Composite functional electrical contact and 3D forming preparation method thereof

Abstract

The invention belongs to the technical field of electrical contact structures, and particularly relates to a composite functional electrical contact and a 3D forming preparation method thereof.The composite functional electrical contact comprises a rivet-shaped copper layer body, the end face of the head of the copper layer body is concaved downwards to form a pot-bottom-shaped cavity, the edge of the pot bottom is right flush with the upper end of the copper layer body in height, and the pot-bottom-shaped cavity is filled with an inner pure silver layer; a silver metal oxide layer is arranged outside the inner pure silver layer, a silver tungsten carbide layer is arranged outside the silver metal oxide layer, and an outer pure silver layer is arranged outside the silver tungsten carbide layer. Innovative design is carried out from the angle of a contact structure, multi-layer composite design is carried out on a silver layer of a traditional silver-copper composite rivet, all layers of materials are tightly combined into a whole, and the comprehensive excellent performance of high impact resistance, long electrical life, low surface contact resistance and low loop impedance is achieved, so that the electrical performance stability of a magnetic latching relay is improved, and the service life of the magnetic latching relay is prolonged. And the electrical performance reliability of the electrical appliance is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of electric contact structures, and in particular relates to a composite functional electric contact and a 3D molding preparation method thereof. Background Art

[0002] After my country proposed the concept of building a national smart grid, the smart meters directly supporting it have become the focus of attention. The magnetic latching relay is one of the core components of the smart meter. Due to its high reliability, safety and short-circuit current resistance, it plays the role of an intelligent switch in the smart meter. Due to the large working current and the large short-circuit current during the short-circuit withstand test, the magnetic latching relay often fails during use or testing. According to statistics, the failure rate of the relay electrical life caused by the failure of the electrical contact is more than 75%. The failure modes of the silver-copper composite contacts commonly used in magnetic latching relays are mainly: 1) high contact resistance on the contact surface leads to local welding failure; 2) low electrical life of the contact, which cannot meet the design requirements; 3) large loop impedance and high energy consumption; 4) poor resistance to large current impact and contact welding. Therefore, the magnetic latching relay requires the contact to have the following properties: 1) low and stable contact resistance; 2) high anti-burning performance; 3) low body resistance and good conductivity; 4) high resistance to large current impact. Traditional silver-copper composite rivet electrical contacts have a silver layer made of wire, and the material is a single component. However, electrical contacts made of a single material usually cannot have the characteristics of good conductivity, excellent burn-out resistance and strong resistance to large current shocks. For example, selecting materials with low resistance can meet energy consumption requirements, but such materials have poor burn-out resistance and cannot withstand large current shocks. Materials that meet the requirements of resistance to large current shocks usually have high resistance and cannot meet energy consumption requirements. Therefore, in the process of selecting contact materials for magnetic latching relays, one often loses sight of the other, and it is impossible to obtain electrical contact materials with superior comprehensive performance, which leads to unstable electrical performance of the magnetic latching relay. Summary of the invention

[0003] The purpose of the present invention is to overcome the shortcomings and deficiencies of the prior art and to provide a composite functional electrical contact and a 3D molding preparation method thereof.

[0004] The technical solution adopted by the present invention is as follows: a composite functional rivet-type electrical contact, comprising a rivet-shaped copper layer body, the head end face of the copper layer body is concave to form a pot-bottom-shaped cavity, the height of the pot bottom edge is just flush with the upper end of the copper layer body, the pot-bottom-shaped cavity is filled with an inner pure silver layer, the outer side of the inner pure silver layer is a silver metal oxide layer, the outer side of the silver metal oxide layer is a silver tungsten carbide layer, and the outer side of the silver tungsten carbide layer is an outer pure silver layer.

[0005] The silver metal oxide is AgSnO2 or AgSnO2In2O3.

[0006] The silver content in silver tungsten carbide is 50-90%.

