JPH05205534A - Heat resistive insulated wire - Google Patents

Abstract

PURPOSE:To provide a heat resistive insulated wire, capable of being used under a high temperature of 300-600 deg.C such as used in a liquid sodium dipping type non-cooled electromagnetic pump, whose breakdown voltage is high and flexibility is excellent, and which has excellent characteristics even against heat cycles, and capable of being used even under a radiation environment for a long time. CONSTITUTION:A metal plated layer is provided on the outer periphery of a copper-based metal wire so as to form a conductor 1, and subsequently an inorganic reinforcing material is cladded onto the conductor with an inorganic polymer thereby forming a mica insulating layer 2, and further a reinforcing layer 3 braded and armored by an inorganic fiber is provided thereon followed by baking so as to turn the inorganic polymer into a ceramic.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an electromagnetic pump, such as an electromagnetic pump for circulating liquid sodium in a fast breeder reactor.
The present invention relates to a heat-resistant insulated electric wire for electric equipment used at a high temperature of 600 ° C.

[0002]

2. Description of the Related Art Conventionally, as heat-resistant insulated wires that can be used at high temperatures of 300 ° C. or higher, conductors on which ceramic or inorganic paint has been baked have been known.
Since a powdery inorganic layer is formed on the surface, the exposed powdery inorganic layer gradually powders and falls loose and collapses after long-term use, so it cannot be used stably for a long time ..

Further, since a too thick inorganic layer cannot be formed, the dielectric breakdown voltage is low and it cannot be used for lead wires of high voltage equipment. Especially, like the coil connection wire of the liquid sodium immersion cooling electromagnetic pump used for the cooling system of the fast breeder reactor, a heat resistant temperature of 600 ° C and a high voltage of several kv are applied, and the heat resistant insulated wire is used to crawl while bending a narrow space. Not applicable to.

[0004]

Therefore, in the case of a heat-resistant high-voltage electric wire, it is necessary to heat-mold an insulating tape or mica tape using an inorganic polymer or an inorganic adhesive and then bake it to form a safely inorganicized insulation. Can be considered. However, since the electric wire that is entirely hardened with an adhesive in this way is poor in flexibility, cracks occur in the insulation due to thermal stress due to the difference in thermal expansion between the metal conductor and the inorganic insulating material when the equipment is repeatedly operated and stopped. However, the insulation performance deteriorates. In addition, the insulating layer may be cracked by electromagnetic vibration. In particular, such a phenomenon is likely to occur in a large-capacity machine such as a liquid sodium immersion type uncooled electromagnetic pump used in the primary cooling system of a fast breeder reactor, or a device used at a higher temperature. Further, glass is generally used as a coating material for insulated wires for high temperatures, but the strength is remarkably reduced when the temperature exceeds 500 ° C., and when neutrons are irradiated, the strength is also lowered due to the influence of boron as a contained component. .. Therefore, it is not suitable for use near the reactor.

Therefore, for example, a device used at a high temperature of 300 ° C. to 600 ° C., such as a liquid sodium immersion type uncooled electromagnetic pump for circulating liquid sodium in a fast breeder reactor,
It has been desired to develop a heat-resistant insulated wire that has a high dielectric breakdown voltage, excellent flexibility, and excellent heat cycle characteristics and can withstand long-term use in a radiation environment.

The present invention has been made in order to meet such a demand, and an object of the present invention is to provide a heat-resistant insulated wire having a conductor and an insulating coating that can be used at a high temperature of about 300 ° C to 600 ° C. ..

[0007]

The heat-resistant insulated electric wire of the present invention is provided with a metal plating layer, which is less likely to be oxidized than copper at high temperature, on the outer periphery of a copper-based metal wire having good heat resistance. Wrap a mica tape made by bonding an inorganic reinforcing material with an adhesive made of an inorganic polymer or an inorganic coating, and then braid an inorganic fiber with high mechanical strength, excellent heat resistance, and no adhesive. After being packaged, it is characterized by being baked at a temperature of 300 ° C or higher to be inorganicized to form an insulating layer.

