JP7351022B2 - Electrical contacts and vacuum valves - Google Patents

Description

This application relates to electrical contacts and vacuum valves.

Vacuum circuit breakers installed in high-voltage power distribution equipment are used to cut off current in the event of a failure or abnormality in the high-voltage power distribution equipment. A vacuum circuit breaker is equipped with a vacuum valve that has the function of cutting off current. A vacuum valve has a structure in which a fixed electrode and a movable electrode are disposed coaxially and facing each other inside an insulating container maintained at a high vacuum. Opposite surfaces of the fixed electrode and the movable electrode of the vacuum valve are each provided with electrical contacts. The vacuum valve is closed and opened by contacting and separating these electrical contacts.

When an overload current or short circuit current occurs in the power distribution equipment, the movable electrode is instantly opened from the fixed electrode of the vacuum valve to cut off the current. However, since an arc is generated between the electrodes, the current is not cut off instantly when the electrodes are opened. When interrupting an alternating current, the arc becomes weaker as the alternating current becomes smaller, and the arc is extinguished to complete the interrupt. Cutting is a phenomenon in which the current is cut off before the alternating current reaches zero.

In a vacuum valve, a large surge voltage called a switching surge is generated when the electrodes are opened or closed. If the equipment connected to the power distribution equipment is capacitive or inductive, the large voltage surges generated can damage these equipment. In order to lower the surge voltage, it is necessary to reduce the cutting current, which is the current at the time when cutting occurs. The cutting current can be reduced by sustaining the arc that occurs between the electrodes when the electrodes open until close to the zero point of the alternating current.

The electrical contacts of conventional vacuum valves are made of a base material whose main component is a conductive substance such as Cu (copper), particles of a high melting point substance such as Cr (chromium) dispersed in this base material, and Te. (tellurium) or a low boiling point metal material such as Se (selenium). Low boiling point metal materials such as Te or Se are evaporated from the electrical contacts by the heat of the arc when it occurs. Conventional vacuum valves can sustain the arc with this evaporated low-boiling metal material to reduce the cutting current. Such electrical contacts are manufactured by mixing powder raw materials containing the above metal elements and then sintering the mixture. During this manufacturing process, Te, which is a low boiling point metal material, reacts with Cu to produce Cu ₂ Te, which is an intermetallic compound. In conventional electrical contacts, Cu ₂ Te is thermally unstable and the Te evaporates during sintering, making the electrical contacts brittle. As an electrical contact that avoids this problem, an electrical contact further added with Ti (titanium) has been disclosed (for example, see Patent Document 1).

Japanese Patent Application Publication No. 2001-236865

When Ti is further added to a conventional electric contact composed of a Cu-based base material, high-melting point material particles, and Te, Ti and Te react preferentially, resulting in an intermetallic bond between Ti and Te. A compound is produced. Therefore, in this electrical contact, the generation of Cu ₂ Te is suppressed and the electrical contact is prevented from becoming brittle. However, in conventional electrical contacts, since Ti is added at a weight ratio of 0.2 or more to Te, there has been a problem that the density of the electrical contacts is reduced. The decrease in the density of electrical contacts is caused by the fact that when electrical contacts are brazed to fixed and movable electrodes in the vacuum valve assembly process, the solder metal is drawn into the void inside the electrical contacts by capillary action, resulting in poor brazing. becomes.

The present application was made to solve the above-mentioned problems, and even when Ti is further added to an electrical contact made of a base material mainly composed of Cu, high melting point material particles, and Te, the density does not decrease. The purpose is to provide high electrical contact.

The electrical contact of the present application includes a base material containing Cu as a main component, high melting point substance particles composed of at least one of a high melting point metal and a carbide of the high melting point metal dispersed in the base material, and An electrical contact containing Te and Ti dispersed in the area, where the concentration of Te is 3.5% by mass or more and 14.5% by mass or less, and the concentration of Ti is 100% by mass. The value obtained by dividing Te by the concentration of Te is 0.01 or more and less than 0.12, and Te exists as a compound of Te and Ti and a compound of Te and Cu. The compound with Cu coexists to form one particle .

