JP3074741B2 - Insulated wire - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an insulated wire used as a wiring wire or a winding wire in a high vacuum device or a device using a high temperature.

[0002]

2. Description of the Related Art Insulated wires are sometimes used for equipment requiring high temperature safety such as heating equipment and fire alarms. Further, the insulated wire is also used in an environment where a vehicle is heated to a high temperature. As such an insulated wire, an insulated wire in which a conductor is coated with a heat-resistant organic resin such as polyimide or fluororesin has been known.

When used in applications requiring high heat resistance or in environments requiring a high degree of vacuum, organic coating alone is not sufficient in terms of heat resistance and gas release. Therefore, insulated wires in which a conductor is passed through a ceramic insulator tube, and tubes in which a conductor is passed through a tube made of a heat-resistant alloy made of stainless steel or the like filled with metal oxide fine particles such as magnesium oxide. MI cables and the like have been used for such applications.

[0004] Examples of the insulated wire which is required to have heat resistance and flexibility include a glass braided insulated wire using a fiber woven fabric as an insulating member.

[0005] Further, for heat-resistant applications, see JP-A-55-0437.
No. 46 and the Fujikura technique (April 1989, No. 76
No. 51-56). This is because an insulating layer made of a mixture of silicon resin and ceramic powder is formed on a nickel-plated copper, platinum, silver, or stainless steel wire, and even if the silicon resin is heated to a temperature above which it can be thermally decomposed, This is a ceramicized electric wire that retains ceramic powder after decomposition to maintain insulation.

[0006]

With an insulated wire coated with an organic resin as described above, the maximum temperature at which insulation can be maintained is at most about 300 ° C. Therefore, 30
Such an organic insulated wire cannot be used for applications that require insulation assurance at a high temperature of 0 ° C. or higher.

[0007] Insulated wires having improved heat resistance using ceramic insulator tubes have drawbacks such as poor flexibility. Since the MI cable is composed of a heat-resistant alloy tube and a conductor, the outer diameter of the cable increases. For this reason, the MI cable is a cable having a relatively large cross section with respect to the allowable power amount. The outer layer of the MI cable is made of a heat-resistant alloy tube, and therefore has good flexibility. However, in order to use it as a winding wire wound in a coil shape on a bobbin or the like, a heat-resistant alloy is used. It is necessary to bend a pipe made of a predetermined curvature.
At this time, bending work performed on the pipe made of a heat-resistant alloy involves difficulty. Further, when the MI cable is wound in a coil shape, the outer layer tube is thicker than the conductor, so that it is difficult to improve the winding density.

Further, when a glass braided insulated wire having both flexibility and heat resistance is used, there is a problem that glass dust is generated from glass fibers when the wire is arranged in a predetermined shape according to the application. This glass dust can be a gas adsorption source. Therefore, when the glass braided insulated wire is used in an environment where a high degree of vacuum is required, it is impossible to maintain a high degree of vacuum due to a gas adsorption source provided by glass dust.

On the other hand, conventionally, as an insulated wire having good heat resistance, insulation and heat dissipation properties, there has been a so-called alumite wire obtained by anodizing an aluminum or aluminum alloy wire. In this alumite electric wire, the base material is limited to one kind of aluminum. In consideration of heat resistance, since the melting point of aluminum is 660 ° C., the upper limit of the heat resistance is specified by itself.
500 ° C due to lower mechanical strength even at lower temperatures
Degree is the limit of use.

[0010] Further, the insulating film of the ceramic electric wire is particulate and porous, so that dust is easily generated and it is impossible to use the electric wire in a vacuum.

As the conductor, copper or a copper alloy is optimal from the viewpoint of high electrical conductivity, ease of soldering, strength and cost. However, copper has low resistance to an oxidizing agent, and is oxidized even at room temperature in the air, or changes to a basic carbonate patina. Further, in a high-temperature environment, oxidation proceeds, making it impossible to use as a conductor. In order to overcome this problem, a nickel-plated copper wire in which copper is plated with nickel has been used. However, nickel-plated copper wires have no particular problem when used at about 400 ° C. However, at higher temperatures, conductivity is reduced due to diffusion and alloying of copper and nickel. For example, after 2,000 hours at 600 ° C., the conductivity of the conductor decreases by about 20%.

An object of the present invention is to solve such a conventional problem and to provide an insulated wire having the following characteristics.

(A) No deterioration under high temperature environment (b) Excellent flexibility (c) No glass adsorption source

[0014]

An insulated wire according to the present invention comprises a core material made of copper or a copper alloy, a niobium layer provided on the outer surface of the core material, and an oxidation-resistant metal provided on the outer surface of the niobium layer. And an insulating ceramic layer formed on the outer surface of the oxidation-resistant metal layer by heat treatment of the ceramic precursor solution.

