JPS627255B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field] This invention belongs to the field of manufacturing technology for materials used in electrical contacts. [Background Art] Conventionally, silver-cadmium oxide-based, silver-tin oxide-based, and silver-nickel-based contact materials have been used in electrical equipment such as electromagnetic contactors and relays. These contacts are known for their low welding and wear and tear.
On the other hand, silver-nickel contacts are known for their low wear and tear and excellent workability. However, when these contact materials are used as contacts for no-fuse breakers, which limit the current by running an arc using electromagnetic driving force, the large current that flows during a short circuit generates an arc, causing the arc to break. '' is insufficient, resulting in poor short-circuit breaking performance, and improvements in this performance have been desired. The inventors of the present invention have conducted various studies to improve the "breakage" of the arc, and as a result have developed a contact material containing lithium oxide in a silver base material, and have already filed a patent application for the contact material. In other words, by adding lithium oxygen (Li ₂ O) to the silver base, the arc can be cut.
is improved. Furthermore, the welding resistance, which is important as a contact material, is also improved. This contact material was sufficiently practical. but,
In order to obtain even higher practical value, it was found that it was necessary to further improve the wear resistance. Therefore, as a result of further research, the present invention described below was achieved. [Object of the Invention] This invention provides a contact material with improved arc "breakage", welding resistance, and wear resistance.
The aim was to provide a better manufacturing method. [Disclosure of the Invention] This invention is based on silver, and one or more selected from the group consisting of zinc oxide (ZnO), tin oxide (SnO ₂ ), and indium oxide (In ₂ O ₃ ). A contact material containing 0.02 to 1.0% by weight of metal oxides, 0.1 to 3.0% by weight of lithium oxide (Li ₂ O) in terms of lithium, and 0.1 to 1.0% by weight of iron group metals. A contact material that is manufactured by melting and mixing zinc and/or tin and/or indium, and further lithium and iron group metals in advance on the above-mentioned silver base material, and then heat-treating the mixture in an oxygen gas atmosphere. It provides a manufacturing method. This invention will be explained in detail below. In this invention, the lithium oxide contained in the silver matrix is useful for improving arc "breakage" and welding resistance. It is not clear why the inclusion of lithium oxide in the silver base improves arc cutting, but when lithium oxide is dispersed in the silver base, it becomes easier to generate an arc, and as a result of the dispersion of the arc, The arc becomes easier to move,
It is thought that the "cutting" of the arc will improve after all. The amount of lithium oxide blended is preferably 0.1 to 3.0% by weight (hereinafter abbreviated as %) in terms of lithium. If the content exceeds 3.0%, the electrical conductivity required for the contact will be low.
Welding resistance and abrasion resistance are insufficient, and on the other hand, if it is less than 0.1%, the "cutting" of the arc will not be sufficient. Note that a range of 0.8 to 1.5% gives more preferable results. Next, zinc oxide, tin oxide, and indium oxide contained in the silver base will be explained.
The content of this metal oxide is 0.02~ in terms of metal.
It is preferably 1.0%, and more preferably in the range of 0.2 to 0.6%. If the content exceeds the upper limit of these ranges, the electrical conductivity will decrease and the welding resistance will not be improved much. On the other hand, if the lower limit is exceeded, the effect of improving wear resistance will be reduced. Furthermore, if iron, nickel, and cobalt, which are metals belonging to the iron group, are added to the silver base in advance along with metals such as zinc, tin, indium, and lithium, and then subjected to internal oxidation treatment, wear resistance is improved. It was found that this method has the effect of further improving the properties and welding resistance. The reason why the welding resistance and abrasion resistance are improved by the addition of the iron group metal is not clear, but it is presumed that it is because the silver crystal grains are made finer. The content is in the whole contact material.
It is desirable to contain it in the range of 0.1 to 1.0%. If it is less than the lower limit, there will be no grain refining effect, while if it exceeds the upper limit, the distribution of iron group metals will become segregated.
The improvement effect becomes insufficient for both welding and wear. Note that for the internal oxidation method, a usual method is employed, and the specific details thereof will be explained in the examples. The following is a description based on Examples and Comparative Examples. Example A contact material was prepared by using silver as a base metal and adding lithium oxide, zinc oxide, tin oxide, indium oxide, iron group metal, etc. to the base metal. The specific formulation is shown in Table 1. The detailed manufacturing conditions for the contact material are as follows. First, a predetermined amount of any one of zinc, tin, and indium, lithium, and an iron group metal were added to silver and dissolved in an argon gas atmosphere. After melting, it was cast into a bar using a mold, and then annealed at 650°C for 8 hours in a nitrogen gas atmosphere. After a silver plate was crimped onto this, it was rolled to obtain a 1 mm plate material. Then, at 750℃ in an oxygen gas atmosphere.
Heated for 100 hours for internal oxidation. After punching this, it was brazed and used as a sample for ASTM tests and short circuit tests. (Method for Determining Arc Characteristics) The above sample was assembled into a no-fuse breaker, and a short circuit resistance test was conducted using the ASTM method, and the arc sticking time was measured. Here, the arc stagnation time is the time during which the arc remains motionless when it occurs between the contacts. That is, an electromagnetic force is generated at the same time as the arc is generated, and ultimately the arc moves due to this electromagnetic force, but the sticking time is the time from when the arc is generated until it moves. The shorter the sticking time, the better the arc interrupting performance. In addition,
The short circuit current was 5.2KA. (Method for determining wear resistance and welding resistance) A contact test was conducted using ASTM. The conditions were as follows. Load: AC single layer, 100V, 40A Contact force: 200g Dissociation force: 340g Contact shape: Movable contact is 5Φ, 12R spherical fixed contact is 5Φ and flat Final number of openings and closings: 100,000 times The wear amount is 3 The welding performance was evaluated based on the average value of the data, and the total number of weldings for the three pieces of data.