In the electrical contact of the present application, when the whole is 100% by mass, the Te concentration is 3.5% by mass or more and 14.5% by mass or less, and the value obtained by dividing the Ti concentration by the Te concentration is 0.5% by mass. 01 or more and less than 0.12, Te exists as a compound of Te and Ti and a compound of Te and Cu, and the compound of Te and Ti and the compound of Te and Cu coexist to form one particle. , it is possible to obtain electrical contacts with high density.

1 is a schematic cross-sectional view of a vacuum valve according to Embodiment 1. FIG. FIG. 2 is a table showing compositions, mechanical property evaluation results, and electrical property evaluation results of electrical contacts of Examples and Comparative Examples according to Embodiment 1. FIG. 3 is a schematic cross-sectional view of the composition analysis results of the electrical contact according to the first embodiment. FIG. 2 is a table showing compositions, mechanical property evaluation results, and electrical property evaluation results of electrical contacts of Examples and Comparative Examples according to Embodiment 1. FIG. 2 is a table showing compositions, mechanical property evaluation results, and electrical property evaluation results of electrical contacts of Examples and Comparative Examples according to Embodiment 1. FIG. 2 is a table showing compositions, mechanical property evaluation results, and electrical property evaluation results of electrical contacts of Examples and Comparative Examples according to Embodiment 1. FIG. 2 is a table showing the composition, mechanical property evaluation results, and electrical property evaluation results of the electrical contacts of Examples according to the first embodiment.

Hereinafter, vacuum valves and electrical contacts according to embodiments for carrying out the present application will be described in detail with reference to the drawings. In each figure, the same reference numerals indicate the same or corresponding parts.

Embodiment 1.
FIG. 1 is a schematic cross-sectional view of a vacuum valve according to Embodiment 1. The vacuum valve 1 of this embodiment includes a cutoff chamber 2. The cutoff chamber 2 includes a cylindrical insulating container 3 and disk-shaped metal lids 5a and 5b. Both ends of the metal lids 5a and 5b are fixed to the insulating container 3 with sealing fittings 4a and 4b, respectively. The cutoff chamber 2 sealed with the insulating container 3 and metal lids 5a and 5b is kept vacuum-tight. A fixed electrode rod 6 and a movable electrode rod 7 are installed in the cutoff chamber 2 so as to face each other. A fixed electrode 8 and a movable electrode 9 are attached to the ends of the fixed electrode rod 6 and the movable electrode rod 7, respectively. Furthermore, a fixed electrical contact 10 and a movable electrical contact 11 are attached to the contact portions of the fixed electrode 8 and the movable electrode 9 by brazing, respectively. The electrical contact according to this embodiment is applied to at least one of the fixed electrical contact 10 and the movable electrical contact 11.

A bellows 12 is attached to the movable electrode rod 7. The bellows 12 allows the movable electrode rod 7 to move in the axial direction while keeping the inside of the cutoff chamber 2 vacuum-tight. By moving the movable electrode rod 7 in the axial direction, the movable electrode 9 comes into contact with the fixed electrode 8 or moves away from it. A bellows arc shield 13 made of metal is provided above the bellows 12. The bellows arc shield 13 prevents arc vapor from adhering to the bellows 12. Further, an arc shield 14 for an insulating container made of metal is provided at a position covering the fixed electrode 8 and the movable electrode 9 in the interrupting chamber 2 . The insulating container arc shield 14 prevents arc vapor from adhering to the inner wall of the insulating container 3.

Generally, the fixed electrode 8, movable electrode 9, fixed electrical contact 10, and movable electrical contact 11 have a disk shape. Hereinafter, the shape of the electrical contact in this embodiment will be described as being disk-shaped. However, the shape of the electrical contact may be other than a disc shape.

From now on, the electrical contacts in this embodiment will be explained. First, a method for manufacturing an electrical contact according to this embodiment will be explained.
The electrical contact of this embodiment is manufactured through the following steps. The process consists of mixing the raw material powders, pressing the mixed raw material powders with a press mold to create a compact, firing the compact to make a sintered compact, and heating the sintered compact. This is the process of processing it into the shape of a contact.

