JPH0475206A - Inorganic insulated wire - Google Patents

Abstract

PURPOSE:To improve corrosion resistance, an insulating property and flexibility by applying chemical conversion treatment to the surface of a conductive wire provided with an aluminium surface layer by means of an alcali silicate water solution in order to give a solution containing a ceramic precursor to pores of the chemical conversion coating. CONSTITUTION:An inorganic insulated wire 10 is provided with a heat-resisting aluminium alloy wire 11 such as an Al-0.05%Zr alloy wire. A chemical conversion coating 14 is formed on the surface of a heat--resisting aluminium alloy wire 11, further thereon an insulating ceramics layer 15 is formed. On an outer layer part or all over the chemical conversion coating 14, a sealing treatment layer 16 is formed by filling of insulating ceramics powder. In this way, insulation coating is composed only of an inorganic material so as to be excellent in heat resistance while having no deterioration in an insulating characteristic. Also, it has a big dielectric breakdown voltage while being excellent in flex ibility. Further, since the surface is smooth, there occures no problem of emission and adsorption of gas.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] This invention relates to inorganic insulated wires, and in particular, inorganic insulated wires that can be used in high temperature, high vacuum environments, radiation environments, or corrosive environments. It relates to insulated wires.

[Prior Art] Insulated wires conventionally used for internal wiring and windings in devices are mainly coated with organic materials, and for applications that require particularly high heat resistance, fluororesin is used. Electric wires coated with insulation such as polyimide or polyimide are used. However, even with such heat-resistant wires,
Its usage limit is about 300°C at most. Therefore, if such an electric wire is continued to be used above this temperature, the coating material may thermally decompose, resulting in dielectric breakdown.

For this reason, electric wires coated with inorganic materials, aluminum wires, alumite electric wires made by anodizing aluminum wires, electric wires whose conductors are coated with ceramics by vacuum evaporation, etc., are being considered.

In addition, in semiconductor manufacturing equipment, high-vacuum equipment used for high-energy experiments, plasma experiments, etc., because decomposed gases generated from organic materials are disliked, conductors are simply passed through ceramic insulators, or glass tape is applied to the conductors. A rolled one is used.

In addition, in environments where radiation exists or corrosive environments such as acid or alkali, MI cables (MI cables) in which the conductor is passed through a heat-resistant alloy pipe such as stainless steel while insulating it with insulating metal oxide particles ( Mineral In5ula
ted Cable) is used.

[Problems to be Solved by the Invention] However, the above-mentioned electric wires coated with inorganic materials have various problems.

For example, anodized aluminum wire must be anodized thickly to obtain a high dielectric breakdown voltage, but wires that have been anodized this thick are not flexible and can crack when bent. , causing dielectric breakdown. On the other hand, if the material is thin (anodized) to increase flexibility, sufficient dielectric breakdown voltage cannot be obtained.

Furthermore, electric wires whose conductors are coated with ceramics using a vacuum evaporation method or the like cannot be bent because the adhesion of the coating film is small.

Furthermore, wires that are passed through ceramic insulators or wrapped with glass tape have the trouble of having to be manually processed.

Furthermore, MI cables generally have a large wire diameter, so they are less compact and less flexible.

Furthermore, as mentioned above, when organic materials are used as insulation coatings, gas release due to thermal decomposition becomes a problem, especially in high vacuum. If it has a surface, gas adsorption becomes a problem.

Therefore, an object of the present invention is to provide an inorganic insulated wire that can solve the conventional problems as described above.

[Means for Solving the Problems] The present invention is directed to an inorganic insulated wire including a conductor wire comprising aluminum or an aluminum alloy in at least a surface layer. It is characterized by adopting the following configuration.

That is, the insulating coating includes an insulating and porous chemical conversion coating formed by chemically treating the surface of the conductor wire with an aqueous alkali silicate solution, an insulating ceramic powder filled in the pores of the chemical conversion coating, and the chemical conversion coating. It is composed of an insulating ceramic layer formed by applying a solution containing a ceramic precursor onto the film and converting it into ceramic.