[Table] Table 2 shows the results of testing the properties of the above materials as contacts.

[Table] Furthermore, as an effect of the addition of iron group metals in Example No. 3.4.5, the size of crystal grains was measured using a microscope and found to be 47 μ in Example No. 3 and 50 μ in Example No. 4. , in Example No. 5, it was 45μ. On the other hand, in Comparative Example No. 6, which will be described later, the crystal grain size was 122μ. Comparative Example Comparative experiments were conducted using the formulations shown in Table 3, using the sintering method for Comparative Examples Nos. 1 to 5, and using the internal oxidation method for Comparative Example No. 6. The experiment was conducted under the same conditions as in the example. The results of the performance test are shown in Table 4.

【table】

[Table] [Effects of the invention] This invention uses silver as a base material, and zinc oxide,
One or more metal oxides selected from the group consisting of tin oxide and indium oxide with a metal equivalent of 0.02~
1.0%, and 0.1 to 3.0% of lithium oxide in terms of lithium, and 0.1 to 3.0% of iron group metals.
A method for producing a contact material containing 1.0%, in which zinc oxide and/or tin oxide and/or indium oxide and lithium oxide and iron group metal are melt-mixed in advance into the above-mentioned silver base, and then
Since the method is characterized by heat treatment in an oxygen gas atmosphere, it is effective in providing a contact material with improved arc "breakage", welding resistance, and wear resistance.

Claims (1)

[Claims] 1 Silver is the base material, and zinc oxide, tin oxide,
One or more metal oxides selected from the group consisting of indium oxide in a range of 0.02% by weight or more and less than 1.0% by weight in terms of metal, and lithium oxide in a range of 0.1% by weight or more and less than 3.0% by weight in terms of lithium. A method for manufacturing a contact material containing an iron group metal in a range of 0.1% by weight or more and 1.0% by weight or less, wherein the above-mentioned silver substrate is preliminarily coated with zinc or/or iron group metal.
and tin and/or indium, further lithium and an iron group metal are melt-mixed, cast, and then heat-treated in an oxygen gas atmosphere.