JPS62116736A - Production of electrode for vacuum valve circuit breaker - Google Patents

Abstract

PURPOSE:To economically produce an electrode for a vacuum valve circuit breaker having high performance by preliminarily incorporating elements which generate wetting into molten copper, uniformly dispersing metallic particles which are not solutionized with copper therein and sulidifying the molten metal under the pressure. CONSTITUTION:The electrode for the vacuum valve circuit breaker is produced by uniformly dispersing the metallic particles which have >=400 deg.C difference in the m.p. from copper or are not solutionized with copper into a copper or copper alloy matrix. At least one kind selected from the elements which generate wetting with the molten copper or copper alloy and the metallic particles, i.e., Ti, Cr, Zr, V, and Nb are incorporated into the molten metal and thereafter the metallic particles are penetrated and dispersed into the molten metal. The size of the metallic particles is made about 5-200mu in the case of using Ta and W and about 5-500mu in the case of Cr, Co, Mo, and Fe. The elements to generate the wetting are added at about 0.05-3.0 at/O by 1-45amt. of the metallic particles to be added by volume. Such molten metal is cast into a metallic mold mold preheated to about 300-500 deg.C and is pressurized under about 200-2,000kg/cm<2> pressure to solidify.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a method for manufacturing an electrode for a vacuum circuit breaker.

[Background of the invention]

Conventionally, Cu-based alloys have been widely used as electrodes for vacuum circuit breakers because of their good conductivity. For example, there are Cu-Pb-based, Cu-B1-based, and Cu-Co-B1 or PB-based ingot alloys with high voltage resistance.

In the above-mentioned materials, the purpose of adding low melting point metals such as Bi and Pb is generally to prevent welding of the electrically connected surfaces. Many conventional electrode materials contain Cu to which these additive elements have been added.
Base alloys have been used. However, Bi, Pb
There are also some electrode materials that do not contain additives. For example, the electrode contact WC- disclosed in JP-A-54-73284
Ag or Cr-Cu based spark gap electrodes disclosed in Japanese Patent Publication No. 45-35101 have fairly good welding resistance even without containing low melting point metals, and have recently been used for vacuum circuit breakers. It is being used as a. Among the above-mentioned contacts, Cr-Cu and WC-Ag type contacts are relatively difficult to weld because Cr and WC, which form the matrix, have a high melting point. However, each of the above materials has its own drawbacks. For example, WC-
In Ag-based electrodes, when a part of the electrode surface is exposed to high temperature during arc interruption, a large amount of thermoelectrons are likely to be emitted, resulting in a decrease in insulation recovery characteristics and interruption ability. Therefore, it has the disadvantage that it cannot be applied to large capacity applications. On the other hand, in the Cr-Cu system, Cr itself is oxygen (o
2), and therefore, Cr compacts are usually sintered, infiltrated, etc. at high temperatures in a reducing atmosphere. However, oxide residues are still likely to exist when Cr powder is sintered. As a result, when the electrode is exposed to a higher temperature arc, the oxide decomposes and releases oxygen, which may make it impossible to shut off. Various measures are taken to eliminate these oxide residues as much as possible.
As disclosed in No. 0, Cr oxides that tend to remain between the particles of a Cr sintered body are mixed with Cu powder and pressed into powder in advance, and then heated at a temperature higher than the melting point of Cu and not exceeding 100°C. A method of liquid phase sintering and then densification by hot forging.

Alternatively, if the oxide decomposes during shut-off, a third element (Ti, Zr
etc.). The former method of removing oxides by liquid-phase sintering involves an infiltration process in which molten Cu is infiltrated into a Cr sintered matrix, as disclosed in German Patent Application No. 1640039. A method for decomposing and removing oxides is described. Among the conventional techniques described above, the method of infiltrating Cu is particularly effective in decomposing and removing oxides. However, it is difficult to completely remove the oxide slag, and the oxide slag may partially block the pores in the sintered matrix, which hinders the penetration of Cu, resulting in the formation of uninfiltrated defect pores. Sometimes. Gas is likely to be occluded in these defective pores, and when used as an electrode, they often become a source of significant gas release due to repeated shutoff operations, reducing the shutoff ability. At this point, it was necessary to add a pretreatment to further clean the Cr sintered matrix.

As mentioned above, how to clean the Cr sintered matrix,
A very important issue is how to infiltrate Cu at a high density.

[Purpose of the invention]

The object of the present invention is to provide a large-capacity vacuum that eliminates the drawbacks of electrode materials manufactured by powder metallurgy by using a cast alloy in which metal particles effective as a vacuum circuit breaker electrode are uniformly dispersed in Cu or a Cu alloy. An object of the present invention is to provide a method for manufacturing a circuit breaker electrode.

