JP2007012570A - Ag-oxide-based electrical contact material, relay using the same, AC general-purpose relay, automotive relay - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrical contact material having versatility capable of controlling various loads such as an AC general-purpose relay and a vehicle-mounted relay and having excellent durability characteristics even if it is a miniaturized relay.
The present invention relates to an Ag composed of 5.1 to 8.0% by weight of Zn, 0.01 to 5.0% by weight of Sn, 0.01 to 1.5% by weight of Te and the balance of Ag. -Ag-oxide-based electrical contact material obtained by internally oxidizing a Zn-Sn-Te alloy, or 0.01-5.0 wt% Zn, 5.1-8.0 wt% Sn, 0.01- An Ag-oxide-based electrical contact material obtained by internally oxidizing an Ag-Zn-Sn-Te alloy composed of 1.5 wt% Te and the balance Ag was used.
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Description

  The present invention relates to an Ag-oxide-based electrical contact material, and more particularly to an electrical contact material suitable for an AC general-purpose relay or a vehicle-mounted relay.

  An electrical contact that mechanically opens and closes an electrical circuit is generally called an electrical contact. This electrical contact is a metal-to-metal contact that allows the current and signal flowing through the contact to be transmitted without any problems, or when the electrical contact is disconnected. It is necessary to satisfy the characteristics that can be separated without any problem. Although this electrical contact is structurally simple, it is known that various physical or chemical phenomena occur on the contact surface. For example, adsorption, oxidation, sulfurization, synthesis of organic compounds, It is accompanied by very complicated phenomena such as melting, evaporation, consumption, and transition accompanying electric discharge, and there are many unexplained points from an academic viewpoint. When these phenomena occur, the contact function of the electrical contact is hindered, and in some cases, the contact function stops (for example, welding), and the performance and life of an electrical product or the like incorporating the electrical contact is determined. This means that the electrical contact is one of the important components that determine the life and performance of an electrical product or the like.

  Relays, which are representative examples of electrical products using electrical contacts, have a wide range of use ranging from weak electric fields such as telegraph telephones and various electronic devices to high electric fields such as electric devices that cut off a large current. For this reason, the functions required of relays vary widely, and the development of electrical contacts that can realize characteristics tailored to the purpose of use and relays using them has been developed, and a great many types are being supplied to the market. .

  A relay using this electrical contact is a coil magnetic flux generated by an electrical signal applied in the form of direct current, alternating current, impulse, etc., and attracting the movable iron piece with its magnetic force, so that the movement of the movable iron piece A relay that opens and closes electrical contacts. These relays are required to be incorporated in home appliances, air conditioners, acoustics, communication devices, and the like, and to ensure a stable switching operation under various load conditions and environments.

  In recent years, the miniaturization of components constituting these has been promoted rapidly with the advancement of high functionality, high performance, and low power consumption of home appliances, air conditioning, sound, communication equipment, and the like. Relays are no exception, and as the relays become smaller, the contact force and opening force of the contacts become very small, and the environment to which the contact material itself is exposed is extremely severe.

  As an electrical contact material incorporated in a relay used in a general AC load, an Ag—CdO-based electrical contact material has been known for a long time. This Ag—CdO-based contact material satisfies the properties that the electrical contact material should have, such as welding resistance, wear resistance, and contact resistance stability, in a highly balanced manner. However, Cd is an element that is toxic to the human body, and its production and use are not preferred in consideration of recent environmental problems. Therefore, development of electrical contact materials that do not contain Cd is required, and such conventional techniques include the following.

