JPS61148727A - Contact material for vacuum breaker - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application J This invention relates to a contact material for a vacuum breaker that has excellent large current blocking properties and high withstand voltage performance.

[Prior Art] Vacuum circuit breakers have advantages such as no maintenance, no pollution, and excellent breaker performance, so the range of applications of vacuum circuit breakers is rapidly expanding. In addition, as a result, there is a growing demand for higher withstand voltages and larger cut-off current capacities. On the other hand, the performance of a vacuum breaker is determined to a large extent by the contact material in the vacuum volume 4.

Satisfactory characteristics of contact material for vacuum breaker include (1
) have large breaking capacity, (2) have high withstand voltage,
(3) Low contact resistance, (4) Low welding force, (5) Low contact wear, (6) Low cutting current value, (7) Good workability, (8) ) have sufficient mechanical strength, etc.

In actual contact materials, it is quite difficult to satisfy all of these properties, and in general, materials are used that satisfy particularly important properties depending on the application, sacrificing other properties to some extent. This is the actual situation. For example, Japanese Patent Application Publication No. 55
The copper--tungsten contact material described in No. 78429 has excellent withstand voltage performance. fFI L has the disadvantage of poor current cutoff performance.

On the other hand, for example, the copper-chromium contact material 8-//i described in JP-A No. 54-71375 is often used because of its very excellent breaking performance, but the steel-tungsten contact material mentioned above has superior voltage resistance. Inferior.

In addition to the above-mentioned contact materials for vacuum breakers, examples of contact materials generally used in air, oil, etc. are listed in literature such as "Powder Metallurgy" (published by Nikkan Kogyo Shimbun). but,
For example, when the silver-molybdenum contact materials and copper-molybdenum contact materials described in Powder Metallurgy P229-230 are used for vacuum breaker contacts, the withstand voltage performance is inferior to the above-mentioned copper-tungsten contact materials, and the current interrupting performance is inferior to that of the copper-tungsten contact materials. is the above copper −
Because it is inferior to chrome contact materials, it is rarely used at present.

, [Problems to be solved by the invention] As mentioned above, conventional contact materials for vacuum circuit breakers have been used by taking advantage of their respective characteristics, but in recent years, vacuum circuit breakers have become larger in current and voltage. As the requirements for contact materials have become stricter, the only way to meet the required performance with conventional contact materials is to add 1M to the required performance. Also, for miniaturization of vacuum breakers,
There is a need for contact materials with better performance.

This invention was made to solve the above-mentioned problems of the conventional products, and its purpose is to provide a contact material for a vacuum breaker that has excellent large current blocking properties and high withstand voltage performance. .

[Means for solving problems]

The contact material for a vacuum breaker according to the present invention contains copper and chromium as another component of 12 to 38% steel.
It contains molybdenum boride in an amount of 0.2 to 10% by weight.

[Effect]

Copper that can be used in this invention? Contact materials for vacuum circuit breakers contain ROM and molybdenum boride.

Chromium and molybdenum borides are uniformly distributed in the steel, providing excellent breaking performance and high pressure resistance.

[Example] The inventors added various metals, alloys, and intermetallic compounds to copper.
We made a prototype of the added material, incorporated it into a vacuum breaker, and conducted various experiments. As a result, it was found that the contact material containing copper and borides of chromium and molybdenum had very excellent breaking performance.

An embodiment of the present invention will be described below.

(Preparation of contact material) The contact material was prepared using a powder metallurgy method, an atmospheric pressure sintering method, and a pressure sintering method.

The first pressureless sintering method for manufacturing contact materials has a particle size of 70 μm.
The following chromium powder, MOB powder with a particle size of 40 μm or less, and copper powder with a particle size of 40 ttrn or less were each weighed in predetermined proportions and mixed for 2 hours. Subsequently, this mixed powder was filled into a mold with an inner diameter of -30 mm, and press molding was performed. Next, this molded body was sintered in a hydrogen atmosphere just below the melting point of the pot for about 2 hours to obtain a contact material.

