JP4174187B2 - Contact material for vacuum valve and manufacturing method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a superior low chopping characteristic and current interruption characteristic and the contact material for a vacuum valve having both a manufacturing method thereof.
[0002]
[Prior art]
In addition to basic characteristics such as current interruption characteristics and withstand voltage characteristics, vacuum switchgear that interrupts current by diffusing arc plasma in vacuum should have excellent low surge characteristics depending on the application. It is.
[0003]
In particular, when the vacuum switching device is applied to a device such as a motor or a transformer, it is necessary to suppress the generated surge from the viewpoint of preventing dielectric breakdown of these devices. For surge suppression, there are a method of using a vacuum switchgear together with a surge suppressor and a method of reducing the surge generation level of the vacuum switchgear itself.
[0004]
In order to reduce the surge generation level of the vacuum switchgear, a technique for reducing the level of current cutting that is the main cause of surge is used. The cutting current value indicating the level of current cutting depends on the circuit configuration and the contact material used for the vacuum valve for the cutoff part of the vacuum switching device. If the circuit configuration cannot be changed, the cutting current value is substantially determined by the contact material.
[0005]
Cu-Cr-based contact materials with excellent breaking characteristics and Cu-W-based contact materials with excellent withstand voltage characteristics are not sufficiently low in cutting current, so circuit surges such as motors and transformers When applied to equipment with high impedance, a surge suppressor is used in combination.
[0006]
On the other hand, the Ag-WC-based contact material has excellent low cutting characteristics, that is, low surge characteristics, but the interruption performance is not as high as that of the Cu-Cr-based contact material.
[0007]
[Problems to be solved by the invention]
The greatest advantage of the vacuum switchgear that is low noise and does not use an environmentally affecting substance such as SF _{6 as} the blocking medium is its harmony with the environment. However, as described above, when a surge suppression device is used for surge protection using a Cu—Cr-based contact material, the surge suppression device generally contains flammable oil, so the advantages are impaired. There is a problem that it ends up.
[0008]
The Ag-WC-based contact material is a contact material developed from such a viewpoint, and has low surge characteristics, so that it is widely used in small-capacity vacuum switching devices. However, since it is difficult to increase the capacity, the application range is limited. Moreover, there also exists a problem that interruption | blocking performance is inferior to a Cu-Cr type | system | group contact material.
[0009]
In recent years, a Cu—TiC contact material excellent in low cutting characteristics has been developed, but there is a problem that it is difficult to stabilize the current interruption characteristics.
[0010]
The present invention has been made in view of the above, and an object of the present invention is to provide a contact material for a vacuum valve with improved current interruption characteristics for a Cu-TiC-based contact material having low cutting characteristics. It is in.
[0011]
Another object of the present invention is to provide a method for producing the above contact material for a vacuum valve.
[0013]
[Means for Solving the Problems]
In order to achieve the above object, the contact material for a vacuum valve according to the present invention is manufactured by infiltrating particles of an infiltrant containing Cu as a main component into the voids of TiC particles of a molded product containing TiC as a main component. In a Cu-TiC-based vacuum valve contact material, particles of an infiltrant containing Cu of density Rb as a main component are infiltrated into the voids of TiC particles of a molded body having porosity X as a main component of TiC having a density of Ra. In this state, it has a relative density of 98% or more with respect to the theoretical density Rth calculated by Rth = Ra · (1−X) + Rb · X.
[0014]
TiC contains a small amount of active metal Ti, and the metal Ti on the surface of the TiC particles adsorbs or binds oxygen. Such a portion where oxygen is adsorbed or bonded is not sufficiently wettable with Cu. In order to obtain sufficient current interruption characteristics, it is necessary to sufficiently reduce such defects.
[0015]
In the present invention, since the contact material for vacuum valves has a density of 98% or more with respect to the theoretical density Rth according to the above formula, this defect is sufficiently reduced, and good current interruption characteristics can be obtained. I have to.
[0016]
Thus in order to obtain the high density of the Cu-TiC-based contact material, it is desirable to take out from the infiltrated body Cr carbide is formed on the surface of T iC particles. Since Cr carbide has better wettability with Cu than TiC, sufficient current interruption characteristics can be obtained.
[0017]
The thickness of the Cr carbide on the surface of the TiC particles is desirably 0.5mm or more.