As the oxidation-resistant metal layer, nickel, chromium, aluminum, platinum, silver, nickel alloy, chromium alloy, aluminum alloy, platinum alloy, silver alloy or stainless steel can be used.

As the insulating ceramic layer, silica,
Alumina, zirconia, silicon nitride, silicon carbide, aluminum nitride, stabilized zirconia, and the like can be used.

Examples of the precursor of the ceramics forming the insulating ceramic layer include metal alkoxides, organic acid salts of metals, polysilazane, polycarbosilane, and polyborosiloxane.

When a thick insulating ceramic layer is required, fine ceramic particles may be dispersed in a ceramic precursor solution.

Further, for applications requiring a high degree of flexibility, a high degree of adhesion is required so that the insulating ceramic layer does not fall off even during severe bending. In order to form such an insulating ceramic layer, it is preferable to form a chromium oxide-containing layer on the surface of the oxidation-resistant metal layer by electroplating, for example. When the oxidation-resistant metal layer is made of aluminum or an aluminum alloy, the surface is preferably anodized.

FIG. 1 is a sectional view showing an embodiment according to the present invention. Referring to FIG. 1, a niobium layer 2 is provided around a core material 1 of a copper wire. An oxidation-resistant metal layer 3 is provided around the niobium layer 2, and an insulating ceramic layer 4 is provided around the oxidation-resistant metal layer 3.

[0021]

According to the present invention, niobium is used as the substance which comes into direct contact with the core material made of copper or copper alloy.
Niobium diffuses very slowly into copper and copper alloys even at high temperatures, so that little alloying occurs. further,
It also effectively acts as a barrier to the diffusion of other substances into copper. Niobium is excellent in such effects, but does not have high resistance to oxidation at high temperatures. In the present invention, since the outer surface of the niobium layer that is easily oxidized is covered with the oxidation-resistant metal layer such as nickel, the oxidation of the niobium layer is prevented.

Further, the insulating ceramic layer provided on the outer surface of the oxidation-resistant metal layer in the present invention is formed by heat treatment of a ceramic precursor solution, so that it is a smooth thin film and flexible. It has excellent gas absorption and no gas adsorption. According to the present invention, in order to form an insulating ceramics layer, for example, a step of applying a ceramic precursor solution and heating the same can be repeated a plurality of times. Various materials can be selected as the insulating ceramic according to the application.

In the present invention, the ceramic insulating layer can be obtained by applying and heating a ceramic precursor solution.

The solution containing the ceramic precursor is a metal organic compound having an alkoxide group, a hydroxy group, and a metalloxane bond formed by a hydrolysis reaction and a dehydration condensation reaction of a compound having a hydrolyzable organic group such as a metal alkoxide. It is a solution consisting of a polymer of the compound. Further, this solution contains an organic solvent such as alcohol as a solvent, a metal alkoxide as a raw material, and a small amount of water and a catalyst necessary for a hydrolysis reaction.

The solution containing the ceramic precursor may include a metal-organic compound (Metal-organic C).
and a solution obtained by mixing and dissolving the same in a suitable organic solvent. Since the metal organic compound used in the present invention is thermally decomposed by heating to form a metal oxide film, the thermal decomposition temperature at atmospheric pressure is limited to a temperature lower than the boiling point of the metal organic compound. You. For example,
SiO ₂ , Al ₂ O ₃ , ZrO ₂ , TiO ₂ , and M
gO and the like. As the organic acid salt, a metal salt with naphthenic acid, caprylic acid, stearic acid, and octylic acid is preferable. Also, as the metal alkoxide, ethoxide,
Propoxide and butoxide are used.

The oxide insulating layer formed by the organic acid salt pyrolysis method is a ceramic oxide. This oxide may be formed by a heat treatment in an atmosphere of oxygen gas in the heat treatment of the precursor solution of the metal oxide.

Examples of the insulating ceramic layer of nitride and carbide include silicon carbide, silicon nitride, and aluminum nitride. In the case of forming silicon nitride, polysilazane can be used as a precursor of ceramics, and in the case of aluminum nitride, a polymer of alkylaminoaluminum is preferably used. This is because it has been found that any of them has a small shrinkage ratio when converted into ceramics by heating, so that it is difficult to generate defects such as cracks in the formed ceramic film. The carbide insulating layer is formed by a polycarbosilane or polyborosiloxane thermal decomposition method. The heat treatment of polycarbosilane and polyborosiloxane may be performed under an inert atmosphere in a stream of argon or nitrogen. The insulating layer obtained by such a heat treatment is a ceramicized carbide. When heating is performed in the atmosphere, part or most of the carbide may be oxidized to form a mixture of a carbide and an oxide.

[0028] The insulating layer made of a ceramic material thus formed exhibits excellent heat-resistant insulation even at a high temperature of 1000 ° C or higher.

