JPH02215010A - Insulated electric wire - Google Patents

Abstract

PURPOSE:To improve insulating capacity and elasticity under high temperature environments and eliminate the necessity for a gas absorption source by a method wherein an insulated electric wire is constituted of a base material, an aluminum anode oxide layer and an oxide insulating layer. CONSTITUTION:An anode oxide coating 2 is formed on an aluminum layer 1 or an aluminum alloy layer 1, while on the anode oxide coating 2 an insulating oxide coating 3 is formed by means of the sol-gel method being a solution method. The sol-gel method refers to a method wherein solution obtained by hydrolyzing and dehydratingly condensing alkoxide is applied on an outer surface to be formed and a film is formed from the solution, while a film 3 formed by the sol-gel method is ceramic oxide. This provides heat-resistant insulation capacity as well as good elasticity while eliminating the necessity of a gas absorption source.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to insulated wires, and particularly to wiring wires used in high vacuum environments such as high vacuum equipment and high temperature equipment, or in high temperature environments. This relates to insulated wires such as winding wires and winding wires.

[Prior Art] Insulated wires are sometimes used in equipment that requires safety under high temperatures, such as heating equipment and fire alarms. Insulated wires are also used in environments that are heated to high temperatures inside automobiles. As such insulated wire,
2. Description of the Related Art Insulated wires in which a conductor is coated with a heat-resistant organic resin such as polyimide or fluororesin have been conventionally used.

When used in applications that require high heat resistance or in environments that require a high degree of vacuum, organic coating alone is insufficient.
It is insufficient in terms of heat resistance, gas release properties, etc. Therefore, we have developed insulated wires in which the conductor is passed through a ceramic insulator tube, and insulated wires in which the conductor is passed through a tube made of a heat-resistant alloy made of stainless steel or other alloy filled with fine particles of metal oxide such as magnesium oxide. M1 cable (Mineral
In5lated Cable) and the like have been used for such purposes.

Examples of insulated wires that require flexibility as well as heat resistance include glass braided insulated wires that use woven glass fibers as an insulating member.

[Problems to be Solved by the Invention] In an insulated wire coated with a heat-resistant organic resin as described above, the highest temperature at which insulation can be maintained is about 200°C at most. Therefore, it has not been possible to use such organic insulated wires in applications where insulation is required to be guaranteed at high temperatures of 200° C. or higher.

Furthermore, insulated wires whose heat resistance is improved by using ceramic insulator tubes have drawbacks such as poor flexibility. M
1. Since the cable is composed of a heat-resistant alloy tube and a conductor, the outer diameter of the cable is large. Therefore, M.I.
The cable has a relatively large cross-section compared to the amount of power that the conductor passing within the heat-resistant alloy tube can tolerate. Furthermore, since the outer layer of the M1 cable is made of a heat-resistant alloy tube, it has good flexibility.

However, in order to use the tube as a winding wire that is wound into a coil around a bobbin or the like, it is necessary to bend the tube made of a heat-resistant alloy at a predetermined curvature. At this time, the bending process performed on the tube made of heat-resistant alloy is difficult. Furthermore, when winding an M* cable into a coil, the outer layer of the tube is thicker than the conductor, so it is difficult to improve the winding density.

Furthermore, when using a glass braided insulated wire that is flexible and heat resistant, there is a problem in that glass dust is generated from the glass fibers when the wire is arranged in a predetermined shape depending on the application. This glass dust can be a source of gas adsorption. Therefore, when a glass braided insulated wire is used in an environment that requires a high degree of vacuum, it has been impossible to maintain a high degree of vacuum because of the gas adsorption source provided by the glass dust.

Therefore, the present invention was made to solve the above problems, and an object of the present invention is to provide an insulated wire having the following features.

(a) Must have high insulation properties in high temperature environments.

(b) Excellent flexibility.

(C) Not equipped with a gas adsorption source.

