US20120275948A1 - Wiring material for superconducting magnet - Google Patents

Wiring material for superconducting magnet Download PDF

Info

Publication number
US20120275948A1
US20120275948A1 US13/458,095 US201213458095A US2012275948A1 US 20120275948 A1 US20120275948 A1 US 20120275948A1 US 201213458095 A US201213458095 A US 201213458095A US 2012275948 A1 US2012275948 A1 US 2012275948A1
Authority
US
United States
Prior art keywords
aluminum
purity
magnetic field
mass
resistivity
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Abandoned
Application number
US13/458,095
Other languages
English (en)
Inventor
Takayuki Tomaru
Kenichi Sasaki
Hiroaki Hoshikawa
Hiroshi Tabuchi
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
INTER-UNIVERISITY RESEARCH INSTITUTE Corp HIGH ENERGY ACCELERATOR RESEARCH ORGANIZTION
Sumitomo Chemical Co Ltd
Inter University Research Institute Corp High Energy Accelerator Research Organization
Original Assignee
Sumitomo Chemical Co Ltd
Inter University Research Institute Corp High Energy Accelerator Research Organization
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Sumitomo Chemical Co Ltd, Inter University Research Institute Corp High Energy Accelerator Research Organization filed Critical Sumitomo Chemical Co Ltd
Assigned to SUMITOMO CHEMICAL COMPANY, LIMITED, INTER-UNIVERISITY RESEARCH INSTITUTE CORPORATION HIGH ENERGY ACCELERATOR RESEARCH ORGANIZTION reassignment SUMITOMO CHEMICAL COMPANY, LIMITED ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: HOSHIKAWA, HIROAKI, TABUCHI, HIROSHI, SASAKI, KENICHI, TOMARU, TAKAYUKI
Publication of US20120275948A1 publication Critical patent/US20120275948A1/en
Abandoned legal-status Critical Current

Links

Images

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
    • H01B1/02—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors mainly consisting of metals or alloys
    • H01B1/023—Alloys based on aluminium
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
    • H01F41/02—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets
    • H01F41/04—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets for manufacturing coils
    • H01F41/048—Superconductive coils
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F6/00—Superconducting magnets; Superconducting coils
    • H01F6/06—Coils, e.g. winding, insulating, terminating or casing arrangements therefor

