uping pressure according to the measured value of the temperature in the atmosphere.Promptly, come controlled pressure like this: at room temperature make pressure be increased to about 7MPa, arrived about 400 ℃ moment in temperature, make pressure be increased to about 10MPa, arrived about 500 ℃ moment, make pressure be increased to about 12.5MPa in temperature, arrived about 600 ℃ moment in temperature, make pressure be increased to about 15MPa, arrived about 700 ℃ moment, make pressure be increased to about 17MPa in temperature.Have again, in order to generate the stable oxide superconducting phase, partial pressure of oxygen is controlled between often in 0.003 to 0.008MPa the scope of being in.

For the wire rod that pin hole is arranged, the operation of promptly using common pressure method in pressurization atmosphere, to heat-treat, the gas that has pressurizeed also invades wire internal from pin hole, therefore, do not have the inside and outside pressure differential of wire rod, utilize pressurization to prevent that the effect of decline of the critical current density that causes because of space or expansion is less.But, being controlled to like that by the 4th method and making pressure follow temperature to rise and increase steppedly, external pressure increases before the gas that has pressurizeed invades wire internal from pin hole.Thus, produce the inside and outside pressure differential of wire rod, have with wire rod before the heat treated operation that pin hole is not irrelevant, can suppress the generation of space or expansion, can prevent the decline of critical current density effectively.

Moreover, by following method is combined in the said method 1～4, can more effectively suppress the space of wire rod or the generation of expansion.Below, this method is described.

In the method, shown in figure 2 among a certain at least side of the heat treatment (step S6) of the 1st time heat treatment (step S4) and the 2nd time, in heat treated operation, temperature in atmosphere is under the situation more than 200 ℃ or 200 ℃, control like this, the decompression rate that makes the total pressure in the pressurization atmosphere is less than certain speed.

With reference to Figure 15 A～15D, during intensification before heat treatment, control like this, make it the same with above-mentioned the 4th method, pressure is followed the temperature in the atmosphere to rise and is increased steppedly.Have again, do not see that in Figure 15 B the pressure with regulation remained in the regular hour, but this is because the division ratio Figure 14 in elapsed time of Figure 15 B is a lot of greatly, so just see and omitted pressure retaining parts, in fact same with the situation of Figure 14, remain in the regular hour with the pressure of stipulating.Utilize this heating process, temperature is decided to be 815 ℃, pressure is decided to be 20MPa, under this state, carry out 50 hours heat treatment.During intensification before heat treatment and during heat treatment, the temperature in atmosphere is z under the situation more than 200 ℃ or 200 ℃, controls like this, and the decompression rate that makes the total pressure in the pressurization atmosphere is 0.05MPa/min or below the 0.05MPa/min.Therefore heat energy is after heat treatment, makes greenhouse cooling with the speed of 50 ℃/h.Even after heat treatment, the temperature in atmosphere is under the situation more than 200 ℃ or 200 ℃, to control like this, and the decompression rate that makes the total pressure in the pressurization atmosphere is 0.05MPa/min or below the 0.05MPa/min.Having, is under the situation of 50 ℃/h in the cooling rate after the heat treatment again and since follow natural decompression rate that temperature descends between often for 0.05MPa/min or below the 0.05MPa/min, so there is no need to control decompression rate.Moreover, before heat treatment, during heat treatment, after the heat treatment, oxygen concentration is remained 0.04%, thus, partial pressure of oxygen is between often in 0.003 to 0.008MPa the scope, can generate the stable oxide superconducting phase.

If the temperature in atmosphere is decompression sharp in the heating container under the situation more than 200 ℃ or 200 ℃, then the pressure height of the pressure ratio wire rod outside of wire internal just generates the expansion of wire rod thus.Therefore, the decompression rate by being controlled to the total pressure of pressurization in the atmosphere is less than certain speed, and the effect of generation that suppresses the expansion of the wire rod that the rapid decompression because of (before the heat treatment, during heat treatment, after the heat treatment) in the heat treatment causes becomes more remarkable.

