A rapid hot-pressing sintering forming process for copper-chromium contact materials

Abstract

The present application relates to copper-chromium contact preparation technical field, specifically to a kind of copper-chromium contact material rapid hot-pressing sintering forming process, preparation method includes: S1, ball milling powder mixing, S2, mould pressing, S3, pad nest, S4, loading hot-pressing, S5, electrodeposition treatment;The present application can improve the bulk density of mixed powder by ball milling raw materials, which plays a polishing role on the sharp corners of metal powder particles, avoids the "bridge" phenomenon in the micro area during mould pressing process, and forms internal closed pores;Vacuum firing treated graphite paper is laid along the inner wall of graphite mould for hot-pressing sintering, which facilitates subsequent demoulding;The holding temperature is controlled at 900~980℃, to avoid copper powder melting and liquid penetration due to excessive temperature;The present application carries out electrodeposition treatment on copper-chromium contact material, which can make copper-chromium contact show better resistance to welding and heat resistance.

Description

Technical Field

[0001] This invention relates to the field of copper-chromium contact preparation technology, specifically to a rapid hot-pressing sintering process for copper-chromium contact materials. Background Technology

[0002] Copper-chromium contact materials are widely used in medium- and high-voltage vacuum switches due to their excellent breaking performance, resistance to welding, resistance to arc erosion, and high electrical and thermal conductivity. Currently, there are four main processes for producing copper-chromium contact materials: powder mixing and sintering, melt infiltration, vacuum casting, and arc melting. Among these, powder mixing and sintering is the primary production method, which can be further divided into solid-state sintering and liquid-state sintering.

[0003] Solid-state sintering offers advantages such as high material utilization, low energy consumption, and high product performance consistency. However, copper-chromium materials produced by solid-state sintering have relatively low density, thus requiring subsequent densification processes such as re-pressing and re-sintering, hot extrusion, or hot forging. These subsequent processes not only increase production costs but also extend the production cycle.

[0004] Liquid phase sintering typically requires a liquid phase content of less than 30%, but in copper-chromium contacts, the liquid phase source—copper—accounts for an excessively high percentage, ranging from 50% to 75%. Therefore, during sintering, excessive liquid phase can easily lead to copper leakage, collapse, or severe deformation of the billet, making this method unsuitable for copper-chromium contact production. To reduce production costs and cycle time while ensuring the stability of copper-chromium contact quality and performance, it is necessary to improve the preparation process of copper-chromium contact materials to meet the demand for high-quality contacts in the medium- and high-voltage vacuum switch field. Therefore, finding a new copper-chromium contact production method is crucial to solving these problems. Summary of the Invention

[0005] This invention addresses the shortcomings of existing technologies by providing a rapid hot-pressing sintering process for copper-chromium contact materials, comprising the following steps:

[0006] S1, Ball milling and powder mixing:

[0007] By mass percentage, 25-50% Cr powder, 0.1-0.3% CuZr alloy powder, and the balance Cu powder are mixed to obtain raw materials; the raw materials are loaded into a ball mill mixing jar, the ball-to-material ratio is controlled at 1:1, and the ball milling time is 7-8 hours to obtain mixed powder.

[0008] S2, Molding:

[0009] After placing the mixed powder into the press mold, the surface is leveled; the pressing pressure is controlled at 2.5~3Mpa for molding to obtain a sample;

[0010] S3, Nesting:

[0011] Cut the vacuum-fired graphite paper into pads according to the inner wall size of the graphite mold, lay them along the inner wall of the graphite mold, press the lower pressure head into the bottom of the mold, and fit the lower pressure head and the graphite paper pads tightly together. Place a vacuum-fired graphite paper disc of the same diameter as the lower pressure head above the lower pressure head, and use a plastic tube to rotate and press the graphite paper disc until it is flat.