Examples of materials that are used for AC general-purpose relays for AC loads and that do not contain Cd include Ag—SnO ₂ (alloy consisting of 5 to 15 wt% SnO ₂ and the balance Ag), Ag—SnO ₂ —In ₂ O _3. Ag-oxide-based electrical contact materials such as those have been known for a long time (Patent Documents 1 and 2). Among these, it has been conventionally known that an Ag—SnO ₂ -based electrical contact material exhibits particularly excellent welding resistance in a capacitive load in which an inrush current is generated. However, in an inductive load, the wear resistance characteristics of the Ag-SnO ₂ electric contact material are slightly inferior to those of the conventional Ag-CdO electric contact material, so that it is equal to or higher than that of the Ag-CdO electric contact material. It was difficult to ensure the durability. Further, in yet _Ag-SnO 2 _-In 2 _{O 3} based electric contact material containing _In 2 _{O 3} in the Ag-SnO ₂ based electrical contact material, for resistive load or inductive load Ag-SnO ₂ based electrical contact material It is known that the wear resistance is remarkably improved and, as with the Ag-CdO-based electrical contact material, it has a well-balanced durability characteristic with respect to various loads. Widely used.
JP 54-110124 A Japanese Patent Publication No.55-4825

However, In, which is a raw material for this Ag—SnO ₂ —In ₂ O ₃ electric contact material, the number of clays calculated for the ratio of the elements constituting the earth's skin (about 0.7% of the total mass of the earth) is all It is a rare metal at position 68 in the element. In addition, since it is widely used as a raw material for ITO transparent electrodes in display devices such as liquid crystals and plasmas in recent years, considering the amount of future use, there is a concern about the depletion of In resources existing on the earth in 2010. There is a problem that. For this reason, the price of In is currently rising, and the production price of electrical contact materials is also having a significant impact. Due to the depletion of In resources and the problem of high costs, the development of In-free electrical contact materials has become an urgent task.

As this In-free electrical contact material, an Ag—ZnO—SnO ₂ -based electrical contact material is known (Patent Document 3). This electrical contact material has good durability comparable to an Ag-CdO-based electrical contact material for a relatively large relay that can take a large contact force and opening force of the contact. Relays tend to cause a welding failure very easily in the initial stage of switching operation due to the problem of welding resistance. For this reason, there is almost no example in which this Ag—ZnO—SnO ₂ -based electrical contact material is used for an AC general-purpose relay.
Japanese Examined Patent Publication No. 56-22086

  In addition, relays mounted on automobiles are often used to control electrical components and drive system components mounted on automobiles. For example, in a 2.0L class car, as many as 50 relays are used, and the load of these relays is a capacitive load represented by a headlight, a resistive load represented by a rear defogger, and a blower motor. There are a wide variety of loads, such as inductive loads. And about this vehicle-mounted relay, it is requested | required that it is a relay which can implement | achieve switching operation with respect to all the loads with one electrical contact material.

Currently, the above-described Ag—SnO ₂ -based electrical contact materials and Ag—SnO ₂ —In ₂ O ₃ -based electrical contact materials are often used for such onboard relays. Ag-SnO ₂ system electrical contact material has been used for a long time as a relay for mounting on automobiles, but, like the above-mentioned AC general-purpose relay, it is inferior in wear resistance to a DC inductive load, so it is limited to a specific load. Have been used. The Ag—SnO ₂ —In ₂ O ₃ -based electrical contact material is known to have general-purpose characteristics that can satisfy all of capacitive load, resistance load, and inductive load, and is known to be suitable for an automotive relay. It has been. However, as described above, there is a problem of depletion of In resources and a rise in In price, and the current situation is that development of In-free electrical contact materials is also demanded for relays mounted on automobiles.

  The present invention has been made against the background as described above, and does not include Cd and In, and has versatility that can control various loads such as an AC general-purpose relay and a vehicle-mounted relay, and is smaller than the conventional one. It is an object of the present invention to provide an electrical contact material having excellent durability characteristics even if the relay is made into a relay.