Have, than the wire rod that is 3.0, the temperature in atmosphere is under the situation more than 200 ℃ or 200 ℃, to control like this for silver again, and making decompression rate is 0.03MPa/min or below the 0.03MPa/min.

Secondly, the 5th method is described.In the 5th method, in a certain at least side of the heat treatment (step S6) of the 1st time heat treatment (step S4) and the 2nd time, during intensification before heat treatment, control like this, the total pressure in the atmosphere is increased constantly with 0.05MPa/min or the speed more than the 0.05MPa/min.And, when heat treatment, make the total pressure in the atmosphere be controlled to increase constantly.Moreover, during cooling after heat treatment, control like this, make it to remedy the decline (additonal pressure) of the pressure that causes because of cooling.

With reference to Figure 16, during intensification before heat treatment, under the temperature of atmosphere for example was situation below 700 ℃ or 700 ℃, according to the equation of state of gas, pressure gently increased.And when the temperature of atmosphere surpassed 700 ℃, the pressure in the atmosphere was increased to about 10MPa.At this moment, increase pressure in the atmosphere without a break with 0.05MPa/min or the pressing speed more than the 0.05MPa/min.

At this, the present application person have found, when in pressurization atmosphere the oxide superconducting wire rod that pin hole is arranged being heat-treated, the gas that has pressurizeed is about less than 0.05MPa/min from the speed that pin hole invades wire internal.Thereby, during intensification before heat treatment, increase constantly with 0.05MPa/min or the speed more than the 0.05MPa/min, so can keep the pressure in the atmosphere than wire internal height constantly during the intensification before heat treatment by the total pressure that is controlled to atmosphere.

When heat treatment, for example temperature remained in for example 830 ℃ thereafter.On the other hand, the pressure in the atmosphere increases constantly.Pressing speed when heat treatment is preferably fast as much as possible, if but since pressing speed too soon then total pressure has surpassed 50MPa, increase constantly so the total pressure of pressure must be with heat treatment the time is no more than the such suitable pressing speed of 50MPa.In Figure 16, pressure is increased to about 30MPa.Thus, be retained as constant situation with pressure when the heat treatment and compare, the time that the pressure of wire internal can be equated with pressure in the atmosphere is from time t ₁Be delayed to time t ₂Like this, in heat treatment, the high state of pressure of the pressure ratio wire internal in the atmosphere can be kept the long period.

Thereafter, during cooling after heat treatment just, according to the equation of state of gas, make it in the decrease of temperature in atmosphere, pressure also descends.At this moment, come controlled pressure like this, make it to remedy the decline (additonal pressure) of the pressure that causes because of cooling.Have again, in order to generate the stable oxide superconducting phase, partial pressure of oxygen is controlled to the scope that is in 0.003～0.02MPa between often.

According to the 5th method, the pressure height of the pressure ratio wire internal during owing to the intensification before heat treatment in the atmosphere is so apply the power of compression to wire rod.In addition, when heat treatment, the high state of pressure of the pressure ratio wire internal in the atmosphere can be kept the long period.Its result, during intensification before heat treatment and when heating up, can suppress the generation of space or expansion, utilize 1MPa or more than the 1MPa to less than the heat treatment in the pressurization atmosphere of 50MPa, can suppress the decline of critical current density effectively.

Embodiment 3

In order further to improve the critical current density of oxide superconducting wire rod.During the intensification of the application's inventors before for heat treatment and the partial pressure of oxygen of the best during heat treatment carried out deep research.Thus, can obtain the result shown in Figure 17.