[0012] S4. Loading and hot pressing:

[0013] The sample or mixed powder described in step S2 is placed into the prepared mold, kept flat, and then the graphite paper discs and the upper pressure head are placed in sequence. After wrapping a layer of insulation material around the outside of the mold, it is placed into the vacuum pressing chamber of the sintering furnace. The upper punch is controlled to descend, and after the upper punch just contacts the upper pressure head, the furnace door is closed and a vacuum is drawn to maintain the vacuum level in the furnace chamber below 1.0 × 10⁻⁶. -1 Pa, while heating and pressurizing the furnace, controlling the heating rate at 100℃ / min and the pressurization rate at 1.3~1.5T / min, stop heating and pressurizing after heating to 900~980℃, hold for 8~10min and then cool down with the furnace; demold to obtain copper-chromium contact material;

[0014] S5, Electrodeposition treatment:

[0015] An electrolyte solution is prepared, and the copper-chromium contact material is pre-plated. The material is then placed in an electrolytic tank containing the electrolyte solution for electrodeposition. After cleaning and post-treatment, the copper-chromium contact product is obtained.

[0016] Notes: The density of the alloy after molding is controlled between 75% and 80%. This ensures the molded sample does not break during transfer while maintaining a certain porosity, facilitating good venting during subsequent vacuum hot pressing sintering. Using a rotating plastic tube for pressing maintains flatness and avoids the graphite paper being pressed into the sample during direct powder pressing. The holding temperature is controlled between 900 and 980℃, primarily depending on the depth of the thermocouple inserted into the graphite mold. Electrodeposition treatment of the copper-chromium contacts allows the copper-chromium material to form a uniform and stable deposition layer on the substrate surface. The microstructure and chemical composition of this layer are similar to the substrate, thus improving the material's uniformity, stability, and consistency.

[0017] Further, the vacuum firing process for graphite paper described in step S2 is as follows: the graphite paper is heated from room temperature to 400°C for 1-2 hours and held for 30-40 minutes; then heated from 400°C to 1100°C for 2-3 hours and held for 30-40 minutes; subsequently heated from 1100°C to 1350°C for 2-3 hours and held for 2-3 hours, and then cooled in the furnace after the holding period is stopped to obtain the vacuum-fired graphite paper.

[0018] Explanation: Vacuum sintering removes gases, moisture, and impurities from graphite paper, making its internal structure more compact and reducing porosity and defects. This improves the stability and heat resistance of the graphite paper, enabling it to better withstand high temperatures and pressures. By removing gases and impurities, the internal thermal resistance of the graphite paper is reduced, allowing it to conduct heat better, accelerating heat transfer, and improving thermal efficiency.

[0019] Further, in step S1, the particle size of the Cr powder is -140 to +240 mesh, the particle size of the Cu powder is -200 to +325 mesh, and the particle size of the CuZr alloy powder is -200 to +250 mesh.

[0020] Note: Finer particle size can increase the surface area of ​​the material and improve its reactivity. In the preparation of copper-chromium alloy contact materials, finer particle size of Cr powder, Cu powder, and CuZr alloy powder can promote the reaction between elements and help form a more uniform alloy phase; selecting an appropriate particle size range can reduce sintering temperature, lower energy consumption, and improve sintering efficiency.

[0021] Further, the electrolyte preparation method in step S5 is as follows: by mass percentage, take 1-15% copper salt, 1-10% chromium salt, 0.1-1% sodium dodecyl sulfate, 0.1-2% octylphenol polyoxyethylene ether, 0.1-2% potassium dihydrogen phosphate, and the remainder water, stir evenly, and adjust the pH value to an acidic environment of 2.0-3.0 using sulfuric acid or hydrochloric acid to obtain the electrolyte, and control the temperature of the electrolyte at 30-50℃; wherein, the copper salt is one of copper sulfate or copper chloride; and the chromium salt is one of hexavalent chromic acid or hexavalent chromium chloride.

[0022] Note: Adjusting the pH to 2.0-3.0 using sulfuric acid or hydrochloric acid ensures good electrolytic performance of the electrolyte. A suitable acidic environment promotes the electrodeposition reaction of copper-chromium materials, improving electrolysis efficiency and quality. Adding sodium dodecyl sulfate and octylphenol polyoxyethylene ether improves the wettability and diffusivity of the electrolyte, promoting ion transport and reaction within the electrolyte, thus enhancing the uniformity and quality of electrodeposition. Adding potassium dihydrogen phosphate regulates the buffering capacity of the electrolyte, maintaining a suitable acid-base balance, preventing excessive acidification or alkalization, and improving the stability and durability of the electrolyte. Controlling the electrolyte temperature within the range of 30-50℃ helps improve electrolyte fluidity and reaction rate, further enhancing electrolysis efficiency and quality.