The raw material powders for the electrical contact of this embodiment include, for example, Cu powder as a base material of a conductive component, Cr powder as high melting point material particles serving as an arc-resistant component, and Te powder as a low melting point metal for sustaining an arc. , and Ti powder for thermally stabilizing Te. The raw material powders used in the Examples and Comparative Examples described below are, for example, Cu powder with an average particle size of 10 μm, Cr powder with an average particle size of 40 μm, Te powder with an average particle size of 40 μm, and Ti powder with an average particle size of 30 μm. It is a powder. Note that the average particle size of the raw material powder can be measured using a laser diffraction particle size distribution measuring device based on the laser diffraction scattering method.

These raw material powders were mixed for 30 minutes or more using a V-type mixer. This mixed powder was put into a steel press mold with an inner diameter of 23 mm, and compression molded using a hydraulic press at a pressure of 600 MPa to obtain a molded product with a thickness of about 5 mm. Next, this molded body was fired in a hydrogen atmosphere at a temperature of 900° C. or higher and lower than the melting point of Cu to obtain a sintered body. The shape of the obtained sintered body was a disk shape with a diameter of about 23 mm and a thickness of about 5 mm. However, the shape of the sintered body is not limited to this.
In the Examples and Comparative Examples described below, the concentrations of Cr, Te, and Ti are 100% by mass (hereinafter referred to as wt%) of the total mass of the mixed raw material powder. It is the proportion of mass each occupied by Ti powder, and the proportion is expressed in wt%. Further, in the examples described later, materials other than Cr powder may be used as the high melting point substance particles.

To evaluate the mechanical properties of the obtained sintered body, density and processing characteristics were evaluated.
Evaluation of density was performed as follows. The density was measured by cutting out a 1 cm ³ piece of the sintered body and measuring its mass. Then, the ratio of the measured mass to the theoretical maximum density obtained from the composition ratio (hereinafter referred to as density ratio) was calculated. It was determined that if the density ratio of the sintered body was 95% or more, it could be applied to electrical contacts. If the density ratio of the sintered body is less than 95%, when the sintered body is brazed to an electrode as an electrical contact, the brazing material is drawn into the void inside the electrical contact by capillary action, causing poor brazing. Therefore, if the density ratio of the sintered body was 95% or more, it was determined to be a pass, and if the density ratio of the sintered body was less than 95%, it was determined to be a failure.

The processing characteristics were evaluated as follows. The obtained sintered body was machined into a disk-shaped electrical contact with a diameter of 20 mm and a thickness of 3 mm. If a determined disk shape cannot be obtained due to the brittleness of the sintered body during this machining process, such as visually visible chips or cracks, the machining characteristics were determined to be unacceptable. If a predetermined disk shape was obtained without chipping or cracking during machining, the machining characteristics were passed.

As electrical property evaluations of the electrical contacts that passed the processing properties, cutting properties, welding resistance properties, and breaking properties were evaluated. A test contact was prepared by tapering approximately 15° from the end of a disc-shaped electrical contact having a diameter of 20 mm and a thickness of 3 mm to a 2 mm inner diameter side. Two of these test contacts were produced, and a vacuum valve for evaluation was produced in which these two test contacts were used as a fixed electrical contact and a movable electrical contact, respectively.

Evaluation of cutting characteristics was performed as follows. A circuit was assembled in which a 20Ω resistor and a vacuum valve for evaluation were connected in series. An AC 200 V power source was connected to this circuit, and a current of 10 A was applied to the evaluation vacuum valve in a closed state. In this state, the evaluation vacuum valve was forcibly opened from the closed state, the current value immediately before the arc current became zero was measured, and the current value was taken as the cutting current value. The cutting current value was measured 1000 times using the same evaluation vacuum valve, and the average value was taken as the final cutting current value. The cutting current value needs to be 1 A or less in order to avoid damage to electrical equipment due to the rise in surge voltage that occurs when the circuit is cut off. In the evaluation of cutting characteristics, a case where the cutting current value was 1A or less was judged as a pass, and a case where the cutting current value exceeded 1A was judged as a failure.

