JPS5916367B2 - Silicon carbide composite electrical contact material and its manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a silicon carbide composite electrical contact material and a method for manufacturing the same.

In general, electrical contact materials (hereinafter simply referred to as contact materials) are required to have low wear during use, low and stable contact resistance, and excellent welding resistance.

The following materials are used as actual contact materials, and each has its own advantages and disadvantages. Silver has the highest electrical and thermal conductivity, can be easily deformed into contacts of various shapes, and can maintain low contact resistance for long periods of time; however, the disadvantage of silver is that its melting point is 960°C.
It has low hardness, low hardness, and tends to form a sulfide film.

These drawbacks include copper, cadmium, nickel, manganese,
It can be reduced by alloying elements such as palladium. Furthermore, platinum, palladium, gold, and their alloys are resistant to oxidation caused by localized high temperatures caused by arcs, and have the characteristic of maintaining low contact resistance for a long period of time. To ensure that the above advantages are not lost, other platinum metal elements such as iridium, lutetium, osmium, and rhodium are used as alloying elements, but silver, gold,
Baladium is also often alloyed. Palladium is the closest to platinum among the white metals, and is particularly resistant to sulfurization (tungsten has the highest melting point, so there is no need to worry about it melting or boiling between "cut" and "turn on", and it can be used in arcs. It has strong characteristics against

Molybdenum has a deafness between that of silver and tungsten, and is used as a substitute for silver when wear resistance is required, and as a substitute for tungsten when low contact resistance is required.
・Can be done. In addition to the above, Afl is used as an Ag-based contact material.
r-Ni (Ni5f! or less), Ag-Cd; Cu-Cd. ．． Cu-Be (B5% or less)
, Cu-Pb, Cu-Bi, Cu-Sn (Sn+8(F
6), Cu-Zn (Zn+35%); Au-based contact material;
As a Pt-based contact material, Pt-er(So(F.tO・~7
0%), Pt-0s-1r, . Pt-Rh,. Pt-R
h; Other contact materials include Re; etc. High (゛conductivity and resistant to melting) (・Contact materials include silver with high conductivity;L; There is a mixture of tungsten carbide and tungsten carbide that retains the characteristics of both after sintering. It is called a bonded metal contact material.

The contact materials listed above are selected depending on the current, voltage, etc. used, but materials whose main components are gold, silver, copper, etc., which are electrically conductive metals, are wear-resistant. On the other hand, platinum, palladium, iridium, rhodium, osmium, which are refractory metals, or alloys mainly composed of these metals have high wear resistance and low two-contact resistance (・However, the price is high (・There are drawbacks, and therefore its uses are limited.

In addition, as mentioned above, tungsten and molybdenum are used in various fields because they are difficult to melt and have low contact resistance, but they have the disadvantage of being expensive.For this reason, sintered alloy contact materials with high conductivity and difficult to melt are used. Although sintered tungsten or tungsten carbide has recently been developed, tungsten carbide is expensive, so the disadvantage is that the more tungsten carbide is added to strengthen the refractory arc resistance, the more expensive it becomes. In addition, combinations of silver or copper with nickel, cadmium oxide, graphite, etc. have better wear resistance than silver or copper alone and are used for various purposes, but they still have insufficient resistance. It takes a long time to demonstrate its abrasive properties (・na(・.

Although conventionally known contact materials have been used in fields where their unique characteristics suit the conditions of use, the present invention aims to create materials that can withstand long-term use and are inexpensive. In addition, it is inexpensive and durable enough for fields where the conditions of use have traditionally forced the use of expensive contact materials such as platinum, palladium, iridium, lutetium, rhodium, etc. Another object of the present invention is to provide a novel contact material.In order to achieve the above objects, the present invention provides a powder mainly composed of silicon carbide with ultrafine crystal particles.
The present invention aims to provide a new composite contact material in which fibers made of ultrafine packed crystal grain silicon carbide are combined with conventionally used contact materials.

Next, the present invention will be explained in detail.

