JPS589952A - Electrical contact material - Google Patents

Abstract

PURPOSE:To obtain an electrical contact material having superior melt sticking resistance, hardly dissipative property and insulation resistance by dispersing the nitride of a specified metal and graphite in an iron group metal and silver and solubilizing part or all of the metallic nitride in the iron group metal. CONSTITUTION:A powdered mixture consisting of 5-50wt% powder of the nitride of at least 1 kind of metal belonging to the IVa, Va, VIa, VIIa or VIII group in the periodic table such as Ti, Zr, Nb, Cr, Mo, Mn, Fe, V or Ta, 2-60wt% powder of at least 1 kind of iron group metal such as Ni, Fe or Co, 1-11wt% graphite powder, and the balance Ag powder is compacted, sintered in a hydrogen atmosphere, and compacted again to manufacture an alloy having porosity close to zero. In the sintering stage, the iron group metal reacts with the metallic nitride, whereby the metallic nitride is solubilized in the iron group metal, and an electrical contact material having superior heat resistance and satisfactory hardly arc dissipative property is obtd.

Description

[Detailed Description of the Invention] The present invention relates to electrical contact materials used in devices that conduct current and switch. In recent years, devices such as no-fuse breakers, air breakers, and switches have become smaller and more expensive. There is a trend toward improved performance, and as a result, the load on contact materials has become severer, and there is a strong demand for improved contact performance.

In addition, as devices become smaller, contact dimensions tend to become smaller and contact pressure decreases, which increases wear and tear that occurs when current is cut off, increases the risk of contact welding, insulation deterioration of devices, and increases temperature when switching at the rated current. There are problems that can easily occur. like this .

Ag-Ni is one of the solutions to meet the demand for improved characteristics.
-Nitride alloys are being developed. However, although this alloy has excellent abrasion resistance, it has high contact resistance and unsatisfactory welding resistance, so its range of use is limited.

The present invention has been made in view of the above points, and it is an object of the present invention to provide a contact alloy having excellent welding resistance, abrasion resistance, and insulation resistance, and having low temperature rise and excellent practicality. Furthermore, the alloy of the present invention provides an inexpensive contact alloy that can be used as a contact even when the amount of expensive silver is considerably reduced.

The alloy according to the invention contains IVa, Va in iron group metal and silver.

This is an electrical contact material characterized by containing nitrides of group Vla, Vlla, and group (1) metals and graphite (Gr) dispersed therein, and in which some or all of the nitrides are dissolved in solid solution in the iron group metal.

The characteristics of the alloy according to the present invention will be explained below.

As a result of conducting a study on the already known Ag-Ni-nitride alloy, it was found that in a sintered body below the melting point of silver, only nickel and nitride particles exist independently, and in terms of contact performance, Ag- Compared to Cd0, the consumption under large current was rather poor. However, when sintered at a temperature above the melting point of silver, an alloy is created in which 7 or all of the nitrides are dissolved in the nickel metal, resulting in less wear and scattering due to the arc heat generated when the current is turned on and off, and less deterioration of the insulation of equipment. I found it to be effective. However, it has been confirmed that nickel and nitride have poor oxidation resistance and are oxidized by the arc heat generated during opening and closing, increasing contact resistance and increasing the temperature of the equipment. For this reason, it was found that the range of use was narrow and the practicality was poor. The present inventors have attempted to prevent oxidation of iron group metals such as nickel, iron and cobalt, and nitrides, suppress temperature rise, and create a welding-resistant material. As a result of various studies on improving the properties, we found that when Gr, which has excellent reducing properties, is added to the above contact alloy, the Gr decomposes with the heat of electrical switching and generates reducing gas, preventing iron group metals and nitrides from oxidizing. It was found that the contact resistance was kept low, the temperature rise of the equipment was reduced, and the welding resistance was improved due to the lubricity of the or. Furthermore, due to the addition of Gr, the arc heat generated during opening and closing causes nitrides to react with dispersed Gr to form carbides, resulting in an endothermic reaction and arc extinguishing action due to the release of N2 gas, which greatly improves arc wear resistance. I knew it would happen.

Figure 1 shows the free energy change of this reaction, which is almost /! It can be seen that this reaction progresses at 000K.

Iron group metals include Fe, Co, Ni, etc., and 2 to 1
．． 0% by weight, preferably 2O-j (7% by weight is appropriate. If it is less than 2% by weight, the iron group metal will be dispersed in the chain, nitrides will not dissolve and the wear resistance will not improve. If it exceeds the weight percentage, even if ar is added, the contact resistance will not decrease and there will be no effect of improving the temperature rise characteristics.

