Silver-based contact material resistant to soldering and method for manufacturing the same

Abstract

The application discloses a silver-based contact material resistant to welding, which is composed of the following components in percentage by mass: W 0-2%, WO3 0-2%, Ag2WO4 0.1-2%, SnO2 0-4%, Ni 0-4%, GNPs 0.01-2.0%, and the balance of Ag. The application also provides a preparation method of the silver-based contact material resistant to welding, which comprises the following steps: weighing, grinding, dispersing raw materials in deionized water, adding excess Na2WO4, washing, suction filtration and drying, adding GNPs dispersion liquid, ultrasonic stirring, heating and mechanical stirring, drying, and then performing three times of pressing and three times of sintering to obtain the silver-based contact material resistant to welding. In the application, the three times of pressing and three times of sintering process is adopted, the pressure is gradually increased, the first two times of sintering are high-temperature sintering, and the last time of sintering is medium-temperature sintering, so that the internal gas can be fully discharged, the sintering neck can be fully grown, and the density and mechanical properties are improved.

Description

Technical Field

[0001] This invention belongs to the field of electrical contact materials technology, specifically relating to a silver-based contact material resistant to welding and its preparation method. Background Technology

[0002] Silver-based contacts are widely used in low-voltage electrical appliances. Their excellent oxidation resistance and low contact resistance make them a core component of electrical systems, playing a crucial role in connecting, disconnecting, and carrying current, thus determining the reliability and stability of the electrical system. With industrial development, electrical systems are becoming increasingly miniaturized, complex, and high-powered, placing higher demands on silver-based contact materials. Increased load power leads to a higher probability of welding between moving and stationary contacts. Once welding occurs, the moving and stationary contacts will fail to disconnect, resulting in failure. Traditional AgCdO contact materials reduce arc energy through CdO decomposition, thereby reducing the probability of welding; however, the production and use of Cd toxicity cause environmental pollution. AgSnO2 contact materials also experience increased contact resistance under certain loads, easily leading to welding problems.

[0003] Therefore, it is necessary to redesign the material composition and use a specific preparation method to prepare a new type of silver-based contact material that is resistant to welding. Summary of the Invention

[0004] The technical problem to be solved by this invention is to provide a silver-based contact material that is resistant to fusion welding, addressing the shortcomings of the prior art. This resistant silver-based contact material uses W, WO3, Ag2WO4, SnO2, and Ni in conjunction with GNPs to strengthen the silver-based contact material. During service, the GNPs react with O2 to generate CO2, which can extinguish the arc; the evaporation and decomposition of SnO2 also reduces the arc energy; the distribution of Ni on the surface can disperse the arc; and the presence of GNPs, W, WO3, and Ag2WO4 in the fusion welding zone causes stress concentration in the matrix, reducing fusion welding efficiency.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a silver-based contact material resistant to welding, characterized in that the silver-based contact material is composed of the following components in mass percentage: W 0%~2%, WO3 0%~2%, Ag2WO4 0.1%~2%, SnO2 0%~4%, Ni 0%~4%, GNPs 0.01%~2.0%, with the balance being Ag.

[0006] This invention employs W, WO3, Ag2WO4, SnO2, and Ni in synergistic graphene nanosheets (GNPs) to reinforce silver-based contact materials. During service, the GNPs react with O2 to generate CO2, which can extinguish the arc. The evaporation and decomposition of SnO2 also reduce the arc energy. The distribution of Ni on the surface can disperse the arc. The presence of GNPs, W, WO3, and Ag2WO4 in the welding zone causes stress concentration in the matrix, reducing welding efficiency. Therefore, this silver-based contact material has excellent comprehensive performance.

[0007] The aforementioned anti-fusion welding silver-based contact material is characterized in that it comprises the following components by mass percentage: W 0%–1%, WO3 0%–1%, Ag2WO4 0.1%–1%, SnO2 0%–4%, Ni 0%–4%, GNPs 0.01%–0.2%, with the balance being Ag. This invention achieves a synergistic effect of W element interface regulation and corrosion resistance by adding appropriate proportions of W, WO3, and Ag2WO4. SnO2, Ni, and GNPs, through their synergistic effects of arc dispersion and arc extinguishing, achieve the anti-fusion welding capability and comprehensive performance of the silver-based contact material.

[0008] The aforementioned anti-fusion welding silver-based contact material is characterized in that it comprises the following components by mass percentage: 0.1% Ag₂WO₄, 4% SnO₂, 4% Ni, 0.2% GNPs, with the balance being Ag. By controlling the composition of the silver-based contact material, compared to traditional Ag-SnO₂-Ni contact materials, the presence of a small amount of Ag₂WO₄ improves the interfacial bonding of the material during sintering due to its melting and coating effect. The presence of GNPs, by reacting with O₂ to generate CO₂, effectively enhances the arc-extinguishing performance, thus improving the anti-fusion welding capability of the silver-based contact material.