The welding resistance was evaluated as follows. Note that the evaluation vacuum valve is equipped with a movable screw that moves the movable electrode rod in a direction to separate the movable electrode from the fixed electrode. By applying an axial force to this movable screw, the movable electrode can be separated from the fixed electrode. In the vacuum valve for evaluation, a current of 10 A was applied in a closed state to create a pseudo welded state of electrical contacts. In this vacuum valve for evaluating the welded state, an axial force was applied to the movable screw of the movable electrode rod. The axial force was gradually increased, and when the axial force exceeded the welding force of the electrical contact, the electrical contact opened. The welding force was determined by measuring the axial force required when the electrodes were opened. The welding force of the conventional Cu--Cr contact measured in this way was about 10 kN, and the welding force of the electric contact to which Te was added was about 5 kN. In this embodiment, it was determined that a welding resistance equal to or higher than that of a conventional electrical contact was required, and the criterion for welding force was set at 5 kN. Therefore, in the evaluation of the welding resistance, a case where the welding force was 5 kN or less was judged as a pass, and a case where the welding force exceeded 5 kN was judged as a failure.

The evaluation of the blocking characteristics was performed as follows. We assembled a circuit in which a thyristor that opens and closes a capacitor bank is connected in series with a vacuum valve for evaluation. In this circuit, a current using discharge from a capacitor bank was passed through a vacuum valve for evaluation in a closed state. The capacitor bank is charged by an external power source. A cutoff test was conducted in which the evaluation vacuum valve was forcibly opened by increasing the applied current from 2 kA to 1 kA increments. The pass/fail of the cut-off characteristics was determined based on whether the cut-off test was successful when the applied current was 4 kA. Note that the success of the interruption test means that the arc is completely extinguished when the evaluation vacuum valve is opened. Failure of the interruption test means that when the evaluation vacuum valve is opened, arcing continues or arcing that has been extinguished occurs again. That is, in the evaluation of the interrupting characteristics, a case where the interrupting test was successful when the applied current was 4 kA was judged as a pass, and a case where the interrupting test was unsuccessful when the applied current was 4 kA was judged as a fail.

Hereinafter, specific examples and comparative examples will be described regarding the electrical contacts of this embodiment.
[Examples 1 to 4] [Comparative Examples 1 to 3]
FIG. 2 is a table showing the compositions, mechanical property evaluation results, and electrical property evaluation results of the electrical contacts of Examples 1 to 4 and Comparative Examples 1 to 3. Examples 1 to 4 and Comparative Examples 1 to 3 show differences in the characteristics of electrical contacts when the Ti concentration is varied, with the Cr concentration being constant at 30 wt% and the Te concentration at 8 wt%. Note that the value obtained by subtracting the sum of the Cr concentration, Te concentration, and Ti concentration from 100 wt% becomes the Cu concentration, which is a conductive component. Furthermore, in the table shown in FIG. 2, Ti/Te is the value obtained by dividing the Ti concentration by the Te concentration.

From Examples 1 to 4, when Ti/Te was 0.01 or more and less than 0.12, all of the density, processing properties, cutting properties, welding resistance properties, and barrier properties passed. On the other hand, Comparative Examples 1 and 2 in which Ti/Te was less than 0.01 had poor processing characteristics. In Comparative Example 1 and Comparative Example 2, the processing characteristics were not acceptable, so test contacts could not be manufactured and electrical characteristics evaluation could not be performed. On the other hand, in Comparative Example 3 in which Ti/Te exceeded 0.12, the density was rejected. In Comparative Example 3, the processing characteristics were acceptable, so a test contact could be produced, but the welding resistance and breaking characteristics were unacceptable.

