JPH0654626B2 - Electrode and manufacturing method thereof - Google Patents

Description

TECHNICAL FIELD The present invention relates to an electrode used in a power switchgear for a gas switch, a vacuum switch, and the like, and a manufacturing method thereof.

[Prior Art] The electrodes used in power switchgear, vacuum switch, etc.
As shown in the figure, the copper-tungsten alloy contact 1 was brazed to the tip of the current-carrying base member 3.
However, recently, as shown in FIG. 3, an electrode has been used in which the copper-tungsten alloy contact 1 is formed by infiltration of copper, and the infiltration copper residue 2 is directly joined to the energization base member 3.

[Problems to be solved by the invention]

In the case shown in FIG. 4, when the joining is performed by brazing, it is difficult to braze the copper-tungsten alloy and other members, and the joining strength is not stable. In addition, since a brazing material having a low melting point and a low electric conductivity is present in the joint, the copper-tungsten alloy contact may sometimes drop from the brazing portion due to a severe thermal shock when the short-circuit current is cut off. Therefore, there is a risk that a major accident may occur in the power supply system.

In the case of directly joining without using a brazing material, the heating of the energizing base member is annealed by the heating at the time of joining, the mechanical strength is lowered, and the copper-tungsten alloy contact is easily oxidized, so the heating of the joint is minimized. You have to keep it to the limit. Therefore, as a direct joining method, friction welding and electron beam welding have been conventionally performed. However, even if they are joined by these methods, the tungsten itself in the copper-tungsten alloy contact is easily oxidized, and since it is a refractory metal, it is difficult to form an alloy at the joint, and the hardness difference between the contact and the energization base member is also high. If it is large, it may be difficult to bond directly, and stable and sufficient bonding strength cannot be obtained.

Therefore, in order to prevent the oxidation of the copper-tungsten alloy contact, the copper-tungsten alloy contact 1 shown in FIG. An electrode has been used in which the infiltrated copper residue 2 welded to the above is directly joined to the current-carrying base member 3.

However, the contact 1 is formed through the infiltrated copper residue 2 as described above.
Even if an electrode is manufactured by joining the energization base member 3 with the energization base member 3, since there are many holes such as casting holes in the remaining infiltrated copper, the joining strength between the copper-tungsten alloy contact and the energization base member is high. And the mechanical strength against bending and the like is low and the electrical conductivity is poor.

[Means for Solving Problems] In order to solve the above problems, the remaining infiltrated copper is heated and melted by a heater, an electron beam, or the like in an inert gas atmosphere before being joined to the energization base member. The present inventor has found that it is optimal to remove the voids by performing a degassing treatment and a hardening treatment such as cold forging.

That is, the electrode of the present invention is an electrode formed by joining the end surface of a copper-tungsten alloy contact obtained by infiltrating copper to a tungsten skeleton via the remainder of the infiltration copper, wherein the remainder of the infiltration movement is degassed and hardened copper. It is characterized by consisting of.

The electrode of the present invention, the copper residue at the time of infiltration is melted and degassed in an inert gas atmosphere, and after forging and hardening treatment, pressure contact with the tip surface of the current-carrying base member, electron beam welding, or friction welding. It is obtained by joining with joining means.

As the inert gas, a gas such as Ar gas or nitrogen gas that forms an inert atmosphere with respect to the copper-tungsten alloy contact and the current-carrying base member, particularly infiltrated copper can be used.

Then, by heating and pressure welding in an inert gas atmosphere to bond the remaining infiltrated copper and the current-carrying base member that have been treated as described above, the bonding strength is sufficient and the manufacturing can be performed at low cost. By friction welding, even greater joining strength can be obtained. In particular, when the energization base member is made of copper or a copper alloy, the copper or copper and the copper alloy are bonded to each other, and the bonding strength is high and stable bonding strength can be obtained even at high temperature.

Further, if the remaining infiltrated copper thus treated and the current-carrying base member are welded together by using an electron beam or a laser, a strong joint can be easily obtained. Furthermore, if a large amount of infiltrated copper residue is generated and the treatment of the present invention is applied, this can be directly used as a current-carrying base member, and the conventional process of joining the contact portion and the current-carrying base member is unnecessary. In addition, a stable electrode strength can be obtained.

The electrode created by the above method is a joint of the copper-tungsten alloy contact and the current-carrying base member, and has no pores in the remaining infiltrated copper, and the bonding strength is extremely large, and the mechanical strength is also improved. Also, the electrical conductivity is improved.

Hereinafter, the present invention will be specifically described with reference to examples.

