JPH0230370B2 - DENKISETSUTENZAIRYONOSEIZOHO - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for manufacturing electrical contact materials used in devices that conduct electrical current to open and close devices. Moreover, it is particularly aimed at improving the properties of Ag-carbide alloys. Among Ag-carbide alloys
Ag-WC alloys have traditionally had excellent arc resistance,
Because of its welding resistance, it is widely used as contacts in devices such as air vents, disconnectors, and switches. However, in recent years, devices such as no-fuse breakers, disconnectors, switches, and other devices have become smaller and more sophisticated, and as a result, the load on contact materials has become severer, requiring improvements in contact performance. is strongly requested. Furthermore, due to the miniaturization of devices, there is a tendency for contact dimensions to become smaller and contact pressure to decrease, resulting in increased wear and tear that occurs when current is interrupted, increased wear and tear, welding of contacts, deterioration of equipment insulation, and even lower rated current switching. Problems have arisen, such as the tendency for temperature rises to occur at times.
A contact made by adding graphite (Gr) to an Ag-WC alloy was developed as one way to meet the demand for improved characteristics. In this contact, the arc heat generated during opening and closing turns Gr into a reducing gas, preventing oxidation of WC and suppressing temperature rise, and the lubricity of Gr has the effect of increasing welding resistance. However, Gr.
On the other hand, the addition of oxides had the disadvantage of causing consumption and deterioration of the insulation properties. For this reason, small, high-performance circuit breakers and switches have had to use a combination of Ag-WC contacts for the movable contacts and Ag-WC-Gr contacts for the fixed contacts. However, changing and combining materials for the movable part and the fixed part makes parts management extremely troublesome. Furthermore, even when using such a combination, the contact pressure is small in recent small, high-performance devices, and the arc heat generated during opening and closing often causes abnormal temperature rises, wear, insulation deterioration, and welding, and further improves contact performance. is requested. The present invention has been made in view of the above points, and has welding resistance, wear resistance, and insulation resistance.
The present invention also provides a method for manufacturing a contact alloy that has low temperature rise and is highly practical. Furthermore, the method for producing the alloy of the present invention provides a method for producing an inexpensive contact alloy that can be used as a contact even when the amount of expensive silver is considerably reduced. The method for producing the alloy according to the present invention includes iron group metals, silver,
A mixed powder of group a, a, a, a metal (A) and graphite is molded and sintered at a temperature higher than the melting point of silver, and during sintering, part or all of the metal (A) is converted into carbide to form silver and It is characterized by being dispersed in iron group metals. The method for manufacturing the alloy according to the present invention will be explained below. The inventors conducted various studies on alloys in which iron group metals and metals (A) of groups A, A, A, and A, which are difficult to dissolve solidly in silver and have high melting points, were added to silver. The alloy in which some or all of the carbides of metal (A) are dispersed is consumed by the arc heat generated when the current is switched on and off.
It has been found that there is extremely little scattering, and that it has the effect of reducing insulation deterioration and welding of equipment. Metal (A) in iron group metals
It is known in the field of heat-resistant alloys that carbides in which Ag is dispersed have excellent strength and bonding at high temperatures. It was discovered that the performance was significantly improved. Metal (A) and Gr tend to react to form carbides and further react with iron group metals, but these reactions generally only occur at high temperatures, but when Ag is present, Ag becomes a liquid phase during sintering. It was found that the reaction was promoted through this liquid phase. The reaction of metal (A) with Gr and iron group metals depends on the sintering temperature and time.
(A) is all carbide. However, iron group metals and metals (A) or metals (A)
Carbide has poor oxidation resistance and is oxidized by the arc heat generated during opening and closing, increasing contact resistance and increasing the temperature of the equipment. Therefore, when Gr, which has excellent reducing properties, is added to the above contact alloy to prevent the oxidation of iron group metals, metals (A), or carbides of metals (A), Gr decomposes with the heat generated during electrical switching and releases reducing gas. Prevents oxidation of iron group metals, metal (A), or carbides of metal (A) that occur, and reduces contact resistance.
It was found that it lowers the temperature rise of the equipment and improves welding resistance due to the lubricity of Gr. In other words, carbide of metal (A) is dispersed in silver, which is an iron group metal with excellent mechanical strength and bonding strength at high temperatures, to improve wear resistance and welding resistance, and to improve reducing and lubricity. By adding excellent Gr, the conventional
We were able to obtain an alloy that has high performance welding resistance, wear resistance, insulation resistance, and temperature rise characteristics that could not be expected from Ag-WC or Ag-WC-Gr contacts. Iron group metals include Fe, Co, Ni, etc., and are suitably 5 to 60% by weight, preferably 20 to 50% by weight.
At 5% by weight or less, iron group metals are dispersed in silver, and the metal
Dispersion of carbides (A) does not occur and wear resistance does not improve. Further, if Gr is added in an amount of 60% by weight or more, the contact resistance does not decrease and there is no effect of improving temperature rise characteristics. Metals (A) include W, Mo, Ta, Nb, Ti, Cr,
Metals of group a, a, a, a, such as Mn, V, etc. (A)
is effective, and the amount thereof is preferably 5 to 70% by weight, and particularly 20 to 50% by weight has good properties. Metal(A)
is less than 5% by weight, metal (A) in Ag or metal
There is too little carbide in (A) and the welding resistance is insufficient, and even if Gr is added in an amount of 70% by weight or more, the contact resistance does not decrease and no improvement in temperature rise characteristics is observed. Next, the effective range of Gr is 1 to 11% by weight, preferably 3 to 7% by weight. If it is less than 1% by weight, no improvement in temperature rise characteristics is observed even if the iron group metal, metal (A), or carbide of metal (A) is within the above range, and if it is more than 11% by weight, it is difficult to manufacture the alloy. It's not practical. In addition, approximately 0.1% by weight of Al, Si, Se,
There is no problem even if metal elements such as Te, Bi, Zn, Cd, In, Sn, Ca, Na, etc. are included. The above alloys can be obtained by sintering at a temperature higher than the melting point of silver. The atmosphere is preferably a reducing gas such as H ₂ CO or ammonia decomposition gas. Next, the characteristics of the contact alloy according to the present invention will be specifically explained with reference to Examples. Example 1 Each powder was blended in the proportions shown in Tables 1, 2, 3, and 4, and after mixing, a molded body was made, and the molded body was sintered at a temperature of 1100°C in a hydrogen atmosphere. concluded.
When sintered for 1 hour, a portion was dispersed as carbide in the silver or iron group metal. After sintering for 5 hours, all of the material turned into carbide and was dispersed in silver and iron group metals. A1, A3, A5, A7, A9 is 1 hour, A2, A4,
A6, A8, and A10 were sintered for 5 hours. Table 2, 3
The alloys shown were sintered for 5 hours. This sintered body was pressurized again to produce an alloy with almost zero porosity. Among the alloys, those in Table 4 are conventional alloys as comparative materials.