The following is estimated from the results of Comparative Example 1 and Comparative Example 2. When Ti/Te is less than 0.01, Te mainly contributes to the production of Cu ₂ Te, so Cu ₂ Te increases. Since Cu ₂ Te is thermally unstable, Te evaporates during sintering, making the electrical contact brittle. Therefore, it is estimated that Comparative Example 1 and Comparative Example 2 failed in processing characteristics. On the other hand, the following is inferred from the results of Comparative Example 3. When Ti/Te exceeds 0.012, Te reacts with Ti to produce a Ti-Te compound, suppressing the production of Cu ₂ Te. Therefore, it is estimated that Comparative Example 3 passed the processing characteristics. However, since the Ti--Te compound is thermally stable, it is thought that the progress of sintering is suppressed. It is presumed that Comparative Example 3 failed in terms of density as a result of the progress of sintering being hindered. Furthermore, in Comparative Example 3, since the density was low, there was a large amount of gas remaining inside the electrical contact, and it is presumed that the breaking property was rejected. Furthermore, in Comparative Example 3, it is presumed that due to the high Ti concentration, the generation of Cu ₂ Te was suppressed more than necessary, and the generation ratio of Cu ₂ Te was further lowered, so that the welding resistance property was rejected. .

In addition, regarding the cutting characteristics, Comparative Example 3 was also passed. The reason is that the cutting characteristics mainly depend on the amount of evaporation of the low melting point metal during arc generation. Since Examples 1 to 4 and Comparative Example 3 have the same Te concentration of 8 wt%, it is presumed that all of the cutting characteristics passed the test.

A compositional analysis of the cross section of the electrical contact of Example 2 was performed using a scanning electron microscope (SEM) and an attached energy dispersive X-ray spectroscopy. FIG. 3 is a schematic cross-sectional view of the composition analysis results. As shown in FIG. 3, the electrical contact of Example 2 includes Cr particles 16 which are high melting point material particles, Ti-Te compound particles 17 containing a large amount of Ti, and Cu in a base material 15 made of Cu. Cu--Te compound particles 18 containing a large amount were present in a dispersed manner. The particle size of these particles was 0.1-100 μm. In other words, it was found that Te reacts with both Ti and Cu and exists as Ti--Te compound particles 17 and Cu--Te compound particles 18. Furthermore, it has been found that these compound particles are not separately dispersed inside the electrical contact, but coexist to form one particle. Further, as a result of performing a compositional analysis of the Ti--Te compound particles 17 in a point analysis mode, the atomic weight ratio of Ti and Te was 1:2 to 3:4. From this compositional analysis result and the phase diagram of Ti--Te, it was estimated that the Ti--Te compound particles 17 were in the form of a compound in which TiTe ₂ and Ti ₃ Te ₄ were mixed. Further, as a result of performing a compositional analysis of the Cu--Te compound particles 18 in a point analysis mode, the atomic weight ratio of Cu and Te was 2:1. From this compositional analysis result, it was estimated that the Cu--Te compound particles 18 were Cu ₂ Te.
Note that the particle size of each particle in the cross section of the electrical contact was the particle size calculated when the shape of the particle was approximated to a spherical shape based on the geometric shape of the particle in the observed cross-sectional image.

[Examples 5 to 8] [Comparative Examples 4 to 7]
FIG. 4 is a table showing the compositions, mechanical property evaluation results, and electrical property evaluation results of the electrical contacts of Examples 5 to 8 and Comparative Examples 4 to 7. Examples 5 to 8 and Comparative Examples 4 to 7 show the characteristics of electrical contacts when the Ti concentration is changed when the Cr concentration is constant at 30 wt% and the Te concentration is constant at 3.5 wt% or 14.5 wt%. shows the difference. From Examples 5 to 8, even if the Te concentration is 3.5 wt% or 14.5 wt%, if Ti/Te is 0.01 or more and less than 0.12, the density, processing characteristics, cutting characteristics, and welding resistance are improved. All of the characteristics and cutoff characteristics were passed. On the other hand, Comparative Examples 4 and 6 in which Ti/Te was less than 0.01 had poor processing characteristics. In Comparative Example 4 and Comparative Example 6, the processing characteristics were not acceptable, so test contacts could not be manufactured and electrical characteristics evaluation could not be performed. On the other hand, Comparative Example 5 and Comparative Example 7 in which Ti/Te exceeded 0.12 were rejected for density. In Comparative Example 5 and Comparative Example 7, test contacts were able to be produced because the processing properties were passed, but the welding resistance and breaking properties were not passed.