The second pressure sintering method for manufacturing contact materials has a particle size of 70 μm.
The following chromium powder, MOB powder with a particle size of 40 μm or less, and copper powder with a particle size of 40 μm or less were each weighed in predetermined proportions and mixed for 2 hours. Next, add this mixed powder to an inner diameter of −3
Filled into a 0.5 carbon die and heated in a vacuum at 1000 to 1050°C for 2 hours using a hot press machine, during which time 100 to 3001e/wf - for example, 200va
d pressure was applied to obtain the soul of the contact material.

In addition, after filling the mixed powder into a mold with an inner diameter of −30 mm and performing press molding, the molded product is hot pressed in a hot press machine to obtain a contact material, and as described in No. 11. A contact material can also be obtained by vacuum-sealing a cold press-formed product of the mixed powder in a stainless steel container, heating it in argon to just below the melting point of copper for 2 hours, and applying hydrostatic pressure at 1 to 2 ton/d during this time. We did it together.

Although the first pressureless sintering method also yields a contact material with a theoretical density of 9 or higher, the second pressure sintering method achieves a theoretical density of almost 9 or higher. Contact material is obtained,
The electrical conductivity and hardness were slightly better with the pressure sintering method.

FIG. 1 shows Cu-Cr-MO as an embodiment of the present invention.
A SaW photograph of the metal structure of the B alloy contact material is shown at a magnification of 100. This was done by weighing chromium powder, MOB powder, and copper powder at a ratio of 25:5:700, mixing for 2 hours, press-forming at a pressure of 3 ton/m, and molding this compact with an inner diameter of -30, Filled into a carbon die No. 5 and heated for 2 hours just below the melting point in a vacuum pot, during which time 200Kp/
-30.5X10t C obtained by applying csf pressure
It is a u-Cr-MOB alloy. In the first figure, MO
It can be seen that B is uniformly and finely distributed.

FIG. 4 shows a micrograph of the metal structure of a conventional Cu-Cr alloy contact material at a magnification of 100 as a comparative example.

This is done by weighing powder with a particle size of 7011 m or less and copper powder with a particle size of 40 μm or less in a ratio of 25:75, mixing for 2 hours, and then pouring this mixed powder into a mold with an inner diameter of -30 mm. This is a Cu--Cr alloy obtained by filling the molded body with water, press-forming it at a pressure of 3 ton/cj, and then heating this molded body in a hydrogen atmosphere just below the melting point of the pot for 2 hours.

(Characteristics of contact materials, experiments) The above contact materials manufactured by each method were machined into electrodes with a diameter of 20 fins, and then incorporated into a vacuum breaker and their electrical characteristics were measured.

Figures 2 and 3 both show the breaking performance of the contact material according to an embodiment of the present invention.
Breaking property fII of r weight% alloy! , is a graph showing the breaking performance of the contact material according to the present invention when , is taken as l. This evaluation of the cutoff performance was determined from the results of a composite cutoff test in which DC rJi, 'jf and fBit during arcing were varied rapidly.First, a test was conducted on a conventional Cu-25%Cr product, and the reference value was t-calculated.

Next, we started testing the inventive product at the level of conventional products.
The blocking performance was measured. The data in the range below that of the conventional product is not detailed and is indicated by a broken line in the figure.

Figure 2 shows the Crfi (wt%) in the alloy at 12.15.
The graph shows the relationship between the amount of MOB added and the breaking performance when the amount of MOB is fixed at 20.25, and when the amount of Cr is 12% by weight or more, the breaking performance is improved by adding goBi. Cr
When the amount is 25% by weight, MOB is about 5% by weight and conventional product C
Although it increased to about 1.15 times that of u-25 wt% Cr, no effect was observed when the MOB amount was less than 0.2 wt%. On the other hand, if the amount of MOB exceeds 10% by weight, the breaking performance will decrease.

