TWI401714B - Anti-arc erosion of the silver base - no cadmium composite material of the electrical contact material - Google Patents

Description

Silver-based arc-free cadmium-free composite electrical contact material

This creative department is related to the field of electrical contact materials, especially for a silver base with high hardness and wear resistance, which still has a low contact resistance characteristic and maintains a good anti-arc erosion ability. Electrical contact material for cadmium composites.

Electrical contact materials are currently used in a wide variety of applications where electrical contact is required to operate. For example, communication transmission, system or power output control, electronic instrument connection, and computer (computer) peripherals. Generally, when the electrical connector or the relay switch is operated, the current between the two electrical contacts will be based on the distance between the two electrode contacts at the moment of contact or just separation. A discharge phenomenon occurs, which in turn forms the physical manifestation of the so-called "arc".

Generally speaking, during the arc erosion process, the material quality between the two electrical contacts is transferred, and a convex or concave shape is formed on the surface of the electrical contact; or the metal is melted after the surface is eroded by the arc. After solidification, the surface which is roughened is formed; and other pollution or damage caused by the original, the surface of the original electrical contact is lost, and the contact resistance value is increased, thereby affecting the working efficiency of the electrical contact.

As for the practical application, the industry generally used platinum as its material in the early stage, but the cost of platinum was too high, so there was a tendency to be replaced by copper. Although copper has the advantages of high electrical conductivity, heat, low cost, etc., it is easy to form an oxide on the copper surface. Therefore, a silver substrate having the same advantages as copper has been proposed. However, although silver can resist oxidation, its strength is low, wear resistance is not good, and arc erosion is serious, which is not conducive to the application of electrical contact materials for a long time. In the later stage, although it has developed a more economical CdO/Ag contact material, it has high conductivity, high thermal conductivity, corrosion resistance, and can conduct more current and is used in heavy-duty or high-pole switches and relays. However, Cd is highly toxic and the EU has officially adopted the WEEE and RoHS bills, prohibiting the use of various types of electronic products with highly toxic substances, such as Cd, Pb, etc.

Please refer to Figures 1A and 1B for the appearance of the connector (1) (2) of the conventional AuCo electrical contact material after 500 arc erosion tests. According to the figure, after the 500-degree arc erosion test of the conventional electrical contact material, the surface of the material has been seriously damaged, and the product life performance is not good.

Accordingly, under the premise of the above-mentioned items and restrictions, it is proposed to conduct high current, better corrosion resistance and improve the hardness of the contact material, and to meet the electrical contact materials under the international non-toxic materials regulations. It is a subject that the practitioners in the field are eager to improve.

In view of the above problems, the purpose of the present invention is to provide an electrical contact material which has high hardness and high wear resistance and still has a low contact resistance characteristic to maintain a good arc erosion resistance.

In order to achieve the above objectives, the present invention proposes a silver-based cadmium-free composite electrical contact material capable of resisting arc erosion, characterized in that the dimension hardness (Hv) of the electrical contact material is 100~ 150, and the contact resistance is 5~60 mohm (milliohm) under the condition of test current of 1~5 amps and 10~20 volts, and the arc erosion resistance is 2*10 ³ ~10*10 ³ times; when the electrical contact material is formed on the surface of the metal substrate of the electrical connector, the two electrical contacts can effectively maintain the ability to resist arc erosion under the condition of low contact resistance.

The electrical contact material is composed of Ag-(SnO ₂ +In ₂ O ₃ ) composite material. Further, the proportion of the (SnO ₂ + In ₂ O ₃ ) component of the Ag-(SnO ₂ + In ₂ O ₃ ) composite is 9 to 11%.

The electrical contact material may also be composed of an Ag-Cu oxide composite. Further, the proportion of Cu oxide (oxide) component of the Ag-Cu oxide composite is 15 to 25%.

The effect of this creation is to provide a silver-based cadmium-free composite electrical contact material that is resistant to arc erosion, thereby complying with the European Community (EC) Waste Electrical Appliances (WEEE) and RoHS regulations, and The contact material can also have the requirements of conducting large current, better corrosion resistance and improving the hardness of the contact material, effectively reducing the arc erosion effect, and achieving the goal of low contact resistance, thereby greatly improving the service life of the product.