The following is estimated from the results of Comparative Example 4 and Comparative Example 6. When Ti/Te is less than 0.01, Te mainly contributes to the production of Cu ₂ Te. Since Cu ₂ Te is thermally unstable, Te evaporates during sintering, making the electrical contact brittle. Therefore, it is presumed that Comparative Example 4 and Comparative Example 6 failed in processing characteristics. On the other hand, the following is inferred from the results of Comparative Example 5 and Comparative Example 7. When Ti/Te exceeds 0.012, Te reacts with Ti to produce a Ti-Te compound, suppressing the production of Cu ₂ Te. Therefore, it is estimated that Comparative Example 5 and Comparative Example 7 passed the processing characteristics. However, since the Ti--Te compound is thermally stable, it is thought that the progress of sintering is suppressed. It is estimated that the density of Comparative Examples 5 and 7 was rejected as a result of the progress of sintering being hindered. Further, it is presumed that Comparative Examples 5 and 7 had low densities, so that a large amount of gas remained inside the electrical contacts, and therefore the breaking characteristics failed. Furthermore, in Comparative Examples 5 and 7, the high Ti concentration suppressed the production of Cu ₂ Te more than necessary, resulting in an even lower production ratio of Cu ₂ Te, resulting in failure of the welding resistance. It is estimated that

Attention will be paid to the difference in density between Example 8 and Comparative Example 5. Example 8 passed the test because the Ti concentration was 1.67 wt% and the density ratio was 95% or more. On the other hand, in Comparative Example 5, the Ti concentration was 0.44 wt%, lower than that in Example 8, and the density ratio was less than 95%, resulting in a failure. This result shows that the sinterability of the electrical contact is not determined only by the Ti concentration, but is influenced by Ti/Te. Ti/Te in Example 8 is 0.115, whereas Ti/Te in Comparative Example 5 is 0.125, so from the viewpoint of density, Ti/Te is preferably less than 0.12. I understand. This can also be seen from the fact that the density of Comparative Example 7 with a Ti/Te ratio of 0.125 was also rejected.

Next, attention will be paid to the differences in processing characteristics between Examples 5 to 8 and Comparative Examples 4 to 7. Even if the Te concentration was 3.5 wt% or 14.5 wt%, the processing characteristics were acceptable in Examples 5 to 8 and Comparative Examples 5 and 7 in which Ti/Te was 0.01 or more. On the other hand, even if the Te concentration was 3.5 wt% or 14.5 wt%, the processing characteristics of Comparative Examples 4 and 6, in which Ti/Te was less than 0.01, were rejected. This result shows that the processing characteristics of electrical contacts are not determined only by the Ti concentration, but are influenced by Ti/Te. It can be seen that from the viewpoint of processing characteristics, Ti/Te is preferably 0.01 or more.

Regarding the welding resistance property and the blocking property, Comparative Example 5 and Comparative Example 7, in which the density was determined to be unacceptable, failed. Similarly, in Comparative Example 3 in which the density was determined to be unacceptable, the welding resistance property and the blocking property were also unacceptable.

From the results of Examples 1 to 8 and Comparative Examples 1 to 7, Ti/Te is 0.01 or more in electrical contacts in which Ti is added with a Cr concentration of 30 wt% and a Te concentration of 3.5 to 14.5 wt%. It can be seen that if it is less than 0.12, an electrical contact with high density can be obtained, and all of the processing characteristics, cutting characteristics, welding resistance characteristics, and breaking characteristics are passed.