Further, for applications requiring a high degree of flexibility, it is necessary to have strong adhesion so that the insulating ceramic layer does not fall off even under severe bending. In such a case, it is preferable to form a chromium oxide-containing layer around the oxidation-resistant metal layer by electroplating. When the oxidation-resistant metal layer is made of aluminum or an aluminum alloy, it is preferable to subject this surface to anodic oxidation.

Chromium oxide layer is formed by electroplating
If necessary, add a small amount of organic acid to the aqueous solution of chromic acid.
Is used. Generally, chrome plating
Chromic acid and sulfuric acid
A sargent bath mainly composed of
Differs from the following. That is, mix in the electrolytic bath
Mineral acids are oxidized on the plating surface during electroplating.
It works to dissolve chromium. For this reason, glossy metal
The chrome layer is plated. In the present invention, this oxidation
The plating is done preferentially. In addition, the main component is chromium oxide.
Treatment of precursor solution of metal nitride on outer surface of layer
Thus, a thin film of an insulating ceramic is formed. Of this thin film
In order to increase adhesion, chromium oxide is mainly used.
The surface of the layer to be formed is preferably rough. For this reason,
Bright plating, which is commonly performed,
different. For bright plating, depending on the processing temperature,
60A / dm^TwoCurrent density is used, but in the present invention
Is 100 to 200 A / dm ^TwoUse the current density of
Get a face.

Since a method using a solution is used for forming the insulating layer, it is possible to coat a linear substrate with simple equipment at a high speed.

[0032]

EXAMPLE 1 A wire having a structure in which a niobium layer was provided around a core material of oxygen-free copper and a nickel layer was provided outside the core material was prepared by a fitting method. The wire diameter is 0.5 mm, the nickel layer is 25 μm,
The niobium layer had a thickness of 10 μm. Initial conductivity is 7
9% IACS.

In a nitrogen stream, 1,1,1,3,3,3-
40 g of hexamethyldisilazane and trichlorosilane 1
5 g were mixed and stirred at 70 ° C. for 5 hours. In addition, 16
Distillation was carried out at 0 ° C., and by-products were distilled off. Next, by-products were completely removed by vacuum distillation at 120 ° C. and 5 mmHg to obtain 5 g of polysilazane. The by-products here are mainly trimethylchlorosilane and oligosilazane. The polysilazane was diluted 5-fold with toluene to obtain a coating solution containing a ceramic precursor.

The conductor prepared by the above-mentioned fitting method was immersed in this coating solution. The wire was taken out, heated at 700 ° C. for 10 minutes in a nitrogen atmosphere, and the coating solution was dried to form a ceramic layer on the surface. This coating and heating process was repeated 10 times to form an insulating ceramic layer.

A 30 cm long sample was collected from the insulated wire thus obtained. A platinum foil having a thickness of 0.02 mm was placed on the sample at an interval of about 50 mm.
Each of them was wound with a length of about 10 mm. Conductor
When an AC voltage of 60 Hz is applied between metal foils, 50
Dielectric breakdown occurred at 0V. When the insulated wire was bent, the insulation was maintained even when the wire was bent to a diameter of 10 mm.

Further, this insulated wire was heated at 600 ° C. for 200 hours.
After heating for 0 hours, a 30 cm long sample was taken. This means that a platinum foil having a thickness of 0.02 mm was applied to four places of the sample at an interval of about 50 mm in the same manner as described above.
When a length of 0 mm was wound and an AC voltage of 60 Hz was applied between the conductor and the metal foil, insulation breakdown occurred at 500 V. Further, when the conductivity was measured, 79% IACS was maintained.

Example 2 Polyborodiphenylsiloxane (Polyborodi)
phenylsiloxane) (SiPh ₂ -OP)
₂ ) _n was dissolved in toluene to form a 40% by weight solution.
Furthermore, silicon carbide powder (nominal particle size 0.50 μm)
g was mixed to obtain a coating solution. A wire produced by the same fitting method as in Example 1 was immersed in this coating solution. It was pulled up from the coating solution and heated at a temperature of 500 ° C. for 10 minutes. This coating and heating process was repeated five times to form an insulating ceramic layer.

From the obtained insulated wire, a sample having a length of 30 cm was collected. Platinum foil with a thickness of 0.02 mm
The sample was closely wound around each of four locations at a distance of 0 mm to a length of about 10 mm. When an AC voltage of 60 Hz is applied between the conductor and the metal foil, 800 V
Dielectric breakdown occurred. When the insulated wire was bent, the insulation was maintained even when the wire was bent to a diameter of 50 mm.

Further, this insulated wire was heated at 600 ° C. for 200 hours.
After heating for 0 hours, a 30 cm long sample was taken. As above, a 0.02 mm thick platinum foil is
The sample was closely wound at a length of about 10 mm on each of four points of the sample at an interval of mm. When an AC voltage of 60 Hz was applied between the conductor and the metal foil, breakdown occurred at 800 V. Further, when the conductivity was measured, it was found that 79% I
ACS was maintained.