With reference to Figure 17, be under the situation of 0.007MPa for example in partial pressure of oxygen, so long as 815 ℃ to 825 temperature range, can generate the stable oxide superconducting phase as can be known, and improve critical current density.In addition, though not shown, be under the situation of 0.0003MPa in partial pressure of oxygen, so long as 750 ℃ to 800 ℃ temperature range, preferably be equal to or greater than the temperature range of 770 ℃ of sizes to 800 ℃, just can generate the stable oxide superconducting phase, and improve critical current density.In addition, be under the situation of 0.02MPa in partial pressure of oxygen, so long as in 820 ℃ to 850 ℃ the temperature range, preferred 830 ℃ to 845 ℃ temperature range just can generate the stable oxide superconducting phase, and improve critical current density.Moreover, under temperature is situation below 650 ℃ or 650 ℃, also partial pressure of oxygen must be controlled at the scope of 0.00005MPa to 0.02MPa as can be known.

According to the above temperature and the relation of partial pressure of oxygen, the value of best partial pressure of oxygen rises with temperature in the generation of oxide superconducting phase increases.Thereby, during intensification before heat treatment, follow temperature in the atmosphere to rise to increase by being controlled to partial pressure of oxygen, can make partial pressure of oxygen be in the scope of the best in the generation of oxide superconducting phase.Thus, can generate the stable oxide superconducting phase, and improve critical current density.

In addition, when keeping wire rod under the certain temperature when heat treatment, the change (error) of several ℃ of most generations for temperature.If consider the change of this temperature and the relation of the scope of the partial pressure of oxygen of the best, then for example keeping under 822.5 ℃ under the situation of wire rod, best partial pressure of oxygen is 0.006MPa to 0.01MPa, but is that best partial pressure of oxygen is 0.007MPa to 0.011MPa under 825 ℃ the situation in temperature change.In addition, be that best partial pressure of oxygen is 0.005MPa to 0.009MPa under 820 ℃ the situation in temperature change.Therefore, even in order there to be such temperature change to become best partial pressure of oxygen between also can be often, wire rod is being remained under 822.5 ℃ the situation, the mobility scale (Figure 17 bend part) that partial pressure of oxygen is controlled at 0.007MPa to 0.009MPa is constant getting final product.

But, the mobility scale of this partial pressure of oxygen be partial pressure of oxygen value about 10%.Thereby the partial pressure of oxygen when being controlled to heat treatment is 10% with interior mobility scale, even owing to have the change of temperature also can make partial pressure of oxygen be in the scope of best partial pressure of oxygen, so can generate the stable oxide superconducting phase, and the raising critical current density.

Embodiment 4

In order further to improve the critical current density of oxide superconducting wire rod, the application's inventors are controlled to be 0.05MPa/min with the decompression rate of the total pressure in the heat treatment, have carried out deep research for the relation of the generation of the expansion of the value of total pressure and wire rod.

Adjusted Bi: Pb: Sr: Ca: Cu=1.82: 0.33: 1.92: 2.01: the raw material powder of 3.02 ratio of components.After under 750 ℃ this raw material powder having been carried out 10 hours heat treatment, under 800 ℃, carried out 8 hours heat treatment.850 ℃ under the powder that by pulverizing obtained carried out 4 hour heat treatment after, once more pulverize thereafter.Under reduced pressure the powder that is obtained by pulverizing has been carried out after the heat treated, it has been filled in the metal tube that is made of silver of external diameter 36mm, internal diameter 31mm.Secondly, for filling the metal tube of powder carried out Wire Drawing.Moreover, the wire rod boundling of wire drawing is become 61, be fitted in the metal tube of external diameter 36mm, internal diameter 31mm.Secondly, carry out Wire Drawing and 1 calendering, obtained having thickness 0.25mm, the superconducting wire of the Bi2223 phase of the band shape of width 3.6mm.Secondly, this wire rod is carried out the 1st heat treatment.In atmosphere, carry out the 1st heat treatment, heat treatment temperature is decided to be 842 ℃, heat treatment time is decided to be 50 hours.Secondly, after having carried out 2 calenderings, carried out the 2nd heat treatment.In the 2nd heat treatment, partial pressure of oxygen is controlled to be 0.008MPa, heat treatment temperature is controlled to be 825 ℃, heat treatment time is controlled to be 50 hours, the decompression rate of the total pressure in the heat treatment is controlled to be 0.05MPa/min, as shown in table 1ly total pressure is changed carry out.After the 2nd heat treatment, studied the having or not of expansion of wire rod.The having or not of expansion of total pressure and wire rod is shown in table 1 simultaneously.

