Electrical contact for improving reliability of direct-current relay and preparation method

Abstract

The invention belongs to the technical field of electrical contact preparation, and particularly relates to an electrical contact for improving the reliability of a direct-current relay and a preparation method. According to the prepared contact material, the 3D printing technology is adopted, partition design is carried out on materials of different parts, and a working layer still keeps a CuTe0.3 material with excellent arc erosion resistance and welding resistance; the connecting layer is made of CuW or CuWC, and the material has extremely high hardness, so that the connecting layer can bear high load and abrasion of a connecting structure, and the performance of long-term stable connection is ensured; the conduction layer is made of pure silver, silver has excellent flow guide performance, all parts are effectively combined through the conductive adhesive to form a whole, contact resistance can be effectively reduced, contact heating is reduced, and therefore energy consumption is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of electric contact preparation, and in particular relates to an electric contact for improving the reliability of a DC relay and a preparation method thereof. Background Art

[0002] With global warming and increasingly tight energy supply, the implementation of national energy strategies and the continuous improvement of human environmental awareness, electric vehicles have gradually replaced traditional fuel vehicles. As people's demand for electric vehicle power performance and cruising range continues to increase, the power, current and voltage levels of electric vehicles continue to increase, which in turn puts higher requirements on the safety performance of electric vehicle electrical systems. As an executive component that controls the on and off of each high-voltage circuit, the high-voltage DC relay is an important guarantee for the safety of electric vehicles. The operating conditions of new energy vehicles are relatively demanding: 1. Higher current and voltage; 2. Frequent impact current; 3. Large fault current; 4. Large heat generation and temperature rise.

[0003] The contact material used in traditional high-voltage relays is CuTe0.3, which is widely used due to its good resistance to arc erosion and welding. However, the hardness of this material is relatively low. Under the high electric repulsion caused by the high current in the main circuit, the displacement of the moving and static contacts leads to a decrease in the strength of the threaded connection of the static contacts. The unstable contact between the moving and static contacts causes continuous arcing, which accelerates the erosion of the material and causes failure. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings and deficiencies of the prior art and to provide an electrical contact and a preparation method for improving the reliability of a DC relay.

[0005] The technical solution adopted by the present invention is as follows: an electric contact for improving the reliability of a DC relay, comprising:

[0006] The working layer is a copper-based material, wherein the copper-based material is CuTe0.3 or CuTe0.3 containing additives;

[0007] The connecting layer is made of CuMe material, wherein the CuMe is CuW or CuWC, is fixedly connected to one side of the working layer, and is provided with a connecting structure;

[0008] The conducting layer is made of pure silver, fixedly connected to one side of the working layer and surrounding the outer periphery of the connecting layer, and the end surface of the conducting layer away from the working layer constitutes a conducting surface;

[0009] The working layer, the connecting layer and the conducting layer are connected by a conductive adhesive.

[0010] Preferably, the conductive adhesive is a polymer conductive copper adhesive.

[0011] Preferably, the connection structure is a threaded connection hole.

[0012] Preferably, the radial thickness of the connection layer is 0.5-1 mm, and the radial direction is the radial direction relative to the threaded connection hole, that is, the single-side thickness of the outer peripheral area of ​​the threaded connection hole is 0.5-1 mm.

[0013] Preferably, the working layer has a thickness of 2-5 mm, where the thickness refers to the thickness from the end adjacent to the conductive layer to the end away from the conductive layer, that is, the axial thickness relative to the threaded connection hole.

[0014] The method for preparing an electric contact for improving the reliability of a DC relay as described above is characterized by comprising the following steps:

[0015] Step 1: Prepare CuMe powder, pure silver powder and copper-based powder;

[0016] Step 2: Establish a 3D contact model, construct the working layer, connection layer, and conduction layer;

[0017] Step 3: Forming a blank by 3D printing;

[0018] Step 4: Sintering the blank in an inert atmosphere in stages with gradient pressure;

[0019] Step 5: Clean the sintered blank to obtain a finished product.

[0020] Preferably, the inert atmosphere is nitrogen or argon.

[0021] Preferably, in step 4, the sintering process is to enter the furnace at room temperature, with a heating rate of 3-4°C / min, 120-150°C, keep warm for 1-3h, and have an air pressure of 0.1MPa; 450-600°C, keep warm for 2-4h, and have an air pressure of 0.1MPa; 800-900°C, keep warm for 4-6h, and have an air pressure of 8-10Mpa.

