JP2008171622A - Contact material for vacuum valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To comprehend an arc-resistant component in which a conductive component is made solid-soluble from a measurement method of the arc-resistant component, and improve withstand voltage characteristics and barrier characteristics. <P>SOLUTION: In a contact material which is used for a vacuum valve having a pair of contacts 13a, 13b that can be separable in a vacuum insulation container 2, and which is constituted of a conductive component, the arc-resistant component, and an auxiliary component if necessary, when the content of the arc-resistant component obtained through a wet type chemical analytical method is A, and the content of the arc-resistant component obtained through a texture photograph of an optical microscope is B, then there exists a relationship that B≥1.1×A between these, and the conductive component becomes solid-soluble in the arc resistant component, so that the barrier characteristics and the withstand voltage characteristics are improved. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a contact material for a vacuum valve that can improve a withstand voltage characteristic and a cutoff characteristic among characteristics required for a contact material of a vacuum valve used for a vacuum circuit breaker or the like.

The characteristics required for a contact material for a vacuum valve include a withstand voltage characteristic, a cut-off characteristic, and a welding resistance characteristic, but it is difficult to satisfy all the characteristics with a single metal material. Therefore, contact materials made of two or more kinds of metal materials such as a combination of a conductive component and an arc resistant component have been developed. As an example of this, there is known a technique in which a fine arc-proof component having a particle diameter of several to several tens of μm is present in Cu as a conductive component, thereby improving withstand voltage characteristics and cutoff characteristics (for example, Patent Documents). 1).
JP 2006-32036 A (pages 3 to 5, FIG. 1)

The above-described conventional contact materials have the following problems.
The presence of a fine arc-proof component in the conductive component can improve the withstand voltage characteristics and the cut-off characteristics. However, if only the fine arc-proof component is used, the total surface area of the arc-proof component is extremely increased. However, the gas content may increase after the contact is manufactured, and the interruption characteristics may be deteriorated. For the arc-resistant component, raw material powder is often used, and the gas content tends to increase.

  Therefore, it is preferable that not only the fine arc-proof component is present but also the conductive component is dissolved in the arc-proof component to reduce the gas content. However, when the conductive component is dissolved in the arc-proof component, the arc-proof component content in the measurement of the arc-proof component after manufacturing the contact does not always match with each measurement method.

  Here, the arc resistance component is measured based on the content of the arc resistance component obtained by a combination of wet chemical analysis and subsequent inductively coupled plasma optical emission spectrometry. The ratio of the arc resistance component and the ratio of the arc resistance component content by simple analysis with an electron microscope were determined, and the arc resistance component in which the conductive component was dissolved was examined from the difference in measurement method. That is, when the conductive component is dissolved in the arc resistant component, the optical microscope and the electron microscope may be measured so as to contain a large amount of the arc resistant component. The optical microscope can measure up to the wavelength of visible light, and the electron microscope has a resolution up to the wavelength of the electron beam, which is considered to have an influence. For this reason, it has been desired that the arc-resistant component in which the conductive component is dissolved can be grasped from the difference in measurement method.

  The present invention has been made to solve the above problems, and provides a contact material for a vacuum valve having improved withstand voltage characteristics and interruption characteristics by grasping an arc resistance component in which a conductive component is dissolved from a difference in measurement method. The purpose is to do.

  In order to achieve the above object, the vacuum valve contact material of the present invention is a vacuum valve contact material composed of a conductive component, an arc resistant component and, if necessary, an auxiliary component. When the content rate of the component is A and the content rate of the arc resistant component obtained from the structure photograph of the optical microscope is B, there is a relationship of B ≧ 1.1 × A between them, and the arc resistant component The conductive component is in solid solution.

  ADVANTAGE OF THE INVENTION According to this invention, the contact material for vacuum valves which improved the withstand voltage characteristic and interruption | blocking characteristic can be provided.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  Examples of the present invention will be described. First, the configuration of a vacuum valve to which the contact material of the present invention is applied will be described with reference to FIG. 1 and FIG. FIG. 1 is a cross-sectional view showing a configuration of a vacuum valve to which a contact material according to an embodiment of the present invention is applied, and FIG. 2 is a pair of contactable and separable contacts to which a contact material according to an embodiment of the present invention is applied. It is sectional drawing which shows one structure of these.