[Function] A chemical conversion film is formed on the surface of aluminum or aluminum alloy by chemically treating the surface of the conductor wire with an aqueous alkali silicate solution. Therefore, between such a chemical conversion film and the conductor wire, , no problems with adhesion arise.

As a liquid for chemical conversion treatment, 20 to 6 as 5i02
It is preferable to use an aqueous alkali silicate solution containing 0 g/l. This is because if it is less than 20 g/L, reaction with aluminum is difficult to occur, and if it is too much, the reaction will be saturated, so 60 g/L or less is sufficient. The conductor wire to be treated is immersed in this liquid for several minutes. Considering the reactivity, the temperature of the treatment liquid is suitably 40 to 120°C.

At lower temperatures, the reaction slows down, and at higher temperatures,
This is because softening of aluminum becomes a problem. Incidentally, if the treatment time is increased, the treatment can be carried out satisfactorily even at a low temperature, but this is not preferable because the production rate will decrease. Therefore,
The appropriate treatment time is, for example, 1 to 30 minutes.

The chemical conversion film formed by the above-mentioned chemical conversion treatment has aluminum oxide and silicon oxide as main components, and preferably aluminum oxide accounts for 70 to 100 wt% and silicon oxide accounts for 0 to 30 wt%, respectively. Ru. Although the thickness of the film can be controlled by the processing time, for example, if the film is thickened by processing for a long time, a reduction in the cross-sectional area of the conductor becomes a problem. Furthermore, as the thickness of the film increases, deterioration of flexibility also becomes a problem. Therefore, it is preferable to suppress the thickness of the chemical conversion film to 100 μm or less.

The chemical conversion film formed in this way is an insulator,
It also exhibits some degree of corrosion resistance. However, since chemical conversion coatings are porous, they cannot be said to be sufficient in terms of insulation and corrosion resistance. In addition, the pores present in the chemical conversion coating tend to adsorb various gases, so it is not preferable to use it in a high vacuum. Therefore, in order to close such holes, insulating ceramic powder is filled into the holes.

As described above, a powder electrodeposition method is applied to fill the pores of the chemical conversion coating with insulating ceramic powder. Insulating ceramic powders that can be used include Al2
03, AIN, BN% StO2, 5iCSSi3 N
4. There are powders such as TiO2 and ZrO2.

In this way, by filling the pores of the chemical conversion coating with insulating ceramic powder, the pores almost disappear, and corrosion resistance is considerably improved, as well as improved insulation properties.

Furthermore, an insulating ceramic layer is formed on the chemical conversion coating in order to compensate for the retention of the insulating ceramic powder in the pores as described above. As a result, the surface of the obtained inorganic insulated wire is further smoothed. This insulating ceramic layer is formed by applying a solution containing a ceramic precursor onto the chemical conversion film and turning it into a ceramic.
A solution containing a metal alkoxide or a metal carboxylic acid ester containing one or more metals selected from the group consisting of Si, Al5Ti, Zr, and Mg is used, or an aqueous solution that dissolves water glass is used. Since the ceramic layer and the chemical conversion coating are made of substantially the same material, there is no problem in terms of adhesion.

The inorganic insulated wire thus formed has excellent corrosion resistance, insulation, flexibility, etc., and has a smooth surface.

[Example] FIG. 1 shows an inorganic insulated wire 1 according to an example of the present invention.
0 is shown in cross-section.

Referring to FIG. 1, the inorganic insulated wire 10 is made of Al-0,0
A heat-resistant aluminum alloy wire 11 such as a 5% Zr alloy wire is provided. A chemical conversion coating 14 is formed on the surface of the heat-resistant aluminum alloy wire 11, and an insulating ceramic layer 15 is further formed thereon. The outer layer portion or the entirety of the chemical conversion film 14 is filled with insulating ceramic powder, thereby forming the pore sealing layer 16 .

FIG. 2 shows an inorganic insulated wire 2 according to another embodiment of the present invention.
FIG.