[0018]
Also, if the side surface which is arranged dissolved Hitazai was processed so that the contact surface, it is possible to increase the density of the largest contact surface of the impact on the current interrupting characteristics.
[0019]
Desirably , the content of TiC is in the range of 30 to 45 wt% (weight%), so that the balance between the amount of TiC thermoelectrons emitted and the amount of Cu ions generated is in an appropriate range for maintaining stable arcs. And the current interruption characteristics of the contact material can be optimized.
[0020]
The method for producing a contact material for a vacuum valve according to the present invention includes a molding step in which a powder mainly composed of TiC is formed as a molded body, and an infiltrant having Cu as a main component is disposed on the surface of the molded body. An infiltration process in which particles of the infiltrant are infiltrated into the voids of the TiC particles of the body to form an infiltrant in which Cr carbide is formed on the surface of the TiC particles, and on the side where the infiltrant of the infiltrant is disposed And a processing step of taking out the contact material by a predetermined depth from the surface.
[0021]
In the present invention, Cr carbide is formed on the surface of the TiC particles in the vicinity of the surface on the side where the infiltrant of the molded body is disposed by the infiltration process, and the infiltrant enters the inside of the molded body. The contact material is taken out by a predetermined depth from the surface on which the infiltrant of the infiltrated body thus formed is arranged in the processing step, so that a high-density contact material can be obtained. I try to get it.
[0022]
As a method for producing a contact material having a tissue characteristics such as described above, it is most effective to moistened with Cr particles infiltrant composed mainly of C u. By such a manufacturing method, Cr contained in the infiltrating material in the infiltration step reacts with unbonded C in TiC, and Cr carbide is formed on the surface of the TiC particles.
[0023]
On the other hand, when made to contain the Cr particles in powder constituting the formed configuration, and Cr dissolved from the shaped body and a C unbound in the TiC reacts during infiltration, the Cr carbide in the surface of the TiC particles formed Will be.
[0024]
Further, by previously moistened with Cu particles in powder constituting the formed configuration, powder containing the Cu particles are dissolved during infiltration, infiltration is facilitated to the molded body of infiltrant mainly containing Cu Therefore, infiltration property can be improved.
[0025]
Further, it is desirable to form the thickness of 0.5mm or more Cr carbide on the surface of the TiC particles, a predetermined depth when retrieving contact point material is desirably 0.5mm or more.
[0026]
Also , by processing so that the surface of the contact material on which the infiltrant is placed becomes the contact surface when it is set in the vacuum valve, the density of the contact surface that has the greatest effect on the current interruption characteristics can be increased. .
[0027]
By the way, gas adsorption by unbound Ti on the surface of TiC particles is also a factor that impedes the wettability of Cu and TiC particles to be infiltrated.
[0028]
Therefore, by performing the degassing process at infiltration temperature immediately before immersion solvent, so as to prevent the adsorption of gases.
[0029]
Further, by cooling at the melting point to 5 ° C. / min or less a cooling rate of infiltrant immediately after immersion solvent, it is possible to lengthen the time required to generate the Cr carbide on the surface of the TiC particles, and more of Cr carbide It can be formed uniformly.
[0030]
Such tissues vacuum valve using the contact material, and the manufacturing process vacuum valve using the contact material produced by the gas discharge is extremely small at the time of blocking, stably obtain a high current interruption characteristic be able to.
[0031]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0032]
FIG. 1 is a diagram showing a table summarizing manufacturing conditions for a plurality of Cu—TiC-based contact materials according to an embodiment. In the figure, Examples 1 to 9 are Cu-TiC contact materials to which the present invention is applied, and Comparative Examples 1 to 6 are conventional Cu-TiC contact materials prepared for characteristic comparison with Examples. It is.
[0033]
The production conditions are as follows: the mixing process conditions for mixing TiC particles with Cr particles and / or Cu particles to make the powder mainly composed of TiC, and putting the mixed powder into a metal mold and applying pressure to the molded body By placing the infiltrant on the surface of the compact and sintering at the melting point of the infiltrant (here, 1150 ° C.), the infiltrant is placed in the voids of the TiC particles of the compact. It consists of the conditions of the infiltration process which infiltrate particle | grains to make an infiltrant, and the conditions of the process of processing which determines the direction with respect to the contact surface of the surface which has arrange | positioned the infiltrant of an infiltrant. Examples 1 to 9 and Comparative Examples 1 to 6 were each produced by this series of production steps.