Table 1

Total pressure (MPa)	Wire rod expands
		????0.1	Do not have
????0.2	Do not have
		????0.3	Do not have
????0.4	Do not have
		????0.5	Do not have
????0.8	Do not have
		????1.0	Have
????2.0	Have
		????3.0	Have
????5.0	Have
		????10.0	Have
????20.0	Have
		????30.0	Have

According to the result of table 1, be under 1MPa or the situation more than the 1MPa in total pressure, the expansion of wire rod has taken place.Therefore, in order to suppress the expansion of wire rod, be the decompression rate in the pressurization atmosphere must be controlled to be 0.05MPa/min under 1MPa or the situation more than the 1MPa or below the 0.05MPa/min in total pressure.

Then, the 2nd heat treated heat treatment temperature is decided to be 500 ℃, similarly studied the having or not of expansion of wire rod.The having or not of expansion of total pressure and wire rod is shown in table 1 simultaneously.

Table 2

Total pressure (MPa)	Wire rod expands
		????0.1	Do not have
????0.2	Do not have
		????0.3	Do not have

????0.4	Do not have
		????0.5	Do not have
????0.8	Do not have
		????1.0	Have
????2.0	Have
		????3.0	Have
????5.0	Have
		????10.0	Have
????20.0	Have
		????30.0	Have

From the result of table 2 as seen, even be under 500 ℃ the situation in heat treatment temperature, total pressure is 1MPa or 1MPa when above, and the expansion of wire rod takes place.Therefore, though in heat treatment temperature under 500 ℃ situation, be to suppress the expansion of wire rod, be the decompression rate in the pressurization atmosphere must be controlled to be 0.05MPa/min under 1MPa or the situation more than the 1MPa or below the 0.05MPa/min in total pressure.

Embodiment 5

With reference to Figure 18, total pressure be 1MPa or more than the 1MPa to the superconductor filament 2 less than the oxide superconducting wire rod 1 after the heat treatment in the pressurization atmosphere of 50MPa, on long side direction (Figure 18 middle horizontal square to), almost eliminated long space, and on the direction vertical, stayed the space 20 of very a spot of extension with long side direction.Have again, in Figure 18, show the oxide superconducting wire rod that filaments is 1 a single-core line.

That is, the application's inventors have found, even utilize the heat treatment in the pressurization atmosphere also to be difficult to reduce in upwardly extending space 20, the side vertical with the long side direction of oxide superconducting wire rod 1.Can think that this point is based on following reason.In pressurization atmosphere, on whole of oxide superconducting wire rod, equally exert pressure.And because the cause of this pressure, the oxide superconducting crystallization causes the deformation of creep, and shrink in the space that exists on the mutual joint interface of crystallization.Like this, reduce in the space that generates between the oxide superconducting crystallization.But because oxide superconducting wire rod 1 has the shape of extending more longways on long side direction, power is difficult to transmit on long side direction, and wire rod 1 is difficult to be compressed on long side direction.Its result is difficult to utilize the heat treatment in the pressurization atmosphere to reduce in upwardly extending space 20, the side vertical with the long side direction of oxide superconducting wire rod 1.

Owing to covered the electric current in the filaments, so become one of the reason of the critical current density decline of oxide superconducting wire rod 1 in upwardly extending space 20, the side vertical with the long side direction of oxide superconducting wire rod 1.Thereby, if can suppress the generation in this space 20, then can further improve the critical current density of oxide superconducting wire rod 1.

Therefore, the application's inventors have found, in 1 calendering (step S5) of Fig. 2, by the reduction ratio that makes oxide superconducting wire rod is below 84% or 84%, preferably below 80% or 80%, then can be suppressed at the generation in the side upwardly extending space vertical with the long side direction of oxide superconducting wire rod before heat treatment, its result can improve the critical current density of oxide superconducting wire rod.Its reason below is described.