Referring to FIG. 2, the inorganic insulated wire 20 includes an aluminum-covered copper conductor wire 21. As shown in FIG. This aluminum-clad copper conductor wire 21 is formed by fitting aluminum 23 to an oxygen-free copper wire 22. A chemical conversion film 24 is formed on the surface of the aluminum-covered copper conductor wire 21, and an insulating ceramic layer 25 is further formed thereon. Chemical conversion film 2
A sealing layer 26 is formed on the outside, main part, or the whole of 4 by filling with insulating ceramic powder.

FIG. 3 is a schematic diagram of an apparatus used to manufacture the above-mentioned inorganic insulated wire 10 or 20.

Referring to FIG. 3, the conductor wire 30 to be treated is supplied from a supply section 31 to a degreasing tank 32, where it is degreased. Subsequently, the conductor wire 30 to be treated introduced into the chemical conversion treatment tank 33 is
Processed in an aqueous alkali silicate solution kept at a constant temperature,
An insulating chemical conversion film is formed on the surface.

Thereafter, the conductor wire 30 to be processed is subjected to preliminary cleaning and main cleaning in cleaning tanks 36 and 37, respectively.

Next, insulating ceramic powder is electrophoretically deposited onto the conductor wire 30 to be processed in the electrodeposition tank 38 . More specifically, a mixture of acetone and water at a volume ratio of 10:1 was used as the dispersion medium for the insulating ceramic powder.
The ceramic powder is dispersed by a method such as mechanical stirring or air stirring. Iodine is added as a charging agent, a DC voltage is applied using a stainless steel plate or the like as an anode, ceramic powder is electrodeposited on the surface of the conductor wire 30 to be treated, and the chemical conversion coating is sealed. Note that since the pore diameter of the chemical conversion film formed by chemical conversion treatment is generally approximately 2 μm, it is desirable that the size of the insulating ceramic powder is 2 μm or less.

Next, the conductor wire 30 to be treated passes through a dryer 39, and a solution containing a ceramic precursor is applied onto the chemical conversion film in a coating tank 40. Next, in a baking tank 41, this is turned into a ceramic and insulating. A ceramic layer is formed.

The inorganic insulated wire 30a thus obtained is wound up by a winding machine 42.

Experimental examples carried out according to the present invention will be described below.

(Experimental Example 1) A JIS 1070 aluminum wire having a wire diameter of 0.5 mm was prepared and degreased using trichlene. Next, an aqueous alkali silicate solution kept at 80°C (35g/l as Si02, 8°5g/l as Li, 10g/l as Na) was added.
The aluminum wire was immersed for 5 minutes in 5 g/l (containing 5 g/l). Furthermore, pre-wash with warm water at 40°C for 5 minutes,
Next, after main washing with 80°C hot water for 15 minutes, 70°C
Dry thoroughly with warm air. An insulating chemical conversion film with a thickness of 10 μm was formed on the surface of the aluminum wire treated in this way.

Next, the following operation was performed to seal the pores of the porous chemical conversion coating described above with insulating ceramic powder. Acetone and water were mixed at a volume ratio of 10:1, and 50 g of SiC with an average particle size of 0.7 μm was added to this solution IL.
s 1 g of iodine was added, and the powder was electrodeposited in a bath with air agitation, using a stainless steel plate as an anode, and applying DC 150 V.

Next, the process of applying a solution containing a ceramic precursor to the outside of the above-mentioned chemical conversion film and heat-treating it at 500° C. for 10 minutes in the atmosphere was repeated five times. The coating solution used here was a solution obtained by reacting a mixed solution containing 5 mol% tributoxyaluminum, 10 mol% triethanolamine, 5 mol% water, and 80 mol% isopropyl alcohol at 50°C for 1 hour. Met.

The thickness of the final film formed through these processes is 1
It was 4 μm. In addition, when we measured the surface roughness of the film, we found that the Ra value specified by JIS was 0°09 μm6.For comparison, we measured the surface roughness immediately after chemical conversion treatment and found that the Ra value was 2 μm. It was found that the surface smoothness was significantly improved. Furthermore, the dielectric breakdown voltage of the obtained inorganic insulated wire was 950 V, and the bending diameter was 15 mm in terms of flexibility.