[0022] High-voltage DC relays have high requirements on the comprehensive performance of electrical contact materials. CuTe0.3 material has good resistance to arc erosion and welding and is widely used. However, the hardness of this material is relatively low. Under the harsh working conditions of high-voltage DC relays, the threaded connection strength is low, and it is easy to cause unstable contact between the moving and static contacts under the action of high electric repulsion, increasing the risk of failure. At the same time, because its body resistance is higher than that of pure copper, it consumes more energy during the charging process of electric vehicles.

[0023] Compared with the prior art, the advantages and positive effects of the present invention are as follows: the contact material prepared by the present invention adopts 3D printing technology, and the working layer still maintains the CuTe0.3 material with excellent arc erosion resistance and welding resistance by partitioning the materials in different parts; the connecting layer is made of CuW or CuWC, which has extremely high hardness, so that it can withstand the high load and wear of the connecting structure, thereby ensuring the performance of long-term stable connection; the conductive layer is pure silver, which has excellent current conduction performance, and each part is effectively combined by conductive adhesive to form a whole, which can effectively reduce the contact resistance, reduce the heating of the contact, and thus reduce energy consumption. The present invention has made an innovative design from the perspective of the contact structure, with a working layer of CuTe0.3 material, a connecting layer of CuW or CuWC layer, and a conductive layer of pure silver. By partitioning the functional design of the materials in different parts, the problem of high resistance and low connection strength of a single CuTe0.3 material is solved, and excellent electrical performance, low energy consumption, and reliable connection are obtained, thereby improving the electrical performance stability of the DC relay. Furthermore, the present invention forms a blank by 3D printing, and then forms a whole by step-by-step pressure sintering, which is highly efficient. The contact material of the present invention effectively meets the comprehensive performance of the contact required by the high-voltage DC relay, and improves the reliability of the electrical performance of such electrical appliances. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, without paying creative labor, other drawings obtained based on these drawings still belong to the scope of the present invention.

[0025] Figure 1 It is a process flow chart of the present invention.

[0026] Figure 2 The figure is a schematic diagram of a cross-sectional model of an embodiment of an electric contact of the present invention. DETAILED DESCRIPTION

[0027] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention will be further described in detail below with reference to the accompanying drawings.

[0028] Embodiment 1:

[0029] (1) CuWC90 powder is prepared by a powder mixing process, atomized pure silver powder and CuTe0.3 powder with a purity greater than 99.99% are prepared, and each type of powder is pretreated separately;

[0030] (2) Establish 3D contact model: Figure 1As shown, it includes a working layer 1, a connecting layer 2, and a conducting layer 3: the working layer 1 is CuTe0.3 with a thickness of 4 mm; the connecting layer 2 is connected to one end of the working layer 1, and is made of CuW90 material, and is provided with a threaded connecting hole 201 therein, and the outer periphery of the threaded connecting hole 201 has a single-side thickness of 0.96 mm; the conducting layer 3 is connected to one end of the working layer 1 and is sleeved on the outer periphery of the connecting layer 2, and is made of pure silver, and its end surface away from the working layer 1 constitutes a conducting surface;

[0031] (3) The powder is loaded into a 3D printer material box and a blank is printed, and each layer is connected with a polymer conductive copper adhesive;

[0032] (4) The blank was subjected to staged gradient pressure sintering in a nitrogen atmosphere: entering the furnace at room temperature, heating rate 3.1°C / min, 128°C, holding for 1.1 h, gas pressure 0.1 MPa; 525°C, holding for 2.4 h, gas pressure 0.1 MPa; 810°C, holding for 3.8 h, gas pressure 8.4 MPa;

[0033] (5) The sintered blank is then cleaned to obtain a finished product.

[0034] The electrical performance test of the 150A high-voltage DC relay assembled with the contact showed an electrical life of 4030 times and a contact resistance of 0.09Ω.

[0035] Embodiment 2:

[0036] (1) CuW96 powder is prepared by a powder mixing process, atomized pure silver powder and CuTe0.3 powder with a purity greater than 99.99% are prepared, and each type of powder is pretreated separately;

[0037] (2) Establish 3D contact model: Figure 1 As shown, it includes a working layer 1, a connecting layer 2, and a conducting layer 3: the working layer 1 is CuTe0.3 with a thickness of 5 mm; the connecting layer 2 is connected to one end of the working layer 1, and is made of CuW90 material, and is provided with a threaded connecting hole 201 therein, and the outer periphery of the threaded connecting hole 201 has a single-side thickness of 0.7 mm; the conducting layer 3 is connected to one end of the working layer 1 and is sleeved on the outer periphery of the connecting layer 2, and is made of pure silver, and its end surface away from the working layer 1 constitutes a conducting surface;

[0038] (3) The powder is loaded into a 3D printer material box and a blank is printed, and each layer is connected with a polymer conductive copper adhesive;

[0039] (4) The blank was subjected to staged gradient pressure sintering in an argon atmosphere: entering the furnace at room temperature, heating rate 3.7°C / min, 139°C, holding for 2.7 h, gas pressure 0.1 MPa; 480°C, holding for 3.2 h, gas pressure 0.1 MPa; 860°C, holding for 5.2 h, gas pressure 9.3 MPa;

[0040] (5) The sintered blank is then cleaned to obtain a finished product.