1 calendering is the operation of carrying out for the density that improves the raw material powder that is filled with in metal tube.In 1 calendering, the reduction ratio of oxide superconducting wire rod big more (working modulus is big more), the density of the raw material powder that is filled with in metal tube is high more.If the density of raw material powder improves, then utilize the density of the superconduction crystallization of heat treatment (step S4 and step S5) generation thereafter to improve, thereby improved the critical current density of oxide superconducting wire rod.

On the other hand, if in 1 calendering, strengthen the reduction ratio of oxide superconducting wire rod, then can see sometimes resulting from 3 following phenomenons that working modulus increases.The 1st, in raw material powder, produced be full of cracks.The 2nd, the shape that generates the filament in the oxide superconducting wire rod easily is uneven sausage-like on long side direction.The 3rd, because the cause of allantoid generation, occur in the part that the area of section of filaments increases partly the overlap joint phenomenon that contacts with other filaments easily.These phenomenons all can become the reason of the critical current density decline that makes oxide superconducting wire rod.

Thereby, must improve and in raw material powder, not produce such reduction ratio such as space with the density of raw material powder and carry out 1 calendering.In existing 1 calendering, oxide superconducting wire rod is rolled with 86～90% such reduction ratios.

But, under the 1MPa or the situation of heat-treating to the pressurization atmosphere more than the 1MPa, even when heat treatment, also can obtain the compressed effect of oxide superconducting wire rod less than 50MPa.Thereby, promptly use the reduction ratio below 84% or 84% to carry out 1 calendering, because raw material powder is compressed in the heat treatment in pressurization atmosphere thereafter, so the result also can improve the density of the filaments of oxide superconducting wire rod.On the other hand, by carry out 1 calendering with the reduction ratio below 84% or 84%, owing in raw material powder, being difficult to produce the space, so can suppress to be created in upwardly extending space, the side vertical with the long side direction of oxide superconducting wire rod.Moreover, by carry out 1 calendering with the reduction ratio below 80% or 80%, in raw material powder, can not produce the space fully.According to above reason, can improve the critical current density of oxide superconducting wire rod.

With reference to Figure 19, under the situation of heat-treating in atmosphere, when carrying out 1 calendering with about 86% reduction ratio, the critical current density of oxide superconducting wire rod is for the highest.On the other hand, under the situation of heat-treating in pressurization atmosphere of the present invention, when carrying out 1 calendering with about 82% reduction ratio, the critical current density of oxide superconducting wire rod is for the highest.Like this, under the 1Mpa or the situation of heat-treating to the pressurization atmosphere less than 50MPa more than the 1MPa, the reduction ratio of 1 calendering of the best of using for the critical current density that improves oxide superconducting wire rod moves towards low reduction ratio one lateral deviation as can be known.

The application's inventors make the oxide superconducting wire rod in the present embodiment, and have carried out the detection of critical current density in order to confirm above-mentioned effect under following condition.

According to the manufacturing process of the oxide superconducting wire rod shown in Fig. 2, filling raw material powder in metal tube has carried out Wire Drawing.Secondly, carry out 1 calendering, obtained banded superconducting wire.Carried out 1 calendering with 82%, 87% these 2 kinds of reduction ratios.In addition, in 1 calendering, use the roller of diameter 100mm, used dynamic viscosity to be 10mm ²The lubricating oil of/s.Secondly, this wire rod has been carried out the 1st heat treatment.Partial pressure of oxygen is decided to be 0.008MPa, and heat treatment temperature is decided to be 830 ℃, and heat treatment time is decided to be 30 hours, carries out the 1st heat treatment.Secondly, 2 calenderings have been carried out.Reduction ratio with 5～30%, use the roller of diameter 300mm, carried out 2 calenderings under the lubricated oil condition not using.Secondly, carry out the 2nd heat treatment.Partial pressure of oxygen is decided to be 0.008MPa, and heat treatment temperature is decided to be 820 ℃, and heat treatment time is decided to be 50 hours, carries out the 2nd heat treatment.After the 2nd heat treatment, the critical current density of resulting oxide superconducting wire rod is detected.