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[Table] About the alloys made as described above
The current carrying characteristics and wear characteristics were evaluated using an ASTM testing machine. The conditions are AC100V, 50A,
Pf1.0, contact pressure 200gr, opening force 200gr, contact shape 5x5x1.5tmm, and opened and closed 20,000 times. 2
Table 5 shows the results of voltage variation and amount of wear after 10,000 times of opening and closing.

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[Table] Example 2 Movable contacts 4× were made from the alloys prepared in Example 1, A6, B2, C2, and comparative materials D1, D2, D3, and D4.
The fixed contact was cut to a size of 7 x 2 mm and the fixed contact was cut to a size of 8 x 8 x 2 mm, and then bonded to the base metal using resistance brazing. This was then assembled into a 50A rated wiring disconnector under the test conditions shown below. As a result of contact performance evaluation, Table 6 was obtained. Test conditions: Overload test: AC220V, 200Apf 50 times Endurance test: AC220V, 50Apf 54 times Temperature rise test: AC220V, 50A 2H Short circuit test: AC220V, 7.5KA pf0.5 1PO−CO, 2PO−CO

[Table] As shown in Table 6, it can be seen that the alloy of the present invention has low wear, low temperature rise, high dielectric strength, and high performance contact characteristics. The alloy of the present invention not only has excellent contact performance as mentioned above, but also contains a large amount of iron group metals and metal (A), and can greatly reduce the amount of expensive silver, so it is of high industrial value. be.

Claims (1)

[Scope of Claims] 1 5 to 70% by weight of metals (A) of groups a, a, a, and a of the periodic table of elements, 1 to 11% by weight of graphite, 5 to 60% by weight of iron group metals, and the balance An electric device characterized in that a powder mixture made of silver is molded and sintered at a temperature higher than the melting point of silver, and during sintering, part or all of the metal (A) is dispersed as a carbide in silver or an iron group metal. Method of manufacturing contact materials. 2. The electrical contact according to claim 1, wherein the metal (A) is at least one metal (A) among tungsten, molybdenum, tantalum, niobium, titanium, chromium, manganese, and vanadium. Method of manufacturing materials. 3. The method for producing an electrical contact material according to claim 1, wherein the iron group metal is at least one of nickel, iron, and cobalt.