  As shown in FIG. 1, reference numeral 1 denotes a blocking chamber. This blocking chamber 1 is made of an insulating container 2 formed in a cylindrical shape with an insulating material, and is made of metal provided at both ends via sealing fittings 3a and 3b. The lids 4a and 4b are vacuum-tight. A pair of electrodes 7 and 8 attached to opposite ends of the conductive rods 5 and 6 are disposed in the shut-off chamber 1, and the upper electrode 7 is a fixed electrode and the lower electrode is a movable electrode. In addition, a telescopic bellows 9 is attached to the conductive rod 6 of the electrode 8 to enable the electrode 8 to move in the axial direction while maintaining the inside of the blocking chamber 1 in a vacuum-tight manner. A metal arc cover 10 is attached to the upper portion of the bellows 9 in the figure to prevent the bellows 9 from being covered with arc vapor. Reference numeral 11 denotes a metal arc shield provided in the shut-off chamber 1 so as to cover the electrodes 7 and 8 and prevents the insulating container 2 from being covered with arc vapor. Further, as shown in FIG. 2, the electrode 8 is fixed to the end of the conductive rod 6 by a brazing portion 12 or is crimped and connected by caulking. The contact 13 a is fixed to the electrode 8 with a brazing portion 14. In addition, 13b in FIG. 1 is a contact on the fixed side, and can be freely contacted and separated from the contact 13a.

Next, referring to Table 1, examples of the contact material for vacuum valves according to the present invention and comparative examples will be described.

(Comparative Example 1, Example 1)
In Comparative Example 1, a Cu-50% Cr contact was manufactured by a sintering infiltration method. Cr powder with an average particle size of 100 μm is pressed with a φ60 mm mold so that the relative density is 50%, and this green compact is in a non-oxidizing atmosphere in a vacuum atmosphere at 1000 ° C. for 1 hour. Was pre-sintered. Then, a Cu block as an infiltrant was placed on the Cr skeleton and infiltrated under the conditions of 1150 ° C. × 1 hour to obtain a plurality of cylindrical Cu-50% Cr alloys.

  The Cu-50% Cr alloy thus obtained was cut in a plane perpendicular to the bottom, and the Cr content was determined by wet chemical analysis, subsequent inductively coupled plasma emission spectroscopy, and a structure photograph of an optical microscope. (Weight ratio) was determined. In the wet chemical analysis method, for example, 1 g of a predetermined amount of Cu—Cr alloy was dissolved only in Cu with nitric acid to separate the Cu phase and Cr particles, and the approximate Cu content was determined by neutralization titration. Thereafter, trace components in the Cu phase and Cr particles were determined by an inductively coupled plasma emission spectrometer. The trace components include Fe, Ni, Al, Cr in the Cu phase, Cu in the Cr phase, and the like. As a result, the Cr content A is from 100% to the content of components other than Cr, that is, the Cu content (the approximate Cu content obtained by wet analysis and the Cr particles obtained by inductively coupled plasma emission spectrometry). The sum of the Cu content ratios) and the total content of the trace components was subtracted, and A = 49.5 wt%.

  Moreover, in the optical microscope, the area ratio of Cr, that is, the volume ratio was obtained from the entire cross-sectional structure photograph magnified several hundred times by an image processing apparatus. As a result, from the density of Cu and Cr, the Cr content B was B = 53.2 wt%.

  In addition, these were measured several times and the average value was calculated | required. The ratio of the Cr content obtained by inductively coupled plasma emission spectroscopy and the optical microscope was found to be B / A = 1.07. The wet chemical analysis method and the optical microscope measurement are the same thereafter.

  Further, the remaining Cu-50% Cr alloy was processed into a contact shape having a diameter of 50 mm and a thickness of 5 mm, and incorporated in a vacuum valve to perform a breaking test and a withstand voltage test. In the interruption test, the maximum interruption current value was measured by gradually increasing the current from 5 kA. In the withstand voltage test, the dielectric breakdown voltage was measured several tens of times with the distance between the contacts being constant, for example, 5 mm, and the average value was obtained. The maximum cut-off current value and breakdown voltage value in Comparative Example 1 are, for example, values for contact materials as disclosed in Patent Document 1 described above, which is 1.0 as a reference, and will be described below. The measurement results are shown as relative values.