Its result in 1 calendering, being in 87% the oxide superconducting wire rod with reduction ratio, becomes 30kA/cm ²Critical current density.On the other hand, being in 82% the oxide superconducting wire rod with reduction ratio, become 40kA/cm ²Critical current density.In addition, according to above result, in 1 calendering (step S5), by the reduction ratio that makes oxide superconducting wire rod is below 84% or 84%, can be suppressed at the generation in the side upwardly extending space vertical with the long side direction of oxide superconducting wire rod before heat treatment, its result can improve the critical current density of oxide superconducting wire rod as can be known.

Have again, in above-mentioned each embodiment, manufacture method for the oxide superconducting wire rod with the Bi2223 phase that is obtained by hot isobar pressurization method is illustrated, but so long as in the 1MPa or the method for heat-treating to the pressurization atmosphere more than the 1MPa, also can utilize the pressurization beyond the hot isobar pressurization method to implement the present invention less than 50MPa.In addition, the present invention also can be applicable to have other the manufacture method of oxide superconducting wire rod of composition such as yttrium class beyond the bismuth.

In embodiment of the present invention 2, show the situation of carrying out, but so long as the operation that wire rod is adhered to silver or silver alloy to the operation of wire material electroplating silver or silver alloy, for example also can utilize sputtering process to implement the present invention.In addition, in Figure 14, Figure 15 A～15D, show the concrete controlled condition of temperature, pressure, oxygen concentration, partial pressure of oxygen, but the present invention is not limited to this condition, be controlled to pressure follow temperature to rise and increase steppedly, temperature in the atmosphere is to be equal to or higher than under 200 ℃ the situation, to be that 0.05MPa/min or 0.05MPa/min are following get final product the decompression rate that is controlled to the total pressure in the pressurization atmosphere.

Combine by heat-treat condition, can prevent the generation of pin hole,, also can suppress the space of wire rod or the generation of expansion effectively even perhaps under the situation that pin hole has taken place with the 1st of embodiment of the present invention 2～the 5th method and embodiment 1.

In addition, by the 1st of embodiment of the present invention 2～the 5th method is suitably combined, can more effectively suppress the space of wire rod or the generation of expansion.

In the 5th method of embodiment of the present invention 2, be controlled to the situation of the decline (additonal pressure) that remedies the pressure that causes because of cooling when showing the cooling after heat treatment just, but the present invention is not limited to such situation, and being controlled to pressure in the atmosphere at least when heat treatment increases constantly and get final product.

In embodiment of the present invention 3, when showing the intensification before heat treatment and an example of the number range of the partial pressure of oxygen of the best during heat treatment, but the present invention is not limited to the situation in this number range inner control partial pressure of oxygen, follows the temperature in the atmosphere to rise and increase as long as be controlled to partial pressure of oxygen.

In embodiment 5, one example of the diameter of the roller that uses in the dynamic viscosity of the lubricating oil when showing or the calendering about calendering, but the present invention is not limited to such rolling condition, as long as the reduction ratio of the wire rod in the operation of calendering is below 84% or 84%.

It is exemplary rather than restrictive that above disclosed embodiment should be considered to aspect whole.Scope of the present invention is not that above-mentioned embodiment is represented, and is represented by the scope of claim yet, is intended that to comprise and the meaning of the scope equalization of claim and whole corrections or the distortion in the scope.

The possibility of the utilization on the industry

As mentioned above, the manufacture method of the oxide superconducting wire rod relevant with the present invention can be applicable to prevent the manufacture method of oxide superconducting wire rod of the decline of critical current density.