[0023] Furthermore, the pre-plating treatment method for the copper-chromium contact material in step S5 is as follows: after grinding and deburring the copper-chromium contact material, surface activation treatment is performed, and then it is immersed in a sodium chromate solution with a concentration of 10~20% for passivation treatment for 5~15 minutes.

[0024] Explanation: Deburring makes the surface of copper-chromium contact materials smoother and more even, removing impurities and defective parts, and providing a good base surface. The surface of the copper-chromium contact material is cleaned and activated using an appropriate chemical solution. This removes surface oxides, contaminants, and harmful substances, increases surface energy, and improves adhesion to the electroplated layer. A thin oxide passivation film is formed on the surface of the copper-chromium contact material to improve its corrosion resistance and chemical stability. Passivation treatment with sodium chromate solution forms a hard, dense passivation film, effectively preventing metal oxidation and corrosion.

[0025] Further, the surface activation treatment method for the copper-chromium contact material is as follows: immerse the copper-chromium contact material in a sodium hydroxide solution with a concentration of 1-10 wt% or an ammonium phosphate solution with a concentration of 1-5 wt% for 5-15 minutes; then remove the copper-chromium contact material and immerse it in an HCl solution with a concentration of 5-20 wt% for 4-6 minutes; then immerse the copper-chromium contact material in an acetone solution with a concentration of 30-50 wt%; wipe the surface of the copper-chromium contact material with a cloth; finally, ultrasonically clean the copper-chromium contact material in deionized water for 3-10 minutes, controlling the temperature at 30-50℃ and the frequency at 60-80 kHz.

[0026] Note: Soaking in sodium hydroxide or ammonium phosphate solution can remove stains, grease, and organic contaminants from the surface of copper-chromium contact materials, making the surface cleaner and purer. Soaking in HCl solution can remove surface oxides and particles, activate the surface of the copper-chromium contact materials, improve surface energy and chemical activity, and enhance the adhesion to the electroplated layer. Acetone solution can be used to wipe the surface of the copper-chromium contact materials to remove residual stains, particles, and organic matter, further improving surface cleanliness and smoothness, which helps to improve the adhesion and quality of the electroplated layer.

[0027] Furthermore, the temperature in the electrolytic cell is 20~40℃, the stirring intensity is 600r / min, and the current density is controlled at 2~6A / dm³. 2 The electrodeposition treatment time is 0.5~2h.

[0028] Note: Maintaining the temperature in the electrolytic cell within the range of 20~40℃ can preserve suitable reactivity and ion transport rate, improve the fluidity and reaction rate of the electrolyte, promote the deposition process of metal ions, and obtain a uniform and stable electroplated layer.

[0029] Further, the post-processing method described in step S5 is as follows: polishing the electrodeposited copper-chromium contact material, spraying the copper-chromium contact material with an adhering liquid accounting for 0.1~0.3% of the copper-chromium contact material by mass; then heat-treating it at a temperature of 800~1050℃ for 0.5~4h, and then cooling it to 300~400℃ and reducing it in a hydrogen atmosphere for 0.5~1h; the adhering liquid is prepared by mixing 0.001~0.01% tellurium dioxide, 0.001~0.05% Cr powder and the balance ethylene glycol by mass percentage to obtain the adhering liquid; the particle size of the Cr powder is -140~+240 mesh.

[0030] Explanation: Polishing can make the surface of the electrodeposited copper-chromium contact material smoother, removing any roughness and defects, and improving surface quality and smoothness. A solution of mixed chromium powder and trace tellurium powder is dissolved in ethylene glycol solvent. The solution is sprayed onto the copper-chromium contact in a mist. After drying, the solvent in the solution evaporates quickly, removing residual solvent and allowing the sprayed layer to cure. Chromium and trace tellurium dioxide are deposited on the surface of the copper-chromium contact to form a chromium-tellurium cured layer. The copper-chromium contact is then placed in a hydrogen atmosphere and reduced at an appropriate temperature. The reduction reaction converts chromium and trace tellurium dioxide into chromium-tellurium compounds, which are evenly distributed and prevent tellurium enrichment. This enhances the anti-welding performance of the copper-chromium contact surface without affecting its tensile strength.