Definitions

  • the present invention relates to a wiring material for superconducting magnet, which exhibits excellent conductivity at low temperature(s) of, for example, 77 K or lower, especially cryogenic temperature(s) of 20 K or lower; and more particularly to a wiring material which exhibits excellent conductivity even when used in a strong magnetic field of, for example, 1 T or more.
  • a superconducting magnet has been used in various fields, for example, MRIs (magnetic resonance imaging) for diagnosis, NMRs (nuclear magnetic resonance) for analytical use or maglev trains.
  • MRIs magnetic resonance imaging
  • NMRs nuclear magnetic resonance
  • maglev trains There have been used, as a superconducting magnet, low-temperature superconducting coils cooled to its boiling point of 4.2 K (Kelvin) using liquid helium, and high-temperature superconducting coils cooled to about 20 K by a refrigerator.
  • a wiring material (wiring material for superconducting magnet) cooled to extremely low temperatures of a boiling point 77 K of liquid nitrogen or lower is arranged on the periphery of the superconducting coils. Through the wiring material for superconducting magnet, power is supplied to the superconducting coils.
  • such a wiring material for superconducting magnet preferably has low electrical resistivity at extremely low temperatures.
  • JP 2009-212522A discloses a superconducting apparatus in which silver (Ag), gold (Au), rhenium (Re), platinum (Pt), copper (Cu), zinc (Zn), aluminum (Al), iron (Fe) and the like are used as wiring materials for electrically connecting members to each other.
  • silver Au
  • Au gold
  • Au rhenium
  • Pt platinum
  • Cu copper
  • Zn zinc
  • Al aluminum
  • Fe iron
  • oxygen-free copper having a purity of 99.99% by mass or more (hereinafter sometimes referred to as “4N” (four nines) and, in the mass percentage notation which indicates a purity, notation is sometimes performed by placing “N” in the rear of the number of “9” which is continuous from the head, for example, purity of 99.9999% by mass or more is sometimes referred to as “6N” (six nines), similarly) is used as copper.
  • 4N oxygen-free copper having a purity of 99.99% by mass or more
  • JP H7-15208A and JP H7-166283A disclose high purity aluminum conductors for cryogenic temperatures, having a purity of 99.98% by mass or more, which causes little increase in electrical resistivity even when they undergo repeated strain at cryogenic temperatures.
  • a wiring material for superconducting magnet used in the vicinity of the superconducting coil is used in a state where a strong magnetic field of, for example, a magnetic flux density of 1 T (Tesla) or more is applied. Therefore, there arises a problem that deterioration of conduction characteristics of the above-mentioned material having sufficient conductivity in the state where the magnetic field is not applied is caused by the magnetoresistance effect in such a strong magnetic field.
  • an object of the present invention is to provide a wiring material which is easy to handle and also exhibits excellent conductivity even in a strong magnetic field of, for example, a magnetic flux density of 1 T or more.
  • the present invention provides, in an aspect 1, a wiring material to be used in the magnetic field of a magnetic flux density of 1 T or more, including aluminum having a purity of 99.999% by mass or more.
  • the present inventors have found that the magnetoresistance effect can be remarkably suppressed by controlling a purity to 99.999% by mass or more even in aluminum (Al).
  • An electrical wiring material composed of such aluminum can maintain excellent electrical conductivity even when used in a strong magnetic field of a magnetic flux density of 1 T or more.
  • Such an electrical wiring material according to the present invention enables a decrease in heat generation caused by electrical resistivity in an electrical wiring material even in a state where the magnetic field of a magnetic flux density of 1 T or more is applied from a superconducting coil. Whereby, vaporization of a coolant such as liquid helium can be suppressed and also a cross section of an electrical wiring material can be reduced, and thus enabling miniaturization of various apparatuses using a superconducting apparatus.
  • the electrical wiring material according to the present invention is easy to handle.
  • the present invention provides, in an aspect 2, the wiring material according to the aspect 1, wherein the aluminum has the content of iron of 1 ppm by mass or less.
  • the present invention provides, in an aspect 3, the wiring material according to the aspect 1 or 2, wherein the aluminum has a purity of 99.9999% by mass or more.
  • the present invention provides, in an aspect 4, the wiring material according to the aspect 1 or 2, wherein the aluminum has a purity of 99.99998% by mass or more.
  • the present invention provides, in an aspect 5, the wiring material according to any one of the aspects 1 to 4, wherein the aluminum contains an intermetallic compound Al 3 Fe.