Claims (22)

1. the manufacture method of an oxide superconducting wire rod is characterized in that:

This method comprises:

Make the operation (S1, S2) of wire rod, this wire rod has the form that has covered the raw material powder of oxide superconductor with metal; And

The operation (S4, S6) of in pressurization atmosphere, above-mentioned wire rod being heat-treated,

The total pressure of above-mentioned pressurization atmosphere is that 1MPa or 1MPa are above extremely less than 50MPa.

2. the manufacture method of the oxide superconducting wire rod described in claim 1 is characterized in that:

Each carries out above-mentioned heat treated operation (S4, S6) to the isobar pressurization method to utilize heat.

3. the manufacture method of the oxide superconducting wire rod described in claim 1 is characterized in that:

Above-mentioned oxide superconductor comprises bismuth, lead, strontium, calcium and copper, is to comprise (bismuth and lead): strontium: calcium: copper is approximately 2: 2: 2: the oxide superconductor of the 3 Bi2223 Bi-Pb-Sr-Ca-Cu-O series of recently representing as its atom mutually.

4. the manufacture method of the oxide superconducting wire rod described in claim 1 is characterized in that:

In oxygen atmosphere, carry out above-mentioned heat treated operation (S4, S6), and partial pressure of oxygen is 0.003MPa to 0.02MPa.

5. the manufacture method of the oxide superconducting wire rod described in claim 4 is characterized in that:

Control during intensification before the heat treatment in above-mentioned heat treated operation (S4, S6), so that above-mentioned oxygen partial pressure is followed temperature in the above-mentioned pressurization atmosphere to rise and increased.

6. the manufacture method of the oxide superconducting wire rod described in claim 1 is characterized in that:

When heat treatment, control, so that the total pressure in the above-mentioned pressurization atmosphere becomes constant.

7. the manufacture method of the oxide superconducting wire rod described in claim 1 is characterized in that:

In oxygen atmosphere, carry out above-mentioned heat treated operation (S4, S6), and control, so that the partial pressure of oxygen during heat treatment is constant 10% in interior mobility scale.

8. the manufacture method of the oxide superconducting wire rod described in claim 1 is characterized in that:

Injecting gas when lowering the temperature at once after heat treatment is to remedy the decline of the pressure that causes because of cooling.

9. the manufacture method of the oxide superconducting wire rod described in claim 8 is characterized in that:

The above-mentioned metal that covers above-mentioned raw material powder comprises silver, and the area of the above-mentioned metal part (3) in the cross section of the above-mentioned wire rod (1) after the above-mentioned heat treated operation is 1.5 for the ratio of the area of above-mentioned oxide superconducting body portion (2),

Decompression rate when lowering the temperature at once after the above-mentioned heat treatment is 0.05MPa/min or below the 0.05MPa/min.

10. the manufacture method of the oxide superconducting wire rod described in claim 9 is characterized in that:

The above-mentioned metal that covers above-mentioned raw material powder comprises silver, and the area of the above-mentioned metal part (3) in the cross section of the above-mentioned wire rod (1) after the above-mentioned heat treated operation is 1.5 for the ratio of the area of above-mentioned oxide superconducting body portion (2),

In above-mentioned heat treated operation (S4, S6), the temperature in above-mentioned pressurization atmosphere is to control under the situation more than 200 ℃ or 200 ℃, so that the decompression rate of the total pressure in the above-mentioned pressurization atmosphere is 0.05MPa/min or below the 0.05MPa/min.

11. the manufacture method of the oxide superconducting wire rod described in claim 8 is characterized in that:

The above-mentioned metal that covers above-mentioned raw material powder comprises silver, and the area of the above-mentioned metal part (3) in the cross section of the above-mentioned wire rod (1) after the above-mentioned heat treated operation (S4, S6) is 3.0 for the ratio of the area of above-mentioned oxide superconducting body portion (2),

Decompression rate during cooling after the above-mentioned firm heat treatment is 0.03MPa/min or below the 0.03MPa/min.