[0034]
In the mixing step, Cr was included in the powder composition only in Example 4 in addition to TiC and Cu, and Cr was not included in other examples and comparative examples.
[0035]
In the infiltration process, Cr was included in the composition of the infiltrant only in Example 1, Example 2, and Comparative Example 3, and Cr was not included in the other Examples and Comparative Examples. Moreover, only the comparative example 3 decided not to perform the degassing process just before infiltration. Furthermore, the cooling rate when cooling to the melting point (1050 ° C.) of the infiltrant after infiltration is 10 ° C./min in Comparative Example 4, 1 ° C./min in Examples 7, 8 and 6, and others. In Examples and Comparative Examples, the temperature was set to 5 ° C./min.
[0036]
FIG. 2 is a diagram showing the state and electrical characteristics of an infiltrated body manufactured under the manufacturing conditions of FIG. 1 for each Cu—TiC-based contact material.
[0037]
The item of the infiltrated state is composed of the material composition and the thickness (mm) and density of the Cr carbide layer formed on the surface of the TiC particles, and the electrical characteristics are composed of the current interruption characteristic and the current cutting characteristic. .
[0038]
The theoretical density Rth (g / cm ³ ) of the material is such that the particles of the infiltrant containing Cu of the density Rb as the main component are completely formed in the voids of the TiC particles of the molded body having the porosity X of the TiC having the density Ra. About the state infiltrated into
Rth = Ra · (1-X) + Rb · X
Is a theoretical value calculated by
[0039]
The actual density (g / cm ³ ) of the material is a measured value measured by the Archimedes method, and the relative density is a relative value (%) of the actual density with respect to the theoretical density.
[0040]
The current interrupting characteristic is obtained by taking out a contact material having a predetermined depth and a diameter of 50 mm from the surface of the infiltrant manufactured by the above-described manufacturing process on the side where the infiltrant is arranged, by cutting or the like, and performing the vacuum valve shown in FIG. It was obtained by conducting a blocking characteristic evaluation by a synthetic blocking test. In the evaluation method, the breaking current value was gradually increased from a low current value (5 kA), and the current value that failed to break first was taken as the breaking current value. In the current interruption characteristics of FIG. 2, the interruption current value of Example 1 is represented by a relative value, and 1 or more was judged to be good.
[0041]
The current cutting characteristics were evaluated using the vacuum valve shown in FIG. 3 as described above. In the evaluation method, a current drop (cutting current) when cutting off the current value 20A was repeatedly measured 500 times using a digital oscilloscope, and the maximum value of the cutting current was used as the evaluation result. The current cutting characteristics shown in FIG. 2 are expressed as relative values with the maximum value of the cutting current of Example 9 having a result equivalent to the cutting characteristics of the Ag-WC-based contact material measured in advance, being 1 or less. Was judged as good.
[0042]
FIG. 3 is a cross-sectional view showing a configuration of a vacuum valve to which a Cu—TiC-based contact material is applied, and FIG. 4 is an enlarged cross-sectional view of the contact portion and the electrode portion. 1 is a shut-off chamber, 2 is an insulating container, 3a and 3b are sealing fittings, 4a and 4b are lids, 5 and 6 are conductive rods, 7 and 8 are electrodes, 9 is bellows, 10 and 11 are arc shields, 13a , 13b are Cu-TiC-based contact materials. The contact materials 13a and 13b are arranged to face each other with a predetermined interval, and are provided at the tips of the conductive rods 6 and 5 via the electrodes 8 and 7, respectively.
[0043]
Next, the results of studying each example and each comparative example will be described.
[0044]
(Examples 1 and 2 and Comparative Example 1) Through the infiltration process described above, as shown in FIG. 5, particles 22 of the infiltrant containing Cu as a main component were dissolved in the voids of the TiC particles 21a to 21c of the molded body. Cr carbides 23 are formed on the surfaces of the TiC particles 21a to 21c when immersed. The relative density and electrical characteristics were evaluated using the thickness of the Cr carbide layer as a parameter. As shown in the infiltrant composition of FIG. 1, Cr carbide on the surface of the TiC particles was generated by including Cr in the infiltrant. In addition, as shown in the conditions of the processing step, the contact material was processed so that the surface on the side where the infiltrant of the infiltrated body was disposed was the contact surface.
