JPH0514366B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field] The present invention relates to a contact material in which a metal oxide produced by an internal oxidation method is dispersed in Ag. [Background technology] Various contact materials are used in electromagnetic contactors, relays, breakers, etc. These contact materials are required to have characteristics such as low wear, resistance to welding, and low contact resistance.
However, in reality, it is difficult to find a material that simultaneously satisfies these three properties. Currently, there is a tendency for relays to be frequently used to control the input and output of circuits and devices, and therefore there is a strong demand for contact materials that do not cause welding even when inrush current flows through the contacts, that is, have excellent welding resistance. ing. Specific contact materials include Ag−CdO, Ag−
SnO ₂ etc. are used. Of these, Ag−CdO
System contacts are known as a stable material with low contact resistance because the oxide CdO sublimates due to the arc heat generated by the opening and closing of the contacts, and oxides do not accumulate on the contact surfaces. Although Ag-SnO ₂ -based contacts have unstable contact resistance, they are known to have excellent welding resistance. Ag-CdO-SnO ₂ type contacts are a material that incorporates the advantages of both Ag-CdO and Ag-SnO ₂ , but the welding resistance is still insufficient and further improvements are required. [Object of the Invention] In view of the above circumstances, an object of the present invention is to provide an internally oxidized Ag-CdO-SnO ₂ -based contact material that has excellent welding resistance. [Disclosure of the Invention] In order to solve the above problems, the inventors conducted studies from various angles, going back to the welding resistance and the physical properties of the contact material. As a result, it was revealed that there is a correlation between welding resistance and high temperature curing properties.
For example, they discovered that there is a positive correlation between the number of times a contact used for a capacitive load with a peak current of 1 kA is welded and the A/B value, which indicates high-temperature hardness characteristics. Here, A is the hardness of 0K, B represents the softening coefficient due to temperature,
Let the A/B value be the thermal intensity coefficient. The larger the A/B value, the better the welding resistance. As a result of further investigation, it was discovered that the A/B value could be improved by making the oxide finer in the contact material, and in order to do so, Ag-CdO-SnO ₂
In addition, Mn and Al are added to the internal oxidation type contact material.
discovered that it was sufficient to contain it in the form of an oxide,
This is where we completed this invention. By the way, the reason why the welding resistance improves as the high temperature hardness property (A/B value) increases is as follows. That is, welding of the contacts occurs because the contact portions of the contacts melt and soften due to arc heat during opening and closing of the contacts, and the contacts are joined in this state, making it impossible to separate the contacts. Therefore, it can be said that a material that does not easily soften at high temperatures, that is, a material that has high thermal stability at high temperatures, has excellent welding resistance. A material with high thermal stability and excellent welding resistance, that is, a material with a large A value and a small B value, has a large value obtained by dividing A by B, that is, an A/B value.
Therefore, the A/B value correlates with the strength (thermal strength coefficient) including temperature factors, and serves as an index representing the thermal stability of the material at high temperatures. On the other hand, the reason why the A/B value improves when the oxide is made finer is as follows. Generally, the strength (hardness) when particles are dispersed in a matrix using the internal oxidation method correlates with the dispersion Preston-Grant parameter expressed by the following formula: 1/γ{(3f/4π) ^1/3 −3f /4} Here, γ: Average diameter of dispersed particles (μm) f: Volume fraction (%) Therefore, when the volume fraction (f) is constant, the strength is proportional to 1/γ. That is, the smaller the dispersed particles, the greater the strength (A) at 0〓. On the other hand, the softening coefficient (B) due to temperature is thought to decrease as the particles become finer because the deformation resistance increases if the particles become finer. As a result of the above, when the oxide is made finer, the A/B value improves. Therefore, the present invention provides a contact material in which a metal oxide produced by an internal oxidation method is dispersed in Ag, in which the metal element of the metal oxide is