12. the manufacture method of the oxide superconducting wire rod described in claim 11 is characterized in that:

The above-mentioned metal that covers above-mentioned raw material powder comprises silver, and the area of the above-mentioned metal part (3) in the cross section of the above-mentioned wire rod (1) after the above-mentioned heat treated operation (S4, S6) is 3.0 for the ratio of the area of above-mentioned oxide superconducting body portion (2),

In above-mentioned heat treated operation (S4, S6), the temperature in above-mentioned pressurization atmosphere is to control under the situation more than 200 ℃ and 200 ℃, so that the decompression rate of the total pressure in the above-mentioned pressurization atmosphere is 0.03MPa/min or below the 0.03MPa/min.

13. the manufacture method of the oxide superconducting wire rod described in claim 1 is characterized in that:

In above-mentioned heat treated operation (S4, S6), the total pressure in above-mentioned pressurization atmosphere is to control under 1MPa or the situation more than the 1MPa, so that the decompression rate of the total pressure in the above-mentioned pressurization atmosphere is 0.05MPa/min or below the 0.05MPa/min.

14. the manufacture method of the oxide superconducting wire rod described in claim 1 is characterized in that:

In the operation (S1, S2) of making above-mentioned wire rod afterwards and before in above-mentioned heat treated operation (S4, S6), also have the operation (S3) of utilizing roller (15) that above-mentioned wire rod is rolled, the skin thickness of the above-mentioned wire rod (1) after the operation of above-mentioned calendering (S3) is 200 μ m or more than the 200 μ m.

15. the manufacture method of the oxide superconducting wire rod described in claim 1 is characterized in that:

In the operation (S1, S2) of making above-mentioned wire rod afterwards and before, also have and make silver or silver alloy (16) be attached to the lip-deep operation (S11) of above-mentioned wire rod (1) in above-mentioned heat treated operation (S4, S6).

16. the manufacture method of the oxide superconducting wire rod described in claim 1 is characterized in that:

In the operation (S1, S2) of making above-mentioned wire rod afterwards and before, also have the operation (S3) of utilizing roller (16) that above-mentioned wire rod is rolled in above-mentioned heat treated operation (S4, S6),

Maximum height Ry with the surface roughness contacted part of above-mentioned wire rod (1) above-mentioned roller (16) is 320 μ m or below the 320 μ m.

17. the manufacture method of the oxide superconducting wire rod described in claim 1 is characterized in that:

Control during intensification before the heat treatment in above-mentioned heat treated operation (S4, S6), so that pressure is followed temperature in the atmosphere to rise and increased steppedly.

18. the manufacture method of the oxide superconducting wire rod described in claim 1 is characterized in that:

Control during intensification before the heat treatment in above-mentioned heat treated operation (S4, S6), so that the total pressure in the atmosphere increases with 0.05MPa/min or the speed more than the 0.05MPa/min.

19. the manufacture method of the oxide superconducting wire rod described in claim 18 is characterized in that:

Control during heat treatment in above-mentioned heat treated operation (S4, S6), so that the total pressure in the above-mentioned atmosphere increases constantly.

20. the manufacture method of the oxide superconducting wire rod described in claim 1 is characterized in that:

In the operation (S1, S2) of making above-mentioned wire rod afterwards and before in above-mentioned heat treated operation (S4, S6), also have the operation (S3) that above-mentioned wire rod is rolled, the reduction ratio of the above-mentioned wire rod (1) in the operation of above-mentioned calendering (S3) is below 84% or 84%.

21. the manufacture method of the oxide superconducting wire rod described in claim 20 is characterized in that:

The reduction ratio of the above-mentioned wire rod (1) in the operation of above-mentioned calendering (S3) is below 80% or 80%.

22. the manufacture method of the oxide superconducting wire rod described in claim 1 is characterized in that:

Above-mentioned wire rod is carried out repeatedly heat treatment (S4, S6), be 1MPa or carry out at least 1 heat treatment in the above-mentioned repeatedly heat treatment (S4, S6) more than the 1MPa to the pressurization atmosphere less than 50MPa in total pressure.

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