Example 3 A wire having a structure in which a niobium layer was formed around a core material of oxygen-free copper and a copper layer was further formed around the niobium layer was prepared by a fitting method. After this was drawn and reduced in diameter, the copper in the outermost layer was dissolved and removed with nitric acid. This wire was plated with chrome with a thickness of 3 μm using a surge bath. As a result, a wire having a wire diameter of 0.45 mm and a niobium layer thickness of 10 μm was obtained. The initial conductivity of this wire was 91% IACS.

A chromium oxide-containing layer was formed on the outer surface of this wire as follows. An electroplating solution having a concentration of 200 g / l of chromic anhydride, 20 g / l of ammonium metavanadate, and 6.5 g / l of acetic acid was used as the electroplating solution. / Dm ² and a treatment time of 2 minutes to perform chromium plating. Thus, a chromium oxide-containing layer was formed on the outer surface with a thickness of about 1 μm.

To an n-butanol solution containing 10 mol% of zirconium butoxide and 20 mol% of ethanolamine, diethylene glycol monomethyl ether diluted 2.1 times with respect to zirconium alkoxide was added and stirred at 110 ° C. for 2 hours. Then, a coating solution was prepared.

The wire on which the chromium oxide-containing layer was formed was immersed in this coating solution. The wire was pulled up and heated at 800 ° C. for 10 minutes. This dip coating and heating steps are
This operation was repeated 0 times to form an insulating ceramic layer.

A 30 cm long sample was collected from the insulated wire obtained. Platinum foil with a thickness of 0.02 mm
The sample was wound around each of four places at a distance of 0 mm with a length of about 10 mm. 60 between conductor and metal foil
When an AC voltage of Hz was applied, dielectric breakdown occurred at 1000 V. When the insulated wire is bent, the diameter is 20mm
Insulation was maintained even when bent to a diameter of.

Further, the insulated wire was heated at 600 ° C. for 200 hours.
After heating for 0 hours, a 30 cm long sample was taken. A platinum foil having a thickness of 0.02 mm was wound around four places on the sample at an interval of about 50 mm and a length of about 10 mm. When an AC voltage of 60 Hz was applied between the conductor and the metal foil, breakdown occurred at 1000 V. Further, when the conductivity was measured, it was maintained at 91%.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 core material 2 niobium layer 3 oxidation-resistant metal layer 4 insulating ceramic layer

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-192214 (JP, A) JP-A-3-15113 (JP, A) JP-A-49-27487 (JP, A) Jiko 50- 16230 (JP, Y1) (58) Field surveyed (Int. Cl. ⁷ , DB name) H01B 7/02 H01B 7/28 H01B 7/29

Claims (7)

(57) [Claims] 1. A core member made of copper or a copper alloy, a niobium layer provided on an outer surface of the core member, an oxidation-resistant metal layer provided on an outer surface of the niobium layer, and the oxidation-resistant metal layer Chromium oxide formed on the outer surface of
Layered and the oxidation by heat treatment of the ceramic precursor solution
An insulated wire comprising: an insulating ceramic layer formed on an outer surface of a chromium-containing layer. 2. The chromium oxide-containing layer according to claim 1 , wherein
Claims that are formed by electroplating on the surface of the metal layer
Item 2. The insulated wire according to item 1. 3. The oxidation-resistant metal layer is made of nickel,
Aluminum, platinum, silver, nickel alloy, chrome alloy
Gold, aluminum alloy, platinum alloy, silver alloy or stainless steel
The insulated wire according to claim 1, wherein 4. A core material made of copper or a copper alloy, a niobium layer provided on an outer surface of the core material, an oxidation-resistant metal layer provided on an outer surface of the niobium layer, and a ceramic precursor solution. The acid resistance by heat treatment
Ceramics layer formed on outer surface of plasticizable metal layer
With the door, the oxidation-resistant metal layer is aluminum or an aluminum
Made of an alloy, wherein the surface of the oxidation-resistant metal layer is anodized.
Insulated wires. 5. The method according to claim 1, wherein the precursor of the ceramic is a metal alloy.
Coxide, metal organic acid salt, polysilazane, polycarbo
A silane or a polyborosiloxane.
5. The insulated wire according to any one of items 4 to 5. 6. The insulating ceramic layer comprises silica,
Alumina, zirconia, silicon nitride, silicon carbide, nitride
Aluminum or mixtures or partially stable
The method according to any one of claims 1 to 4, comprising zirconia fluoride.
Insulated wire. 7. A ceramic precursor solution, comprising :
5. Any of claims 1-4, wherein Lamix microparticles are dispersed.
Or the insulated wire according to claim 1.