JPS5884943A - Electrical contact material - Google Patents

Abstract

PURPOSE:To improve the welding resistance and hardly dissipative property of the resulting titled material, to control the temp. rise, and to reduce the cost by dispersing the nitride of a IVa, Va, VIa, VIIa or VIIIa group metal and graphite in silver. CONSTITUTION:This electrical contact material has a composition consisting of 5-50wt% nitride of a IVa, Va, VIa, VIIa or VIIIa group metal, 1-11wt% graphite and the balance silver. Said nitride and graphite are dispersed in the silver.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to electrical contact materials used in equipment that conducts current and switches on and off.

In recent years, electromagnetic switches and contactors have become smaller and more sophisticated, and as a result, the load on contact materials has become severer, and there is a strong demand for improved contact performance. In addition, due to the miniaturization of devices, there is a trend toward smaller contact dimensions and lower contact pressure, which increases the wear and tear that occurs when switching current and increases the risk of contact welding and temperature rise when switching the rated current. is occurring. Ag-nitride alloys have been developed as one of the materials that meet the demand for improved properties. However, although this alloy has excellent abrasion resistance, it has high contact resistance and is not fully satisfactory in i1#i adhesion, 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 that has both welding resistance and abrasion resistance, has low temperature rise, and is excellent in practical use. Furthermore, the alloy of the present invention provides an inexpensive contact alloy that can be used as a contact even if the amount of expensive silver is considerably reduced.

The alloy according to the invention has silver IVaSVa%VIa%■a
This is an electrical contact material characterized by containing a nitride of a Group 11 metal and Graphi (Gr) dispersed therein.

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

As a result of studying the already known Ag-nitride alloys, we found that nitrides have poor oxidation resistance and are oxidized by the arc heat generated during opening and closing, increasing contact resistance and increasing the temperature of equipment. It was confirmed that the oxide film increases the amount of heat generated, leading to accelerated wear and tear. For this reason, it has been found that the scope of use is narrow and the practical compatibility is poor.

The present inventors have conducted various studies to prevent nitride oxidation, suppress wear due to temperature rise and oxide film, and improve adhesion resistance. As a result, when Gr, which has excellent reducibility, is added to the above contact alloy, Gr decomposes with the heat generated during electrical switching and generates reducing gas, which prevents nitrides from oxidizing, keeps contact resistance low, lowers the temperature rise of equipment, and improves T3r.
It was found that the welding resistance was improved by the lubricity of . Furthermore, due to the addition of Gr, the nitrides react with the dispersed Gr due to the arc heat generated during opening and closing to form carbonized substances, resulting in an endothermic reaction and an arc extinguishing effect due to the release of N gas, which greatly improves arc wear resistance. was found to be improved.

It can be seen that Figure 1 shows the free energy change of this reaction.

As nitrides, nitrides of rva, vas■as■a1■A group metals such as titanium, zirconium, niobium, chromium, molybdenum, manganese, iron, vanadium, tantalum, etc. are effective, and the amount thereof is 5 to SO weight. % is preferred;
In particular, 70 to 25% by weight has good properties. 5% by weight of nitrides
Below this, the amount of nitride in the chain is too small, resulting in insufficient wear resistance, and above 50% by weight, even if Gr is added, the contact resistance does not decrease and no improvement in temperature rise characteristics is observed.

Next, the effective range of Gr is /-11% by weight, preferably 3 to 7% by weight. If the nitride content is less than 7% by weight, no improvement in welding or temperature rise characteristics will be observed even if the nitride content is within the above range, and if it is more than 17% by weight, alloy production will be difficult and impractical.

It should be noted that 0.00% does not impair the purpose of the present invention. /wt% A/S
Si, 5eSTe, Bi, Zn, Cd, Engn5S
n.

There is no problem even if metal elements such as Oa and Na are included.

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 Tables 1, 2, and 3, and after mixing, a molded body was made, and the molded body was sintered at a temperature of 9 OC in a hydrogen atmosphere. This sintered body is re-pressurized to form an alloy with almost zero porosity, and further heated to 920C in a hydrogen atmosphere.
heat treated at a temperature of Alloy inner cylinders shown in Table 3 are conventional alloys used as comparison materials.

Table 1 Unit: Weight % Horse mackerel Table Unit: 8 weight % Dew Table Unit: Weight % Regarding the alloy prepared as described above, Mu B
The current conduction characteristics and consumption characteristics were evaluated using a TM tester. The conditions are AO100V s 10 A: P
f/-Os contact pressure m00 gr s separation force 2000
gr s contact shape! X j X /,! - One door was opened and closed 10,000 times. The results of the voltage variation width and amount of wear at 20,000 all'J are shown in the table below.

*Table 4 As a result of analyzing the phase formed on the surface of the contact point before and after the BTM test by X-ray diffraction, the results shown in Table 3 were obtained.

From this, by entering Gr into Mug-Ta1l!
It is thought that the formation of 102 is almost eliminated, and this is why the voltage drop becomes low.

Table S Examples, Alloys prepared in Example 1, Muco, B4I and comparative materials O/
After cutting the movable contact to the dimensions of the movable contact/j
Om*S electromagnetic j! The contact performance was evaluated under the test conditions shown below by incorporating it into an rR device, and the results shown in Table 6 were obtained.

Test conditions: Voltage (OOV), current (l) (θOm), power factor (O, ko!) As shown in Table 1 and Table 6 of S 10,000 Opening and Closing Times, it can be seen that the alloy of the present invention exhibits low wear and contact resistance, and has high-performance contact characteristics.

The alloy of the present invention not only has excellent contact performance as described above, but also contains a large amount of nitride, and the amount of expensive silver can be reduced significantly, so it is of high industrial value.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the reaction energy between carbon and nitride. Applicant: Sumitomo Electric Industries, Ltd.

Claims (1)

[Claims] (/') IVa%Va%VIa%■ of the periodic table of elements
a1■ Group A metal nitride is S-SO wt%, GRA77
An electrical contact material comprising 447 to 71% by weight, the balance being silver. (, 2) The electricity according to claim (1), wherein the if compound is a nitride of at least one of titanium, zirconium, niobium, chromium, molybdenum, manganese, iron, vanadium, and tantalum. Contact material.