[0031] Compared with the prior art, the beneficial effects of the present invention are:

[0032] (1) By ball milling and mixing the raw materials, the loose density of the mixed powder can be improved, which can polish the sharp corners of the metal powder particles and avoid the "bridging" phenomenon in the micro-regions during the molding process, thus forming closed pores inside. Vacuum-sintered graphite paper is used to line the inner wall of the hot-pressing graphite mold, which facilitates subsequent demolding. The pressure head and the graphite paper are tightly attached, which can prevent powder leakage during the hot pressing process and avoid damage to the inner graphite paper. The heat preservation temperature is controlled at 900~980℃ to avoid the copper powder from melting and seeping out due to excessive temperature. The density of the copper-chromium contact material sintered and pressed by this method is greater than or equal to 97.5%, which is close to the density of the copper-chromium alloy prepared by the melt infiltration method, and at the same time, it ensures the uniformity of copper-chromium distribution in the copper-chromium alloy material.

[0033] (2) The electrodeposition treatment of copper-chromium contact materials in this invention can remove impurities and oxides from the surface of the copper-chromium materials, making the surface smooth and uniform. This can improve the conductivity and mechanical properties of the copper-chromium contacts, reduce friction and wear during operation, and enable the copper-chromium contacts to exhibit better resistance to welding and heat resistance. Under harsh environments such as high temperature, high pressure and severe electrolytic corrosion, its stability and reliability are higher. Electrodeposition treatment is an automated, efficient and low-cost material processing technology that can complete the processing of a large amount of copper-chromium contact materials in a short time, effectively improving production efficiency. Attached Figure Description

[0034] Figure 1 This is a 50X as-cast metallographic image of Embodiment 1 of the present invention;

[0035] Figure 2 This is a 50X as-cast metallographic image of Embodiment 5 of the present invention;

[0036] Figure 3 This is a 50X as-cast metallographic image of Embodiment 6 of the present invention; Detailed Implementation

[0037] The present invention will now be described in more detail with reference to specific embodiments, so as to better demonstrate the advantages of the present invention.

[0038] Example 1

[0039] A rapid hot pressing sintering process for copper-chromium contact materials includes the following steps:

[0040] S1, Ball milling and powder mixing:

[0041] By mass percentage, 37.5% Cr powder, 0.2% CuZr alloy powder, and the remainder Cu powder are mixed to obtain raw materials; the raw materials are loaded into a ball mill mixing jar, the ball-to-material ratio is controlled at 1:1, and the ball milling time is 7.5 hours to obtain mixed powder; the particle size of the Cr powder is -190 to +195 mesh, the particle size of the Cu powder is -260 to +265 mesh, and the particle size of the CuZr alloy powder is -225 to +230 mesh;

[0042] S2, Molding:

[0043] After the mixed powder is placed into the press mold, the surface is leveled; the pressing pressure is controlled at 2.75 MPa for molding to obtain a sample;

[0044] S3, Nesting:

[0045] Cut the vacuum-fired graphite paper into pads according to the inner wall size of the graphite mold, lay them along the inner wall of the graphite mold, press the lower pressure head into the bottom of the mold, and fit the lower pressure head and the graphite paper pads tightly together. Place a vacuum-fired graphite paper disc of the same diameter as the lower pressure head above the lower pressure head, and use a plastic tube to rotate and press the graphite paper disc until it is flat.

[0046] The vacuum firing process for the graphite paper is as follows: the graphite paper is heated from room temperature to 400°C for 1.5 hours and held for 35 minutes; then heated from 400°C to 1100°C for 2.5 hours and held for 35 minutes; subsequently heated from 1100°C to 1350°C for 2.5 hours and held for 2.5 hours, then cooled in the furnace to obtain the vacuum-fired graphite paper.

[0047] S4. Loading and hot pressing:

[0048] The sample from step S2 is placed into the prepared mold, kept flat, and then the graphite paper discs and the upper pressure head are laid out in sequence. After wrapping a layer of insulation material around the outside of the mold, it is placed into the vacuum pressing chamber of the sintering furnace. The upper punch is controlled to descend, and after the upper punch just contacts the upper pressure head, the furnace door is closed and a vacuum is drawn to maintain the vacuum level in the furnace chamber below 1.0 × 10⁻⁶. -1 Pa, while heating and pressurizing the furnace, controlling the heating rate at 100℃ / min and the pressurization rate at 1.4T / min, stop heating and pressurizing after heating to 940℃, hold for 9 minutes and then cool down with the furnace; demold to obtain copper-chromium contact material;

[0049] S5, Electrodeposition treatment:

[0050] An electrolyte solution was prepared, and the copper-chromium contact material was pre-plated. The material was then immersed in an electrolytic cell containing the electrolyte solution for electrodeposition. Following cleaning and post-treatment, the copper-chromium contact product was obtained. The temperature in the electrolytic cell was 30°C, the stirring intensity was 600 r / min, and the current density was controlled at 4 A / dm³. 2 The electrodeposition process took 1.25 hours; the post-treatment was polishing.