Silicon carbide fibers that can be advantageously used in the present invention are disclosed in Japanese Patent Application No. 50-50529, Japanese Patent Publication No. 57-53891, which the present inventors have previously applied for,
No. 52471, JP-A-51-130324,
Japanese Patent Publication No. 52472, Japanese Patent Publication No. 57-53892, Japanese Patent Publication No. 58033, Japanese Patent Publication No. 149925-1980, Japanese Patent Publication No. 58034, Japanese Patent Publication No. 149926-1970, Japanese Patent Publication No. 70302, Japanese Patent Publication No. 57-53893 Publication No., same-
It can be produced according to the inventions disclosed in JMo V219 and Japanese Patent Publication No. 57-56566.

That is, a spun yarn made of an organosilicon polymer compound whose main skeleton components are carbon and silicon is heated at a low temperature in an oxidizing atmosphere, then preheated within a temperature range of 600 to 1000°C, and further heated in a vacuum ( is a silicon carbide fiber obtained by firing at a high temperature within the temperature range of 1000 to 2000°C in an atmosphere of one or more of the following selected from inert gas, CO gas, and hydrogen gas. Silicon carbide powder that can be advantageously used in the present invention is produced by preheating the organosilicon polymer compound having carbon and silicon as main skeleton components within a temperature range of 600 to 1000°C, and then heating it in a vacuum. (・ is a temperature selected from inert gas, CO gas, hydrogen gas, or 1
Silicon carbide powder is obtained by finely pulverizing a sintered lump obtained by sintering a seed or two or more kinds of materials in an atmosphere at a high temperature within a temperature range of 1000 to 2000° C. using an appropriate means.

In the present invention, when manufacturing the contact material of the present invention, when compounding silicon carbide powder or fibers, 10%
If the powder is heated above 00°C, it is not necessary to use high-temperature fired silicon carbide powder or fibers if there is a chance that the fibers will be heated; in such cases, preheated silicon carbide intermediates It is advantageous to use powdered fibers and heat them to 1000° C. or more for compounding, so that the intermediate can be made into powdered fibers made of SiC microcrystals.

In particular, silicon carbide pre-fired intermediates are much easier to pulverize than silicon carbide high-temperature fired products, so they can be used advantageously.

The silicon carbide fibers that can be advantageously used in the present invention at a temperature of 0.degree. C. have properties as shown in Table 1 below.

The particle size of the crystal particles constituting the silicon carbide powder and fibers varies depending on the high-temperature firing temperature at which they are manufactured, and when this temperature is 1100°C, the average particle size is about 20°C.
λ, about 30λ at 1200°C, about 80λ at 1500°C, and as the firing temperature increases, the average grain size increases, but it is incomparably larger than the crystal grains constituting conventionally known SiC. Ultra-fine particles.

On the other hand, the tensile strength of silicon carbide fibers, for example, decreases when the firing temperature is high. These relationships are shown in FIGS. 1 and 2. In the present invention, the diameter of the silicon carbide fibers to be composited is preferably 20 to 100μ, and it can be used as a single fiber or as a twisted fiber.Silicon carbide powder is also preferably used. It is advantageous to use a fine powder of 300 mesh or less.In the present invention, the fibers are made of pure SiC.
You can use only 1, but also S
In addition to iC, silicon carbide powders containing up to about 20% free carbon and fibers can also be advantageously used.

Silicon carbide powder and fibers containing such free carbon can be freely carbonated by making the atmosphere in the final firing process close to non-oxidizing. In the present invention, when carbon-containing silicon carbide is combined with a base metal, for example, when the base metal is an element that combines with C to form a carbide, the free content in the carbon-containing silicon carbide can be adjusted. Carbon and base metal form carbides at the contact interface and form a strong bond, so using such a contact material increases wear resistance and arc resistance, and carbon-containing silicon carbide The higher the C content, the better the conductivity (
In this case, the contact resistance becomes smaller, which is advantageous.

However, silicon carbide containing a large amount of C has poor oxidation resistance and compression resistance, so it is advantageous for the C content to be 20% or less. Next, the structure of the contact material of the present invention will be described.