Examples of nitrides include titanium, zirconium, niobium, chromium, manganese molypide, iron, palladium, tantalum, etc. IVa, Va, Via, Vlla, ■
Group nitrides are effective, and the amount thereof is preferably from j to 23% by weight, with particularly good properties at 10-23% by weight. If the nitride is less than 5 times 1 tq6, the amount of nitride in the chain is too small and the wear resistance is insufficient, and if it is more than 5% by weight of SO, or
Even if added, the contact resistance did not decrease and no improvement in temperature rise characteristics was observed. Next, the effective range of Gr is /-11% by weight
and preferably 3 to 7% by weight. If it is less than 1% by weight, no improvement in temperature rise characteristics will be observed even if the iron group metal or nitride is within the above range, and if it is more than 1% by weight, it will be difficult to manufacture the alloy and it will not be practical.

Next, the characteristics of the contact alloy according to the present invention will be specifically explained using examples.

Example 1 Each powder was blended in the proportions shown in Table 1, Table 2, Table 3, and Table 4, and after mixing, a molded body was made, and the molded body was placed in a hydrogen atmosphere. The sintered body was sintered at a temperature of 0.000 °C and then pressed again to produce an alloy with almost zero porosity. The alloys listed in Table 1 are conventional alloys for comparison.

1″ Unit: Weight % Table Q
Unit duplex weight % Figure 2 shows one example (A-J) of the alloy according to the invention.
This is a micrograph of the structure magnified 1,000 times. In FIG. 2, the white part is the silver phase, the light gray part is the nickel phase, the dark gray particles around the nickel phase are the TiN phase, and the irregularly shaped black part is the graphite phase. As can be seen from the figure, the alloy of the present invention has an alloy structure in which the iron group metal and nitride react with each other during the sintering process, and the nitride forms a solid solution in the iron group metal and precipitates.

It is thought that because the hard phase forms a skeleton, it exhibits characteristics of high heat resistance and low arc wear resistance.

The alloys prepared as described above were evaluated for current conduction characteristics and wear characteristics using an ASTM tester.

The conditions are ACloOV, ! ;OA, pf
iO, contact pressure 200gr, separation force 200gr, contact shape! X! ;X/,! ;M, and opened and closed 20,000 times. Table 5 shows the results of voltage variation and amount of wear after 20,000 times of opening and closing.

As a result of analyzing the phase formed on the surface of the contact points before and after the ASTM test in Table 5 by X-ray diffraction, the results of the Jth period were obtained.

From this, it is considered that the introduction of Ag--Ni--TiN-K-Gr 1) almost eliminated the formation of Ni◯ and TiO2, which led to a lower voltage drop.

Table 6 Example 2 The alloys prepared in Example 1, A6, B2, C2 and comparative materials DI, D2, D3, D4 were machined to dimensions of a movable contact 11X7XJJII and a fixed contact 1fXf×28. Afterwards, it was bonded to the base metal by resistance rating, and this was assembled into a jOA-rated circuit breaker.The contact performance was evaluated under the test conditions shown below, and the results shown in Table 1 were obtained.

Test conditions: Overload test: AC220V, 200Apf! ;
0 times durability test: AO22'OV, ! ;0Apf
311 times temperature rise test: AC220vl! ;oA2H short circuit test: AC220V, 7. ! KA pfOJ
/PO-Cov 2po-c.

Table 7 As shown in Table 7, 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 large amounts of iron group metals and nitrides, and can greatly reduce the amount of expensive silver, so it is of high industrial value. be.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the reaction energy between carbides and nitrides,
FIG. 2 is a micrograph showing the alloy structure of an example of the alloy of the present invention.

Claims (3)

[Claims] (1) IVa+ Va + vIa+ of the periodic table of elements
Vlla + Nitride of group metal is S - SO wt%
, Gelaphyte 1 to 1/weight East iron group metal 2 to 60% by weight,
An electrical contact material characterized in that the balance consists of silver and nitrides are dispersed in iron group metals and steel. (2) The electricity according to claim (1), wherein the nitride is at least one nitride selected from titanium, zirconium, niobium, chromium, molybdenum, manganese, iron, vanadium, and tantalum. Contact material. (3) The electrical contact material according to claim (1), wherein the iron group metal is at least one of nickel, iron, and cobalt.