  • a wiring material which is easy to handle and also exhibits excellent conductivity even in a strong magnetic field of, for example, a magnetic flux density of 1 T or more.
  • FIG. 1 is a graph showing a relation between the electrical conductivity index and the applied magnetic field (magnetic flux density).
  • the wiring material according to the present invention includes aluminum having a purity of 99.999% by mass or more so as to be used in the magnetic field of a magnetic flux density of 1 T or more.
  • the present inventors have found, first, that aluminum having a purity of 99.999% by mass or more does not remarkably exert the magnetoresistance effect even when the magnetic field of a magnetic flux density of 1 T or more is applied, and thus electrical conductivity does not decrease. Consequently, the present invention has been completed.
  • JP 2010-106329A aluminum having a purity of 99.999% by mass or more and also having the content of iron of 1 ppm by mass or less has also been known.
  • the amount of iron contained in aluminum is preferably controlled to 1 ppm by mass or less.
  • the reason is considered as follows: the magnetoresistance effect is more surely suppressed by controlling the amount of iron as a ferromagnetic element, and thus making it possible to surely suppress a decrease in electrical conductivity in a strong magnetic field (caused by the applied strong magnetic field).
  • the wiring material according to the present invention remarkably exhibits the effect by use in a state where the temperature is 77 K ( ⁇ 196° C.) or lower, and more preferably 20 K ( ⁇ 253° C.) or lower, and also the magnetic field of a magnetic flux density of 1 T or more is applied.
  • the wiring material according to the present invention is characterized by being composed of aluminum having a purity of 99.999% by mass or more.
  • the purity is preferably 99.9999% by mass or more, and more preferably 99.99998% by mass or more (hereinafter sometimes referred to as “6N8”) for the following reasons. That is, the higher the purity, the lesser a decrease in electrical conductivity under a strong magnetic field becomes.
  • the electrical resistivity may sometimes decrease in a strong magnetic field of 1 T or more as compared with the case where the magnetic field is not applied.
  • the content of iron in aluminum is preferably 1 ppm by mass, and more preferably 0.1 ppm by mass or less.
  • the reason is that a decrease in conductivity in a strong magnetic field can be suppressed more surely, as mentioned above.
  • Ni and Co are known as ferromagnetic elements other than iron. However, since these elements are easily removed in a known process for highly purification of aluminum, the numerical value of the content is out of the question. However, the contents of these Ni and Co are also preferably 1 ppm or less, and more preferably 0.1 ppm or less.
  • the purity of aluminum can be defined in some methods. For example, it may be determined by the measurement of the content of aluminum. However, it is preferred that the purity of aluminum is determined by measuring the content (% by mass) of the following 33 elements contained as impurities in aluminum and subtracting the total of these contents from 100%, so as to determine the purity of aluminum with high accuracy in a comparatively simple manner.
  • 33 elements contained as impurities are lithium (Li), beryllium (Be), boron (B), sodium (Na), magnesium (Mg), silicon (Si), potassium (K), calcium (Ca), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), nickel (Ni), cobalt (Co), copper (Cu), zinc (Zn), gallium (Ga), arsenic (As), zirconium (Zr), molybdenum (Mo), silver (Ag), cadmium (Cd), indium (In), tin (Sn), antimony (Sb), barium (Ba), lantern (La), cerium (Ce), platinum (Pt), mercury (Hg), lead (Pb) and bismuth (Bi).
  • the contents of these elements can be determined, for example, by glow discharge mass spectrometry.
  • Such high purity aluminum may be obtained by using any purification (refinement) method.
  • Some purification methods for obtaining high purity aluminum according to the present invention are exemplified below. However, the purification method is not limited to these methods as a matter of course.
  • a unidirectional solidification process can be used so as to further increase a purity of the high purity aluminum obtained by a three-layer electrolysis process.
  • the content of Fe and the respective contents of Ti, V, Cr and Zr can be selectively decreased by the unidirectional solidification process.