[0051] The electrolyte is prepared as follows: 8% copper salt, 5% chromium salt, 0.5% sodium dodecyl sulfate, 1% octylphenol polyoxyethylene ether, 1% potassium dihydrogen phosphate, and the remainder water are taken by mass percentage. After stirring evenly, the pH value is adjusted to an acidic environment of 2.5 using hydrochloric acid to obtain the electrolyte. The temperature of the electrolyte is controlled at 40℃. The copper salt used is copper sulfate, and the chromium salt used is hexavalent chromic acid.

[0052] The pre-plating treatment method for the copper-chromium contact material is as follows: after grinding and deburring the copper-chromium contact material, surface activation treatment is performed, and then it is immersed in a 15% sodium chromate solution for passivation treatment for 10 minutes.

[0053] The surface activation treatment method for the copper-chromium contact material is as follows: the copper-chromium contact material is immersed in a 5 wt% sodium hydroxide solution for 10 min; then the copper-chromium contact material is removed and immersed in a 12.5 wt% HCl solution for 5 min; then the copper-chromium contact material is immersed in a 40 wt% acetone solution; the surface of the copper-chromium contact material is wiped with a cloth; finally, the copper-chromium contact material is ultrasonically cleaned in deionized water for 6.5 min at a temperature of 40℃ and a frequency of 70 kHz.

[0054] Example 2

[0055] The difference between this embodiment and Embodiment 1 is that the post-processing method in step S5 is as follows: after polishing the electrodeposited copper-chromium contact material, an adhering liquid accounting for 0.1% of the mass of the copper-chromium contact material is sprayed onto the copper-chromium contact material; then, it is heat-treated at 800°C for 0.5 hours, and then cooled to 300°C and reduced in a hydrogen atmosphere for 0.5 hours; the adhering liquid is prepared by mixing 0.001% tellurium dioxide, 0.001% Cr powder and the balance ethylene glycol by mass percentage to obtain the adhering liquid; the particle size of the Cr powder is -140~+145 mesh.

[0056] Example 3

[0057] The difference between this embodiment and Embodiment 1 is that the post-processing method described in step S5 is as follows: after polishing the electrodeposited copper-chromium contact material, an adhering liquid accounting for 0.2% of the mass of the copper-chromium contact material is sprayed onto the copper-chromium contact material; subsequently, it is heat-treated at 925°C for 2.5 hours, and then cooled to 350°C and reduced in a hydrogen atmosphere for 0.75 hours; the adhering liquid is prepared by mixing 0.005% tellurium dioxide, 0.025% Cr powder and the balance ethylene glycol by mass percentage to obtain the adhering liquid; the particle size of the Cr powder is -190~+195 mesh.

[0058] Example 4

[0059] The difference between this embodiment and Embodiment 1 is that the post-processing method described in step S5 is as follows: after polishing the electrodeposited copper-chromium contact material, an adhering liquid accounting for 0.3% of the mass of the copper-chromium contact material is sprayed onto the copper-chromium contact material; then, it is heat-treated at 1050℃ for 4 hours, and then cooled to 400℃ and reduced in a hydrogen atmosphere for 1 hour; the adhering liquid is prepared by mixing 0.01% tellurium dioxide, 0.05% Cr powder and the balance ethylene glycol by mass percentage to obtain the adhering liquid; the particle size of the Cr powder is -235~+240 mesh.

[0060] Example 5

[0061] The difference between this embodiment and Embodiment 1 is that 25% Cr powder, 0.1% CuZr alloy powder, and the remainder Cu powder are mixed to obtain the raw material; the ball milling time is 7 hours; the particle size of the Cr powder is -140 to +145 mesh, the particle size of the Cu powder is -200 to +205 mesh, and the particle size of the CuZr alloy powder is -200 to +205 mesh.