[Means for Solving the Problems] An insulated wire according to the present invention includes a base material, an anodized layer,
and an oxide insulating layer. The base material includes a conductor and has at least one of an aluminum layer and an aluminum alloy layer on its outer surface. An anodized layer is formed on the surface layer. The oxide insulating layer is
It is formed on an anodized layer by a sol-gel method.

The core material of the base material may contain copper. At this time,
Preferably, the base material is produced by a pipe fitting method.

Preferably, the oxide insulating layer contains silicon oxide or aluminum oxide.

[Effect 1 of the invention] In this invention, an anodic oxide film is formed on an aluminum layer or an aluminum alloy layer, and an insulating oxide film is formed on the anodic oxide film by a sol-gel method, which is a solution method. It is formed.

The insulating oxide film is formed by a sol-gel method. The sol-gel method involves applying a solution of hydrolyzed and dehydrated alkoxide to the outer surface to be formed.
This method forms a film from the solution. The film formed by the sol-gel method is a ceramicized oxide. This oxide is preferably formed by heat treatment in an atmosphere of oxygen flow in a sol-gel method. The oxide insulating layer made into a ceramic in this manner exhibits excellent heat-resistant insulation even at high temperatures of 500° C. or higher.

The anodic oxide film firmly adheres to the aluminum layer or aluminum alloy layer. Further, this anodic oxide film exhibits a certain degree of insulation as an insulator. However, the anodic oxide film has a highly uneven surface. Therefore, the outer surface of the anodic oxide film has a large surface area and provides a source of gas adsorption. Therefore, a conductor having only an anodic oxide film formed on its outer surface cannot be used in an environment where a high degree of vacuum is required.

Further, the anodic oxide film has porosity, and there are a large number of pores that penetrate from the surface to the base material.

Therefore, it is often impossible to obtain insulation properties proportional to the thickness of the anodic oxide film.

Therefore, the present invention has discovered that if an oxide film is formed on the outer surface of the anodic oxide film using a sol-gel method, the pores in the anodic oxide film can be filled and the surface can be smoothed. As a result, a high dielectric breakdown voltage proportional to the film thickness can be obtained, and by reducing the outer surface area, the number of gas adsorption sources can be reduced.

Furthermore, the anodic oxide film has excellent adhesion to at least the aluminum layer or aluminum alloy layer that constitutes the outer surface of the base material. Therefore, the adhesion between the oxide film and the outer surface of the base material is improved compared to the case where the oxide film is directly formed on the outer surface of the conductor by the sol-gel method. Therefore, the insulated wire provided by the present invention has heat-resistant insulation and good flexibility.

[Examples] Example 1 (a) Formation of anodic oxide film A pure aluminum wire with a wire diameter of 2 mmφ was immersed in 23% by weight dilute sulfuric acid maintained at a temperature of 38°C. After that, a positive voltage was applied to the aluminum wire, and the bath current was 2.5A/d.
The outer surface of the pure aluminum wire was anodized for 20 minutes under conditions of m2. In this way, an anodic oxide film with a thickness of about 20 μm was formed on the outer surface of the pure aluminum wire. The obtained wire rod was dried in an oxygen stream at a temperature of 500°C.

(b) Preparation of coating solution used in sol-gel method Tetrabutyl orthosilicate: Water: Ethanol-8:
To a solution mixed at a molar ratio of 32:60, 1.2N concentrated nitric acid was added at a ratio of 1/100 mole to tetrabutyl orthosilicate.

Thereafter, this solution was heated and stirred at a temperature of 70° C. for 2 hours. Thereby, a coating solution used in the sol-gel method was synthesized.

(C) Coating The wire rod obtained by (a) was immersed in the coating solution of (b). The wire rod whose outer surface was coated with the coating solution in this way was heated five times at a temperature of 400° C. for 10 minutes. Finally, this wire is heated to a temperature of 500°C.
The mixture was heated for 10 minutes in an oxygen stream.

