JP4455871B2 - Electrical relay contact material and electrical relay contact - Google Patents

Description

  The present invention relates to an electrical relay contact material that can suppress the amount of contact consumption as much as possible when opening and closing an electrical relay contact at a load voltage of 15 V or less.

  Conventionally, an Ag alloy has been generally used as a material for switching contacts used in breakers and relays. When pure Ag is used as the switching contact material, it is not used as it is because the electrical consumption of the contact is severe, and practically Ag-W alloy, Ag-Ni alloy, Ag-Pd alloy, etc. Various Ag alloys or Ag-oxide alloys such as Ag-cadmium oxide are used. Of these, Ag-oxide alloys such as Ag-cadmium oxide have been widely used in the past because they exhibit excellent wear resistance.

  However, materials containing cadmium are not used much because of environmental problems. Therefore, materials such as an Ag-indium oxide alloy (Patent Document 1) and an Ag-manganese oxide alloy (Patent Document 2) that do not contain cadmium have been proposed in place of the Ag-cadmium oxide system.

  On the other hand, a copper alloy (Cu alloy) is also widely used as a material for electrical contacts as a material having a high electrical conductivity, and a contact material for a high power Cu-Cr-based vacuum circuit breaker (Patent Document 3) or high power. Cu-W-based materials (Patent Document 4) and the like have also been developed, and are also used as switch contacts for automobile starters. However, since the Cu alloy is inferior to the Ag-oxide alloy in terms of wear resistance at the current-carrying contact portion, there is a drawback that it is difficult to use as a contact material that is frequently opened and closed.

  For these reasons, Ag-oxide alloys are mainly used for relay contacts, which are contacts that are frequently opened and closed. In addition, a technology for improving the wear resistance of contacts by attaching tungsten having a high melting point to the surface of a Cu-based metal has been proposed for an automobile starter switch or the like (for example, Patent Document 5).

  Conventionally used Ag alloys and W alloys are expensive, so contact parts using such materials as raw materials have to be expensive. Cu alloys are inherently low conductivity materials, and are metals that can be adjusted for mechanical properties by mixing various additives. Therefore, if the wear resistance of Cu alloys can be improved while taking advantage of these characteristics. Even without using an expensive material, it can be expected to form a switching contact such as a relay contact at a relatively low cost.

From such a viewpoint, Patent Document 5 proposes a relatively inexpensive metal material for encapsulation in which a predetermined amount of ZnO is contained in Cu. In this technique, a cheaper one than the Ag alloy is obtained, but since the Cu alloy is manufactured by a sintering method, it is still more expensive than a general Cu alloy. Further, Cu alloy is not used as a general-purpose relay contact as a substitute for Ag alloy, and in reality, an Ag alloy is still used for many relay contacts.
JP 52-9625 A (Claims etc.) JP-A-51-136170 (Claims) JP 11-50177 A (Claims etc.) JP-A-11-374088 (Claims etc.) JP-A-8-22728 (Claims etc.) JP-A-55-186406 (Claims etc.)

  The present invention has been made paying attention to such a situation, and the object thereof is an electric relay made of Cu alloy that has excellent wear resistance equivalent to that of an Ag-oxide alloy contact and can be realized at low cost. It is to provide a contact material.

  The electrical relay contact material of the present invention that has solved the above-mentioned problems is a contact material used for an electrical relay contact having a load voltage of 15 V or less, and Zn: 1.5 to 9.8% by mass It has a gist in that it is made of a Cu alloy containing.

  In the present invention, by using a Cu alloy containing a predetermined amount of Zn, there is provided a Cu alloy electric relay contact material that has excellent wear resistance equivalent to that of an Ag-oxide alloy contact and can be realized at low cost. This material can be realized and has excellent wear resistance due to opening and closing while being energized, and is optimal as an electrical relay contact material.

  The present inventors examined the consumption phenomenon when Cu alloy was used as a contact material. As a result, the following knowledge was obtained. When the Cu contact leaves during energization ("open" state), current concentration occurs, Joule heat is generated near the energization point, and the contact surface reaches the melting point of the Cu alloy and melts. become. At this time, the melting mark on the plus side of the contact becomes a relatively large depression, and the melting mark on the minus side forms a small protrusion. The energization at the moment when the contact is released is performed through a very thin molten metal bridge connecting the plus contact and the minus contact, and then the bridge is broken and the contact is cut. At this time, it was found that if the bridge connecting the contacts is quickly destroyed, the consumption of the contacts can be suppressed.

  Based on the above findings, the present inventors have further studied to achieve a Cu alloy that can suppress contact wear. As a result, in the case where a Cu alloy containing a predetermined amount of Zn is used as the contact material, when the contact is opened and closed while energized, the effect of Zn having a low melting point and a high vapor pressure causes the Zn in the vicinity of the bridge. The bridge could be destroyed by evaporating in large quantities.

  The effect achieved by the Cu alloy as described above cannot be achieved by other Cu alloys. For example, it can be confirmed that such an effect is not exhibited by a Cu-Ag alloy in which Ag is alloyed with Cu. It was.