〔Example〕

Example 1 Tungsten powder with a pressure of 2 t / cm ² and a shape of φ12 mm × 6 mm
A tungsten skeleton was produced by pressure forming into a glass and sintering it in a hydrogen furnace at 1300 ° C. And the skeleton is φ12
It was put in a carbon box having a hole of mm × 40 mm, a copper cutting layer was filled on the box, and copper infiltration was performed in the hydrogen furnace to produce a copper-tungsten alloy. At this time, a carbon jig was used so that the remaining infiltrated copper was left on one surface of the copper-tungsten alloy. Then, the alloy integrated with the remaining infiltrated copper is put into a nitrogen furnace at 1150 ° C. to remelt the remaining infiltrated copper,
A degassing process was performed. Then, the remaining infiltrated copper was cold forged and machined to a shape of φ10 mm × 30 mm (here, copper-tungsten alloy thickness is 5 mm). Then, the composition and physical property values of this contact member were measured. The results are shown in Table 1.

Next, the sample and a copper rod of φ30 mm × 100 mm were joined by heating pressure welding, friction welding and electron beam welding in a nitrogen gas atmosphere. Then, the hardness of this joint portion was measured, and it was HRF-70 or higher in all of the above three joining methods. The conventional method that does not process the remaining infiltrated copper has a hardness of about HRF-25, whereas the hardness is four times or more higher. Even if a 60 kg load of Rockwell was applied and the steel ball indenter did not peel or crack at the joint surface. Further, according to FIG. 2 showing a cross-sectional photograph of the joined portion, the infiltrated copper residual portion 2 has no holes, and the contact member 1, the infiltrated copper residual portion 2, and the infiltrated copper residual portion 2
It can be seen that and the copper rod (the energization base member 3) are firmly joined. As described above, it can be seen that the mechanical strength is improved at the joint.

Example 2 A copper member of a φ3 mm × 1 mm copper-tungsten alloy contact integrally formed with a copper member having a thickness of 5 mm obtained in the same manner as in Example 1 and a copper current-carrying member of φ3 mm × 4 mm were used as nitrogen gas. Electrodes that were heated and pressure welded in an atmosphere and friction and pressure welded were electron beam welded. As a comparative sample, the copper-tungsten alloy contact (φ3mm × 1mm), which has been used by conventional copper infiltration, is heated in a nitrogen gas atmosphere on a copper current-carrying base member without treatment. Electrodes welded by pressure welding and friction welding were produced in the same shape as above. In addition, make a φ3 mm × 1 mm copper-tungsten alloy contact as shown in Fig. 4
Create a conventional electrode brazed to a 3mm x 4mm copper rod and
A durability test was conducted by generating a half-cycle arc of C 220V, 3000A. Ten samples were tested each. The results are shown in Table 2.

From Table 2, the service life is extended by about 25-40% by more than the conventional electrode made by joining the remaining infiltrated copper to the contact without treatment, and it is extended by more than about 2 times compared with the one in which the contact is brazed. I understood it. It was found that the electrode using the manufacturing method of the present invention has stable bonding strength even at high temperature. Furthermore, when the electric conductivity of the copper member was measured, it was found that the electrode of the present invention was better than the conventional electrode formed without processing the remainder of the infiltrated copper.

[Effects of the Invention] When the electrode of the present invention is used, the copper-tungsten alloy contact does not fall off even at high temperatures, the life is extended, and the mechanical strength at the joint and the electrical conductivity of the copper member are improved.

Furthermore, when the electrode manufacturing method of the present invention is used, the copper-tungsten alloy contact can be firmly joined to the energizing base member via the copper member, and the mechanical strength of the energizing base member is prevented from lowering due to heating during the joining. To be done.

[Brief description of drawings]

FIG. 1 is a sectional view of an electrode of the present invention. FIG. 2 shows a photograph of a cross-sectional structure of a joint portion between a copper member and a current-carrying base member integrally formed with the copper-tungsten alloy contact of the present invention. FIG. 3 shows a metaphysical view of a conventional electrode in which the remaining infiltrated copper is left untreated and joined to a current carrying base member. FIG. 4 shows a sectional view of a conventional electrode formed by brazing. In the figure, 1 ... Copper-tungsten alloy contact, 2 ... Copper member, 3 ... Conducting base member, 4 ... Joining surface

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takami Honda Nihon Tungsten Co., Ltd. 2-2031 Shimizu, Minami-ku, Fukuoka City, Fukuoka Prefecture (56) References Japanese Patent Publication No. 44-14450 (JP, B1)

Claims (2)

[Claims] 1. An electrode comprising a tungsten-skeleton infiltrated with copper and bonded to an end face of a copper-tungsten alloy contact through the remainder of the infiltrated copper, wherein the remainder of the infiltrated copper is degassed and hardened copper. . 2. A method for producing an electrode, wherein the remainder of the infiltrated copper adhered to the end surface of a copper-tungsten alloy contact obtained by infiltrating copper into a tungsten skeleton is joined to the leading end surface of a current-carrying base member. The rest is melted and degassed in an inert gas atmosphere,
A method for producing an electrode, which is forged and hardened, and then joined to a leading end surface of a current-carrying base member by any one of a pressure welding method, an electron beam welding method, and a friction welding method.