[0041] The electrical performance of the 200A high-voltage DC relay assembled with the contact was tested, and the electrical life was 3800 times and the contact resistance was 0.11Ω.

[0042] Embodiment 3:

[0043] (1) CuW93 powder is prepared by a powder mixing process, atomized pure silver powder and CuTe0.3 powder with a purity greater than 99.99% are prepared, and each type of powder is pretreated separately;

[0044] (2) Establish a 3D contact model: including a working layer 1, a connecting layer 2, and a conducting layer 3: the working layer 1 is CuTe0.3 with a thickness of 2.3 mm; the connecting layer 2 is connected to one end of the working layer 1 and is made of CuW90 material, and is provided with a threaded connection hole 201, and the outer circumference of the threaded connection hole 201 has a single-side thickness of 0.52 mm; the conducting layer 3 is connected to one end of the working layer 1 and is sleeved on the outer circumference of the connecting layer 2, and is made of pure silver, and its end surface away from the working layer 1 constitutes a conducting surface;

[0045] (3) The powder is loaded into a 3D printer material box and a blank is printed, and each layer is connected with a polymer conductive copper adhesive;

[0046] (4) The blank was subjected to staged gradient pressure sintering in a nitrogen atmosphere: entering the furnace at room temperature, heating rate 3.5°C / min, 148°C, holding for 1.6 h, gas pressure 0.1 MPa; 590°C, holding for 3.4 h, gas pressure 0.1 MPa; 870°C, holding for 4.5 h, gas pressure 9.7 MPa;

[0047] (5) The sintered blank is then cleaned to obtain a finished product.

[0048] The electrical performance test of the 60A high-voltage DC relay assembled with the contact showed an electrical life of 3950 times and a contact resistance of 0.06Ω.

[0049] The above disclosure is only the preferred embodiment of the present invention, which certainly cannot be used to limit the scope of the present invention. Therefore, equivalent changes made according to the claims of the present invention are still within the scope of the present invention.

Claims

1. An electrical contact for improving the reliability of a DC relay, characterized in that: These include, The working layer (1) is a copper-based material, wherein the copper-based material is CuTe0.3 or CuTe0.3 containing additives; The connecting layer (2) is made of CuMe, wherein the CuMe is CuW or CuWC, is fixedly connected to one side of the working layer (1), and is provided with a connecting structure; The conducting layer (3) is made of pure silver, is fixedly connected to one side of the working layer (1) and surrounds the outer periphery of the connecting layer (2), and the end surface of the conducting layer (301) is away from the working layer (1); The working layer (1), the connecting layer (2) and the conducting layer (3) are connected by means of a conductive adhesive.

2. The electrical contact for improving the reliability of a DC relay according to claim 1, characterized in that: The conductive adhesive is a polymer conductive copper adhesive.

3. The electrical contact for improving the reliability of a DC relay according to claim 1, characterized in that: The connection structure is a threaded connection hole (201).

4. The electrical contact for improving the reliability of a DC relay according to claim 3, characterized in that: The radial thickness of the connecting layer (2) is 0.5-1 mm.

5. The electrical contact for improving the reliability of a DC relay according to claim 1, characterized in that: The thickness of the working layer (1) is 2-5 mm.

6. The method for preparing an electric contact for improving the reliability of a DC relay according to any one of claims 1 to 5, characterized in that The following steps are involved: Step 1: Prepare CuMe powder, pure silver powder and copper-based powder; Step 2: Establish a 3D contact model, construct a working layer (1), a connection layer (2), and a conduction layer (3); Step 3: Forming a blank by 3D printing; Step 4: Sintering the blank in an inert atmosphere in stages with gradient pressure; Step 5: Clean the sintered blank to obtain a finished product.

7. The method for preparing an electric contact for improving the reliability of a DC relay according to claim 6, characterized in that: The inert atmosphere is nitrogen or argon.

8. The method for preparing an electric contact for improving the reliability of a DC relay according to claim 6, characterized in that: In step 4, the sintering process is as follows: entering the furnace at room temperature, heating rate 3-4°C / min, 120-150°C, keeping warm for 1-3h, air pressure 0.1MPa; 450-600°C, keeping warm for 2-4h, air pressure 0.1MPa; 800-900°C, keeping warm for 4-6h, air pressure 8-10Mpa.

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