  • the unidirectional solidification process is, for example, a method in which aluminum is melted in a furnace tube using a furnace body moving type tubular furnace and then unidirectionally solidified from the end by pulling out a furnace body from a furnace tube, and that the contents of the respective elements of Ti, V, Cr and Zr selectively increase at the side of the solidification initiation end, and also the content of Fe selectively increases at the side of the solidification completion end (opposite side of the solidification initiation end). Therefore, it becomes possible to surely decrease the contents of the respective elements of Fe, and Ti, V, Cr and Zr by cutting off the side of solidification initiation end and the side of the solidification completion end of the obtained ingot.
  • purification by the three-layer electrolysis process and purification by the unidirectional solidification process There is no particular limitation on the order of implementation of purification by the three-layer electrolysis process and purification by the unidirectional solidification process. Usually, purification is implemented by the three-layer electrolysis process, and then purification is implemented by the unidirectional solidification process. Purification by the three-layer electrolysis process and purification by the unidirectional solidification process may be implemented, for example, alternately and repeatedly, or any one of or both purifications may be repeatedly implemented, respectively. It is particularly preferred that purification by the unidirectional solidification process is repeatedly implemented.
  • aluminum having a purity of 99.9999% by mass or more can be obtained by using the three-layer electrolysis process in combination with the unidirectional solidification process. It is also possible to suppress the content of iron in aluminum to 1 ppm by mass or less, and more preferably 0.1 ppm by mass or less in a comparatively easy manner.
  • a zone melting process can be used so as to obtain aluminum having high purity, for example, a purity of 99.99998% by mass or more.
  • the content of iron in aluminum can be suppressed to 1 ppm by mass or less, and more preferably 0.1 ppm by mass or less, more surely.
  • an alumina layer is formed in advance on a surface of a boat in which aluminum is placed, and also zone melting purification is performed in vacuum under a pressure of 3 ⁇ 10 ⁇ 5 Pa or less, and more preferably from 3 ⁇ 10 ⁇ 6 Pa to 2 ⁇ 10 ⁇ 5 Pa, so as to surely separate impurities from molten aluminum.
  • a pretreatment in which a surface layer of an aluminum raw material to be subjected to zone melting purification is dissolved and removed in advance, before zone melting purification is performed.
  • a pretreatment method there is no particular limitation of the pretreatment method, and various treatments used in the relevant technical field can be used so as to remove the surface layer of the aluminum raw material.
  • Examples of the pretreatment include an acid treatment, an electrolytic polishing treatment and the like.
  • the above-mentioned boat to be used in the zone melting purification process is preferably a graphite boat, and is preferably baked in an inert gas or vacuum in advance after formation of the above-mentioned alumina layer.
  • the width of the melting section where aluminum is melted during the zone melting purification is preferably adjusted to w ⁇ 1.5 or more w ⁇ 6 or less based on a cross sectional size w of the aluminum raw material.
  • An aluminum raw material to be used in the purification is obtained by using the three-layer electrolysis process in combination with the unidirectional solidification process and, for example, high purity aluminum having a purity of 99.9999% by mass or more is preferably used.
  • the melting section is moved from one end of a raw aluminum toward the other end by moving a high frequency coil for high frequency heating, and thus the entire raw aluminum can be subjected to zone melting purification.
  • impurity metal element components peritectic components (Ti, V, Cr, As, Se, Zr and Mo) tend to be concentrated to the melting initiation section and eutectic components (26 elements as a result of removal of peritectic 7 elements from the above-mentioned 33 impurity elements) tend to be concentrated to the melting completion section, and thus a high purity aluminum can be obtained in the region where both ends of the aluminum raw material are removed.
  • the aluminum raw materials in a longitudinal direction are brought into contact with each other to treat as one aluminum raw material in a longitudinal direction, and then the melting section is moved from one end (i.e., one of two ends where adjacent aluminum raw materials are not present in a longitudinal direction among ends of the plurality of aluminum raw materials) to the other end (i.e., the other one of two ends where adjacent aluminum raw materials are not present in a longitudinal direction among ends of the plurality of aluminum raw materials).
  • zone melting zone melting purification
  • zone melting can be repeated again from one end to the other end.
  • the number of repeat times is usually 1 or more and 20 or less. Even if the number of passes is more than the above range, an improvement in the purification effect is restrictive.
  • the number of passes is preferably 3 or more, and more preferably 5 or more.