In order for your review board to have a clear understanding of the content of this creation, please use the following instructions to match the schema and the experimental form.

Since the electrical contact point is at the moment of disconnection, the current will be forced to pass through a small but still connected electrical contact. At this time, an arc effect will occur in a small area of the conduction contact, and the current density through which the current is passed may be even higher. 5*10 ⁴ A/cm ² . As a result, the temperature at the contact point rises rapidly and a strong magnetic field is accelerated to accelerate the movement of electrons or positive and negative ions, resulting in a more severe arc erosion effect. Therefore, in order to reduce the occurrence of such damage phenomena, the electrical contact material should have a high conductivity, so that less energy is generated when the current passes, to avoid softening caused by high temperature, thereby affecting the strength performance of the material; If the electrical contact material has better thermal conductivity, the heat on the electrical contact can be effectively conducted and dispersed, so as not to cause material damage due to overheating and reduce the influence caused by the arc effect. Moreover, the electrical contact materials are often used in the environment of various corrosive gases, so the corrosion resistance or oxidation resistance of the electrical contact materials is also one of the characteristics required for use. In this way, it is avoided that the formation of non-conductive compounds or oxides on the surface of the material occurs, resulting in an increase in the contact resistance value and a decrease in the service life of the material. As for the moment when the electrical contacts are turned on or off, there is usually mechanical wear and tear, and the surface of the electrical contact materials will be damaged for a long time. Therefore, a hard or more wear-resistant electrical contact material is also one of the requirements for use.

However, the above-mentioned characteristics of the harder or more wear-resistant characteristic materials are usually accompanied by higher contact resistance values, so the creation of the system can generally meet these requirements and Electrical contact materials with these characteristics are more effectively implemented in various fields of the industry. Accordingly, please refer to the following table to explain the difference between the physical properties and the anti-arc erosion ability between the two materials proposed in this creation and the conventional electrical contact materials.

It can be seen from the above table that the silver-based cadmium-free composite electrical contact material provided by the present invention is characterized in that the electrical contact material does not contain toxic substances and conforms to the international agreement. Specification. Moreover, the use of silver as a substrate can achieve the above requirements such as higher conductivity or better thermal conductivity. At the same time, the dimension hardness value (Hv) of the electrical contact material can also reach 100-150, which effectively exhibits the required characteristics of wear resistance. In addition, when the conventional material has a better hardness, the contact resistance thereof also rises, and the electric contact material proposed by the present invention is also improved. As described in the above table, the two materials still have a low contact resistance value between 5 and 60 mohms in the case of high hardness. For example, a composite material of Ag-(SnO ₂ + In ₂ O ₃ ), wherein the ratio of the (SnO ₂ + In ₂ O ₃ ) component is 9 to 11%, or Ag-Cu oxide (oxide) composite The material, and the ratio of the Cu oxide component is 15 to 25%. At the same time, the addition of SnO ₂ and In ₂ O ₃ can also be dispersed and strengthened to enhance the mechanical properties. At the same time, SnO ₂ is less likely to decompose at high temperatures, and can also increase the viscosity of the material to protect the silver substrate and reduce the silver substrate. Loss of volume due to arc erosion. Compared with the traditional electrical contact materials, for example, the AuCo alloy, although the hardness value is higher than the original material, the contact resistance is also increased to 50-100 mohm (milliohms), which will cause arc discharge. The process is more serious material damage. Further, the experimental operation of the Vickers hardness value referred to herein can be measured by the following relationship Hv = 1.584 * P (Kg) / d ² (mm ² ). The P value can be known from the load; the d value can be obtained by multiplying the load time by the load rate, and this is explained.