[0062] Example 6

[0063] The difference between this embodiment and Embodiment 1 is that 50% Cr powder, 0.3% CuZr alloy powder, and the remainder Cu powder are mixed to obtain the raw material; the ball milling time is 8 hours; the particle size of the Cr powder is -235 to +240 mesh, the particle size of the Cu powder is -320 to +325 mesh, and the particle size of the CuZr alloy powder is -245 to +250 mesh.

[0064] Example 7

[0065] The difference between this embodiment and Embodiment 1 is that the pressing pressure is controlled at 2.5 MPa for molding to obtain the sample; and the vacuum degree in the furnace cavity is maintained below 1.0 × 10⁻⁶. -1 Pa, while simultaneously heating and pressurizing the furnace, controlling the heating rate at 100℃ / min and maintaining the pressurization rate at 1.3T / min, stop heating and pressurizing after heating to 900℃, hold for 8 minutes and then cool down with the furnace; demold to obtain copper-chromium contact material.

[0066] Example 8

[0067] The difference between this embodiment and Embodiment 1 is that the pressing pressure is controlled at 3 MPa for molding to obtain the sample; and the vacuum degree in the furnace cavity is maintained below 1.0 × 10⁻⁶. -1 Pa, while simultaneously heating and pressurizing the furnace, controlling the heating rate at 100℃ / min and maintaining the pressurization rate at 1.5T / min, stop heating and pressurizing after heating to 980℃, hold for 10 minutes and then cool down with the furnace; demold to obtain copper-chromium contact material.

[0068] Example 9

[0069] The difference between this embodiment and Embodiment 1 is that the vacuum firing process of the graphite paper in step S2 is as follows: the graphite paper is heated from room temperature to 400°C for 1 hour and held for 30 minutes; then heated from 400°C to 1100°C for 2 hours and held for 30 minutes; subsequently heated from 1100°C to 1350°C for 2 hours and held for 2 hours, and then cooled in the furnace after the holding time is stopped to obtain the vacuum-fired graphite paper.

[0070] Example 10

[0071] The difference between this embodiment and Embodiment 1 is that the vacuum firing process of the graphite paper in step S2 is as follows: the graphite paper is heated from room temperature to 400°C for 2 hours and held for 40 minutes; then heated from 400°C to 1100°C for 3 hours and held for 40 minutes; subsequently heated from 1100°C to 1350°C for 3 hours and held for 3 hours, and then cooled in the furnace after the holding time is stopped to obtain the vacuum-fired graphite paper.

[0072] Example 11

[0073] The difference between this embodiment and Embodiment 1 is that the electrolyte preparation method in step S5 is as follows: by mass percentage, take 1% copper salt, 1% chromium salt, 0.1% sodium dodecyl sulfate, 0.1% octylphenol polyoxyethylene ether, 0.1% potassium dihydrogen phosphate, and the remainder water, stir evenly, and use hydrochloric acid to adjust the pH value to an acidic environment of 2.0 to obtain the electrolyte, and control the temperature of the electrolyte at 30°C.

[0074] Example 12

[0075] The difference between this embodiment and Embodiment 1 is that the electrolyte preparation method in step S5 is as follows: by mass percentage, take 15% copper salt, 10% chromium salt, 1% sodium dodecyl sulfate, 2% octylphenol polyoxyethylene ether, 2% potassium dihydrogen phosphate, and the remainder water, stir evenly, and use hydrochloric acid to adjust the pH value to an acidic environment of 3.0 to obtain the electrolyte, and control the temperature of the electrolyte at 50°C.

[0076] Example 13

[0077] The difference between this embodiment and Embodiment 1 is that the copper-chromium contact material is ground and deburred, then surface activated, and then immersed in a 10% sodium chromate solution for passivation for 5 minutes; the copper-chromium contact material is then immersed in a 1 wt% sodium hydroxide solution for 5 minutes; subsequently, the copper-chromium contact material is removed and immersed in a 5 wt% HCl solution for 4 minutes, then immersed in a 30 wt% acetone solution, the surface of the copper-chromium contact material is wiped with a cloth, and finally the copper-chromium contact material is ultrasonically cleaned in deionized water for 3 minutes at a temperature of 30°C and a frequency of 60 kHz.