The gist is a contact material characterized by the use of Cd, Sn, Mn, and Al. The contact material according to the present invention will be explained in detail below. First, the preferred content range of metal oxides contained in Ag will be shown. In addition, when expressing the content, metal oxides are expressed in terms of metal elements. In other words, it is expressed as a percentage in the alloy before undergoing internal oxidation treatment. Cd is preferably in the range of 1 to 20 wt%, and Sn is in the range of 0.5 to 20 wt%.
5wt% is desirable. Cd is less than 1wt%,
If Sn is less than 0.5 wt%, welding resistance and abrasion resistance tend to be insufficient. CD is
If it exceeds 20wt% or if Sn exceeds 5wt%, internal oxidation treatment becomes difficult and workability tends to deteriorate. Mn and Al are from 0.001 to
A range of 0.5 wt% is desirable, and a range of 0.005 to 0.2 wt% is more preferred to ensure the effect. If it is less than 0.001wt%, the effect of refining the metal oxide, that is, the effect of improving the thermal strength coefficient, will be reduced, and if it exceeds 0.5wt%, the agglomeration of oxides at grain boundaries will become noticeable, resulting in poor conductivity and processing. There is a tendency for sexual performance to decline. When Mn and Al are contained alone, the oxide refinement effect, that is, the improvement effect on the thermal strength coefficient, is not sufficient, but by containing both at the same time,
It can bring about remarkable effects. Next, regarding the forms of CdO and SnO ₂ , these may be a composite oxide (for example, Cd ₂ SnO ₄ ) or a single oxide in the Ag matrix. Further, in order to refine the crystal grains of the Ag matrix, even better effects can be obtained by containing 0.05 to 0.5 wt % of each Fe group element, that is, Fe, Ni, and Co. Next, examples and comparative examples will be shown. Examples 1-11 Ag, Sn, Cd, Al, Mn, Fe, Ni, and Co
Each element was selected and weighed as appropriate. These metals
The ingots were melted using a high frequency furnace in an argon gas atmosphere and cast into molds to obtain ingots with different desired compositions as shown in Table 1. Next, this ingot was heated and annealed in an argon gas atmosphere. Then, after hot rolling, the material was internally oxidized by heating at a temperature of 600° C. for about 100 hours in an oxygen atmosphere to obtain a plate-shaped contact material. A sample for high temperature hardness measurement was obtained from this contact material,
The high-temperature hardness of each sample was measured using a Micro-Vickers high-temperature hardness meter, and the A/B value was calculated from the measurement results. The results are shown in Table 1. Comparative Examples 1 to 3 Each element of Ag, Sn, Cd, Mn, and Al was appropriately selected and weighed. These metals are melted using a high frequency furnace in an argon gas atmosphere and cast into a mold.
As shown in Table 1, ingots with different desired compositions were obtained. Next, this ingot was heated and annealed in an argon gas atmosphere. Then, after hot rolling, in an oxygen atmosphere at a temperature of 600℃,
A plate-shaped contact material was obtained by internal oxidation treatment by heating for about 100 hours. A sample for high temperature hardness measurement was obtained from this contact material,
The high-temperature hardness of each sample was measured using a Micro-Vickers high-temperature hardness meter, and the A/B value was calculated from the measurement results. The results are shown in Table 1. For some of the materials of the above Examples and Comparative Examples, the size of oxide particles was measured using an electron microscope, and the morphology of the oxides was measured using an X-ray diffraction method. The results are also shown in Table 1.

〔Effect of the invention〕

Since the contact material according to the present invention has the above-described structure, the high-temperature hardness is increased and the metal oxide particles become finer, so that the welding resistance of the contact material is significantly improved. Moreover,
Because CdO is dispersed in the Ag matrix,
Contact resistance is low and stable. In this way, Ag−CdO− has excellent adhesion resistance and low contact resistance.
We were able to obtain a SnO ₂ -based contact material.

Claims (1)

[Claims] 1. The metal oxide produced by the internal oxidation method is Ag.
In the contact material dispersed in the metal oxide, Cd, Sn, Mn, and
A contact material characterized by the use of Al. 2 The metal oxide contains 1 to 20 wt% of Cd, 0.5 to 5 wt% of Sn, and 0.001 to 0.001 wt% of Mn in terms of metal elements.
The contact material according to claim 1, wherein Al is 0.001 to 0.5 wt%.