  • the number of passes is less than the above range, peritectic 7 elements are less likely to moved, and thus sufficient purification effect is not obtained.
  • the reason is as follows.
  • a shape (especially, height size) of the purified aluminum after uniting becomes un-uniform, and thus the melting width may sometimes vary during purification and uniform purification is less likely to be obtained.
  • the ingot of the high purity aluminum obtained by the above-mentioned purification method is formed into a desired shape using various methods.
  • the forming method will be shown below. However, the forming method is not limited thereto.
  • a wiring material to be obtained is a plate or a wire
  • rolling is an effective forming method.
  • the rolling may be performed using a conventional method, for example, a method in which an ingot is passed through a pair of rolls by interposing into the space between these rolls while applying a pressure.
  • a conventional method for example, a method in which an ingot is passed through a pair of rolls by interposing into the space between these rolls while applying a pressure.
  • concrete techniques and conditions treatment of materials and rolls, treatment time, reduction ratio, etc.
  • these concrete techniques and conditions may be appropriately set unless the effects of the present invention are impaired.
  • the thickness is from 0.1 mm to 3 mm in case of the plate, or the diameter is from 0.1 mm to 3 mm in case of the wire rod.
  • the thickness is less than 0.1 mm, sufficient conduction characteristics required as the wiring material may be sometimes less likely to be obtained since a cross section decreases. In contrast, when the thickness is more than 3 mm, it may sometimes become difficult to deform utilizing flexibility.
  • the thickness is from 0.1 mm to 3 mm, there is an advantage such as easy handling, for example, the material can be arranged on a side surface of a curved container utilizing flexibility.
  • the shape obtainable by rolling is not limited to the plate or wire and, for example, a pipe shape and an H-shape can be obtained by rolling.
  • the rolling may be hot rolling or warm rolling in which an ingot is heated in advance and then rolling is performed in a state of being set at a temperature higher than room temperature, or may be cold rolling in which the ingot is not heated in advance.
  • hot rolling or warm rolling may be used in combination with cold rolling.
  • a conventional method may be employed, but is not limited to, for example, a method in which high purity aluminum is heated and melted to form a molten metal and the obtained high purity aluminum molten metal is solidified by cooling in a mold.
  • the heating temperature is usually from 700 to 800° C.
  • heating and melting is usually performed in vacuum or an inert gas (nitrogen gas, argon gas, etc.) atmosphere in a crucible made of graphite.
  • Wire drawing or extrusion may be performed as a forming method other than rolling. There is no limitation on the shape obtained by drawing or extrusion. For example, drawing or extrusion is suited to obtain a wire having a circular cross section.
  • a desired wire shape may be obtained by rolling before drawing to obtain a rolled wire (rolled wire rod) and then drawing the rolled wire.
  • the cross section of the obtained wire is not limited to a circle and the wire may have a noncircular cross section, for example, an oval or square cross section.
  • the desired shape may also be obtained by cutting the ingot, except for drawing or extrusion.
  • the molded article of the present invention obtained by the above forming method such as rolling may be optionally subjected to an annealing treatment. It is possible to remove strain, which may be usually sometimes generated in case of cutting out a material to be formed from the ingot, or forming, by subjecting to an annealing treatment.
  • strain (dislocation) included in the ingot is not sufficiently decreased for the following reason. Since strain (dislocation) serves as a factor for enhancing electrical resistivity, excellent conduction characteristics may not be sometimes exhibited.
  • the heat treatment temperature is higher than 600° C., solution of impurities in solid, especially solution of iron into a matrix proceeds. Since solid-soluted iron has large effect of enhancing electrical resistivity, conduction characteristics may sometimes deteriorate.
  • the temperature is maintained at 430 to 550° C. for one or more hours for the following reason.
  • strain can be sufficiently removed and also iron exists as an intermetallic compound with aluminum without being solid-soluted into the matrix.
  • an intermetallic compound of iron and aluminum for example, plural kinds such as Al 6 Fe, Al 3 Fe and Al m Fe (m ⁇ 4.5) are known. It is considered that the majority of (for example, 50% or more, and preferably 70% or more in terms of volume ratio) of an intermetallic compound of iron and aluminum, which exists in a high purity aluminum material obtained after annealing within a temperature range (430 to 550° C.), is Al 3 Fe.