In order to solve the above-mentioned problems, the present inventors have conducted various experiments and studies on the composition and additive elements relating to the Ag—ZnO—SnO ₂ -based electrical contact material, and as a result, have found the electrical contact material according to the present invention. It came. The present invention relates to Ag-Zn-Sn composed of 5.1 to 8.0 wt% Zn, 0.01 to 5.0 wt% Sn, 0.01 to 1.5 wt% Te, the balance being Ag. -Ag-oxide-based electrical contact material obtained by internally oxidizing a Te alloy, or 0.01 to 5.0 wt% Zn, 5.1 to 8.0 wt% Sn, 0.01 to 1. This is an Ag-oxide-based electrical contact material obtained by internally oxidizing an Ag—Zn—Sn—Te alloy containing 5 wt% Te and the balance being Ag.

In the Ag-oxide-based electrical contact material according to the present invention, ZnO and SnO ₂ uniformly dispersed in the Ag substrate mainly play a role with respect to welding resistance and wear resistance. In addition, TeO _{When 2} is present, the welding resistance can be further improved. The welding resistance in this Ag-oxide-based electrical contact material greatly depends on the particle size and degree of dispersion of the oxide in the Ag substrate, so that the heat resistance is improved as the oxide is uniformly and finely dispersed. As a result, the welding resistance can be improved. However, when the oxide becomes finer, the workability of the material itself deteriorates, so the particle size of the oxide is desirably about 0.5 μm to 2.0 μm.

The heat resistance of the electrical contact material, which is an important factor for welding resistance, is greatly influenced by the thermal stability of the oxide dispersed in the Ag substrate. Both ZnO and SnO ₂ are stable up to 1500 ° C. in the atmosphere. Therefore, it has an effect of improving heat resistance. However, oxides with high thermal stability are generally considered to have poor wettability with molten Ag, and when a part of the contact surface is melted by arc discharge generated during the opening / closing operation of the relay, the Ag constituting the contact is formed. The oxide is separated from the oxide, and an Ag rich portion and an oxide aggregate portion are formed. When such a separation phenomenon occurs, there is a very high possibility that the Ag-rich portions or the oxide aggregate portions will come into contact with each other, and the welding resistance and the stability of contact resistance will be significantly deteriorated. However, in the Ag-oxide-based electrical contact material of the present invention, the added Te acts on the contact interface of ZnO or SnO ₂ having poor wettability with molten Ag, and has an effect of improving wettability. Conceivable. Therefore, the Ag-oxide-based electrical contact material of the present invention minimizes the separation of Ag and oxide even when a part of the contact surface is temporarily dissolved by an arc or the like. In the subsequent opening / closing operation, good welding resistance and stability of contact resistance can be maintained.

In the Ag-oxide-based electrical contact material according to the present invention, it is desirable that the oxide formed in the Ag substrate by internal oxidation, that is, ZnO, SnO ₂ and TeO ₂ are uniformly and finely dispersed. These oxide amounts are preferably the following composition amounts from the viewpoint of welding resistance and workability. First, the Zn amount for forming ZnO is preferably 5.1 to 8.0% by weight. In this Zn amount, the Sn amount for forming SnO ₂ is 0.01 to 5.0% by weight. Preferably there is. Then, Te amount to form a TeO ₂ is preferably 0.01 to 1.5 wt%. When the Zn content is less than 5.1% by weight, a practical level of welding resistance cannot be realized. When the Zn content exceeds 8.0% by weight, a thick oxide layer (oxidation band) is formed during internal oxidation. There is a tendency to form, and workability deteriorates. If the Sn amount is less than 0.01% by weight, it becomes impossible to improve the welding resistance due to the synergistic effect with ZnO. If the Sn amount exceeds 5.0% by weight, an oxidation band is formed during internal oxidation in the same manner as Zn. It tends to be formed and processability is reduced. On the other hand, if the amount of Te is less than 0.01% by weight, good welding resistance cannot be maintained.