  In Example 1, a Cu-50% Cr alloy was manufactured in the same process as Comparative Example 1 using raw material Cr powder having an average particle diameter of 50 μm and a finer particle diameter than Comparative Example 1. The Cr content of this Cu-50% Cr alloy is A = 49.7 wt% in the wet chemical analysis method (including the subsequent inductively coupled plasma emission spectroscopy), and B = 57.7 wt% in the optical microscope. These ratios were B / A = 1.17. As a result of the electrical test, the interruption characteristics were 1.0 times and the withstand voltage characteristics were 1.1 times.

  Thus, when the Cr content of the Cu-50% Cr alloy produced by the sintering infiltration method was compared by a measuring method, when B / A was 1.1 times or more, 1.1 times or more, the breaking characteristics and anti-resistance It was found that the voltage characteristics were improved to be equal to or higher than that of Comparative Example 1. In addition, it is thought that it is measured that an optical microscope contains many arc-proof components that the Cr content differs depending on the measurement method. In addition, the larger the total surface area of the Cr particles in contact with the Cu matrix, that is, the finer the Cr particles, the more the reaction between the Cu matrix and the Cr particles is promoted. This is thought to have increased. As described above, the reason why the Cr content varies depending on the measurement method is that, although manufactured based on Cr 50%, the amount of Cu dissolved in Cr particles increases and the material structure differs.

(Comparative Example 2, Example 2)
In Comparative Example 2, a Cu-50% Cr contact was produced by solid phase sintering. A compact of Cu powder and Cr powder in a weight ratio of 1: 1 and molded at 7 t / cm ² with a φ60 mm mold at 1000 ° C. for 5 hours in a hydrogen atmosphere in a non-oxidizing atmosphere Were subjected to solid phase sintering to obtain a plurality of cylindrical Cu-50% Cr alloys.

  The Cu-50% Cr alloy thus obtained was cut in a plane perpendicular to the bottom as in Comparative Example 1, and wet chemical analysis (including subsequent inductively coupled plasma emission spectroscopy), The Cr content (weight ratio) was determined using an electron microscope. In the wet chemical analysis method, the Cr content A was A = 50.4 wt%.

  Moreover, in the measurement with the electron microscope of a Cu-Cr50% alloy, Cr content rate was calculated | required by the compositional analysis of the attached energy dispersive X-ray-analysis method (EDX). As a result, the Cr content C was C = 54.9 wt%. When the ratio of the Cr content in the wet chemical analysis method and the electron microscope was determined, it was C / A = 1.09. The measurement with an electron microscope is the same thereafter. Further, the remaining Cu-50% Cr alloy was incorporated into a vacuum valve, and a cutoff test and a withstand voltage test were performed. As a result, the breaking characteristics were 1.0 times and the withstand voltage characteristics were 0.9 times.

  In Example 2, a Cu-50% Cr alloy was manufactured by solid-phase sintering similar to Comparative Example 2, but the manufacturing process was performed by repeating the pressing process and the sintering process twice. The Cr content of this Cu-50% Cr alloy was Cr content A = 50.1 in the wet chemical analysis method, and Cr content C = 58.4 wt% in the electron microscope. And C / A = 1.17. The remaining Cu-50% Cr alloy was incorporated in a vacuum valve and subjected to a breaking test and a withstand voltage test. As a result, the breaking characteristic was improved by 1.0 times and the withstand voltage characteristic by 1.1 times compared to Comparative Example 2.

  Thus, when the Cr content of the Cu-50% Cr alloy manufactured by the solid-phase sintering method was compared by a measuring method, when C / A was 1.17 times, 1.1 times or more, the breaking characteristics and resistance It was found that the voltage characteristics were improved to be equal to or higher than that of Comparative Example 2. In addition, it is thought that it is that the amount of solid solution increased by repeating a pressurization and sintering twice that Cr content rate changes with a measuring method. The reason why the Cr content varies depending on the measurement method is considered to be that the amount of Cu dissolved in Cr particles increases and the material structure differs.