(Experimental Example 2) A wire made of a heat-resistant aluminum alloy and having a wire diameter of 1 mm was prepared. After degreasing this wire using trichlene,
Alkaline silicate aqueous solution (35g as SiO□) kept at ℃
/l, t, i: 12°8g/l, Na: 92g
/l) for 5 minutes. Next, it was preliminarily washed with hot water at 40°C for 5 minutes, then main washed with hot water at 80°C for 15 minutes, and then thoroughly dried with hot air at 70°C. A chemical conversion film with a thickness of 20 μm was formed on the surface of the wire treated in this way.

Next, the following operation was performed to seal the chemical conversion coating. Acetone and water were mixed at a volume ratio of 10:1, and to 1 ton of this solution was added 40 g of Al2O3 with an average particle size of 0.5 μm and 1 g of iodine. While applying
Electrodeposited powder.

Furthermore, on the outside of the chemical conversion film, commercially available water glass No. 3 was added for 10 minutes.
After applying the aqueous solution diluted to wt%, it was dried at room temperature, followed by 10 min at 70 °C and 30 min at 150 °C.
After each heat treatment for 1 minute, the operation of immersing the sample in a 10 wt % dilute nitric acid aqueous solution for 5 minutes was repeated twice.

The thickness of the final film formed through these processes is 1
The surface roughness of the film was 0.08 μm in Ra value according to JIS. For comparison, the surface roughness immediately after the chemical conversion treatment was found to have an Ra value of 2 μm, indicating a significant improvement in smoothness. Further, the dielectric breakdown voltage of the obtained inorganic insulated wire was 100 OV, and the bending diameter of the wire was 20 mm.

(Experiment Example 3) On the outside of the heat-resistant aluminum alloy, 1050 according to JIS
Wire diameter 1mm coated with aluminum with a thickness of 80μm
I prepared a line. After degreasing this wire using trichlene, it was immersed for 5 minutes in an aqueous alkali silicate solution (containing 35 g/l as SiO2, 8.5 g/L as Li, and 105 g/L as Na) maintained at 80°C. next,
After pre-washing with 40°C hot water for 5 minutes, then main washing with 80°C hot water for 15 minutes, it was thoroughly dried with 70°C hot air. The surface of the wire treated in this way has a thickness of 10 μm.
A chemical conversion film was formed.

As a pore sealing treatment for this chemical conversion film, the following operation was performed.

Mix acetone and water at a volume ratio of 10:1, and add this solution IL
To this, 30 g of BN with an average particle size of 0.5 μm and 1 g of iodine were added, and the powder was electrodeposited in an air-stirred bath while applying DC 150 V using a stainless steel plate as an anode.

Furthermore, the process of applying a solution containing a ceramic precursor to the outside of this chemical conversion film and heat-treating it at 500° C. for 10 minutes in the air was repeated seven times.

The coating liquid used here was a toluene solution of zirconium naphthenate (4% Zr), which is commercially available under the trade name "Zirconium Naphthenate" manufactured by Nihon Kagaku Sangyo Co., Ltd.
It was diluted twice with toluene and stirred day and night.

The thickness of the final film formed through these processes is 1
The surface roughness of the film was 0.07 μm in Ra value specified by JIS.

For comparison, the surface roughness immediately after chemical conversion treatment has an Ra value of 2μ.
It was found that the surface smoothness was significantly improved. Further, the dielectric breakdown voltage of the obtained inorganic insulated wire was 850 V, and the bending diameter was 15 mm in terms of flexibility.

(Experimental Example 4) A wire having a wire diameter of 1 mm and having a thickness of 84 μm coated with 1050 aluminum according to JIS was prepared on the outside of oxygen-free copper. After degreasing this wire using trichlene, it was heated to 80°C.
Alkaline silicate aqueous solution (35g/Si02) maintained at
12°8g/l as Li, 92g/l as Na
(containing) for 5 minutes. Next, it was preliminarily washed with 40°C hot water for 5 minutes, then main washed with 80°C hot water for 30 minutes, and then thoroughly dried with 70°C warm air.