Further, the Ag-oxide-based electrical contact material of the present invention may be the reverse of the above-described composition amounts of Zn and Sn. That is, the amount of Zn that forms ZnO is preferably 0.01 to 5.0% by weight. In this case, the amount of Sn that forms SnO ₂ is 5.1 to 8.0% by weight. Is preferred. The amount of Te forming TeO ₂ is preferably 0.01 to 1.5% by weight, as in the above case. Since ZnO and SnO ₂ are considered to have substantially the same effect for determining the characteristics of the electrical contact material, even if the Zn content and the Sn content are the composition amounts that are opposite to the above, good welding resistance and That is, it has workability. When the Zn content is less than 0.01% by weight, a practical level of welding resistance cannot be realized, and when it exceeds 5.0% by weight, a thick oxide layer (oxidation band) is formed during internal oxidation. There is a tendency to form, and workability deteriorates. If the Sn amount is less than 5.1% by weight, the improvement of the welding resistance due to the synergistic effect with ZnO cannot be obtained, and if it exceeds 8.0% by weight, an oxidation band tends to be formed during internal oxidation. As a result, workability is reduced. The amount of Te is the same as that described above.

In the oxide-based electrical contact material according to the present invention, even if ZnO, part of SnO ₂ dispersed in the Ag substrate, or most of it is dispersed as a complex oxide of Zn ₂ SnO ₄ , There is no significant difference in the characteristics of the contact material.

  According to the present invention, since it does not contain Cd or In, it is not affected by environmental problems or In resource depletion, and has versatility that can control various loads such as an AC general-purpose relay and a vehicle-mounted relay, An electrical contact material having excellent durability characteristics can be provided even with a relay further downsized than before.

  Preferred embodiments of the present invention will be described based on the following examples and conventional examples. Examples 1 to 5 are electrical contact materials having the compositions shown in Table 1, and Conventional Examples 1 to 3 are electrical contact materials for comparison with the examples.

  The electrical contact materials of Examples 1 to 5 and Conventional Examples 1 to 3 were manufactured using a normal high-frequency melting furnace. An Ag alloy having each composition was melted, cast into an ingot, and hot extruded to obtain a wire having a diameter of 6 mm. Subsequently, the wire was stretched to φ2 mm while being repeatedly annealed (700 ° C.) and drawn, and cut to a length of 2 mm, thereby producing a chip of φ2 mm × 2 mmL. This chip was subjected to internal oxidation treatment at an oxygen pressure of 0.5 MPa and a temperature of 750 ° C. for 48 hours, and the chips after the internal oxidation treatment were collected and compression molded to produce a φ50 mm cylindrical billet.

  And each cylindrical billet obtained as mentioned above was stored in the cylindrical container, and the cylindrical billet was compression-processed by applying a pressure from a cylinder longitudinal direction. In this compression processing, since the side surface of the column billet is constrained by the cylindrical container, deformation in the longitudinal direction of the column is possible, but deformation in the direction of the column side that is perpendicular to the column is prevented. Following this compression process, a sintering process was performed at 900 ° C. for 4 hours. This compression process and sintering process were repeated four times.

  The billet subjected to such compression processing and sintering treatment was formed into a φ7 mm wire by hot extrusion processing (extrusion area ratio of about 51: 1). Subsequently, a wire rod having a diameter of 2.3 mm was formed by wire drawing, and a rivet contact having a head diameter of 3.2 mm and a head thickness of 1 mm was produced by a header machine.

  The produced rivet contacts (Examples 1, 2, 4, 5, and Conventional Examples 1 to 3) were incorporated into a flexure type relay and subjected to an endurance test under the AC load conditions shown in Tables 2 and 4. In this durability test, five or more relays were used, and the number of times of opening and closing was measured until each relay failed. The results of the durability test are shown in Table 3 (results of test conditions in Table 2) and Table 5 (results of test conditions in Table 4). In this flexure type relay, the ON bounce is larger than that of a commercially available relay. Therefore, it is considered that this endurance test has a strong meaning as an acceleration test. Based on past experience, the durability performance of this flexure type relay and the commercial relay is consistent, so it is required for the flexure type relay that is necessary to satisfy the durability of the commercial relay. The durability of each rivet contact was investigated using the target durability as the required life. Tables 2 and 4 show the number of durability as the required life in each durability test. The required life is also shown in the endurance tests for Tables 6 and 8 to be described later.