[0078] Example 14

[0079] The difference between this embodiment and Embodiment 1 is that the copper-chromium contact material is ground and deburred, then surface activated, and then immersed in a 20% sodium chromate solution for passivation for 15 minutes; the copper-chromium contact material is then immersed in a 10 wt% sodium hydroxide solution for 15 minutes; subsequently, the copper-chromium contact material is removed and immersed in a 20 wt% HCl solution for 6 minutes, then immersed in a 50 wt% acetone solution, the surface of the copper-chromium contact material is wiped with a cloth, and finally the copper-chromium contact material is ultrasonically cleaned in deionized water for 10 minutes at a controlled temperature of 50°C and a frequency of 80 kHz.

[0080] Example 15

[0081] The difference between this embodiment and Embodiment 1 is that the temperature in the electrolytic cell is 20°C, the stirring intensity is 600 r / min, and the current density is controlled at 2 A / dm³. 2 The electrodeposition treatment time was 0.5 h.

[0082] Example 16

[0083] The difference between this embodiment and Embodiment 1 is that the temperature in the electrolytic cell is 40°C, the stirring intensity is 600 r / min, and the current density is controlled at 6 A / dm³. 2 The electrodeposition treatment time was 2 hours.

[0084] Experimental example:

[0085] The samples obtained from Examples 1-4, 7, 8, 11, 12, 15, 16 and the comparative example were subjected to performance tests. The results of the above performance tests are detailed in Table 1.

[0086] The comparative example differs from Example 1 in that the copper-chromium contact material was not subjected to electrodeposition treatment;

[0087] Table 1: Performance Test Table for 11 Different Copper-Chromium Contact Products

[0088]

[0089] 1. To investigate the influence of post-treatment process parameters on the performance of the prepared copper-chromium contacts.

[0090] Conclusion: As can be seen from the data in Table 1, comparing Examples 1 to 4, Example 1 has the lowest electrical conductivity and welding strength, Example 4 has the best electrical conductivity but the lowest hardness, Example 3 has the best anti-welding performance, and the hardness difference between Examples 1 and 3 is not significant. It can be seen that attaching a chromium telluride curing layer to the copper-chromium contact can improve the uniformity of the contact surface and increase the surface quality of the copper-chromium contact, which can further improve the electrical conductivity of the copper-chromium contact. Without affecting the strength of the copper-chromium contact, it can also improve the anti-welding performance and heat resistance of the copper-chromium contact. Overall, the copper-chromium contact of Example 3 has better comprehensive performance.

[0091] 2. Investigate the influence of hot pressing process parameters on the performance of the prepared copper-chromium contacts.

[0092] Conclusion: As can be seen from the data in Table 1, compared with Example 1, the process parameters of hot pressing the copper-chromium contact in Example 8 have better electrical conductivity. Overall, the copper-chromium contact of Example 1 has better comprehensive performance.

[0093] 3. Investigate the influence of electrodeposition process parameters on the performance of the prepared copper-chromium contacts.

[0094] Conclusion: As shown in Table 1, compared with Example 1, Example 1 exhibits better conductivity and resistance to welding. Electrodeposition treatment can remove impurities and oxides from the surface of the copper-chromium material, improving the conductivity and mechanical properties of the contact, reducing friction and wear during operation, and enhancing resistance to welding and heat resistance. It also demonstrates higher stability and reliability under harsh environments such as high temperature, high pressure, and severe electrolytic corrosion. Compared with Example 16, the copper-chromium contact prepared using Example 16 has better conductivity, while the copper-chromium contact of Example 1 shows the best overall performance.