As for the anti-arc erosion capacity of the two materials, it can reach 2*10 ³ ~10*10 ³ times respectively. Compared with the conventional materials, it can only achieve 500 times of anti-arc erosion ability, greatly improving its products. Service life. In this way, it is necessary to provide the electrical contact material to have a lower contact resistance value when the surface of the metal substrate of the electrical connector is formed, thereby effectively maintaining the ability to resist arc erosion. Here, for the test of the arc erosion ability, the experiment uses the fixed distance single arc erosion test or the multiple arc erosion test. The behavior of the single-arc erosion of the distance is different from the behavior of multiple arc erosion. The latter is a simulation test that is closer to the damage situation under real electrical contact operation. For example, in multiple arc erosion processes, continuous arc erosion and electrical contact back and forth impact tests will be included; as for the former, a simpler and faster research method is provided to understand the situation and process of arc erosion. For example, maintaining a fixed spacing between the cathode and the anode, eroding the surface of the material in a highly concentrated discharge, while avoiding mechanical contact damage, and this is illustrated.

Please refer to the 2A, 2B and 3A, 3B drawings, which are the appearance of the connector after the 5000 arc erosion test of the AgSnIn electrical contact material (1) (2) and the created AgCu electrical contact. Appearance surface diagram of the connector after 2000 arc erosion tests (1) (2). According to the figure, after the arc contact test of the created electric contact material, the surface still has to maintain better flatness and integrity, and the better hardness performance makes the material to avoid damage by arc erosion. Please refer to Fig. 4 again, which is an SEM photomicrograph of the material of the electrical contact material. In particular, the observation of the electron microscope can be found that the material properties of the additive are effectively dispersed uniformly in the silver substrate to enhance the dispersion strengthening and enhance the mechanical wear resistance.

The effect of this creation is to provide a silver-based cadmium-free composite electrical contact material that is resistant to arc erosion, thereby complying with the European Community (EC) Waste Electrical Appliances (WEEE) and RoHS regulations, and The contact material can also have the requirements of conducting large current, better corrosion resistance, wear resistance and improving the hardness of the contact material, effectively reducing the damage caused by the arc erosion effect, and achieving the goal of low contact resistance value, greatly improving each The service life of products with electrical contact requirements and the overall suitability of products used in various fields.

The above is only the preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. Therefore, it is possible to make changes in the equivalent or easy changes of the technology without departing from the spirit and scope of the present invention. Equivalent changes and modifications made below shall be covered by the scope of this creation.

Figure 1A shows the appearance of the connector (A) of the conventional AuCo electrical contact material after 500 arc erosion tests.

Figure 1B shows the appearance of the connector after the 500-degree arc erosion test of the conventional AuCo electrical contact material (2).

Figure 2A shows the appearance of the connector after the 5,000 arc erosion test of the AgSnIn electrical contact material (1).

Figure 2B shows the appearance of the connector after the 5,000 arc erosion test of the AgSnIn electrical contact material (2).

Figure 3A shows the appearance of the connector (A) after the 2000 arc erosion test of the AgCu electrical contact material.

Figure 3B shows the appearance of the connector after the 2000 arc erosion test of the AgCu electrical contact material (2).

Figure 4 is a SEM photomicrograph of the material of the electrical contact material.

Claims (2)

An electrical contact material capable of resisting arc erosion of silver-free cadmium composite material, which is formed on the surface of the metal substrate of the electrical connector, and the two electrical contacts are effective to maintain resistance under low contact resistance conditions The ability of arc erosion; the electric contact material is Ag-(SnO2+In2O3) composite material, wherein the ratio of (SnO2+In2O3) component of the Ag-(SnO2+In2O3) composite material is 9 ~11%, and the dimension hardness (Hv) of the electrical contact material is 100~150, and the contact resistance is 5~60 mohm (milliohms) under the condition of test current of 1~5 amps and 10~20 volts. ), the electrical contact material has an arc erosion resistance of 2*103~10*103 times. An electrical contact material capable of resisting arc erosion of silver-free cadmium composite material, which is formed on the surface of the metal substrate of the electrical connector, and the two electrical contacts are effective to maintain resistance under low contact resistance conditions The ability of arc erosion; characterized in that the electrical contact material is selected as an Ag-Cu oxide composite, wherein the Cu oxide component of the Ag-Cu oxide composite The ratio is 15~25%, and the dimension hardness (Hv) of the electrical contact material is 100~150. Under the condition of 1~5 amps and 10~20 volts, the contact resistance is 5~60. Mohm (milliohms), the electrical contact material has an arc erosion resistance of 2*103~10*103 times.