[0007] The layers are connected with conductive adhesive.

[0008] The conductive adhesive is a polymer conductive silver glue.

[0009] The central depth of the pot-bottom-shaped cavity is 0.1-0.5 mm, the thickness of the silver metal oxide layer is 0.2-0.6 mm, the thickness of the silver tungsten carbide layer is 20-100 um, and the thickness of the outer pure silver layer is 0.5-5 um.

[0010] The 3D molding preparation method of the composite functional rivet-type electrical contact as described above comprises the following steps:

[0011] Step 1: prepare pure copper powder, pure silver powder, silver metal oxide powder, and silver tungsten carbide powder;

[0012] Step 2: construct a 3D rivet model based on the existing structure of the composite functional rivet-type electrical contact;

[0013] Step 3: Load the powder from step 1 into the 3D printer material box, and print the blank according to the 3D rivet model from step 2;

[0014] Step 4: Sintering the blank printed in step 3 in an inert atmosphere in stages with gradient pressure;

[0015] Step 5: Clean the blank sintered in step 4 to obtain a finished product.

[0016] In step 4, the inert atmosphere is nitrogen or argon, and the sintering process is entering the furnace at room temperature, with a heating rate of 3-4°C / min, 120-150°C, keeping warm for 1-3h, and an air pressure of 0.1MPa; 450-600°C, keeping warm for 2-4h, and an air pressure of 0.1MPa; 800-900°C, keeping warm for 4-6h, and an air pressure of 8-10Mpa.

[0017] The beneficial effects of the present invention are as follows: the present invention has made an innovative design from the perspective of the contact structure, and has made a multi-layer composite design for the silver layer of the traditional silver-copper composite rivet. The bottom of the pot is a pure silver layer, the working layer is a silver metal oxide layer, a silver tungsten carbide thin layer with strong anti-burning ability is added thereon, and the outermost layer is a pure silver film layer. The materials of each layer are tightly combined into a whole. Without changing the original rivet silver-copper composite shape, the materials of different parts are partitioned and designed to solve the problem that a single silver-based composite material cannot fully meet the multiple electrical properties of the magnetic latching relay. The edge of the silver layer of the pot bottom cavity is flush with the copper layer. Silver has the characteristics of excellent electrical conductivity but poor anti-burning performance. Therefore, the design height of this layer of material is not higher than the height of the copper layer (the highest point of the copper layer is the end point of the electrical life of the contact). This layer mainly contributes to the excellent electrical conductivity, but does not participate in the electrical life; the silver metal oxide layer on it has excellent anti-burning performance and mainly bears the electrical life of the contact under the rated current; the silver tungsten carbide thin layer above mainly bears the impact of large current; the surface silver film ensures the low and stable contact resistance of the contact. The electrical contact of the present invention achieves comprehensive excellent performance of high impact resistance, high electrical life, low surface contact resistance and low loop impedance, thereby improving the electrical performance stability of the magnetic latching relay and improving the electrical performance reliability of this type of electrical appliance.

[0018] Furthermore, the present invention realizes one-time forming of rivet contacts with a multi-layer composite structure through 3D printing, and then realizes efficient production through gradient sintering, so that the rivet contacts with a complex structure have the production conditions for industrial application. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] 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.

[0020] Figure 1 It is a schematic diagram of the process of the present invention;

[0021] Figure 2 The figure is a schematic structural diagram of an embodiment of the present invention. DETAILED DESCRIPTION

[0022] 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.