[Examples 9 to 11] [Comparative Examples 8 and 9]
FIG. 5 is a table showing the compositions, mechanical property evaluation results, and electrical property evaluation results of the electrical contacts of Examples 9 to 11 and Comparative Examples 8 and 9. Examples 9 to 11 and Comparative Examples 8 and 9 show the difference in the characteristics of electrical contacts when the Te concentration is changed when the Cr concentration is 30 wt% and the Ti/Te is constant at 0.1. There is. In Examples 9 to 11 and Comparative Examples 8 to 9, in order to keep Ti/Te constant at 0.1, the Ti concentration was changed as the Te concentration changed. From Examples 9 to 11, when the Te concentration was 3.5 wt% or more and 14.5 wt% or less, all of the density, processing characteristics, cutting characteristics, welding resistance characteristics, and blocking characteristics passed. On the other hand, in the electrical contact of Comparative Example 8 in which the Te concentration was 3.0 wt%, the cutting characteristics were unacceptable. It is presumed that this is because in the electrical contact of Comparative Example 8 where the Te concentration was less than 3.5 wt%, Te vapor was no longer stably supplied when an arc occurred, and the arc was extinguished before the cutting current became small. In addition, the electrical contact of Comparative Example 9 with a Te concentration of 15 wt % failed in breaking characteristics. This is because the cutting characteristics and the blocking characteristics are contradictory characteristics. In the electrical contact of Comparative Example 9 in which the Te concentration exceeded 14.5 wt%, when the evaluation vacuum valve was opened, the supply of Te vapor was continued longer than necessary, and the arc continued or disappeared once. It is presumed that this is because the arc is more likely to occur again.

From the results of Examples 9 to 11 and Comparative Examples 8 and 9, in an electrical contact with a Cr concentration of 30 wt% and a Ti/Te ratio of 0.1, if the Te concentration is 3.5 wt% or more and 14.5 wt% or less, , density, processing characteristics, cutting characteristics, welding resistance characteristics, and blocking characteristics all pass the test.

From the results of Examples 1 to 11 and Comparative Examples 1 to 9 explained so far, it is clear that the base material mainly consists of Cu, the Cr particles that exist dispersed in the base material, and the Cr particles that exist dispersed in the base material. In an electrical contact containing Te and Ti, when the whole is 100% by mass, the Te concentration is 3.5% by mass or more and 14.5% by mass or less, and the Ti/Te ratio is 0.01 or more and 0.12% by mass. It can be seen that if it is less than that, all of the density, processing characteristics, cutting characteristics, welding resistance characteristics, and blocking characteristics are passed.

Note that in the electrical contact of this embodiment, the firing temperature for obtaining the sintered body is 900° C. or higher and lower than or equal to the melting point of Cu. Even when Ti/Te exceeds 0.12, the density of the sintered body can be increased by increasing the firing temperature. However, when Ti/Te exceeds 0.12, the formation of Ti--Te compounds progresses and sintering becomes difficult. Furthermore, since the amount of the Ti--Te compound increases, the amount of the Cu--Te compound decreases, resulting in a decrease in welding resistance.

[Examples 12 to 14] [Comparative Examples 10 and 11]
FIG. 6 is a table showing the compositions, mechanical property evaluation results, and electrical property evaluation results of the electrical contacts of Examples 12 to 14 and Comparative Examples 10 and 11. Examples 12 to 14 and Comparative Examples 10 and 11 show the difference in the characteristics of electrical contacts when the Cr concentration is changed when the Te concentration is 8 wt% and Ti/Te is constant at 0.1. There is. From Examples 12 to 14, when the Cr concentration was 20 wt% or more and 60 wt% or less, all of the density, processing characteristics, cutting characteristics, welding resistance characteristics, and blocking characteristics passed. On the other hand, the electrical contact of Comparative Example 10 with a Cr concentration of 15 wt% failed in welding resistance. In the electrical contact of Comparative Example 10 in which the Cr concentration was less than 20 wt%, it is presumed that the Cu component of the closed electrical contacts was welded to each other due to the high Cu concentration, resulting in an increase in welding force. In addition, the electrical contact of Comparative Example 11 with a Cr concentration of 70 wt % failed in breaking characteristics.

The results of Examples 12 to 14 and Comparative Examples 10 and 11 reveal the following. It can be seen that in an electrical contact with a Ti/Te ratio of 0.1, if the Cr concentration is 20 wt% or more and 60 wt% or less, all of the density, processing characteristics, cutting characteristics, welding resistance characteristics, and breaking characteristics pass.