[Summary of the invention]

As mentioned in the Background of the Invention, most recent mass vacuum circuit breaker electrodes are manufactured by powder metallurgy. For example, after Cr powder is molded into a mold, C is poured into the voids in a matrix sintered at high temperatures in a non-oxidizing atmosphere.
The electrode material is manufactured by the step of permeating the molten metal u. These problems include: firstly, the use of a complicated process using a press; secondly, the sintering technology has continuous pores; and thirdly, the problem is caused by oxides on the Cr powder surface or inside the pores. There are many problems to be solved, such as a decrease in blocking ability.

The present inventors believe that if an electrode with a similar composition can be manufactured by casting as an alternative to the conventional powder metallurgy method, the above-mentioned problems can be solved and the interrupting ability can be improved, and various studies have been carried out. As a result, in a method for manufacturing a vacuum circuit breaker electrode in which metal particles are uniformly dispersed in Cu or Cu alloy, at least one of the elements that causes wetting between the molten metal and the metal particles in Cu or Cu alloy molten metal is used.
After impregnating and dispersing the metal particles into the molten metal, the molten metal was solidified while being pressurized, thereby making it possible to manufacture an electrode for a vacuum circuit breaker that solved the above-mentioned problems.

The present invention comprises a process of infiltrating metal particles into a molten Cu or Cu alloy, and a process of solidifying the molten metal in which the metal particles or alloy particles are dispersed.

First, metal particles are infiltrated and dispersed into the molten metal of Cu or Cu alloy, but in the normal casting method, even if metal particles or alloy particles are added to the molten metal or alloy, they float up and separate on the surface of the molten metal. Particles cannot be dispersed into the molten metal because they settle to the bottom of the molten metal and cannot penetrate and disperse into the molten metal.As a result of various studies on infiltration methods, we found that it is possible to suppress flotation and sedimentation on the surface of the molten metal, or agglomeration of particles among themselves. It was found that the important point is to improve the wettability of the interface between the molten metal and the particles. In other words, it has been found that at least one selected from Ti, Cr, ZryV, and Nb is included in advance into a molten metal of Cu or Cu alloy, and then metal particles are introduced from the surface of the molten metal and penetrated into the molten metal to be added. In addition, even if the Cu or Cu alloy molten metal in which metal particles are dispersed and permeated is solidified, remelted, and remelted repeatedly, the metal particles in the molten metal do not float to the surface of the molten metal or settle. It became clear that it would remain.

The metal particles considered in the present invention are Cr and Go.

These are Mo, W, Ta, Fe, and alloy particles thereof. These metal or alloy particles are made of Ti in advance.

As a result of adding Cu or Cu alloy containing at least one selected from Cr, Zr, V, and Nb into the molten metal, none of the metal or alloy particles float to the surface of the molten metal or settle into the molten metal. It was confirmed that it penetrated and dispersed.

In the present invention, the size of the metal particles that can be permeated and dispersed in the Cu or Cu alloy molten metal is determined by the metal particle distribution state in the Cu or Cu alloy ingot, and T a .

In the case of W particles, it is 5 to 200. um, Cr, Co.

In the case of Mo and Fe, it was found that the range of 5 to 500 μm is sufficient. In other words, if any metal particles have a particle size of 5 μm or less, they can be penetrated and dispersed into the molten metal. However, the metal particles distributed in the ingot aggregate and the particles -
Cakes cannot be dispersed. On the other hand, when the particle size of Ta and W exceeds 200 μm, the particles distributed in the ingot tend to settle to the bottom of the ingot. Also, Cr, Co.

It has been found that when the particle size of Mo or Fe is 500 μm or more, contact between metal particles increases when the electrodes come into contact, resulting in a decrease in the blocking properties.

The amount of metal particles that can be permeated and dispersed into the molten metal varies depending on the particle size. For example, if particles with a particle size of 5 μm are added and dispersed in a volume ratio of 30% or more, the fluidity of the molten metal will be poor and casting will not be possible. On the other hand, it was found that when the particle size was 500 μm, casting could be performed even if the particles were charged and dispersed to a volume ratio of 45%.

On the other hand, the amount of Ti, Cr, Zr, V, Nb, etc. added for penetrating and dispersing metal or alloy particles into the molten metal is 0.05 to 3.0at1 at a volume ratio of 1 to 45 particles.
A range of 0 is sufficient and an ingot in which particles are uniformly dispersed can be obtained. When the amount added is 3 at/0 or more, the added element reacts with the matrix, and an intermetallic compound tends to be generated in the matrix and become coarse, which becomes a factor that reduces the blocking performance.

The composition of the matrix in which metal or alloy particles are dispersed is the same as in general casting methods.
It is also possible to alloy metal elements such as e H5a.