The contact material of the present invention can be a single element constituting the conventionally used contact material, or an alloy thereof, or a certain °C.
・ is a mixed sintered body of elements as a base, and this base is a base】0
0 parts by volume, 0.5 to 30 parts by volume of powder or fibers made of the ultra-fine grained silicon carbide are dispersed (* is a contact material formed by embedding.Next, first, silicon carbide fibers are composited. The structure and manufacturing method of the contact material will be explained below.

The contact material of the present invention can be manufactured by injecting and filling the molten metal of a conventional contact material into the gaps between the silicon carbide fiber aggregates.

In this case, as mentioned above, the silicon carbide fiber is not a fiber fired at a temperature of 1000°C or higher;
Fibers pre-fired at around 0°C can be used.

However, in this case, the temperature of the injected molten metal is preferably 1000° C. or higher, and during the pouring operation, the prefired fibers are fired to a temperature of 1000° C. or higher to become complete SiC microcrystals. In the present invention, the silicon carbide fibers are made of a metal or an alloy of the same type as the molten metal previously injected into the surface of the pre-sintered fibers, or a metal of a different type without impairing the properties of the base, which is a conventional contact material. This coating 4 is advantageous in that it can prevent the decomposition of SiC that may occur when molten metal is injected. Said coating may be applied by coating, vapor deposition, plating or any other suitable method. However, said coating does not decompose the SiC and is particularly intended to cause carbide formation between the free carbon in the silicon carbide fibers and the implanted metal. If you do, it's not worth doing (
・. The above-mentioned silicon carbide fiber aggregate may be one in which single fibers or braided fibers are stacked in parallel in a predetermined direction, vertically and horizontally, or non-directionally stacked in a random manner, either individually or in combination. I can do it.

Next, the composite contact material of the present invention in which silicon carbide powder is combined with the base contact material and the method for manufacturing the same will be explained.

In this case, unlike the case where the fibers are composited, it is preferable to perform an operation to uniformly disperse the fibers in the base.

For this reason, after the powder is added to the molten metal and until the molten metal solidifies, it is desirable to constantly stir the powder using an external force, and it is advantageous to use, for example, mechanical stirring, electric induction stirring, etc. as the external force. In the present invention, the composite contact material of the present invention can be obtained by composite sintering an alloy powder with a base metal and a silicon carbide powder. In addition to those that have been fired at a high temperature of 1,000°C or higher, the fibers can be prefired at a temperature range of about 600 to 1,000°C, and a final high-temperature firing can be performed, for example, at the same time as hot-breathing. The particle size of the silicon carbide powder used in the present invention is preferably 300 mesh or less. Therefore, in order to obtain such a fine powder, it is necessary to grind the high-temperature fired product to a fine powder as described above. It is easier to crush the pre-fired product into a fine powder.The sintered composite contact material of the present invention requires a sintering temperature higher than the temperature at which the base metal or alloy powder sinters. do.

A contact material made of a composite of silicon carbide powder of the present invention is formed after uniformly mixing the powder of the base contact material and the powder consisting of ultrafine SlC crystal particles with a binder whose main component is a liquid organosilicon polymer compound. , can be manufactured by pressure sintering.

Alternatively, it can be manufactured by filling the gaps between silicon carbide fiber aggregates with base contact material powder, impregnating it with a liquid organosilicon polymer compound, and then sintering it under pressure. The liquid organosilicon polymer compound used in the above production is one that mainly produces SiC when an organosilicon polymer compound whose main skeleton components are C and Si is fired at 1000°C or higher in a non-oxidizing atmosphere. If it is difficult to impregnate due to high viscosity (. If impregnation time is required, it can be dissolved in a suitable solvent and used at °C.).

Furthermore, it is advantageous to perform this impregnation step under reduced pressure and/or high pressure because the impregnating liquid can permeate into the interior in a short time. The contact material of the present invention includes a composite silicon carbide powder.The volume ratio of fibers must be within the range of 0.65 to 30 parts per 100 parts of base material metal volume.

If the temperature is less than 0.5 parts, there will be no combined effect, and if it exceeds 30 parts, the contact resistance will become too large.
It is necessary to keep it within the range of ~30 parts.

Next, the present invention will be explained with reference to examples.

Example 1 - 200 meshes of silver and tungsten (approximately 1.5μ
) Mix the powders uniformly at a ratio of 2:3 to approximately 12X30Tfm.
Silicon carbide fibers with a diameter of about 20μ are placed in a mesh mold at a volume ratio of 0.5' in the mixed powder.
16 (b), 2% 8, 10% (d) and 30% (e)
It is embedded and molded with a plane pressure of about 10t/Cd so that
Thickness number? For comparison, we also made a green compact (a) without silicon carbide fiber composite.

These compacts were sintered by heating and holding at 850°C for 1 hour in a hydrogen stream, and the density and electrical resistance of the obtained sintered alloy were measured.
A lifespan test was conducted using a strong current contact test method similar to 2).

The conditions were 60A, and the test results were shown in Table 2 and FIG. As is clear from Figure 3, compared to (a), (b), (
As the amount of silicon carbide fibers (c) and (d) increases, the amount of wear in a steady state of approximately 20,000 cycles or more decreases. However, compared to (d), the life of (e) mixed with 30(f) does not improve much, and on the contrary, as shown in Table 2, the electrical conductivity decreases considerably, making it undesirable as a contact material for this type of heavy load interruption. It turned out to be ℃. Example 2 200 meshes of copper and tungsten powder in a ratio of approximately 3:7
Silicon carbide fibers were mixed uniformly in the same proportion as in Example 1.
0% (1) and 30% (ri) uniformly embedded sintered alloys were made.

Silicon carbide fiber coated with alumina (10% mixed) was used as the material (8), and the temperature was 900°C during sintering.
After holding for 1 hour at 1100℃, just above the melting point of copper.
Two-stage sintering method (in vacuum ≦10-4 mHV
). The same density, electrical resistance and life tests as in Example 1 were conducted. The results are shown in Table 3 and Figure 4, respectively. As shown in FIG. 4, the wear level is almost the same as that of the At/W type (electrical conductivity is low), and the lifespan gradually increases as silicon carbide fibers are mixed in.

Although there remains a difference between (e) and (ri) in °C, it is clear from Table 3 that the electrical conductivity is considerably lower. Also, SiC-C
In order to prevent reactions during the sintering process and when the temperature rises due to the arc during use as a contact point, the u system uses a silicon carbide fiber cone coated with alumina.
It was found that the life value can be greatly improved as shown in FIG. 4 without changing the electrical resistance compared to (e) with 0%).
A microscopic photograph of the composite state of the silicon carbide fibers in the above examples is shown in FIG.

It has been found that this type of metal (alloy) has relatively little reaction with the matrix and does not necessarily require coating the fibers with metal ceramics.Example 3 Polycarbosilane was applied to 100 mesh copper powder. About 10 wt % of the mixture was dissolved in xylene and kneaded, thoroughly dried, and molded in the same manner as in Example 1 at a press pressure of about 10 t/c to produce a green compact with a thickness of several inches.

This was gradually heated to 1010℃ in vacuum (100Cp
er1 hour) and sintered for about 1 hour. This sintered body (E)
, it is further immersed in polycarbosilane solution once,
Re-sintered (3σ maintained) c ~ For comparison, sintered under the same conditions as (e) without polycarbosilane added (d)
The same density, electrical resistance and life tests as in Example 1 were carried out. The results are shown in Table 4 and Figure 6. As shown in Figure 6, by strengthening the copper matrix with the silicon carbide component ( In both a) and E7), the amount of consumption is reduced, and unlike the case of fibers, the level of consumption at the initial stage is considerably lower.

Also, when comparing (e) and E7), the electrical conductivity remains the same υ
) t) Life expectancy is extended and the effect of infiltration treatment is clear. Among the conventional contact materials used in the practice of the present invention, those having the compositions shown in Table 5 below can be suitably used.

CP5 with w>99.5 has a specific gravity of 19 or more.The substances in the other columns include impurities, but especially additives.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the relationship between high-temperature firing temperature and the size of SiC crystal particles constituting the fiber when producing silicon carbide fiber from an organosilicon polymer compound, and Figure 2 is a diagram showing the relationship between the size of SiC crystal particles constituting the fiber in the case of producing silicon carbide fiber from an organosilicon polymer compound. Figure 3 shows the relationship between the size of SiC crystal grains and tensile strength. Figure 3 shows the relationship between the SiC crystal grain size and tensile strength. Figure 4 shows the relationship between the number of times and the amount of contact material consumption.
A diagram showing the relationship between the number of disconnections and the amount of contact material consumption in the contact test method of sintered alloys obtained by mixing fibers in various proportions. A micrograph showing the composite state of the contact material matrix and silicon carbide fiber, and FIG. 6 is a diagram showing the relationship between the number of disconnections and the amount of contact material consumption by the contact test method of the sintered bodies obtained in Example 3. It is.

Claims (1)

[Claims] 1. 0.0 parts by volume of silicon carbide obtained by firing an organosilicon polymer compound made of ultrafine crystal grains and whose skeleton components are mainly C and Si per 100 parts by volume of a conventional electrical contact material. Ultrafine silicon carbide composite electrical contact material made of 5 to 30 parts. 2. The ultrafine silicon carbide composite electrical contact material according to claim 1, wherein the silicon carbide obtained by firing an organosilicon polymer compound consisting of ultrafine crystal grains and mainly having C and Si as skeleton components is a powder. 3. The ultrafine silicon carbide composite electrical contact material according to claim 1, wherein the silicon carbide obtained by firing an organosilicon polymer compound consisting of ultrafine crystal grains and having mainly C and Si as skeleton components is a fiber. 4. The silicon carbide powder obtained by firing an organosilicon polymer compound consisting of ultrafine crystal grains and mainly having C and Si as skeleton components contains 30% or less of free carbon. Ultrafine silicon carbide composite electrical contact material. 5. The silicon carbide fiber obtained by firing an organosilicon polymer compound consisting of ultrafine crystal grains and mainly having C and Si as skeleton components contains 30% or less of free carbon. Ultrafine silicon carbide composite electrical contact material. 6. Ultrafine silicon made by dispersing silicon carbide powder obtained by firing an organosilicon polymer compound consisting of ultrafine crystal grains and having skeleton components mainly of C and Si in a molten metal of a conventional electrical contact material and solidifying it. A method for producing a carbide composite electrical contact material. 7. The gap between silicon carbide fiber aggregates obtained by firing an organosilicon polymer compound consisting of ultrafine crystal grains and mainly having C and Si as skeleton components is filled with a molten metal of a conventional electrical contact material. A method for producing an ultrafine silicon carbide composite electrical contact material. 8. A silicon carbide composite electrical contact material obtained by mixing and sintering silicon carbide powder obtained by firing an organosilicon polymer compound consisting of ultrafine crystal particles and mainly having C and Si as skeleton components and a conventional electrical contact material powder. manufacturing method. 9. A liquid organosilicon polymer compound is added as a binder to a mixture of silicon carbide powder obtained by firing an organosilicon polymer compound consisting of ultrafine crystal particles and whose skeleton components are mainly C and Si, and a conventional electrical contact material powder. A method for manufacturing silicon carbide composite electrical contact materials that is uniformly mixed and sintered as a silicon carbide composite electrical contact material. 10 Fill the gaps in the silicon carbide fiber aggregate obtained by firing an organosilicon polymer compound consisting of ultrafine crystal grains and mainly having C and Si as skeleton components with conventional electrical contact material powder, and then shape and sinter. A method for producing a silicon carbide composite electrical contact material. 11 After filling the gaps in a silicon carbide fiber aggregate obtained by firing an organosilicon polymer compound consisting of ultrafine crystal grains and having skeleton components mainly of C and Si, with conventional electrical contact material powder, liquid organic A method for manufacturing a silicon carbide composite electrical contact material, which is impregnated with a silicon polymer compound and then sintered under pressure.