  • Al 3 Fe is a high purity aluminum material obtained after annealing within a temperature range (430 to 550° C.
  • Existence of Al 3 Fe and the volume ratio thereof can be confirmed and measured by by dissolution of a matrix (base material) using a chemical solvent, and collection by filtration, followed by observation of the residue collected by filtration using an analytical electron microscope (analytical TEM) and further analysis.
  • This Al 3 Fe has such an advantage that it scarcely exerts an adverse influence on the conductivity even in case of existing as a precipitate.
  • the wiring material according to the present invention may be composed only of the above-mentioned high purity aluminum having a purity of 99.999% by mass or more and may contain the portion other than the high purity aluminum, for example, protective coating so as to impart various functions.
  • Example 1 (purity of 99.999% by mass or more, 5N-Al), Example 2 (purity of 99.9999% by mass or more, 6N-Al) and Example 3 (purity of 99.99998% by mass or more, 6N8-Al), details of which are shown below, were produced as example samples, and then resistivity (specific electrical resistivity) was measured.
  • Comparative Example 1 (4N-Al) as aluminum having a purity of 4N level
  • Comparative Example 2 (3N-Al) as aluminum having a purity of 3N level are shown below as Comparative Examples.
  • the resistivity of Comparative Examples 1 and 2 was determined by calculation.
  • Comparative Example 4 is copper sample having a purity of 4N level
  • Comparative Example 5 is copper sample having a purity of 5N level
  • Comparative Example 6 is copper sample having a purity of 6N level.
  • a commercially available aluminum having a purity of 99.92% by mass was purified by the three-layer electrolysis process to obtain a high purity aluminum having a purity of 99.999% by mass or more.
  • the high purity aluminum obtained by the above-mentioned three-layer electrolysis process was purified by the unidirectional solidification to obtain a high purity aluminum having a purity of 99.9999% by mass or more.
  • a graphite boat was placed inside a vacuum chamber (a quartz tube measuring 50 mm in outside diameter, 46 mm in inside diameter, 1,400 mm in length) of a zone melting purification apparatus.
  • a high purity alumina powder AKP Series (purity: 99.99%) manufactured by Sumitomo Chemical Company, Limited was applied to the portion, where the raw material is placed, of the graphite boat while pressing to form an alumina layer.
  • the graphite boat was baked by high frequency heating under vacuum.
  • the baking was carried out by heating in vacuum of 10 ⁇ 5 to 10 ⁇ 7 Pa using a high frequency heating coil (heating coil winding number: 3, 70 mm in inside diameter, frequency of about 100 kHz) used in zone melting, and moving from one end to the other end of the boat at a speed of 100 mm/hour thereby sequentially heating the entire graphite boat.
  • a high frequency heating coil heating coil winding number: 3, 70 mm in inside diameter, frequency of about 100 kHz
  • the above-mentioned 9 aluminum raw materials in total weight of about 780 g were arranged on the portion (measuring 20 ⁇ 20 ⁇ 1,000 mm), where the raw materials are placed, provided in the graphite boat.
  • the output of the high frequency power source (frequency: 100 kHz, maximum output: 5 kW) was adjusted so that the melting width of the melting section becomes about 70 mm. Then, the high frequency coil was moved at a speed of 100 mm per hour thereby moving the melting section by about 900 mm. At this time, the pressure in the chamber was from 5 ⁇ 10 ⁇ 6 to 9 ⁇ 10 ⁇ 6 Pa. The temperature of the melting section was measured by a radiation thermometer. As a result, it was from 660° C. to 800° C.
  • the high frequency coil was moved to the melting initiation position (position where the melting section was formed first) and the aluminum raw material was heated and melted again at the melting initiation position to form a melting section while maintaining vacuum inside the chamber.
  • Zone melting purification was repeated by moving this melting section.
  • zone melting purification was carried out three times (3 passes) in total at a melting width of about 70 mm and a traveling speed of 100 mm/hour of the melting section, the shape from the melting initiation section to the completion section became almost uniform, and uniform shape was maintained from then on (during 7 passes mentioned below).
  • zone melting purification was carried out 7 passes at a melting width of about 50 mm and a traveling speed of 60 mm/hour of the melting section.
  • the melting width was from w ⁇ 2.8 to w ⁇ 3.9 based on a cross sectional size w of the aluminum raw material to be purified.
  • the chamber was opened to atmospheric air and then aluminum was removed to obtain a purified aluminum of about 950 mm in length.