[0045]
As shown in FIG. 2, the thickness of the Cr carbide layer is 0.5 mm in Example 1, 2.0 mm in Example 2, and 0 in Comparative Example 1. In Examples 1 and 2 having a layer thickness of 0.5 mm or more, a relative density of 98% or more was obtained in both cases, the current interruption characteristics were both 1.0 or more, and the current cutting characteristics were both 0.9, both good. Met. On the other hand, in Comparative Example 1 having no layer, the relative density was as low as 92% and the current interruption characteristics were insufficient at 0.3.
[0046]
Example 3 and Comparative Example 2 Relative density and electrical characteristics were evaluated by changing the orientation of the contact material with respect to the contact surface when the contact material taken out from the infiltrate by cutting or the like was incorporated in a vacuum valve. As shown in the conditions of the processing steps in FIG. 1, in Example 3, the surface of the infiltrant on the side where the infiltrant is placed at the time of infiltration, that is, the surface on the infiltration side of the infiltrant becomes the contact surface. In Comparative Example 2, the surface of the infiltrant on the side where the infiltrant is disposed is the contact back surface. Here, the contact surface means a surface on which the contact materials 13a and 13b face each other as shown in FIG.
[0047]
As shown in FIG. 2, in Example 3, the relative density is as high as 99%, the current interruption characteristic is 1.1, and the current cutting characteristic is 0.9. On the other hand, in Comparative Example 2, the relative density was as low as 97%, and the current interruption characteristic was insufficient at 0.7.
[0048]
(Example 4) Cr carbide on the surface of TiC particles can also be produced by including Cr particles in the mixed powder composition as shown in Example 4 of FIG. At this time, the thickness of the Cr carbide layer is 7 mm as shown in FIG. 2, the relative density is as high as 98%, the current interruption characteristic is 1.0, and the current cutting characteristic is 0.9. Was also good.
[0049]
Example 5 and Comparative Example 3 The correlation between the presence / absence of degassing treatment at the infiltration temperature immediately before infiltration, the relative density, and the electrical characteristics was examined. As shown in the conditions of the infiltration step of FIG. 1, Example 5 was obtained by performing degassing treatment, and Comparative Example 3 was obtained by not performing degassing treatment.
[0050]
As shown in FIG. 2, in Example 5, the relative density is as high as 99%, and the current interruption characteristics and the current cutting characteristics are sufficient. On the other hand, in Comparative Example 3, the relative density was as low as 97%, and the current interruption characteristic was insufficient at 0.7.
[0051]
Examples 6 and 7 and Comparative Example 4 Immediately after infiltration, the cooling rate when cooling the infiltrate to the melting point of the infiltrant (here, 1050 ° C.) was used as a parameter, and the correlation with the relative density and electrical characteristics. I investigated the relationship. As shown in the conditions of the infiltration step in FIG. 1, in Example 6, the cooling rate was 5 ° C./min, Example 7 was 1 ° C./min, and Comparative Example 4 was 10 ° C./min.
[0052]
As shown in FIG. 2, in Examples 6 and 7, both of the relative densities are as high as 99%, the current interruption characteristics are both 1.1, and the current cutting characteristics are both 0.9. It was. On the other hand, in Comparative Example 4, the relative density was as low as 95% and the current interruption characteristics were insufficient at 0.5.
[0053]
Each of Examples 1 to 7 is a contact material having a TiC content of about 40 wt% (weight%) as shown in the composition column of FIG. It can be seen that it is 9 and is slightly better than the Ag-WC contact material. Next, a case where the Cu / TiC ratio of the contact material is changed will be described.
[0054]
(Examples 8 and 9 and Comparative Examples 5 and 6) The Cu / TiC ratio of the contact material was changed by controlling the molding pressure in the molding process, and the correlation with the relative density and electrical characteristics was examined. As shown in the column of the composition in FIG. 2, the TiC content of Example 8 was 44.5 wt%, and the TiC content of Example 9 was 29.7 wt%, both in the range of about 30 to 45 wt%. 5 was 50 wt%, and Comparative Example 6 was 26.3 wt%.