From the endurance test results shown in Table 3 and Table 5, in an AC load, the Ag—SnO ₂ system electrical contact material of Conventional Example 1 and the Ag—SnO ₂ —In ₂ O ₃ system electrical contact material of Conventional Example 2 are It was confirmed that it has practical durability performance. And it turned out that the electrical contact material of a present Example is provided with the durability performance equivalent or more compared with the prior art example.

  Next, each rivet contact described above was incorporated into a flexure type relay and subjected to an endurance test under a load condition for mounting on an automobile. The durability test conditions are shown in Table 6 (Examples 2, 4 and 5 and Conventional Examples 1 and 2) and Table 8 (Examples 3 and 4 and Conventional Examples 1 and 2). As for the durability test, the number of opening and closing operations was measured using five or more relays until each relay broke down, and the average number of durability lives was examined. The results of each durability test are shown in Table 7 (result of the durability test in Table 6) and Table 9 (result of the durability test in Table 8).

From the durability test results shown in Table 7, in the halogen lamp durability test which is a capacitive load, the Ag—SnO ₂ -based electrical contact material of Conventional Example 1 and the Ag—SnO ₂ —In ₂ O ₃ -based electrical contact material of Conventional Example 2 And have been confirmed to have practical durability. And it turned out that the electrical contact material of a present Example is equipped with equivalent durability compared with a prior art example. In the durability test results shown in Table 9, the Ag—SnO ₂ -based electrical contact material of Conventional Example 1 did not satisfy the required life. The Ag—SnO ₂ -based electrical contact material of Conventional Example 1 exhibits excellent durability in the halogen lamp load that is capacitive as shown in Table 6, but at the same time the durability of the inductive motor load shown in Table 8 Since it was not satisfactory, it was confirmed that it was difficult to use it in a relay for mounting on automobiles that required versatility. Further, since the Ag—SnO ₂ —In ₂ O ₃ -based electrical contact material of Conventional Example 2 shows practical durability performance under the load conditions shown in Table 8, the addition of In ₂ O ₃ is an inductive load. It was confirmed to have an effect of improving durability against That is, it was shown that the Ag—SnO ₂ -based electrical contact material of Conventional Example 1 is not suitable as an electrical contact material for a vehicle-mounted relay that requires general-purpose characteristics because there is no addition of In ₂ O ₃ . As a result. On the other hand, it has been found that the electrical contact materials of Examples 3 and 4 have no practical problem with respect to durability in the motor load that is inductive as shown in Table 8. From the results of this durability test, the Ag—ZnO—SnO ₂ —TeO ₂ -based electrical contact material according to the present invention does not contain In ₂ O ₃ and is suitable for a vehicle-mounted relay that requires general-purpose characteristics. found.

Claims (5)

An Ag—Zn—Sn—Te alloy composed of 5.1 to 8.0 wt% Zn, 0.01 to 5.0 wt% Sn, 0.01 to 1.5 wt% Te and the balance Ag. An Ag-oxide-based electrical contact material characterized by internal oxidation. An Ag—Zn—Sn—Te alloy comprising 0.01 to 5.0 wt% Zn, 5.1 to 8.0 wt% Sn, 0.01 to 1.5 wt% Te, and the balance being Ag. An Ag-oxide-based electrical contact material characterized by internal oxidation. The relay provided with the electrical contactor which used the electrical contact material of Claim 1 or Claim 2 as a constituent material. An AC general-purpose relay comprising an electrical contact made of the electrical contact material according to claim 1 or 2 and controlling a resistive load with an AC voltage of 80 V to 300 V and a rated current of 5 to 30 A. . An electric contact comprising the electric contact material according to claim 1 or 2 as a constituent material, and controlling a resistance load of a DC voltage of 5V to 30V and a rated current of 3 to 30A. relay.