(Comparative Example 3, Examples 3-5)
In Comparative Examples 1 and 2 and Examples 1 and 2, sintering was performed at two temperatures of 1000 ° C. and 1150 ° C., that is, at a temperature within ± 90 ° C. based on the melting point of the conductive component Cu (1083 ° C.). However, the gist of the present invention is not limited to this.

  In Comparative Example 3 and Examples 3 and 4, the sintering temperatures were 850 ° C., 900 ° C., and 1250 ° C., respectively, and Cu-25% Cr contacts were manufactured. When the Cr content of the three types of Cu-25% Cr alloys was determined by a wet chemical analysis method and an optical microscope, the ratio of each Cr content was B / A = 1.10, 1.15, 1.30. Met.

  In the cut-off characteristics and the withstand voltage characteristics, Comparative Example 3 was 1.0 times in both characteristics. This is because sintering did not proceed because the sintering temperature was low, and the relative density was as low as 85%. In Example 3, both characteristics were 1.1 times, and in Example 4, both characteristics were 1.2 times. For this reason, sintering temperature becomes favorable from -183 degreeC or more of melting | fusing point (1083 degreeC) of Cu. In Example 4, B / A = 1.30, which indicates the maximum value due to the difference in measurement method, and both the cutoff characteristics and the withstand voltage characteristics can be stably improved. In Example 5, it manufactured by the vacuum melting method of 1800 degreeC, and ratio of Cr content rate was C / A = 1.25. The breaking characteristics and withstand voltage characteristics were each 1.2 times.

(Examples 6 to 10)
In Examples 6 to 10, Cu-20% Cr contacts were produced by a solid phase sintering method at 950 ° C. in a vacuum atmosphere. Similarly to Example 2, after pressing and sintering twice, heat treatment was performed for 30 minutes in a vacuum atmosphere.

  In Example 6, the heat treatment after sintering was 1070 ° C., and the Cr content ratio was B / A = 1.23. The breaking characteristics were 1.2 times and the withstand voltage characteristics were 1.1 times. In Example 7, the heat treatment after sintering was 1050 ° C., and the Cr content ratio was B / A = 1.22. The breaking characteristics were 1.3 times and the withstand voltage characteristics were 1.2 times. In Example 8, the heat treatment after sintering was 850 ° C., and the Cr content ratio was B / A = 1.24. The breaking characteristics were 1.3 times and the withstand voltage characteristics were 1.2 times. In Example 9, the heat treatment after sintering was 700 ° C., and the Cr content ratio was B / A = 1.23. The breaking characteristics were 1.2 times and the withstand voltage characteristics were 1.1 times. In Example 10, the heat treatment after sintering was 650 ° C., and the Cr content ratio was B / A = 1.24. The interruption characteristic was 1.1 times and the withstand voltage characteristic was 1.1 times.

  From these results, when heat treatment was performed after solid-phase sintering, the Cr content ratio was increased to B / A = 1.2 or more, and in particular, there was a tendency to improve the breaking characteristics. When the heat treatment temperature is −20 ° C. or lower to −400 ° C. or higher on the basis of the melting point (1083 ° C.) of the conductive component Cu, the improvement of the blocking characteristic becomes remarkable.

(Examples 11 to 16)
In Comparative Examples 1 to 3 and Examples 1 to 10, the conductive component is Cu and the arc-proof component is Cr, but the gist of the present invention is not limited to this.

  In Example 11, Ag-60% WC contact was manufactured by liquid phase sintering using Ag as the conductive component and WC as the arc resistant component. As a result, the Cr content ratio was B / A = 1.23, and the breaking characteristics and withstand voltage characteristics were 1.1 times or more. In Example 12, Ag / Cu-60% WC contacts were manufactured by liquid phase sintering using Ag and Cu as the conductive components, WC as the arc resistant component, and liquid phase sintering. As a result, the ratio of Cr content was B / A = 1.28, and the breaking characteristics and withstand voltage characteristics were 1.1 times or more. In Examples 13 to 16, the conductive component was Cu and the arc-proof component was 70% W, 40% Nb, 50% Mo, and 26% Cr + 4% W, respectively, and manufactured by a liquid phase sintering method. As a result, the ratio of Cr content was B / A = 1.2 or more in all cases, and the breaking characteristics and withstand voltage characteristics were 1.2 times.