[0055]
In both Examples 8 and 9, the relative density is as high as 99%, and the current cutting characteristics are both 1.0 or less, and it can be seen that it is similar to or better than Ag-WC. On the other hand, Comparative Example 5 in which the TiC content was increased and Comparative Example 6 in which the TiC content was decreased were both inferior because the current cutting characteristics far exceeded 1.0. This is because the balance between the amount of TiC thermionic emission and the amount of Cu ions produced is not in an appropriate range.
[0056]
【The invention's effect】
As described above, the contact material for a vacuum valve according to the present invention is an infiltrant whose main component is Cu having a density Rb in the voids of TiC particles of a molded body having a porosity X, the main component being TiC having a density Ra. As a vacuum valve contact material having a density of 98% or more with respect to the theoretical density Rth according to the formula Rth = Ra · (1−X) + Rb · X A blocking characteristic can be obtained.
[0057]
Further, according to the method for manufacturing a contact material for a vacuum valve according to the present invention, Cr particles are contained in the infiltrant containing Cu as a main component, or Cr particles are contained in the powder constituting the compact. Thus, when an infiltrant is placed on the surface of the molded body and infiltrated, Cr carbide is formed on the surface of the TiC particles, and a predetermined surface is formed from the surface of the infiltrant on which the infiltrant is placed. By taking out the contact material by the depth, a high-density contact material can be obtained.
[Brief description of the drawings]
FIG. 1 is a diagram showing a table summarizing manufacturing conditions for a plurality of Cu—TiC-based contact materials in an embodiment.
FIG. 2 is a diagram showing an infiltrated state and electrical characteristics of each Cu—TiC-based contact material.
FIG. 3 is a cross-sectional view showing a configuration of a vacuum valve to which a Cu—TiC-based contact material is applied.
FIG. 4 is an enlarged cross-sectional view of a contact portion and an electrode portion of the vacuum valve.
FIG. 5 is a diagram showing a state in which Cr carbide is formed on the surface of TiC particles.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Shut-off chamber 2 Insulation container 3a, 3b Sealing metal fittings 4a, 4b Cover body 5, 6 Conductive rod 7, 8 Electrode 9 Bellows 10, 11 Arc shield 13a, 13b Cu-TiC system contact material

Claims (9)

In a contact material for a Cu-TiC-based vacuum valve manufactured by infiltrating particles of an infiltrant containing Cu as a main component into the voids of TiC particles of a molded product containing TiC as a main component,
About the state where the particles of the infiltrating material mainly containing Cu of density Rb infiltrated into the voids of the TiC particles of the compact body of porosity X having the density Ra Ti as a main component,
Rth = Ra · (1-X) + Rb · X
Having a relative density of 98% or more with respect to the theoretical density Rth calculated by:
A contact material for a vacuum valve, characterized in that a Cr carbide layer is formed on the surface of the TiC particles.   The contact material for a vacuum valve according to claim 1, wherein the Cr carbide has a thickness of 0.5 mm or more.   The contact material for a vacuum valve according to claim 1 or 2, wherein the surface on which the infiltrant is disposed is processed so as to be a contact surface.   The contact material for a vacuum valve according to any one of claims 1 to 3, wherein the content of TiC is in the range of 30 to 45 wt%. A molding step using a powder mainly composed of TiC as a molded body;
An infiltrant containing Cu as a main component is disposed on the surface of the molded body, and particles of the infiltrant are infiltrated into the voids of the TiC particles of the molded body to form a Cr carbide layer on the surface of the TiC particles. An infiltration process to be immersed,
A processing step of taking out the contact material by a predetermined depth from the surface on which the infiltrant of the infiltrant is disposed,
A method for producing a contact material for a vacuum valve, comprising: 6. The method of manufacturing a contact material for a vacuum valve according to claim 5, wherein the infiltration step forms a Cr carbide layer having a thickness of 0.5 mm or more on the surface of the TiC particles.   The said predetermined depth is 0.5 mm or more, The manufacturing method of the contact material for vacuum valves of Claim 5 or 6 characterized by the above-mentioned.   The contact material for a vacuum valve according to any one of claims 5 to 7, wherein the processing step includes a step of processing so that a surface of the contact material on which the infiltrant is disposed becomes a contact surface. Manufacturing method.   9. The vacuum valve contact according to claim 5, wherein the infiltration step includes a step of cooling at a cooling rate of 5 [deg.] C./min or less immediately after infiltration to a melting point of the infiltrant. Material manufacturing method.

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