[0009] The aforementioned anti-fusion welding silver-based contact material is characterized in that it is composed of the following components by mass percentage: 1% Ag₂WO₄, 0.4% GNPs, and the balance being Ag. This invention, by controlling the composition of the silver-based contact material, simultaneously achieves the melting and coating effects of Ag₂WO₄ and the arc-quenching effect of GNPs, resulting in extremely high arc stability and reducing the probability of the material being damaged by excessive arc energy.

[0010] In addition, the present invention provides a method for preparing a silver-based contact material resistant to fusion welding, characterized in that the method includes the following steps:

[0011] Step 1: Weigh the raw materials and prepare a Na2WO4 solution; the raw materials are selected from W powder, WO3 powder, Ag powder, AgNO4 powder, SnO2 powder, Ni powder and GNPs;

[0012] Step 2: Grind the raw materials weighed in Step 1, except for GNPs. After grinding, add them to deionized water, then ultrasonically stir until homogeneous. Add excess Na2WO4 solution and stir to obtain a powder suspension.

[0013] Step 3: Centrifuge and wash the powder suspension obtained in Step 2 in sequence, repeating the process more than twice. Then filter the suspension and finally dry it to obtain a composite powder that does not contain GNPs.

[0014] Step 4: Add the GNPs from the raw materials weighed in Step 1 to anhydrous ethanol and then sonicate to obtain a GNPs dispersion. Add the GNPs-free composite powder obtained in Step 3 to the GNPs dispersion and continue sonicating to obtain a mixed suspension.

[0015] Step 5: Heat and mechanically stir the mixed suspension obtained in Step 4, and then crush the product obtained by heating and mechanical stirring to obtain composite powder;

[0016] Step 6: The composite powder obtained in Step 5 is initially pressed and formed under a pressure of 50MPa to 100MPa and a holding time of 1min to 2min. Then, it is heated to 880℃ to 920℃ under an argon atmosphere at a heating rate of 5℃ / min to 10℃ / min and sintered for 2h to 3h to obtain a sintered block.

[0017] Step 7: Press the primary sintered block obtained in Step 6 under a pressure of 200MPa to 300MPa and a holding time of 1min to 2min. Then, under an argon atmosphere, heat it to 900℃ to 920℃ at a heating rate of 5℃ / min to 10℃ / min and sinter it for 2h to 3h to obtain the secondary sintered block.

[0018] Step 8: Press the secondary sintered block obtained in Step 7 three times under a pressure of 850MPa to 1000MPa and a holding time of 2min to 5min. Then, under an argon atmosphere, heat it to 600℃ to 650℃ at a heating rate of 5℃ / min to 10℃ / min and sinter it three times for 1h to 2h to obtain a silver-based contact material resistant to fusion welding.

[0019] In step two of this invention, an excess of Na2WO4 solution can completely convert AgNO4 in the solution to Ag2WO4, where the following reaction occurs: Na2WO4 + 2AgNO4 = Ag2WO4 + 2NaNO4, improving the accuracy of the mixing ratio. In step three, after centrifuging the powder suspension, the supernatant is discarded, and an equal volume of deionized water is added. After stirring evenly, the suspension is centrifuged again, the supernatant is discarded, and an equal volume of deionized water is added. The suspension is then filtered using a vacuum filter, and the filter paper is placed in an oven to dry. After drying, the filter paper and powder are separated. The purpose of washing and filtering multiple times is to remove as much NaNO4 as possible from the solution. In step five, a heating plate and a mechanical stirrer are placed in a fume hood, and the heating plate is heated. The mechanical stirring paddle is then inserted into the powder suspension. The powder suspension is heated and mechanically stirred at a distance of no more than 1 mm from the bottom of the container. The bottom temperature of the beaker is set to 100°C. The fume hood is opened to allow the anhydrous ethanol in the mixture to evaporate and be removed. When the powder suspension becomes too viscous, the mechanical stirring paddle is removed and manual stirring is used instead. As the suspension becomes more viscous, stirring and heating are alternated. After the powder clumps together, the clumps are broken up with a glass rod to obtain composite powder. In steps six, seven, and eight, the pressure is increased in three stages of pressing and sintering. The first two sinterings are carried out at high temperatures, and the last one is annealed at a medium temperature. The advantage of this three-step combined sintering process is that the gas inside the sample can be fully discharged, the sintering neck can be fully grown, and the stress concentration caused by porosity is minimized, which is beneficial to improving mechanical properties and subsequent processing capabilities.