Examples of the copper-based metal wire having better heat resistance than copper used in the present invention include silver-filled copper, alumina dispersion strengthened copper, copper-chromium alloy, copper-zirconium alloy, copper-cadmium alloy, copper- Examples include various copper-based metal wires such as nickel alloys. Examples of the metal plating layer that is less likely to be oxidized than copper at high temperatures include gold, silver, platinum, nickel and the like. An inorganic filler may be added to the above-mentioned inorganic polymer or inorganic coating material.

Here, as the inorganic filler, alumina (Al ₂ O ₂ ), magnesia (NgO), silica (S
iO ₂ ), zirconia (ZrO ₂ ), steatite (M
gSiO ₂ ), clay, kaolin, mica powder, high melting point glass frit, etc. are included. The particle size of these fillers is preferably 10 μm or less in average particle size for easy mixing with the inorganic polymer and easy coating.

The term "inorganic polymer" is a general term for polymers that are mineralized by baking at high temperature. For example, an alkyl silicate type silicone AY49-208 (trade name of Toray Silicone Co.) and an inorganic filler-containing borosiloxane type are used. Includes paint SMR-109 (trade name of Showa Denko Denki Co., Ltd.) and pressure-sensitive adhesive YR3286 (trade name of Toshiba Silicone Co.) made of methylpolysiloxane. Further, inorganic coating materials include aluminum monophosphate, phosphates such as silicon phosphate, colloidal silica and colloidal alumina.

When a large amount of an inorganic filler is mixed with an inorganic polymer, it is generally thermally stable and the cost is low. However, since the filler itself does not bond by firing, it is necessary to add an inorganic polymer to the extent that a strong bond is formed by firing.

On the other hand, the blending of the inorganic filler and the inorganic polymer must be selected so that the coating will not be difficult and the composition will not become brittle after firing. Usually, the content of the inorganic filler is preferably about 10 to 90% by weight.

As a reinforcing material for the mica tape, a woven fabric or a non-woven fabric made of fibers having heat resistance and high mechanical strength such as alumina and silica is used. In the case of a woven cloth, in order to improve the thermal conductivity of the insulating layer, a woven cloth having a high fiber density is preferable. Generally, as a reinforcing material for mica tape, a thin tape having a thickness of about 30 to 400 μm has a higher space factor of the mica layer and a larger dielectric breakdown voltage per unit thickness, which is advantageous in insulation design. Further, as the inorganic fibers forming the surface braid, fibers having heat resistance and high mechanical strength such as alumina and silica are used.

[0014]

In the heat-resistant insulated electric wire of the present invention thus constructed, a copper-based metal wire having a higher heat resistance than copper is used as a conductor, so that it has a high conductivity even at high temperatures and is excellent in durability. .. Furthermore, a metal plating layer of gold, silver, platinum, nickel or the like, which is not easily oxidized at high temperature, is provided on the outer periphery of the copper-based metal wire, and the copper-based metal wire does not come into direct contact with oxygen, so that it is not oxidized at high temperature, The durability is further improved.

The reason why the mica tape is used here is that mica has high heat resistance and excellent dielectric breakdown voltage and withstand voltage. The mica tape is used near the conductor because the material near the conductor has a higher electric field and a higher withstand voltage, so that the life can be extended.

Since the mica tape has excellent electrical characteristics but is slightly inferior in mechanical strength, a heat-resistant inorganic insulating tape having high mechanical strength is wound on the mica tape inferior in mechanical strength, By pressing down, the mica tape can be prevented from falling apart.

The mica tape is wound and baked while being coated with an inorganic polymer containing an inorganic filler or an inorganic coating material, because the conductor and the mica tape and the mica tapes are adhered to each other to form a strong insulating layer. This is because it is possible to form

Since mica is highly cleavable, the thermal stress due to the heat cycle associated with the operation / stop of the equipment is absorbed by the displacement of the mica layer. Therefore, even if it is fired with an inorganic polymer or an inorganic coating material to be hardened firmly, cracks do not occur.