[Examples 15 to 17]
FIG. 7 is a table showing the composition, mechanical property evaluation results, and electrical property evaluation results of the electrical contacts of Examples 15 to 17. Examples 15 to 17 show the characteristics of electrical contacts when the arc-resistant component is a material other than Cr, when the Te concentration is constant at 8 wt% and Ti/Te is constant at 0.1. In Examples 15 to 17, the concentration of the arc-resistant component was kept constant at 30 wt%. From Examples 15 to 17, even if the arc-resistant components were changed to W (tungsten), WC (tungsten carbide), and Cr ₃ C ₂ (chromium carbide) other than Cr, the density, processing characteristics, cutting characteristics, and welding resistance characteristics remained unchanged. and cutoff characteristics were all passed. The melting points of Cr, W, WC and _Cr3C2 are 1907°C, 3422°C, 2870°C and 1895°C _, respectively. It was found that there is no practical problem as long as the arc-resistant component is a material with a melting point higher than 1800°C. Examples of materials having a melting point higher than 1800° C. include Mo (molybdenum) and Mo ₂ C (molybdenum carbide), and these materials can also be used as arc-resistant components.

Note that in the process of producing the compact of this embodiment, the press pressure was set at 600 MPa, but the press pressure can be set in the range of 200 to 1000 MPa depending on conditions such as the particle size of the raw material powder. In addition, in the process of producing the sintered body, the compact was fired in a hydrogen atmosphere at a temperature of 900°C or higher and lower than the melting point of Cu, but it may also be fired in a vacuum at an atmospheric pressure of 1×10 ⁻⁵ Pa or lower. .

Although this application describes exemplary embodiments, the various features, aspects, and functions described in the embodiments are not limited to application of particular embodiments, and may be used alone or It is applicable to the embodiments in various combinations.
Accordingly, countless variations not illustrated are envisioned within the scope of the technology disclosed herein. For example, this includes cases in which at least one component is modified, added, or omitted.

1 Vacuum valve, 2 Cutoff chamber, 3 Insulating container, 4a, 4b Sealing fittings, 5a, 5b Metal lid, 6 Fixed electrode rod, 7 Movable electrode rod, 8 Fixed electrode, 9 Movable electrode, 10 Fixed electrical contact, 11 Movable electrical contact, 12 bellows, 13 arc shield for bellows, 14 arc shield for insulating container, 15 base material, 16 Cr particles, 17 Ti-Te compound particles, 18 Cu-Te compound particles.

Claims (5)

A base material containing Cu as a main component,
High melting point substance particles composed of at least one of a high melting point metal and a carbide of the high melting point metal dispersed in the base material;
An electrical contact containing Te and Ti dispersed in the base material,
When the whole is 100% by mass, the concentration of Te is 3.5% by mass or more and 14.5% by mass or less, and the value obtained by dividing the concentration of Ti by the concentration of Te is 0.01 or more and 0.01% or more. less than 12 ;
The Te exists as a compound of the Te and the Ti and a compound of the Te and the Cu, and the compound of the Te and the Ti and the compound of the Te and the Cu coexist to form one particle. An electrical contact characterized by forming a A claim characterized in that the compound of Te and Ti is composed of at least one of TiTe ₂ and Ti ₃ Te ₄ , and the compound of Te and Cu is composed of Cu ₂ Te. The electrical contact according to item 1 . 3. The electrical contact according to claim 1, wherein the high melting point substance particles are particles of at least one of Cr, Cr carbide, Mo, Mo carbide, W, and W carbide. The electrical contact according to claim 3 , wherein the high melting point substance particles are Cr particles, and the Cr concentration is 20% by mass or more and 60% by mass or less. a fixed electrode,
A movable electrode that comes into contact with and leaves this fixed electrode,
A vacuum valve comprising a cutoff chamber that holds the fixed electrode and the movable electrode in a vacuum,
At least one of the fixed electrical contact and the movable electrical contact provided at the contact portions of the fixed electrode and the movable electrode, respectively, is constituted by the electrical contact described in any one of claims 1 to 4 . Features a vacuum valve.

Images