[0020] The above method is characterized in that, in step one, the Ag powder has a particle size of 5μm to 20μm and a purity of not less than 99.9%; the W powder has a particle size of 5μm to 7μm and a purity of not less than 99.9%; the WO3 powder has a particle size of 0.7μm to 1.3μm and a purity of not less than 99.9%; the SnO2 powder has a particle size of 0.7μm to 1.3μm and a purity of not less than 99.9%; the Ni powder has a particle size of 0.7μm to 1.3μm and a purity of not less than 99.9%; and the AgNO4 powder and Na2WO4 are of analytical grade. This invention improves product performance by controlling the particle size and purity of raw materials. It avoids the shortcomings of excessively fine Ag powder particles, which lead to excessive surface energy, low surface closed-pore temperature during pressing and sintering, and inability of gas to escape, thus reducing sintering performance. It also avoids the shortcomings of excessively coarse Ag powder particles, which lead to uneven dispersion of various reinforcing phase particles. Furthermore, it avoids the shortcomings of excessively fine W powder particles, which lead to rapid oxidation rate, while excessively coarse W powder particles lead to poor dispersion performance. Finally, it avoids the shortcomings of excessively fine particles causing poor sintering performance.

[0021] The method described above is characterized in that the ratio of the volume of deionized water added in step two to the total mass of the raw materials weighed in step one, excluding GNPs, is 10 to 5:1, where the volume is measured in mL and the mass in g. This invention, by controlling the ratio of deionized water to raw materials, ensures that the raw materials are fully dispersed in the deionized water, preventing waste caused by excessive deionized water and poor powder dispersion caused by insufficient deionized water.

[0022] The above method is characterized in that the amount of Na2WO4 added in step two satisfies the following condition: the molar concentration of Na2WO4 in the solution after adding Na2WO4 is more than half the molar concentration of AgNO4. This invention, by controlling the ratio of Na2WO4 to AgNO4, ensures that Na2WO4 is in excess, allowing AgNO4 in the solution to be completely converted to Ag2WO4, thus improving the accuracy of the mixing ratio.

[0023] The method described above is characterized in that the mass ratio of GNPs to anhydrous ethanol in step four is 0.1:50-200, where the volume is measured in mL and the mass in g. This invention, by controlling the ratio of GNPs to anhydrous ethanol, ensures the thorough dispersion of very thin GNPs while preventing waste caused by excessive anhydrous ethanol.

[0024] Compared with the prior art, the present invention has the following advantages:

[0025] 1. This invention employs W, WO3, Ag2WO4, SnO2, and Ni in synergistic GNPs to strengthen silver-based contact materials. During service, the GNPs react with O2 to generate CO2, which can extinguish the arc. The evaporation and decomposition of SnO2 also reduce the arc energy. The distribution of Ni on the surface can disperse the arc. The presence of GNPs, W, WO3, and Ag2WO4 in the welding zone causes stress concentration in the matrix, reducing welding performance. Therefore, this silver-based contact material has excellent comprehensive performance.

[0026] 2. The present invention involves grinding Ag powder, W powder, WO3 powder, SnO2 powder, Ni powder and AgNO4 powder and adding them to deionized water, then ultrasonically stirring until uniform. Then, excess Na2WO4 is added, and Ag2WO4 is generated in the process. Since Ag2WO4 is generated in the powder suspension, it is uniformly mixed with the powder as soon as it is generated, thus maximizing the uniformity of Ag2WO4 distribution.

[0027] 3. In the preparation method of the present invention, GNPs are first ultrasonically stirred and dispersed in ethanol, and then composite powder without GNPs is added and ultrasonically stirred and dispersed again. This can maximize the uniform dispersion and mixing of each reinforcing phase and prevent the agglomeration of the same reinforcing phase.

[0028] 4. The preparation method of the present invention adopts a three-stage pressing and three-stage sintering process, which allows the gas inside the sample to be fully discharged and the sintering neck to grow fully, minimizing stress concentration caused by porosity. While improving density, it can also improve the mechanical properties of silver-based contact materials, enhance subsequent processing capabilities, and avoid the problem of decreased arc erosion resistance due to excessive porosity.

[0029] 5. In the first pressing and sintering process of this invention, due to the low melting point of Ag2WO4, it will melt during the sintering process. The melted Ag2WO4 uniformly coats the surface of the matrix and reinforcing phase particles, improving the wettability of the material, improving the interfacial bonding, and reducing the problem of cracks or detachment between the eroded layers due to poor interfacial wettability under the action of electric arc. It also reduces the phenomenon of contact stress concentration and electric arc concentration caused by the detachment and displacement of the eroded layer leading to the protrusion of the material surface. Thus, it reduces the probability of fusion welding.

[0030] 6. The silver-based contact material with anti-welding properties prepared by this invention has uniform distribution of various reinforcing phases, good interfacial bonding, good conductivity, hardness and high anti-welding performance, excellent service performance, and is suitable for contact materials in electrical systems.