The next step is to solidify the molten metal in which metal or alloy particles have been permeated and dispersed, and the molten metal can be cast into a separately prepared mold in the same way as in general casting methods. However, by solidifying the permeated and dispersed molten metal while applying pressure, the soundness of the ingot and the uniform dispersibility of particles are further improved. In the pressure casting method, a molten metal in which metal or alloy particles have been permeated and dispersed is poured into a separately prepared mold that has been preheated to 300 to 500°C.
Solidify while pressurizing at a pressure of 00 kg/d. If the preheating of the mold is 300° C. or lower, the cooling rate of the molten metal in contact with the mold will be high, so that the effect of pressurization will not be exhibited. 50 again
If the temperature is 0°C or higher, the cooling rate of the molten metal will be slow and the effect of pressurization will not be exhibited. On the other hand, the pressure applied to the molten metal is 200k
If it is less than g/J, the cooling rate of the molten metal becomes slow and there is no pressurizing effect. Furthermore, it has been confirmed that even if the weight exceeds 2000 kg/J, the effect is the same as that of 200 to 2000 kg/cd.

[Embodiments of the invention]

An embodiment of the present invention will be described below.

Example 1 2033 g of Cu was dissolved in a graphite crucible at 1150°C.
was held at Stir the molten metal using an alumina protection tube.

56.7 g of Cr particles with a particle size of 40 μm were poured into the center of the vortex to study the permeability and dispersion of the Cr particles into the molten metal. As a result, the added Cr particles floated and separated on the surface of the molten metal and did not penetrate and disperse into the molten metal. Similarly, GoyW, Mo.

As a result of examining Ta and Fe particles and their alloy particles, none of the particles penetrated and dispersed into the molten metal.

As described above, it can be seen that various particles cannot penetrate and disperse into the molten metal using normal casting methods.

Example 2 2044 g of Cu-0,5Ti alloy was melted in a graphite crucible and maintained at 1150°C. As a result of examining the permeability and dispersion of each particle of Cr, Co+w, Mo, Ta, and Fe particles and their alloy particles in the same manner as in Example 1, all particles permeated and dispersed into the molten metal, and the addition of Ti element was found to be ineffective. It was found to be effective for osmotic dispersion. In a similar manner, the influence of added elements on penetration dispersibility was investigated. As a result, Cr and Zr.

It has been found that in a molten metal to which about 0.5wt10 of each of V and Nb is added, particles of Cr, Cow, Mo, Ta, Fe and their alloy particles permeate and disperse.

Example 3 1890 g of Cu 0.5Ti alloy was melted in a graphite crucible and kept at 1150°C. Using an alumina protection tube, the molten metal was stirred into the C u -0,5T i molten metal held at 1150°C, and particles with a diameter of 40 μ were introduced into the center of the vortex.
210g of Cr particles were poured into the molten metal and dispersed into the molten metal.The molten metal was poured into a separately prepared 50X2QX200Q mold preheated to 300℃ while stirring, and immediately poured into the molten metal. It was solidified while being pressurized at 600 kg/cd using a plunger to obtain an ingot. As a result of observing the microstructure of the Cr particle-dispersed ingot, the Cr particles were uniformly dispersed in the base material, and almost no casting defects were found.

Example 4 Various Cu-Cr particle dispersed cast steel alloy ingots with various amounts of Cr particles dispersed were produced in the same manner as in Example 3,
Figure 1 shows the results of examining the current interrupting performance and withstand voltage characteristics of each. In addition, the conventional material made only by vacuum infiltration was reduced to 10%.
These are performance comparison values for each of the materials of the present invention when it is set to 0%. The test method uses high voltage (600 Hz) at a frequency of approximately 50 Hz.
~700V) was applied, the current was increased in steps of 500A, and the limit value of the current at which the current could no longer be interrupted was determined and compared with that of the conventional material.

Although the present invention is described as a "method for manufacturing an electrode for a vacuum circuit breaker," it is essentially a method for manufacturing a metal particle dispersed casting alloy.

It is thought that the combination of matrix and metal particles can be reconsidered as a functional material. Examples include lightweight wear-resistant materials.

〔Effect of the invention〕

According to the electrode according to the present invention, since it can be manufactured by a general casting method, it is more economical and has fewer defects than powder metallurgy, resulting in a high-performance electrode.6 Also, because it is a casting method, the matrix composition can be changed arbitrarily.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of electrical performance comparison values of Cr particle dispersed cast alloys manufactured by the method for manufacturing electrodes for vacuum circuit breakers of the present invention. −, Agent: Patent Attorney Katsuma Ogawa 1.

Claims (1)

[Claims] 1. In a method for manufacturing a vacuum circuit breaker electrode in which metal particles having a melting point difference of 400°C or more with copper or not solidly soluble with copper are uniformly dispersed in a copper or copper alloy matrix, copper or copper alloy molten metal and metal particles are uniformly dispersed. At least one element selected from the group consisting of titanium, chromium, zirconium, vanadium, and niobium, which causes wetting with the particles, is included in the molten copper or copper alloy, and then the metal particles are penetrated and dispersed into the molten metal, and the molten metal is added. A method for manufacturing an electrode for a vacuum circuit breaker, which is characterized by solidifying while pressing.