(Examples 17 to 19)
In Comparative Examples 1 to 3 and Examples 1 to 16, the contact point constituted by the conductive component and the arc resistant component has been described, but the gist of the present invention is not limited to this.

  In Examples 17-19, in addition to the conductive component Cu and the arc-proof component Cr, Bi, Te, and Te + Sb were used as auxiliary components, respectively, and contacts were manufactured by a sintering infiltration method. The density of Cr was 50%. As a result, the ratio of Cr content was B / A = 1.2 or more in all cases, and the breaking characteristics and withstand voltage characteristics were 1.1 times or more. In addition, when this auxiliary component is added in a trace amount of 5 wt% or less, the welding characteristics are improved. In general, when 5 wt% or more is added, the conductivity is lowered and embrittlement becomes remarkable. Therefore, the amount of the auxiliary component added is set to 5 wt% or less.

  In Examples 1 to 19, although the conductive component is described as Cu, Ag, and Cu + Ag, the same effect can be obtained if the conductive component is mainly composed of Cu and Ag. Moreover, the same effect can be acquired even if an arc-resistant component uses Cr, W, Nb, Ta, Ti, Mo, and at least one of these carbides. Furthermore, the same effect can be obtained even when the auxiliary component uses at least one of Bi, Te, and Sb.

  According to the vacuum valve contact material of Example 1 above, arc-resistant components such as Cr are measured by a wet chemical analysis method and an optical microscope or an electron microscope, and the ratio of the content ratio of the arc-resistant components is obtained from these measurements. As a result, it is possible to grasp the arc-proof component in which the conductive component is dissolved, and it is possible to improve the withstand voltage characteristic and the cutoff characteristic.

Sectional drawing which shows the structure of the vacuum valve to which the contact material which concerns on the Example of this invention is applied. Sectional drawing which shows one structure of a pair of contact which can be contacted / separated to which the contact material which concerns on the Example of this invention is applied.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Shut-off chamber 2 Insulation container 3a, 3b Sealing metal fitting 4a, 4b Cover body 5, 6 Conductive rod 7, 8 Electrode 9 Bellows 10 Arc cover 11 Arc shield 12, 14 Brazing part 13a, 13b Contact

Claims (7)

In a contact material for a vacuum valve composed of a conductive component, an arc-proof component and, if necessary, an auxiliary component,
Let A be the content of arc-proof components obtained by wet chemical analysis,
When the content rate of the arc resistant component obtained from the structure photograph of the optical microscope is B,
There is a relationship of B ≧ 1.1 × A between them, and the conductive component is dissolved in the arc-proof component. In a contact material for a vacuum valve composed of a conductive component, an arc-proof component and, if necessary, an auxiliary component,
Let A be the content of arc-proof components obtained by wet chemical analysis,
When the content rate of the arc resistant component obtained from the composition analysis by the electron microscope is C,
There is a relationship of C ≧ 1.1 × A between them, and the conductive component is dissolved in the arc-proof component.   The contact material for a vacuum valve is manufactured by a sintering method in a non-oxidizing atmosphere, and the sintering temperature is −183 ° C. or higher based on the melting temperature of the conductive component. The contact material for a vacuum valve according to claim 1 or 2.   The contact material for the vacuum valve is a material subjected to heat treatment in a non-oxidizing atmosphere after liquid phase sintering, and the heat treatment temperature is −20 ° C. or less based on the melting temperature of the conductive component, − The contact material for a vacuum valve according to any one of claims 1 to 3, wherein the contact temperature is 400 ° C or higher.   The contact material for a vacuum valve according to any one of claims 1 to 4, wherein the conductive component contains at least one of Cu and Ag as a main component.   The arc-resistant component contains at least one of Cr, W, Nb, Ta, Ti, Mo, and their carbides, according to any one of claims 1 to 5. The contact material for vacuum valves as described.   The contact material for a vacuum valve according to any one of claims 1 to 6, wherein the auxiliary component contains at least one of Bi, Te, and Sb.

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