[0031] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0032] Figure 1 This is a flowchart illustrating the preparation process of the anti-welding silver-based contact material of the present invention.

[0033] Figure 2 This is a morphological image of the anti-fusion welding silver-based contact material prepared in Example 1 of the present invention after arc erosion.

[0034] Figure 3 This is a microstructure diagram of the anti-welding silver-based contact material prepared in Example 2 of the present invention. Detailed Implementation

[0035] Figure 1 This is a flowchart illustrating the preparation process of the anti-welding silver-based contact material of the present invention. Figure 1As can be seen from the present invention, W powder, WO3 powder, Ag powder, AgNO4 powder, SnO2 powder and Ni powder are ground and then added to deionized water and ultrasonically stirred until uniform. Excess Na2WO4 solution is added and stirred. The mixture is centrifuged and washed in sequence, and repeated more than twice. Then it is filtered and dried. Anhydrous ethanol is added to GNPs and ultrasonically stirred. Then composite powder without GNPs is added and ultrasonically stirred again. The mixed suspension is heated and mechanically stirred. Then the product obtained by heating and mechanical stirring is crushed. The composite powder is subjected to initial pressing, sintering, secondary pressing, sintering, tertiary pressing and sintering in sequence to obtain silver-based contact material resistant to fusion welding.

[0036] Example 1

[0037] The anti-welding silver-based contact material of this embodiment is composed of the following components by mass percentage: W 0.5%, WO3 0.5%, Ag2WO4 1%, SnO2 4%, Ni 4%, GNPs 0.01%, with the balance being Ag.

[0038] This embodiment includes the following steps:

[0039] Step 1: Weigh out W powder, WO3 powder, Ag powder, AgNO4 powder, SnO2 powder, Ni powder, and GNPs, and prepare a Na2WO4 solution; the W powder has a particle size of 5μm to 7μm and a purity of not less than 99.9%; the WO3 powder has a particle size of 0.7μm to 1.3μm and a purity of not less than 99.9%; the SnO2 powder has a particle size of 0.7μm to 1.3μm and a purity of not less than 99.9%; the Ni powder has a particle size of 0.7μm to 1.3μm and a purity of not less than 99.9%; the AgNO4 powder and Na2WO4 are of analytical grade.

[0040] Step 2: Grind the W powder, WO3 powder, Ag powder, AgNO4 powder, SnO2 powder, and Ni powder weighed in Step 1. After grinding, add them to deionized water, then ultrasonically stir until homogeneous. Next, add excess Na2WO4 solution and stir to obtain a powder suspension. The ratio of the volume of deionized water added to the total mass of W powder, WO3 powder, Ag powder, AgNO4 powder, SnO2 powder, and Ni powder added is 10:1. The unit of volume is mL, and the unit of mass is g. The amount of Na2WO4 added satisfies the following condition: the molar concentration of Na2WO4 in the solution after adding Na2WO4 is 3 / 5 of the molar concentration of AgNO4.

[0041] Step 3: Centrifuge and wash the powder suspension obtained in Step 2 in sequence, repeat twice, then filter, and finally dry to obtain a composite powder that does not contain GNPs.

[0042] Step 4: Add anhydrous ethanol to the GNPs weighed in Step 1 and stir ultrasonically to obtain a GNPs dispersion. Add the GNPs-free composite powder obtained in Step 3 to the GNPs dispersion and continue to stir ultrasonically to obtain a mixed suspension. The mass ratio of GNPs to anhydrous ethanol is 0.1:100, where the volume is in mL and the mass is in g.

[0043] Step 5: Heat and mechanically stir the mixed suspension obtained in Step 4, and then crush the product obtained by heating and mechanical stirring to obtain composite powder;

[0044] Step 6: The composite powder obtained in Step 5 is initially pressed into shape under a pressure of 50 MPa and a holding time of 2 min. Then, it is heated to 880℃ under an argon atmosphere at a heating rate of 5℃ / min and sintered for 3 h to obtain a sintered block.

[0045] Step 7: The sintered block obtained in Step 6 is subjected to a second pressing at a pressure of 300 MPa for 2 min, and then heated to 920 °C at a heating rate of 5 °C / min under an argon atmosphere and sintered for 3 h to obtain a second sintered block.

[0046] Step 8: Press the secondary sintered block obtained in Step 7 three times under a pressure of 1000 MPa and a holding time of 5 min. Then, heat it to 650℃ under an argon atmosphere at a heating rate of 5℃ / min and sinter it three times for 2 h to obtain the anti-fusion welding silver-based contact material Ag-4SnO2-4Ni-0.5W-0.5WO3-1Ag2WO4-0.01GNPs.

[0047] Figure 2 The image shows the morphology of the anti-fusion welding silver-based contact material prepared in this embodiment after arc erosion. Figure 2 As can be seen from the data, the silver-based contact material prepared in this embodiment, which is resistant to welding, has a uniformly spread erosion area after arc erosion, and no erosion layer is observed to fall off, indicating that it has good erosion resistance.

[0048] Example 2

[0049] The anti-fusion soldering silver-based contact material of this embodiment is composed of the following components by mass percentage: W 2%, WO3 2%, Ag2WO4 2%, GNPs 0.2%, and the balance being Ag.

[0050] This embodiment includes the following steps:

[0051] Step 1: Weigh out W powder, WO3 powder, Ag powder, AgNO4 powder, and GNPs, and prepare a Na2WO4 solution; the W powder has a particle size of 5μm to 7μm and a purity of not less than 99.9%; the WO3 powder has a particle size of 0.7μm to 1.3μm and a purity of not less than 99.9%; the SnO2 powder has a particle size of 0.7μm to 1.3μm and a purity of not less than 99.9%; the Ni powder has a particle size of 0.7μm to 1.3μm and a purity of not less than 99.9%; the AgNO4 powder and Na2WO4 are of analytical grade.

[0052] Step 2: Grind the W powder, WO3 powder, Ag powder, and AgNO4 powder weighed in Step 1. After grinding, add them to deionized water, then ultrasonically stir until homogeneous. Next, add excess Na2WO4 solution and stir to obtain a powder suspension. The ratio of the volume of deionized water added to the total mass of W powder, WO3 powder, Ag powder, and AgNO4 powder added is 8:1. The unit of volume is mL, and the unit of mass is g. The amount of Na2WO4 added satisfies the following condition: the molar concentration of Na2WO4 in the solution after adding Na2WO4 is 5 / 9 of the molar concentration of AgNO4.

[0053] Step 3: Centrifuge and wash the powder suspension obtained in Step 2 in sequence, repeating the process three times. Then filter the suspension and dry it to obtain a composite powder that does not contain GNPs.

[0054] Step 4: Add anhydrous ethanol to the GNPs weighed in Step 1 and stir ultrasonically to obtain a GNPs dispersion. Add the GNPs-free composite powder obtained in Step 3 to the GNPs dispersion and continue to stir ultrasonically to obtain a mixed suspension. The mass ratio of GNPs to anhydrous ethanol is 0.1:50, where the volume is in mL and the mass is in g.

[0055] Step 5: Heat and mechanically stir the mixed suspension obtained in Step 4, and then crush the product obtained by heating and mechanical stirring to obtain composite powder;

[0056] Step 6: The composite powder obtained in Step 5 is initially pressed into shape under a pressure of 100 MPa and a holding time of 1 min. Then, it is heated to 900℃ under an argon atmosphere at a heating rate of 10℃ / min and sintered for 2 hours to obtain a sintered block.

[0057] Step 7: The sintered block obtained in Step 6 is subjected to a second pressing at a pressure of 200 MPa and a holding time of 1 min. Then, it is heated to 900 °C under an argon atmosphere at a heating rate of 10 °C / min and sintered for 2 h to obtain a second sintered block.

[0058] Step 8: Press the secondary sintered block obtained in Step 7 three times under a pressure of 850 MPa and a holding time of 2 min. Then, under an argon atmosphere, heat it to 600℃ at a heating rate of 10℃ / min and sinter it three times for 1 h to obtain the anti-fusion welding silver-based contact material Ag-2W-2WO3-2Ag2WO4-0.2GNPs.

[0059] Figure 3 This is a microstructure image of the anti-fusion soldering silver-based contact material prepared in this embodiment. Figure 3 It can be seen that the reinforcing phase in the anti-welding silver-based contact material prepared in this embodiment is uniformly distributed on the Ag matrix.

[0060] Example 3

[0061] The anti-welding silver-based contact material of this embodiment is composed of the following components by mass percentage: 1% Ag2WO4, 0.4% GNPs, and the balance being Ag.

[0062] This embodiment includes the following steps:

[0063] Step 1: Weigh Ag powder, AgNO4 powder, and GNPs, and prepare Na2WO4 solution; the AgNO4 powder and Na2WO4 are of analytical grade.

[0064] Step 2: Grind the Ag powder and AgNO4 powder weighed in Step 1. After grinding, add them to deionized water, then ultrasonically stir until homogeneous. Next, add excess Na2WO4 solution and stir to obtain a powder suspension. The ratio of the volume of deionized water added to the total mass of Ag powder and AgNO4 powder added is 5:1. The volume unit is mL, and the mass unit is g. The amount of Na2WO4 added satisfies the following condition: the molar concentration of Na2WO4 in the solution after adding Na2WO4 is 3 / 5 of the molar concentration of AgNO4.

[0065] Step 3: Centrifuge and wash the powder suspension obtained in Step 2 in sequence, repeating the process three times. Then filter the suspension and dry it to obtain a composite powder that does not contain GNPs.

[0066] Step 4: Add anhydrous ethanol to the GNPs weighed in Step 1 and stir ultrasonically to obtain a GNPs dispersion. Add the GNPs-free composite powder obtained in Step 3 to the GNPs dispersion and continue to stir ultrasonically to obtain a mixed suspension. The mass ratio of GNPs to anhydrous ethanol is 0.1:200, where the volume is in mL and the mass is in g.

[0067] Step 5: Heat and mechanically stir the mixed suspension obtained in Step 4, and then crush the product obtained by heating and mechanical stirring to obtain composite powder;

[0068] Step 6: The composite powder obtained in Step 5 is initially pressed into shape under a pressure of 80 MPa and a holding time of 1.5 min. Then, it is heated to 920 °C under an argon atmosphere at a heating rate of 8 °C / min and sintered for 2.5 h to obtain a sintered block.

[0069] Step 7: The sintered block obtained in Step 6 is subjected to a second pressing at a pressure of 250 MPa and a holding time of 1.5 min. Then, it is heated to 910 °C under an argon atmosphere at a heating rate of 8 °C / min and sintered for 2.5 h to obtain a second sintered block.

[0070] Step 8: Press the secondary sintered block obtained in Step 7 three times under a pressure of 900 MPa and a holding time of 3 min. Then, under an argon atmosphere, heat it to 620℃ at a heating rate of 8℃ / min and sinter it three times for 1.5 h to obtain the anti-fusion welding silver-based contact material Ag-0.4GNPs-1Ag2WO4.

[0071] Example 4

[0072] The anti-welding silver-based contact material of this embodiment is composed of the following components by mass percentage: 0.1% Ag2WO4, 4% SnO2, 4% Ni, 0.2% GNPs, with the balance being Ag.

[0073] This embodiment includes the following steps:

[0074] Step 1: Weigh Ag powder, AgNO4 powder, SnO2 powder, Ni powder, and GNPs, and prepare a Na2WO4 solution; the SnO2 powder has a particle size of 0.7μm to 1.3μm and a purity of not less than 99.9%; the Ni powder has a particle size of 0.7μm to 1.3μm and a purity of not less than 99.9%; the AgNO4 powder and Na2WO4 are of analytical grade.

[0075] Step 2: Grind the Ag powder, AgNO4 powder, SnO2 powder, and Ni powder weighed in Step 1. After grinding, add them to deionized water, then ultrasonically stir until homogeneous. Next, add excess Na2WO4 solution and stir to obtain a powder suspension. The ratio of the volume of deionized water added to the total mass of Ag powder, AgNO4 powder, SnO2 powder, and Ni powder added is 7:1. The volume unit is mL, and the mass unit is g. The amount of Na2WO4 added satisfies the following condition: the molar concentration of Na2WO4 in the solution after adding Na2WO4 is 3 / 5 of the molar concentration of AgNO4.

[0076] Step 3: Centrifuge and wash the powder suspension obtained in Step 2 in sequence, repeating the process three times. Then filter the suspension and dry it to obtain a composite powder that does not contain GNPs.

[0077] Step 4: Add anhydrous ethanol to the GNPs weighed in Step 1 and stir ultrasonically to obtain a GNPs dispersion. Add the GNPs-free composite powder obtained in Step 3 to the GNPs dispersion and continue to stir ultrasonically to obtain a mixed suspension. The mass ratio of GNPs to anhydrous ethanol is 0.1:150, where the volume is in mL and the mass is in g.

[0078] Step 5: Heat and mechanically stir the mixed suspension obtained in Step 4, and then crush the product obtained by heating and mechanical stirring to obtain composite powder;

[0079] Step 6: The composite powder obtained in Step 5 is initially pressed into shape under a pressure of 60 MPa and a holding time of 1.5 min. Then, it is heated to 910 °C under an argon atmosphere at a heating rate of 6 °C / min and sintered for 3 h to obtain a sintered block.

[0080] Step 7: The sintered block obtained in Step 6 is subjected to a second pressing at a pressure of 280 MPa and a holding time of 1 min. Then, it is heated to 910 °C under an argon atmosphere at a heating rate of 6 °C / min and sintered for 2 h to obtain a second sintered block.

[0081] Step 8: The secondary sintered block obtained in Step 7 is pressed three times at a pressure of 950 MPa and a holding time of 3 min. Then, it is heated to 630℃ in an argon atmosphere at a heating rate of 6℃ / min and sintered three times for 2 h to obtain the anti-fusion welding silver-based contact material Ag-4SnO2-4Ni-0.2GNPs-0.1Ag2WO4.

[0082] Example 5

[0083] The anti-welding silver-based contact material of this embodiment is composed of the following components by mass percentage: W 1.0%, WO3 1.0%, Ag2WO4 0.5%, SnO2 2%, Ni 2%, GNPs 2%, with the balance being Ag.

[0084] This embodiment includes the following steps:

[0085] Step 1: Weigh out W powder, WO3 powder, Ag powder, AgNO4 powder, SnO2 powder, Ni powder, and GNPs, and prepare a Na2WO4 solution; the W powder has a particle size of 5μm to 7μm and a purity of not less than 99.9%; the WO3 powder has a particle size of 0.7μm to 1.3μm and a purity of not less than 99.9%; the SnO2 powder has a particle size of 0.7μm to 1.3μm and a purity of not less than 99.9%; the Ni powder has a particle size of 0.7μm to 1.3μm and a purity of not less than 99.9%; the AgNO4 powder and Na2WO4 are of analytical grade.

[0086] Step 2: Grind the W powder, WO3 powder, Ag powder, AgNO4 powder, SnO2 powder, and Ni powder weighed in Step 1. After grinding, add them to deionized water, then ultrasonically stir until homogeneous. Next, add excess Na2WO4 solution and stir to obtain a powder suspension. The ratio of the volume of deionized water added to the total mass of W powder, WO3 powder, Ag powder, AgNO4 powder, SnO2 powder, and Ni powder is 6:1. The unit of volume is mL, and the unit of mass is g. The amount of Na2WO4 added satisfies the following condition: the molar concentration of Na2WO4 in the solution after adding Na2WO4 is 4 / 7 of the molar concentration of AgNO4.

[0087] Step 3: Centrifuge and wash the powder suspension obtained in Step 2 in sequence, repeat twice, then filter, and finally dry to obtain a composite powder that does not contain GNPs.

[0088] Step 4: Add anhydrous ethanol to the GNPs weighed in Step 1 and stir ultrasonically to obtain a GNPs dispersion. Add the GNPs-free composite powder obtained in Step 3 to the GNPs dispersion and continue to stir ultrasonically to obtain a mixed suspension. The mass ratio of GNPs to anhydrous ethanol is 0.1:100, where the volume is in mL and the mass is in g.

[0089] Step 5: Heat and mechanically stir the mixed suspension obtained in Step 4, and then crush the product obtained by heating and mechanical stirring to obtain composite powder;

[0090] Step 6: The composite powder obtained in Step 5 is initially pressed into shape under a pressure of 90 MPa and a holding time of 1.5 min. Then, it is heated to 890 °C under an argon atmosphere at a heating rate of 7 °C / min and sintered for 2 h to obtain a sintered block.

[0091] Step 7: The sintered block obtained in Step 6 is subjected to a second pressing at a pressure of 220 MPa for a holding time of 2 min, and then heated to 910 °C under an argon atmosphere at a heating rate of 7 °C / min and sintered for 3 h to obtain a second sintered block.

[0092] Step 8: The secondary sintered block obtained in Step 7 is pressed three times under a pressure of 900 MPa and a holding time of 4 min. Then, it is heated to 640℃ under an argon atmosphere at a heating rate of 7℃ / min and sintered three times for 1 h to obtain the anti-fusion welding silver-based contact material Ag-2SnO2-2Ni-1W-1WO3-0.5Ag2WO4-2GNPs.

[0093] The density and conductivity of the anti-fusion welding silver-based contact materials prepared in Examples 1 to 5 were tested, and the results are shown in Table 1.

[0094] Table 1

[0095] Example 1 57.24 96.01 Example 2 80.52 96.78 Example 3 68.96 97.75 Example 4 89.66 97.96 Example 5 57.16 98.02

[0096] As shown in Table 1, the density of the anti-welding silver-based contact materials prepared in Examples 1 to 5 of the present invention is all above 96%, and the conductivity is above 57% IACS, indicating good overall performance.

[0097] The welding strength of the anti-fusion welding silver-based contact materials prepared in Examples 1-5 was compared with that of the traditional Ag-4SnO2-4Ni contact materials. The results are shown in Table 2. The traditional Ag-4SnO2-4Ni contact materials were prepared by conventional ball milling, pressing and sintering, and repressing and re-firing.

[0098] Table 2

[0099]

[0100]

[0101] As can be seen from Table 2, compared with the traditional Ag-4SnO2-4Ni contact material, the anti-welding silver-based contact materials prepared in Examples 1 and 2, although having a higher number of welding cycles (where the number of welding cycles represents the number of times that the moving and stationary contacts exhibit significant adhesion due to welding during the opening process in 5000 breaking tests), generally have lower welding forces, with the maximum welding force being much lower than that of the Ag-4SnO2-4Ni contact material. The anti-welding silver-based contact materials prepared in Examples 3 and 4 have significantly lower welding cycles and maximum welding forces than the Ag-4SnO2-4Ni contact material. The anti-welding silver-based contact material prepared in Example 5 also has better anti-welding properties than the Ag-4SnO2-4Ni contact material, indicating that the silver-based contact material prepared in this invention has strong anti-welding ability.

[0102] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any way. Any simple modifications, alterations, and equivalent changes made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A silver-based contact material resistant to fusion welding, characterized in that, The silver-based contact material is composed of the following components by mass percentage: W 0%~2%, WO3 0%~2%, Ag2WO4 0.1%~2%, SnO2 0%~4%, Ni 0%~4%, GNPs 0.01%~2.0%, with the balance being Ag; The method for preparing the anti-welding silver-based contact material includes the following steps: Step 1: Weigh the raw materials and prepare a Na2WO4 solution; the raw materials are selected from W powder, WO3 powder, Ag powder, AgNO3 powder, SnO2 powder, Ni powder and GNPs; Step 2: Grind the raw materials weighed in Step 1, except for GNPs. After grinding, add them to deionized water, then ultrasonically stir until homogeneous. Add excess Na2WO4 solution and stir to obtain a powder suspension. Step 3: Centrifuge and wash the powder suspension obtained in Step 2 in sequence, repeating the process more than twice. Then filter the suspension and finally dry it to obtain a composite powder that does not contain GNPs. Step 4: Add the GNPs from the raw materials weighed in Step 1 to anhydrous ethanol and then sonicate to obtain a GNPs dispersion. Add the GNPs-free composite powder obtained in Step 3 to the GNPs dispersion and continue sonicating to obtain a mixed suspension. Step 5: Heat and mechanically stir the mixed suspension obtained in Step 4, and then crush the product obtained by heating and mechanical stirring to obtain composite powder; Step 6: The composite powder obtained in Step 5 is initially pressed into shape under a pressure of 50MPa~100MPa and a holding time of 1min~2min. Then, it is heated to 880℃~920℃ under an argon atmosphere at a heating rate of 5℃ / min~10℃ / min and sintered for 2h~3h to obtain a sintered block. Step 7: Press the primary sintered block obtained in Step 6 under a pressure of 200MPa~300MPa and a holding time of 1min~2min. Then, under an argon atmosphere, heat it to 900℃~920℃ at a heating rate of 5℃ / min~10℃ / min and sinter it for 2h~3h to obtain the secondary sintered block. Step 8: Press the secondary sintered block obtained in Step 7 three times under a pressure of 850MPa~1000MPa and a holding time of 2min~5min. Then, under an argon atmosphere, heat it to 600℃~650℃ at a heating rate of 5℃ / min~10℃ / min and sinter it three times for 1h~2h to obtain a silver-based contact material resistant to fusion welding.

2. The anti-welding silver-based contact material according to claim 1, characterized in that, The silver-based contact material is composed of the following components by mass percentage: W 0%~1%, WO3 0%~1%, Ag2WO4 0.1%~1%, SnO2 0%~4%, Ni 0%~4%, GNPs 0.01%~0.2%, with the balance being Ag.

3. The anti-welding silver-based contact material according to claim 1, characterized in that, The silver-based contact material is composed of the following components by mass percentage: 0.1% Ag2WO4, 4% SnO2, 4% Ni, 0.2% GNPs, with the balance being Ag.

4. The anti-welding silver-based contact material according to claim 1, characterized in that, The silver-based contact material is composed of the following components by mass percentage: 1% Ag2WO4, 0.4% GNPs, and the balance being Ag.

5. The anti-welding silver-based contact material according to claim 1, characterized in that, In step one, the Ag powder has a particle size of 5μm to 20μm and a purity of not less than 99.9%; the W powder has a particle size of 5μm to 7μm and a purity of not less than 99.9%; the WO3 powder has a particle size of 0.7μm to 1.3μm and a purity of not less than 99.9%; the SnO2 powder has a particle size of 0.7μm to 1.3μm and a purity of not less than 99.9%; the Ni powder has a particle size of 0.7μm to 1.3μm and a purity of not less than 99.9%; and the AgNO3 powder and Na2WO4 are of analytical grade.

6. The anti-welding silver-based contact material according to claim 1, characterized in that, The ratio of the volume of deionized water added in step two to the total mass of the raw materials weighed in step one, excluding GNPs, is 10~5:

1. The volume is in mL and the mass is in g.

7. The anti-welding silver-based contact material according to claim 1, characterized in that, The amount of Na2WO4 added in step two satisfies the following condition: the molar concentration of Na2WO4 in the solution after adding Na2WO4 is more than 1 / 2 of the molar concentration of AgNO3.

8. The anti-welding silver-based contact material according to claim 1, characterized in that, In step four, the mass ratio of GNPs to anhydrous ethanol is 0.1:50~200, where the volume is in mL and the mass is in g.

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