Next, the following operation was performed to seal the chemical conversion coating thus obtained. Volume ratio of acetone and water is 10
: 1, and the average particle size is 0.7μ for this solution 11.
50 g of 1 g of iodine and 1 g of iodine were added, and the powder was electrodeposited in an air-stirred atmosphere using a stainless steel plate as an anode while applying DC 150 V.

Furthermore, the process of applying a solution containing a ceramic precursor to the outside of this chemical conversion film and heat-treating it at 350° C. for 20 minutes in the atmosphere was repeated five times.

The coating solution used here was a mixed solution containing 8 mol% of tetrabutyl orthosilicate, 32 mol% of water, and 60 mol% of isopropyl alcohol, and 3/100 of nitric acid based on the number of moles of tetrabutyl orthosilicate. The solution was added dropwise in an amount of 100 ml and reacted at 80° C. for 2 hours.

The thickness of the final film formed through these processes is 1
5 μm, and the surface roughness of the film was 0.09 μm in Ra value specified by JIS. For comparison, the surface roughness immediately after the chemical conversion treatment was 2 μm in terms of Ra value, indicating that the surface smoothness was significantly improved.

Furthermore, the breakdown voltage of the obtained inorganic insulated wire was 900v.
In terms of flexibility, the bending diameter is 15mm.
I was able to achieve this.

[Effects of the Invention] As described above, according to the present invention, the insulating coating is composed only of inorganic materials, so it has excellent heat resistance, and therefore does not thermally decompose even at high temperatures. There is no deterioration in characteristics. Furthermore, it has a high dielectric breakdown voltage and excellent flexibility. Furthermore, since the surface is smooth, there are no problems with gas release or adsorption.

[Brief explanation of the drawing]

FIG. 1 shows an inorganic insulated wire 10 according to an embodiment of the present invention.
FIG. FIG. 2 shows an inorganic insulated wire 2 according to another embodiment of the present invention.
FIG. FIG. 3 is a schematic diagram of an apparatus used for manufacturing an inorganic insulated wire 30a according to the present invention. In the figure, 10.20.30a is an inorganic insulated wire, 11
is heat-resistant aluminum alloy wire, 23 is aluminum, 14
．． 24 is a chemical conversion coating, 15.25 is an insulating ceramic layer, 16.26 is a sealing treatment layer, 21 is an aluminum-clad copper conductor wire, 22 is an oxygen-free copper wire, 30 is a conductor wire to be treated, and 33 is a chemical conversion treatment tank. , 38 is an electrodeposition tank, 40 is a coating tank, 4
1 is a baking tank.

Claims (6)

[Claims] (1) A conductor wire having at least a surface layer made of aluminum or an alloy of aluminum, an insulating and porous chemical conversion coating formed by chemical conversion treatment of the surface of the conductor wire with an aqueous alkali silicate solution, and pores in the chemical conversion coating. An inorganic insulated wire, comprising: an insulating ceramic powder filled with an insulating ceramic powder; and an insulating ceramic layer formed by applying a solution containing a ceramic precursor onto the chemical conversion coating and converting it into a ceramic. (2) The aqueous alkali silicate solution contains 20 to 60 g/l of silicic acid as SiO_2, and has a temperature of 40 to 12 g/l.
The chemical conversion film is maintained at 0°C, and the main components are aluminum oxide and silicon oxide, with aluminum oxide being 70 to 100 wt% of the film, and silicon oxide being 0 to 30 wt% of the film.
2. The inorganic insulated wire according to claim 1, wherein the inorganic insulated wire occupies . (3) The insulating ceramic powder is Al_2O_3
, AlN, BN, SiO_2, SiC, Si_3N_4
, TiO_2, and ZrO_2. (4) The inorganic insulated wire according to any one of claims 1 to 3, wherein the insulating ceramic powder is filled into the holes by a powder electrodeposition method. (5) The solution containing the ceramics precursor contains Si, A
5. The inorganic insulated wire according to claim 1, wherein the inorganic insulated wire is a solution containing a metal alkoxide or a metal carboxylic acid ester containing one or more metals selected from the group consisting of Zr, Ti, Zr, and Mg. (6) The inorganic insulated wire according to any one of claims 1 to 4, wherein the solution containing the ceramic precursor is an aqueous solution that dissolves water glass.