[0023] Embodiment 1:

[0024] (1) preparing AgSnO2(12) powder by a pre-oxidation process, preparing AgWC20 powder by a powder mixing process, preparing atomized pure silver powder with a purity greater than 99.99% and pure copper powder with a purity greater than 99.99%, and pre-treating each type of powder respectively;

[0025] (2) Establish a 3D rivet model: Figure 2 As shown, the bottom layer is a rivet-shaped copper layer body 1, the upper end surface of the copper layer body 1 is concave to form a pot-bottom-shaped cavity, the inner pure silver layer 2 is inside the pot bottom, and the layer just fills the pot bottom, and the center depth of the inner pure silver layer 2 is 0.15mm; the silver metal oxide layer 3 with a thickness of 0.4mm is above it, and the silver metal oxide layer 3 is made of AgSnO2(12) layer material, and the upper layer is a 45um silver tungsten carbide layer 4, and the silver tungsten carbide layer 4 is made of AgWC20 material, and the top is a 1.2um outer pure silver layer 5; the layers are connected by a polymer conductive silver adhesive;

[0026] (3) Loading the powder into the 3D printer box and printing the blank;

[0027] (4) The blank was subjected to staged gradient pressure sintering in a nitrogen atmosphere: entering the furnace at room temperature, heating rate 3°C / min, 125°C, holding for 1 hour, gas pressure 0.1 MPa; 520°C, holding for 2.5 hours, gas pressure 0.1 MPa; 800°C, holding for 4 hours, gas pressure 8.2 MPa;

[0028] (5) The sintered blank is then cleaned to obtain a finished product.

[0029] During the electrical performance test, the 60A magnetic latching relay assembled with this contact meets the impact resistance of 3KA, electrical life of 20,000 times, surface contact resistance of 0.19mΩ, and loop impedance of 0.98mΩ.

[0030] Embodiment 2:

[0031] (1) preparing AgSnO2(8)In2O3(4) powder by a pre-oxidation process, preparing AgWC12 powder by a powder mixing process, preparing atomized pure silver powder with a purity greater than 99.99% and pure copper powder with a purity greater than 99.99%, and pre-treating each type of powder respectively;

[0032] (2) Establish a 3D rivet model: Figure 2As shown, the bottom layer is a rivet-shaped copper layer body 1, the upper end surface of the copper layer body 1 is concave to form a pot-bottom-shaped cavity, the inner pure silver layer 2 is inside the pot bottom, and the layer just fills the pot bottom, and the inner pure silver layer 2 has a depth of 0.3mm at the center of the pot bottom; the silver metal oxide layer 3 with a thickness of 0.4mm is above it, and the silver metal oxide layer 3 is a AgSnO2(12) layer, and the upper layer is a 45um silver tungsten carbide layer 4, and the silver tungsten carbide layer 4 is an AgWC12 layer, and the top is a 3.5um outer pure silver layer 5; the layers are connected by a polymer conductive silver adhesive;

[0033] (3) Loading the powder into the 3D printer box and printing the blank;

[0034] (4) The blank was subjected to staged gradient pressure sintering in an argon atmosphere: entering the furnace at room temperature, heating rate 3.8°C / min, 135°C, holding for 2.5 h, gas pressure 0.1 MPa; 460°C, holding for 3.5 h, gas pressure 0.1 MPa; 850°C, holding for 5 h, gas pressure 9.2 MPa;

[0035] (5) The sintered blank is then cleaned to obtain a finished product.

[0036] During the electrical performance test of the 120A magnetic latching relay assembled with this contact, the impact resistance meets 6KA, the electrical life is 10,000 times, the surface contact resistance is 0.21mΩ, and the loop impedance is 1.27mΩ.

[0037] Embodiment three:

[0038] (1) preparing AgSnO2(10) powder by a pre-oxidation process, preparing AgWC45 powder by a powder mixing process, preparing atomized pure silver powder with a purity greater than 99.99% and pure copper powder with a purity greater than 99.99%, and pre-treating each type of powder respectively;