  • Example 3 Li 0.016 ⁇ 0.001 ⁇ 0.001 ⁇ 0.001 Be 0.042 ⁇ 0.001 ⁇ 0.001 ⁇ 0.001 B 1.5 2.8 0.019 0.007 0.001 Na 1.4 0.012 0.001 0.001 Mg 5.2 0.1 0.48 0.10 0.001 Si 200 25 2.3 0.34 0.003 K ⁇ 0.001 0.013 0.008 0.008 Ca 1.3 0.002 0.002 0.003 Ti 29 0.7 0.060 0.027 0.031 V 53 2.2 0.023 0.027 0.023 Cr 3.9 2.1 0.025 0.026 0.022 Mn 2.1 2.1 0.007 0.004 0.006 Fe 230 12 0.60 0.089 0.001 Ni 0.19 0.018 0.004 0.001 Co 13 0.3 ⁇ 0.001 ⁇ 0.001 ⁇ 0.001 Cu 0.72 1 1.1 0.14 0.016 Zn 13 7 0.22 0.002 0.001 Ga 93 12 0.006
  • the obtained material for wire drawing was drawn to a diameter to 0.5 mm by rolling using grooved rolls and wire drawing.
  • the specimen obtained by wire drawing was fixed to a quartz jig, maintained in vacuum at 500° C. for 3 hours and then furnace-cooled to obtain a sample for the measurement of resistivity.
  • the resistivity was measured by varying the magnetic field to be applied to the sample from a magnetic flux density 0 T (magnetic field was not applied) to 15 T, using a the four-wire method.
  • the magnetic field was applied in a direction parallel to a longitudinal direction of the sample.
  • ⁇ H is an amount of an increase in resistivity in the magnetic field.
  • ⁇ RT is resistivity at room temperature when the magnetic field is not applied, and was set to 2,753 n ⁇ cm since it can be treated as a nearly given value in high purity aluminum having a purity of 3N or more.
  • ⁇ is resistivity at 4.2 K when the magnetic field is not applied and largely varied depending on the purity.
  • RRR is also called a residual resistivity ratio and is a ratio of resistivity at 297 K to resistivity at a helium temperature (4.2 K).
  • ⁇ RT Resistivity at room temperature when magnetic field is not applied
  • the resistivity is small such as a tenth or less as compared with Comparative Example 2 in a state where the magnetic field is absent, and also the resistivity slightly increases even if the magnetic field increases.
  • Example 1 (5N level), the resistivity at 15 T slightly increases (about 1.5 times) as compared with the case where the magnetic field is absent, and it is apparent that the increase of the resistivity caused by magnetic field is small compared with Comparative Example 2.
  • Example 2 (6N level), the resistivity slightly increases (within 10%) even at 15 T as compared with the case where the magnetic field is absent.
  • the magnetic flux density is within a range from 1 to 12 T, the value of the resistivity decreased as compared with the case where the magnetic field is not applied, and thus remarkable magnetoresistance suppression effect is exhibited.
  • Example 3 (6N8 level), the resistivity decreases as compared with the case where the magnetic field is absent even at any magnetic flux density of 1 to 15 T, and thus remarkable magnetoresistance suppression effect is exhibited.
  • FIG. 1 is a graph showing a relation between the electrical conductivity index and the applied magnetic field (magnetic flux density).
  • the electrical conductivity index is an index which indicates the magnitude of the electrical conductivity of the respective samples based on Comparative Example 2 which exhibits the resistivity in a strong magnetic field of aluminum having a purity of 4N. Namely, in each magnetic flux density the electrical conductivity index is determined by dividing the value of the resistivity of Comparative Example 2 with the value of the resistivity of each sample. The larger the value of this index, the superior the conductive properties under the magnetic flux density (strong magnetic field) is as compared with the sample of Comparative Example 2.
  • samples of Examples show the case where the magnetic field is absent, and the conductivity is about 13 to 28 times higher than that of Comparative Example 2.
  • the conductivity compared with Comparative Example 2 increases.
  • the conductivity is 16 times (Example 1) to 65 times (Example 3) higher at 1 T, and the conductivity further increases since it is 26 times (Example 1) to 96 times (Example 1) higher at 15 T.
  • any of copper samples shows a right downward curve and, as the intensity of the magnetic field increases, the magnetoresistance effect increases as compared with Comparative Example 2. Namely, it is found that, in case of copper, a decrease in electrical conductivity due to magneticoresistance cannot be suppressed even if the purity is increased to 6N level (as is apparent from Table 1, in samples of Comparative Examples 3 to 6, the resistivity at 15 T increases by 5 to 18 times as compared with the resistivity in case where the magnetic field is absent), and that the effect capable of suppressing a decrease in conductivity in the magnetic field by increasing the purity to 99.999% by mass or more, found by the present inventors, is peculiar to aluminum.
  • a wiring material which is easy to handle and also exhibits excellent conductivity even in a strong magnetic field of, for example, a magnetic flux density of 1 T or more.