The insulated wire thus obtained is shown in FIG. Figure 1 shows insulation according to the invention! ! ! It is a sectional view showing a cross section of a line. Referring to FIG. 1, an anodic oxide film 2 is formed on the outer surface of an aluminum wire 1. An oxide insulating layer 3 is formed on this anodic oxide film 2 by a sol-gel method. In the first embodiment described above, this oxide insulating layer 3 is silicon oxide. Further, according to Example 1, the thickness of the insulating layer composed of the anodic oxide film 2 and the oxide insulating layer 3 was about 40 μm.

In order to evaluate the insulation properties of the obtained insulated wire, the dielectric breakdown voltage was measured. At room temperature, its dielectric breakdown voltage is 1.6 kV, and at 600°C, it is 1.2 kV.
It was kV. In addition, on the outer peripheral surface of a cylinder with a diameter of 5 cm,
Even when this insulated wire was wound, no cracks occurred in the insulating layer.

Example 2 (a) Formation of anodic oxide film An aluminum/copper clad wire (pure copper) with a wire diameter of 1 mm in which the outer layer is an aluminum (material: JtS designation 1050) layer with a thickness of 100 μm and the core material is oxygen-free copper (OFC). The conductivity is 84% IAC9) when the conductivity of 100 is 3
The outer surface of the aluminum layer was anodized for 2 minutes at a temperature of 8° C. and 5 A/dm 2 . In this way, an anodic oxide film with a thickness of about 10 μm was formed on the surface of the aluminum/copper clad wire. The obtained wire rod was dried in an oxygen stream at a temperature of 500°C.

(b) Preparation of coating solution used in sol-gel method Tributylaluminum: Triethanolamine: Water:
The mixtures were mixed at a molar ratio of ethanol-3:9:81 at a temperature of about 5°C. Thereafter, this solution was heated and stirred at a temperature of 30° C. for 1 hour. Thereby, a coating solution used in the sol-gel method was synthesized.

(c) Coating A coating treatment was performed using the same method as in Example 1.

The insulated wire thus obtained is shown in FIG. FIG. 2 is a sectional view showing a cross section of an insulated wire according to the present invention. Referring to FIG. 2, the copper core wire 10
An aluminum/copper clad wire with an aluminum layer 11 on its outer surface was used as the substrate. An anodic oxide film 2 is formed on the outer surface of this aluminum layer 11.

An oxide insulating layer 3 is formed on this anodic oxide film 2 by a sol-gel method. In the above Example 2,
This oxide insulating layer 3 is aluminum oxide. Also,
According to the second embodiment, the anodic oxide film 2 and the oxide insulating layer 3
The thickness of the insulating layer formed by the above was about 20 μm.

In order to evaluate the insulation properties of the obtained insulated wire, the dielectric breakdown voltage was measured. At room temperature, its dielectric breakdown voltage is 1.5 kV, and at 500°C, i, o
It was kv. In addition, on the outer peripheral surface of a cylinder with a diameter of 3 cm,
Even when this insulated wire was wound, no cracks occurred in the insulating layer.

[Brief explanation of the drawing]

1 and 2 are sectional views showing a cross section of an insulated wire according to the present invention, corresponding to Example 1.2. In the figure, 1 is an aluminum wire, 2 is an anodic oxide film, and 3 is an aluminum wire.
10 is an oxide insulating layer, 10 is a copper core wire, and 11 is an aluminum layer.

Claims (4)

[Claims] (1) A base material containing a conductor and having either a surface layer of an aluminum layer or an aluminum alloy layer on at least its outer surface; an anodized layer formed on the surface layer; and a top of the anodized layer. and an oxide insulating layer formed by a sol-gel method. (2) The insulated wire according to claim 1, wherein the core material of the base material contains copper. (3) The insulated wire according to claim 2, wherein the base material includes a base material produced by a pipe fitting method. (4) The insulated wire according to claim 1, wherein the oxide insulating layer contains either silicon oxide or aluminum oxide.