[0039] (2) Establish a 3D rivet model: Figure 2 As shown, the bottom layer is a rivet-shaped copper layer body 1, the upper end surface of the copper layer body 1 is concave to form a pot-bottom-shaped cavity, the inner pure silver layer 2 is inside the pot bottom, and the layer just fills the pot bottom, and the center depth of the inner pure silver layer 2 is 0.48mm; the silver metal oxide layer 3 with a thickness of 0.6mm is above it, and the silver metal oxide layer 3 is a AgSnO2(10) layer, and the upper layer is a 24um silver tungsten carbide layer 4, and the silver tungsten carbide layer 4 is an AgWC45 layer, and the top is a 4.7um outer pure silver layer 5; the layers are connected by a polymer conductive silver adhesive;

[0040] (3) Loading the powder into the 3D printer box and printing the blank;

[0041] (4) The blank was subjected to staged gradient pressure sintering in a nitrogen atmosphere: entering the furnace at room temperature, heating rate 3.2°C / min, 142°C, holding for 1.5 h, gas pressure 0.1 MPa; 580°C, holding for 3.2 h, gas pressure 0.1 MPa; 880°C, holding for 5.5 h, gas pressure 9.6 MPa;

[0042] (5) The sintered blank is then cleaned to obtain a finished product.

[0043] During the electrical performance test of the 90A magnetic latching relay assembled with this contact, the impact resistance meets 4.5KA, the electrical life is 12,000 times, the surface contact resistance is 0.27mΩ, and the loop impedance is 1.33mΩ.

[0044] 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. A composite function rivet-type electrical contact, characterized in that: The invention comprises a rivet-shaped copper layer body (1), the head end face of the copper layer body (1) is concave to form a pot-bottom-shaped cavity, the pot-bottom edge height is just flush with the upper end of the copper layer body (1), the pot-bottom-shaped cavity is filled with an inner pure silver layer (2), the outer side of the inner pure silver layer (2) is a silver metal oxide layer (3), the outer side of the silver metal oxide layer (3) is a silver tungsten carbide layer (4), and the outer side of the silver tungsten carbide layer (4) is an outer pure silver layer (5).

2. The composite functional rivet-type electrical contact according to claim 1, characterized in that: The silver metal oxide is AgSnO2 or AgSnO2In2O3.

3. The composite functional rivet-type electrical contact according to claim 1, characterized in that: The silver content in silver tungsten carbide is 50-90%.

4. The composite functional rivet-type electrical contact according to claim 1, characterized in that: The layers are connected with conductive adhesive.

5. The composite functional rivet-type electrical contact according to claim 4, characterized in that: The conductive adhesive is a polymer conductive silver glue.

6. The composite functional rivet-type electrical contact according to claim 1, characterized in that: The central depth of the pot-bottom-shaped cavity is 0.1-0.5 mm, the thickness of the silver metal oxide layer (3) is 0.2-0.6 mm, the thickness of the silver tungsten carbide layer (4) is 20-100 um, and the thickness of the outer pure silver layer (5) is 0.5-5 um.

7. The 3D molding preparation method of the composite functional rivet-type electrical contact according to any one of claims 1 to 6, characterized in that The following steps are involved: Step 1: prepare pure copper powder, pure silver powder, silver metal oxide powder, and silver tungsten carbide powder; Step 2: construct a 3D rivet model according to the structure of the composite functional rivet-type electrical contact; Step 3: Load the powder from step 1 into the 3D printer material box, and print the blank according to the 3D rivet model from step 2; Step 4: Sintering the blank printed in step 3 in an inert atmosphere in stages with gradient pressure; Step 5: Clean the blank sintered in step 4 to obtain a finished product.

8. The 3D forming preparation method of the composite functional rivet-type electrical contact according to claim 7, characterized in that: In step 4, the inert atmosphere is nitrogen or argon, and the sintering process is entering the furnace at room temperature, with a heating rate of 3-4°C / min, 120-150°C, keeping warm for 1-3h, and an air pressure of 0.1MPa; 450-600°C, keeping warm for 2-4h, and an air pressure of 0.1MPa; 800-900°C, keeping warm for 4-6h, and an air pressure of 8-10Mpa.

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