Landscapes

  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Conductive Materials (AREA)
  • Non-Insulated Conductors (AREA)
US13/458,095 2011-04-28 2012-04-27 Wiring material for superconducting magnet Abandoned US20120275948A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2011-101774 2011-04-28
JP2011101774A JP5749558B2 (ja) 2011-04-28 2011-04-28 超電導磁石用配線材

Publications (1)

Publication Number Publication Date
US20120275948A1 true US20120275948A1 (en) 2012-11-01

Family

ID=46330436

Family Applications (1)

Application Number Title Priority Date Filing Date
US13/458,095 Abandoned US20120275948A1 (en) 2011-04-28 2012-04-27 Wiring material for superconducting magnet

Country Status (7)

Country Link
US (1) US20120275948A1 (fr)
JP (1) JP5749558B2 (fr)
CN (1) CN102760507A (fr)
DE (1) DE102012008605A1 (fr)
FR (1) FR2974658A1 (fr)
GB (1) GB2490585A (fr)
NL (1) NL1039567B1 (fr)

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2010106329A (ja) * 2008-10-31 2010-05-13 Sumitomo Chemical Co Ltd 極低温熱伝達材

Family Cites Families (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5979505A (ja) * 1982-10-29 1984-05-08 Hitachi Ltd 超電導コイル
US5286577A (en) * 1990-07-23 1994-02-15 Aluminum Company Of America Drawn conductors for cryogenic applications
JPH0715208A (ja) 1993-06-25 1995-01-17 Kokusai Electric Co Ltd 有極型バンドパスフィルタ
US5573861A (en) * 1993-07-06 1996-11-12 Sumitomo Chemical Co., Ltd. High purity aluminum conductor used at ultra low temperature
EP2117056B1 (fr) 2008-03-05 2010-11-03 Bruker HTS GmbH Dispositif supraconducteur pour conditionnement de courant
JP5098750B2 (ja) * 2008-03-31 2012-12-12 住友化学株式会社 高純度アルミニウムの圧延材の製造方法
JP5098751B2 (ja) * 2008-03-31 2012-12-12 住友化学株式会社 超高純度アルミニウム高圧延材の製造方法
JP5355968B2 (ja) 2008-09-09 2013-11-27 本田技研工業株式会社 電動パワーステアリング装置

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2010106329A (ja) * 2008-10-31 2010-05-13 Sumitomo Chemical Co Ltd 極低温熱伝達材

Also Published As

Publication number Publication date
NL1039567A (en) 2012-10-30
DE102012008605A1 (de) 2012-12-06
JP2012234681A (ja) 2012-11-29
GB2490585A (en) 2012-11-07
CN102760507A (zh) 2012-10-31
NL1039567B1 (en) 2017-12-13
FR2974658A1 (fr) 2012-11-02
GB201207377D0 (en) 2012-06-13
JP5749558B2 (ja) 2015-07-15

Similar Documents

Publication Publication Date Title
JP5086598B2 (ja) 冷間加工材
TWI511926B (zh) High purity lanthanum, a high purity lanthanum, a sputtering target composed of high purity lanthanum, and a metal gate film having a high purity lanthanum as a main component
US9103005B2 (en) Magnetic shielding material for superconducting magnet
JP5086592B2 (ja) 冷間加工材
JP5274981B2 (ja) 極低温熱伝達材
NL1039566B1 (en) Low temperature thermal conductor.
JP5291028B2 (ja) アルミニウム材およびその製造方法
Tanaka et al. Refining technology and low temperature properties for high purity aluminium
JP2013064181A (ja) アルミニウム材およびその製造方法
Hashimoto et al. Zone refining of high-purity aluminum
JP2011195902A (ja) アルミニウム材およびその製造方法
JP5478899B2 (ja) 高純度アルミニウム材
JP6176908B2 (ja) 超高純度アルミニウム材およびその製造方法
NL1039567B1 (en) Wiring material for superconducting magnet.
JP2013064182A (ja) アルミニウム材の製造方法
Hashimoto et al. Purification of ultra-high purity aluminum
JP2009242866A (ja) 超高純度アルミニウム高圧延材の製造方法
CN115404385A (zh) 一种有优异室温拉伸延展性的难熔高熵合金及其制备方法
Sumomogi et al. Purification of 6N Aluminum by Ultrahigh-Vacuum Melting
RU2448391C2 (ru) Способ изготовления сверхпроводящего изделия
Watts Alloys with Copper
Toyoda et al. THE EFFECT OF 4d AND 5d TRANSITION METAL IMPURITIES ON THE RESIDUAL RESISTIVITY OF Au, Cu, Zn AND A1

Legal Events

Date Code Title Description
AS Assignment

Owner name: SUMITOMO CHEMICAL COMPANY, LIMITED, JAPAN

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:TOMARU, TAKAYUKI;SASAKI, KENICHI;HOSHIKAWA, HIROAKI;AND OTHERS;SIGNING DATES FROM 20120601 TO 20120606;REEL/FRAME:028564/0350

Owner name: INTER-UNIVERISITY RESEARCH INSTITUTE CORPORATION H

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:TOMARU, TAKAYUKI;SASAKI, KENICHI;HOSHIKAWA, HIROAKI;AND OTHERS;SIGNING DATES FROM 20120601 TO 20120606;REEL/FRAME:028564/0350

STCB Information on status: application discontinuation

Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION