JPH01140526A - Contact material for vacuum bulb and its manufacture - Google Patents

Abstract

PURPOSE:To improve the anti-deposition property extensively by applying an adequate processing rate of plastic process and an adequate heat treatment to designate the crystalline grading in a high conductive material. CONSTITUTION:The crystalline grading of a high conductive material is made to NO.3 to 13 of ASTM by applying an adequate processing rate of plastic process and an adequate heat treatment. In case of Cu-Cr material, a powder formation is obtained by pressure-forming a specific grading of Cr. Then, the powder formation is sintered temporarily in a hydrogen ambiance or in a vacuum at a specific temperature, to obtain a temporarily sintered substance. After that, Cu is molten in the resedual pores of the temporarily sintered substance to obtain a Cu-Cr alloy. Then, the 50% processing rate of process is applied in a cold rolling, and a heat treatment is applied in a vacuum at a specific temperature for a specific time. The contact material manufactured in such a process has the crystalline grading in the conductive material of the level NO.8 of ASTM, and the anti-deposition property is improved extensively.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a vacuum valve, and more particularly to a contact material Fl for a vacuum valve with improved anti-welding properties and a method for manufacturing the same.

(Prior art) The properties required for contact materials for vacuum valves include the three basic requirements of welding resistance, voltage resistance, and resistance to "a breakage," as well as low and stable temperature resistance and contact resistance. However, since some of these requirements are contradictory, it is impossible to satisfy all requirements with a single metal type. Therefore, many contact materials in practical use are made by combining two or more elements that mutually compensate for the lack of performance, and are suitable for specific applications such as for large current or high voltage applications. However, a contact material for vacuum valves that fully satisfies the increasingly increasing demands for higher voltage resistance and larger currents has not yet been obtained. This is the actual situation.

For example, Cu-8, which contains less than 5% of a welding prevention component such as Bi, is used as a contact material designed for high current.
; alloy is known (Japanese Patent Publication No. 12131/1983), but because the solubility of Bi in the Cu-matrix is extremely low, segregation often occurs, the surface roughness after cutting is severe, and processing is difficult and necessary. It has problems such as:

In addition, CLL is another contact material that is oriented towards large currents.
-Te alloys are also known (Japanese Patent Publication No. 44-23751). Although this alloy alleviates the above-mentioned problems of the CcL-Bi alloy, it is more sensitive to the atmosphere than the CcL-Bi alloy and therefore lacks stability in terms of contact resistance and the like.

Generally speaking, a common feature of these Cu, Te, Cc Bi, etc. contacts is that they have excellent welding resistance, but even if their withstand voltage characteristics are sufficient for application to the conventional medium voltage class, It has become clear that this method is not always satisfactory for applications in the field of high voltages.

On the other hand, a CttC+- alloy containing Cr is known as a contact material for vacuum valves. This contact alloy exhibits favorable thermal properties of Cr and Cu at high temperatures, and thus has excellent properties for use with high withstand voltages and large currents. That is, the Cu-Cr alloy is frequently used as a contact that can achieve both high voltage resistance and large-capacity interruption.

However, the CtL-Cr alloy is significantly inferior in welding resistance compared to the aforementioned CtL-Bi alloy to which about 5% or less of B1 is added, which is commonly used as a contact material for circuit breakers.

There are two types of phenomenon: when the contact material melts due to Joule heat generated on the contact surface between the contacts and then solidifies, and when the contact material vaporizes due to the arc discharge that occurs at the moment of opening and closing and then solidifies. Occurs in. Ca
In any Cr alloy, at the stage of solidification, Cr and Ca become fine particles of one size or less and are intermingled with each other to form a layer of several to hundreds of particles. In general, ultra-fine structure is one of the factors that contributes to improving the strength of materials.
This case is no exception. However, this ultrafine Cu-
The strength of the Cr layer is superior to that of the matrix of the CttCr alloy, and welding also occurs when the matrix strength exceeds the designed tripping force.

Therefore, the operating mechanism for driving a vacuum valve using CtL-Cr material needs to be designed to have a larger tripping force than Cu-8, which is difficult in terms of miniaturization and economical efficiency.

(Problems to be Solved by the Invention) As described above, the conventional contact materials for vacuum valves made of highly conductive materials and arc-resistant materials have a drawback of poor welding resistance.

Therefore, the present invention was made in view of the above-mentioned circumstances, and its purpose is to provide a vacuum valve that is made of a highly conductive material and an arc-resistant material, has excellent welding resistance, and reduces the force required to weld and remove the contacts. The purpose of the present invention is to provide a contact material for use in the market and a method for manufacturing the same.

[Structure of the Invention] (Means for Solving the Problems) The present invention provides a contact material for a vacuum valve composed of a highly conductive material and an arc-resistant material.
) f is Nα3 to 13.

Further, the manufacturing method is characterized in that the contact material is subjected to plastic working at least once before it is incorporated into a vacuum valve and until it is completed as a vacuum valve.

Thus, the implementation is as follows.

(1) A contact material for a vacuum valve that has a twin structure in the highly conductive material of the contact material.

(2) The highly conductive material is a contact material for a vacuum valve, which is Cc or/and Ag.

(3) The arc-resistant material is a contact material for vacuum valves, which is Cr or Ti.

(4) 8+, Pb, Te, Se or S for contact material
This is a contact material for a vacuum valve to which at least one or more elements of B are added.

(5) A method for producing a contact material for a vacuum valve, in which heat treatment is performed after plastic working.

(6) Contact material is a method of manufacturing a contact material for vacuum valves in which a highly conductive material is infiltrated into an arc-resistant material skeleton.

(7) A method for manufacturing a contact material for a vacuum valve in which the highly conductive material is Cu or/and Ag.

(8) Arc-resistant material is a method for manufacturing a contact material for a vacuum valve, which is Cr- or Ti.

(9) Plastic working is a method for manufacturing a vacuum valve circumferential contact material, which includes at least one of rolling, fi-forming, and press working.

(10) Plastic working is hot working, and the working rate before heat treatment or cold working is 20% to 80%, preferably 50% to 70%, in a method for manufacturing a contact material for a vacuum valve. .

(11) In plastic working, the processing rate is 10% or more and 70% or less, preferably 30%, until cold working and heat treatment are performed.
What about contact materials for vacuum valves that have a coverage of 60% to 60%? ! It's the way it's built.

(12) A method for producing a contact material for a vacuum valve, in which cold working is performed without heat treatment after hot working.

(13) A method for manufacturing a contact material for a vacuum valve in which the heat treatment temperature is 250° C. or higher.

(14) A method for manufacturing a vacuum valve peripheral contact material in which at least one of B, Pb, Te, Se, or Sb is added to the contact material.

(Function) As with the above-mentioned means, in a contact material composed of a highly conductive material and an arc-resistant material, the crystal grain size in the highly conductive material is defined, and the twin structure is brought out in the crystal. This made it possible to create a contact structure suitable for welding and removing the contact material.

In other words, in highly conductive materials such as R after infiltration, the crystal grains become extremely large, and in many cases, one or more particles of the arc-resistant material are covered with crystals of one conductive material. It also promotes the ductility of the arc-resistant material, making it impossible to obtain the notch effect of the arc-resistant material on the conductive material, and ultimately causing a decrease in welding resistance. On the other hand, when the crystal grains of the highly conductive material are very fine, the strength of the contact material increases as described above, which also causes a decrease in welding resistance. From this point of view, only materials with a certain grain size in the conductive material can contribute to improving the welding resistance.

The reason why materials with twins are suitable for improving welding resistance is that more interfaces can be obtained in the conductive material.

(Example) Examples of the present invention will be described below based on specific embodiments. First, the configuration of a vacuum valve to which the contact material of the present invention is applied will be explained with reference to FIGS. 1 and 2. do.

FIG. 1 shows an example of the configuration of a vacuum valve to which the contact material of the present invention is applied, and in the figure, 1 indicates a cutoff chamber;
This cutoff chamber 1 includes an insulator 2 formed of an insulating material into a substantially cylindrical shape, and sealing fittings 3 a and 3 b at both ends of the insulator 2 .
A metal lid body, /la, and 4b, provided through the cap, is vacuum-tight. A pair of electrodes 7 and 8 attached to opposite ends of conductive rods 5 and 6 are arranged in the cutoff chamber 1, with the upper electrode 7 being a fixed electrode and the lower electrode 8 being a fixed electrode. It is a movable electrode. Further, a bellows 9 is attached to the electrode rod 6 of the movable electrode 8 to enable the electrode 8 to move in the axial direction while keeping the inside of the cutoff chamber 1 vacuum-tight. A shield 10 is provided to prevent the bellows 9 from being covered with arc vapors. Reference numeral 11 denotes a metallic arc shield provided in the cutoff chamber 1 so as to cover the electrodes 7 and 8, and prevents the insulating container 2 from being covered with arc vapor. Roughly speaking, the electrode 8 is fixed to the conductive rod 6 by a brazing portion 12, or is crimped and connected to the conductive rod 6 by caulking, as shown in an enlarged view in FIG. The contact 13a is
It is fixed to the electrode 8 by brazing 14. Note that 13b in FIG. 1 is a fixed side contact.

The contact material according to the present invention includes the contact 13a as described above,
13b.

Here, considerations for obtaining the contact material of the present invention will be explained.

According to the research conducted by the present inventors, when welding Cc Cr-contact materials, (1) when the contact material melts due to Joule heat generated at the contact surface between the contacts and then solidifies, (2) when the contact material is This occurs on one side or in the interaction when the contact material vaporizes due to the arc discharge that occurs at the moment of opening and closing of the device, and then solidifies. In either case, Cr and C
The particles become fine particles with u- of 1 or less, and are mixed with each other to form a layer of several hours to several tens of hours. Generally, refinement of the structure is one of the factors contributing to improving the strength of material H, and this case is no exception. However, this fine Cu
, the strength of the Cr layer is superior to the 71 helix strength of the CtL Cr alloy, and welding occurs when the matrix strength exceeds the designed tripping force.

In order to improve the welding resistance of a contact material composed of a highly conductive material and an arc-resistant material, the present inventors focused on the relationship between the crystal grain size of the highly conductive material and the welding resistance, and aimed to improve the welding resistance. It was found that there is a suitable grain size.

However, if the highly conductive material is too large, one grain of the highly conductive material may surround one or more arc-resistant materials.
It has been found that during melt tripping, the ductility of the highly conductive material also engulfs the arc-resistant material, and the arc-resistant material cannot serve as a notch effect in the highly conductive material. Furthermore, if the crystal grains are too small, the strength of the contact material increases too much as described above, and good results in improving the welding resistance cannot be obtained. From the above viewpoint, the grain size of highly conductive material is ^5T)lN
α5-13 is good.

Further, according to U1 research conducted by the present inventors, it was found that the presence of twin crystals in the crystal grains in the conductive material provides better results in terms of welding resistance. That is, the twin crystals serve to reduce the ductility of the arc-resistant material when the crystal grains of the conductive material are too large, as described above.

Generally speaking, as a method to further improve the welding resistance, it is also effective to add at least one or more of Bi, Pb, Te, Se, or Sb using known techniques and to control the crystal grain size in the same way. I also discovered that. As mentioned above, the grain size contributes to improving the durability. On the other hand, the above additive elements have low solid solubility in highly conductive materials and have the characteristics of embrittling the matrix, and by combining these two factors, the welding resistance performance can be greatly improved when synergistic. It is. However, since each of these elements has a high vapor pressure, there is a risk that the withstand voltage characteristics will be lowered, so the amount of addition thereof should be as small as possible.

Next, a method for manufacturing the crystal grain size in such a highly conductive material will be described. There are no clear grain boundaries in the highly conductive material in the infiltrated contact material.

The present inventors believe that in order to create grain boundaries from this state,
We have discovered that it is possible to create defined grain boundaries in highly conductive materials by performing plastic working at an appropriate working rate and heat treatment at an appropriate temperature.

Plastic working methods, working rates, heat treatments, etc. suitable for this will be explained in the following examples.

Next, an example of a method for manufacturing this contact material will be explained using Cu and -Cr materials. A powder compact is obtained by pressure-molding Cr having a predetermined particle size. Next, this powder compact was heated to a dew point of 150
Hydrogen atmosphere below ℃ or degree of vacuum is 1X 10-3 r
Temporary sintering is performed at a predetermined temperature, for example, 950° C. for 1 hour, at a temperature of 1.0 or less to obtain a temporary sintered body.

Next, Cu is added, for example, to the remaining pores of this temporary sintered body.
Infiltration is carried out at 100°C for 1 hour to obtain a Cu--Cr-alloy. Infiltration is primarily carried out in vacuum, but can also be carried out in hydrogen.

Here, if the sintering heat treatment and/or infiltration heat treatment temperature is selected to be high, Cu evaporates rapidly and it becomes difficult to control its components. However, since the heat treatment temperature varies depending on the performance of the furnace, the amount of material to be heat treated, its size, heat capacity, etc., it is impossible to universally express the temperature, and in reality it is difficult to express the remaining Cttfl. Although a method of directly determining and controlling the temperature by, for example, an X-ray method may be adopted, it has been found that selecting a temperature of 1300° C. or higher generally reduces the presence of CtL and is not preferable. −
On the other hand, in the sintering heat treatment, the lower limit temperature is 600°C or higher, preferably 90°C or higher, from the viewpoint of degassing the raw material or the molded body.
0° C. or above is required, and in the d vague process, at least 1100° C. is required due to the need to degas the skeleton and melt Ctt.

Then, cold rolling is performed at a processing rate of 50%, and heat treatment is performed at 500° C. for 1 hour in a vacuum. The contact material manufactured by this process has a crystal grain size in the conductive material of ASTM
The contact material has excellent welding resistance in terms of ductility and strength.

Therefore, the above-described sintered alloy has excellent welding resistance and is optimal as a contact material for vacuum valves.

Next, each contact material manufactured as described above will be shown in comparison with a comparative example. The conditions and methods used for evaluation on each side are as follows.

(1) Resistance) 8 Adhesion A pair of disc-shaped samples with an outer diameter of 258 φ was opposed to a pressurized iron whose tip had a spherical surface of 100 R, and was heated to 100 K.
5 in a vacuum of 1O-5sH (] with a load of Fi applied.
A current was applied to 0H2, 20 for 20 milliseconds, and the force required for tripping between the sample and the lot at that time was measured to judge the welding resistance. The evaluation was based on relative values, where i and oo are the melting force of the Ctt Cr alloy after infiltration shown in Comparative Example 2. Each person has the above 3 points of contact.
This shows the range of variation in individual measured values.

(2) Withstanding Voltage Characteristics Since there is a concern that the withstanding voltage characteristics may deteriorate, the test was carried out only for samples to which the third element was added.

N1 with mirror finish by puff polishing for each contact alloy
The needle was used as an anode, each mirror-finished sample was used as a cathode, and the gap between the two electrodes was 0.5 mm.
In the vacuum of H(l), the voltage was gradually increased and the voltage value when a spark was generated was measured to determine the static withstand voltage value.Second
The measurement data shown in the table, including the variation value when repeated tests were performed three times, indicates that the static pressure resistance value of the Cu and Cr alloy after infiltration is 1.00 (Comparative Example 1 shown in Table 1). It is shown as a relative value when

Examples 1 to 3, Comparative Examples 2 and 3 In order to investigate the relationship between grain size, cold working rate, and welding resistance, Gu and Cr materials after infiltration were used as standard Q (Comparative Example 1)
The degree of improvement in the welding resistance performance with respect to the crystal grain size of the conductive material 1 was investigated using the cold rolling processing rate as a parameter and the heat treatment temperature constant at 500° C. for 1 hour. The cold working rates were 5, 10, 50, and 70°90%, respectively.

These properties are shown in Table 1.

The grain size of the highly conductive material manufactured by the above process is AS
The Nα of TH was 0, 3, 8, and 12.15, respectively. The one with the best welding resistance was ASTH's Nα
8 is 0.4 to 0.6, and then Nα3 is 0.5 to 0.6.
It is 0.7. The one with Nα15 has a welding resistance improvement of 0.8
~1.0, and even if it is actually incorporated into a vacuum valve, no significant benefit will be obtained. On the other hand, the improvement in welding resistance of the NαO product was 1.0, which is the same as the conventional product. Therefore, the crystal grain size of the highly conductive material is desirably about Nα 3 to 12 of AS-TH. Also, if you look at this in terms of cold working rate, it is 10% ~
It can be seen that about 70% is desirable.

t [4-6, Comparative Example 45 In the same way as determining the optimum value of cold working rate, the grain size,
In order to investigate the relationship between hot working rate and welding resistance, we used infiltrated Ctt Cr material as a standard and investigated the degree of improvement in welding resistance performance with respect to the grain size of the conductive material using hot working rate as a parameter. Hot processing rate is 10% and 20% respectively
, 50%, 80%, and 90%, and heat treatment after hot working was omitted.

These properties are shown in Table 1.

The grain size of the highly conductive material manufactured by the above process is A
Nα of ST) f was 1, 3, 8, and 13.16, respectively. As with cold rolling, the effects on welding resistance were confirmed when Nα of AST)l was 3°8.1.
3, and the welding resistance performance was almost the same as that of the infiltration method. Therefore, in hot working, the working rate is 2
It can be seen that 0% to 80% is desirable.

Actual [Comparison] 6 The following evaluation was performed to find the optimal heat treatment temperature after plastic working.

Using Cμ-〇r infiltration material as the base material, after making the processing rate constant at 50% by cold rolling, the heat treatment temperature was 150°C and 150°C, respectively.
Welding resistance against heat treatment temperatures was evaluated at four levels: 3H°C, 500°C, and 800°C.

These characteristics are shown in Table @2.

When the heat treatment was performed at 150° C., no improvement in welding resistance was observed, probably because recrystallization of the conductive material had not yet been completed and the f1 material was strong in terms of material strength. On the other hand, 300℃,
For those heat-treated at temperatures of 500°C and 800°C, the grain size corresponded to ASTM Nα of 12.8.5, and the welding resistance was 0.4 to 0.7, showing improvement. Therefore, the heat treatment temperature after plastic working is desirably about 250°C or higher. Heat treatment! I! The upper limit of the temperature is preferably below the melting point of the conductive material.

In order to investigate the improvement of welding resistance by a combination of plastic working, cold rolling was performed at a working rate of 20% after hot rolling at a working rate of 30%. Table 2 does not show the improvement in welding resistance of the heat-treated samples. The crystal grain size of the conductive material is AST)fN(17), and the welding resistance is also 0.4 to 0.6, showing signs of improvement.

Therefore, the welding resistance can be improved even when a plurality of plastic workings are combined.

X Dust 5th Edition-■ So far, examples regarding rolling processing have been described, but examples regarding Haku's plastic working will be discussed.

Infiltrated Ctt Cr material is cold pressed at a processing rate of 50%,
Then heat treated at 500°C (Example 10)
and those subjected to hot forging with a processing rate of 60% (Example 11)
).

The results are shown in Table 2.

In both cases, the crystal grain size of the highly conductive material is Nα7 to 8 according to ASTH.
Moreover, the welding resistance is 0.4 to 0.6, and is considered to be an effective means for improving the welding resistance.

In order to further improve the welding resistance of After being infiltrated into a pre-melted 0.3% 5b-Cφ gold alloy Cr-skeleton, it was cold-rolled to 10% and then heat-treated at 500°C (Example 1).
2), 30% hot rolling after infiltrating CI-skeleton with 2% Te Ctt (Example 13)
, '1%Se-0ct alloy was immersed in Cr mis-skeleton and then subjected to 30% hot rolling (Example 14),
This is the fourth level of Example 15, in which the 2% Te -1% Se -CUL alloy was infiltrated into the Cr skeleton and then hot rolled by 30%.

These results are shown in Table 2.

The crystal grain size of the conductive material is Nα of AST) f in Example 12.
3, all other values are Nα5. All welding resistance performance is 0.
3 to 0.4, which is superior to conventional processes that combine plastic working and heat treatment. However, as mentioned above, the withstand voltage characteristic is 0.7 to 0.8, which is inferior to the conventional one. However, this level of decrease in withstand voltage characteristics is a value that poses no practical problem.

In the above, we have focused on Ctt as a conductive material and Cr as an arc-resistant material, but we have investigated the effectiveness of other elements as well.

After pre-sintering Ti powder to produce a Ti skeleton, C
The CtL-Ti material produced by infiltrating u- was 50% cold rolled and heat treated at 500°C (Example 1).
6) and a Cr skeleton infiltrated with Ag.
% cold rolled and heat treated at 500° C. (Example 17) was evaluated.

These results are shown in Table 3.

In both cases, the crystal grain size of the conductive material is ASTH Nα7~8, the welding resistance is 0.4~0.6, and this manufacturing method is Cη-C
It can be seen that this method is effective not only for R materials but also for the above materials.

(Hereinafter, blank space) In Examples 1 to 17, the case where the ratio of the highly conductive material and the arc-resistant material was approximately 50:50 was explained.
Since the purpose of the present invention is achieved depending on the state of the highly conductive material, it is clear that the above-mentioned ratio is not limited to 50:50 and the effect can be achieved.

[Effects of the Invention] Since the present invention is configured as described above, it is possible to provide a contact material for a vacuum valve with significantly improved welding resistance and a method for manufacturing the same.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a vacuum valve to which the present invention is applied;
The figure is an enlarged sectional view of the contact portion. 1... Cutoff chamber 7.8... Electrodes 13a, 13b... Contacts (8733) Agent Patent attorney Yoshiaki Inomata (and others)
1 person) Figure 1 Figure 2

Claims (16)

[Claims] (1) In a vacuum valve contact material composed of a highly conductive material and an arc-resistant material, the crystal grain size of the highly conductive material is AS.
TM No. A contact material for a vacuum valve, characterized in that the number is 3 to 13. (2) The contact material for a vacuum valve according to claim 1, which has a twin structure in the highly conductive material of the contact material. (3) The contact material for a vacuum valve according to claims 1 and 2, wherein the highly conductive material is Cu or/and Ag. (4) The contact material for a vacuum valve according to any one of claims 1 to 3, wherein the arc-resistant material is Cr or Ti. (5) The contact material for a vacuum valve according to claims 1 to 4, wherein at least one element selected from Bi, Pb, Te, Be, or Sb is added to the contact material. (6) In a vacuum valve contact material composed of a highly conductive material and an arc-resistant material, the contact material is assembled into a vacuum valve and the contact material is used at least once before the vacuum valve is completed. A method for manufacturing a contact material for a vacuum valve, characterized by subjecting the material to plastic working. (7) The method for manufacturing a contact material for a vacuum valve according to claim 6, wherein heat treatment is performed after plastic working. (8) The method for manufacturing a contact material for a vacuum valve according to claims 6 and 7, wherein the contact material is made by infiltrating a highly conductive material into an arc-resistant material skeleton. (9) The method for manufacturing a contact material for a vacuum valve according to claims 6 to 8, wherein the highly conductive material is Cu or/and Ag. (10) The method for manufacturing a contact material for a vacuum valve according to claims 6 to 9, wherein the arc-resistant material is Cr or Ti. (11) The method for manufacturing a contact material for a vacuum valve according to claims 6 to 10, wherein the plastic working includes at least one of rolling, forging, and press working. (12) Plastic working is hot working, and the working rate before heat treatment or cold working is 20% to 80%, preferably 50% to 10%.Claims 6 to 11 A method for manufacturing a contact material for a vacuum valve as described in . (13) Plastic working is cold working, and the processing rate before heat treatment is 10% or more and 70% or less, preferably 30%.
A method for producing a contact material for a vacuum valve according to any one of claims 6 to 11, wherein the contact material for a vacuum valve is 60%. (14) A method for manufacturing a contact material for a vacuum valve according to claims 6 to 13, wherein cold working is performed without heat treatment after hot working. (15) The method for manufacturing a contact material for a vacuum valve according to any of claims 6 to 13, wherein the heat treatment temperature is 250°C or higher. (16) Claim 6 in which at least one of Bi, Pb, Te, Se, or Sb is added to the contact material.
A method for producing a contact material for a vacuum valve according to items 1 to 15.