  The contact material of the present invention exhibits wear resistance several times that of pure Cu and other alloys, and has wear resistance equivalent to that of conventional Ag-oxide alloys. In order to exert such an effect, the Zn content needs to be at least 1.5%, but if it exceeds 9.8%, the consumption tends to increase. For example, a copper alloy (brass) containing 30% or more of Zn is not preferable because an arc is generated even when the voltage is about 12 V (this will be described later). The preferable lower limit of the Zn content is about 2%, and the preferable upper limit is about 6%.

  The Cu alloy used in the present invention is basically Cu other than Zn, but inevitably mixed impurity elements (eg, Ag, Fe, Pb, Na, Mg, etc.) are also inevitable impurities. As long as it is acceptable. Although the concrete standard of the amount of inevitable impurities varies depending on the type of impurities, especially Pb excessively causes cracking of the Cu alloy, so it is preferably suppressed to 0.2% or less.

  By the way, in such a contact material, when the load voltage between the contacts exceeds 15V, an arc is generated between the contacts, and an oxide is generated on the contact surface and the contact resistance is easily increased. In addition, the amount of wear increases due to the generation of an arc, which is not preferable. For this reason, in the present invention, as a basic requirement, a material for a contact material “used for an electrical relay contact having a load voltage of 15 V or less” is used.

In addition to the case where the load voltage exceeds 15V, the condition where the arc does not occur is that (1) the current is 1A or less even if the voltage exceeds 15V, and (2) the atmosphere in which the contacts are arranged is an arc. However, the contact material of the present invention can be used under any of these conditions, such as a vacuum atmosphere, an H ₂ gas atmosphere, or an inert gas atmosphere. However, the effect will be demonstrated.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited by the following examples, but may be appropriately modified within a range that can meet the purpose described above and below. It is also possible to implement, and they are all included in the technical scope of the present invention.

  After various copper alloys having different Zn contents were melted and cast in a krypton furnace, the ingot was hot-rolled at 800 ° C. to obtain a hot-rolled sheet having a thickness of 15 mm. After cutting out a cylindrical sample having a diameter of 3.5 mmφ and a length of 5 mm from the obtained hot-rolled sheet, a sample having an end face rounded by R20 (mm) was prepared by cutting.

  For these samples, the processed end faces were abutted to form an electric closed circuit, and the experiment of opening and closing the contacts at a speed of 50 mm / sec was repeated while applying a current voltage of DC voltage: 12 V and current: 30 A. Then, the wear resistance was evaluated by measuring the change in the weight of the contact after 1000 switching operations. Moreover, about the one part (No. 7 of following Table 1), the surface uneven | corrugated property was measured using the Kosaka Laboratory surface roughness clock "SE3500". At this time, the wear resistance of the materials with different contact materials (pure Cu, Ag alloy, etc.) (No. 1 to 3 and 12 in Table 1 described later) was examined in the same manner as described above. The results are shown in Table 1 below together with the chemical composition of each alloy.

  From this result, it can be considered as follows. First, no. In the case of No. 1, pure Cu is used as the contact material, but it can be seen that the amount of wear is relatively large. Moreover, the surface uneven | corrugated state when this material is used is shown in FIG. 1 (plus pole surface depression) and FIG. 2 (minus pole protrusion).

  No. Although the thing of 2 uses an Ag-5% SnO alloy, it turns out that wear resistance is comparatively favorable. No. Although the thing of 3 uses pure silver, it turns out that the consumption is larger than pure Cu. No. Although the thing of 4 uses the Cu alloy containing 1% of Zn, it turns out that the wear resistance improvement effect is not exhibited so much.

  In contrast, no. In the case of Nos. 5 to 9, it is understood that the Cu alloy containing an appropriate amount of Zn is used, and the wear resistance is better than that in the case of using pure Cu (No. 1). In particular, no. It can be seen that the consumption amount is less than that of the Ag-oxide alloy (No. 2) in the cases of 6 to 8.

  Of these, No. FIG. 3 (plus pole surface depression) and FIG. 4 (minus pole projection) show the surface unevenness in the case of No. 7, and it can be seen that the amount of wear is reduced compared to FIGS.

  No. In the case of No. 10, a Cu alloy containing 10% Zn was used, but it was found that the effect of improving wear resistance was not exhibited. No. No. 11 is a Cu alloy containing 30% Zn (so-called brass), but the amount of wear increased drastically because an arc was generated. No. No. 12 is a Cu alloy containing 0.1% Ag, but it is understood that the wear resistance is not improved so much.

It is a graph which shows the positive electrode surface depression state at the time of using pure Cu as a contact material. It is a graph which shows the negative pole protrusion state at the time of using pure Cu as a contact material. It is a graph which shows the positive electrode surface depression state at the time of using a 5% Zn-Cu alloy as a contact material. It is a graph which shows the negative pole protrusion state at the time of using a 5% Zn-Cu alloy as a contact material.

Claims (2)

A contact material used in an uncovered state for both positive and negative contacts of an electrical relay contact having a load voltage of 15 V or less, containing Zn: 1.5 to 9.8% by mass, A material for electrical relay contacts excellent in wear resistance, characterized in that the balance is made of Cu and a copper alloy which is an inevitable impurity. An electrical relay contact obtained by using the electrical relay contact material according to claim 1 and having a load voltage of 15 V or less,
The positive contact and the negative contact both contain Zn: 1.5 to 9.8% by mass, the balance is made of Cu and an inevitable impurity copper alloy, and is uncoated. Electrical relay contact with excellent wear resistance.

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