On the other hand, the braid of the inorganic fibers wound on the surface absorbs the thermal stress due to the heat cycle by itself because it is not coated with the adhesive. Therefore, the braid does not break.

When the heat resistant insulated wire of the present invention is used at a high temperature of about 300 ° C., soft mica is preferable to hard mica as mica. This is because soft mica has a higher crystallization water release temperature and higher heat resistance than hard mica. Further, the boron component in the inorganic fiber accelerates radiation deterioration, so the smaller the content, the better.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, a conductor 1 is formed by twisting 19 fine wires of alumina-dispersion-strengthened copper (trade name: Glid cop AL-15, manufactured by Gliden Metal Co.) plated with nickel and having a diameter of 0.5 mm. A mica tape composed of a 50 μm-thick alumina cloth not containing a boron component and a 100 μm-thick soft unfired laminated mica sheet bonded to the outer periphery with a small amount of silicone (for example, YS3286 manufactured by Toshiba Silicone Co., Ltd.) as an adhesive agent. , An alkyl silicate-based inorganic polymer containing an inorganic filler (trade name AY49-208 manufactured by Toray Silicone Co., Ltd.
2) was applied to the mica insulating layer 2 by applying a double winding. Further, a double braid was applied on this with an alumina yarn containing no boron component without applying an adhesive to form a reinforcing layer 3. This was baked at 600 ° C. for 4 hours to obtain a heat resistant insulated wire.

In order to test the electric insulation performance of the heat-resistant insulated wire, the heat-resistant insulated wire of this example was exposed to nitrogen gas at 600 ° C. for 2 hours.
After being maintained for a month, the breakdown voltage remained 90% of the initial value even after two months. The nickel-plated layer was not peeled off from the alumina dispersion-strengthened copper, and the alumina dispersion-strengthened copper was not oxidized. Next, in order to test the flexibility, before firing the heat-resistant insulated electric wire of the example, the electric wire was wound on a mandrel having a diameter 5 times the diameter of the electric wire, and then fired at 600 ° C. for 4 hours. This electric wire is 600 ℃
When kept in nitrogen gas for 2 months, the breakdown voltage was maintained at 85% of the initial value and almost no thermal deterioration was observed. Moreover, almost no decrease in the strength of the conductor was observed.

In the above embodiment, an example of using an insulated electric wire using a stranded wire conductor has been described, but the present invention should not be limited to such an embodiment, and a rectangular wire may be used. Similarly, an insulated wire using a conductor having a non-circular cross section can be used as well.

[0025]

As described above, the heat-resistant insulated wire of the present invention has a conductor having excellent electrical performance and heat resistance, which has a plated layer having excellent antioxidation property, and a high breakdown voltage, heat resistance,
Since it is composed of an insulating layer with excellent mechanical properties,
There is almost no deterioration in performance even after long-term use at high temperature. Therefore, it has excellent performance as a heat resistant insulated wire used at a high temperature of about 300 ° C to 600 ° C.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a heat resistant insulated wire of the present invention.

[Explanation of symbols]

 1 ... Conductor 3 ... Reinforcing layer 2 ... Mica insulating layer

Claims (3)

[Claims] 1. A mica tape obtained by providing a metal plating layer which is resistant to oxidation at high temperature on the outer periphery of a copper-based metal wire having good heat resistance, and bonding an inorganic reinforcing material with an inorganic polymer on the metal plating layer. A heat-resistant insulated electric wire, characterized in that it is obtained by winding the above, further braiding it with an inorganic fiber having no adhesive, and converting the inorganic polymer into a ceramic. 2. The heat-resistant insulated wire according to claim 1, wherein the inorganic reinforcing material and the inorganic fiber are ceramic fibers which do not contain boron or contain a trace amount thereof in a range not deteriorating radiation resistance. 3. The heat resistant insulated wire according to claim 1, wherein alumina dispersion strengthened copper is used as the copper-based metal wire.