Figure 3 shows the amount of Cr (wt%) in the alloy at 25.30.35
．． It shows the relationship between MOB addition/removal and breaking performance when fixed at 38% by weight.
o: An improvement in the breaking performance can be seen by adding sf%.

Therefore, as a contact material for a vacuum breaker, it is desirable to contain 12 to 38% by weight of I/1cf-violet and 0.2 to 10% by weight of MOB.

It was also confirmed that the voltage resistance performance was also improved by adding MOBI7)/i.

In the above examples, the borides of copper, chromium, and molybdenum are each thought to be distributed as a single wire mesh, a king or a king's alloy, a king or a king's intermetallic compound, or a composite thereof.

Further, in the above embodiment, the case K in which MoB was used as the boride of MO was explained, but 1iloB2. Similar effects were obtained using other MO borides such as Mo2B. However, from the experimental results, MaB and Mo as boride
When at least one of B2 was included, the breaking performance of the trowel was also effectively improved.

In addition, Bi, Te, and Sb are added to the above alloy (not shown).
.

A contact for a low-temperature vacuum breaker containing at least 10% by weight of at least one of Tl, Pb, 8e, Co and pseudo low-melting metals, alloys thereof, intermetallic compounds thereof, and oxides thereof. It has also been confirmed that, in the same manner as in the above embodiment, there is an effect of increasing the blocking performance and withstand voltage performance.

Note that at least one of low melting point metals, alloys thereof, intermetallic compounds thereof, and oxides thereof is
If more than % M is added, the breaking performance will be significantly lower.
did. Furthermore, when the low melting point metal was Ce% or Ca, the properties were slightly degraded.

〔Effect of the invention〕

As described in 1 below, according to the present invention, copper-containing L
, j4;ni, ILLl, II/) i-band No. 4 L7
Te, Ri ``1 mu wo 12-38 heavy-j fuliwa no hoki 111
1. Contains 0.2-10% of boride of molybdenum, so it has 1- and time 1 flood, μs 2, and 1h EE resistance 1 flood. Sky 1. There is a koji ψ: where the contact material for the disconnection F is faced.

・Name, Diagram trri's darkness (11, Kesetsu's funeral 1 Diagram 1, 1L
Manufactured using the hot press method, Ta-no-o January Kazumi IAa I! AI ic a Two C11-25 East amount % Cr-5 ton + 1 Mo
Fig. 2 is a diagram showing the microscopic view of the metallographic structure of the metal structure used in the present invention.
Mo when the quantity ratio is fixed at 12.15 and 20.25
B & Relationship between resistance and cutting performance I'1. 1. The characteristic diagram shown in FIG. 3 is an example of this generator 1I11.
Contact material $”i'p, yield Cr=t i it
Rate Zenzen 25:30. :35. ;(Fixed to H and 7'
Figure 4 shows the relationship between the amount of MoB added and L7 and breaking performance in the case of n. FIG. 2 is a diagram showing the dark microscopic structure of the metallographic structure 100 times larger.

Figure 2 MOB: Delivered δ sword 11 quantity 01 Doriri Figure 3 MoB counter volume practice [9

Claims (3)

[Claims] (1) Contains copper and 1 chromium as other components
Molybdenum boride ranges from 2 to 38% by weight, from 0.2 to 38% by weight.
A contact material for a vacuum shield and disconnector, characterized in that the content is in the range of 10% by weight. (2) The contact material for a vacuum shield or breaker according to claim 1, wherein the molybdenum boride is at least one of MOB and MOB_2. (3) Bismuth, tellurium, antimony, thallium, lead,
Claims characterized by containing 10% by weight or less of at least one of low melting point metals such as selenium, cerium, and calcium, their alloys, their intermetallic compounds, and their oxides. The contact material for a vacuum shield and disconnector according to item 1 or 2.