Claims

1. A rapid hot pressing sintering process for copper-chromium contact materials, characterized in that, Includes the following steps: S1, Ball milling and powder mixing: By mass percentage, 25-50% Cr powder, 0.1-0.3% CuZr alloy powder, and the balance Cu powder are mixed to obtain raw materials; the raw materials are loaded into a ball mill mixing jar, the ball-to-material ratio is controlled at 1:1, and the ball milling time is 7-8 hours to obtain mixed powder. S2, Molding: After placing the mixed powder into the press mold, the surface is leveled; the pressing pressure is controlled at 2.5~3Mpa for molding to obtain a sample; S3, Nesting: Cut the vacuum-fired graphite paper into pads according to the inner wall size of the graphite mold, lay them along the inner wall of the graphite mold, press the lower pressure head into the bottom of the mold, and fit the lower pressure head and the graphite paper pads tightly together. Place a vacuum-fired graphite paper disc of the same diameter as the lower pressure head above the lower pressure head, and use a plastic tube to rotate and press the graphite paper disc until it is flat. S4. Loading and hot pressing: The sample or mixed powder described in step S2 is placed into the prepared mold, kept flat, and then the graphite paper discs and the upper pressure head are placed in sequence. After wrapping a layer of insulation material around the outside of the mold, it is placed into the vacuum pressing chamber of the sintering furnace. The upper punch is controlled to descend, and after the upper punch just contacts the upper pressure head, the furnace door is closed and a vacuum is drawn to maintain the vacuum level in the furnace chamber below 1.0 × 10⁻⁶. -1 Pa, while heating and pressurizing the furnace, controlling the heating rate at 100℃ / min and the pressurization rate at 1.3~1.5T / min, stop heating and pressurizing after heating to 900~980℃, hold for 8~10min and then cool down with the furnace; demold to obtain copper-chromium contact material; S5, Electrodeposition treatment: Prepare an electrolyte solution, pre-plat the copper-chromium contact material, immerse it in an electrolytic tank containing the electrolyte solution for electrodeposition, and then perform cleaning and post-treatment to obtain the copper-chromium contact product. The electrolyte is prepared as follows: By mass percentage, take 1-15% copper salt, 1-10% chromium salt, 0.1-1% sodium dodecyl sulfate, 0.1-2% octylphenol polyoxyethylene ether, 0.1-2% potassium dihydrogen phosphate, and the remainder water. After stirring evenly, adjust the pH to an acidic environment of 2.0-3.0 using sulfuric acid or hydrochloric acid to obtain the electrolyte. Control the electrolyte temperature at 30-50℃. The copper salt is either copper sulfate or copper chloride; the chromium salt is either hexavalent chromic acid or hexavalent chromium chloride. The post-treatment method is as follows: [The text abruptly ends here, so the translation stops.] The deposited copper-chromium contact material is polished, and then an adsorption liquid accounting for 0.1-0.3% of the copper-chromium contact material by mass is sprayed onto the copper-chromium contact material. Subsequently, it is heat-treated at a temperature of 800-1050℃ for 0.5-4 hours, and then cooled to 300-400℃ and reduced in a hydrogen atmosphere for 0.5-1 hours. The adsorption liquid is prepared by mixing 0.001-0.01% tellurium dioxide, 0.001-0.05% Cr powder and the balance ethylene glycol by mass percentage to obtain the adsorption liquid. The particle size of the Cr powder is -140 to +240 mesh.

2. The rapid hot pressing sintering forming process for copper-chromium contact materials according to claim 1, characterized in that, The vacuum firing process for graphite paper described in step S2 is as follows: the graphite paper is heated from room temperature to 400°C for 1-2 hours and held for 30-40 minutes; then heated from 400°C to 1100°C for 2-3 hours and held for 30-40 minutes; subsequently heated from 1100°C to 1350°C for 2-3 hours and held for 2-3 hours, and then cooled in the furnace after the holding period is stopped to obtain the vacuum-fired graphite paper.

3. The rapid hot pressing sintering forming process for copper-chromium contact materials according to claim 1, characterized in that, The particle size of the Cr powder in step S1 is -140 to +240 mesh, the particle size of the Cu powder is -200 to +325 mesh, and the particle size of the CuZr alloy powder is -200 to +250 mesh.

4. The rapid hot pressing sintering forming process for copper-chromium contact materials according to claim 1, characterized in that, The pre-plating treatment method for the copper-chromium contact material in step S5 is as follows: after grinding and deburring the copper-chromium contact material, surface activation treatment is performed, and then it is immersed in a sodium chromate solution with a concentration of 10~20% for passivation treatment for 5~15 minutes.

5. The rapid hot pressing sintering forming process for copper-chromium contact materials according to claim 4, characterized in that, The surface activation treatment method for the copper-chromium contact material is as follows: immerse the copper-chromium contact material in a sodium hydroxide solution with a concentration of 1-10 wt% or an ammonium phosphate solution with a concentration of 1-5 wt% for 5-15 minutes; then remove the copper-chromium contact material and immerse it in an HCl solution with a concentration of 5-20 wt% for 4-6 minutes; then immerse the copper-chromium contact material in an acetone solution with a concentration of 30-50 wt%; wipe the surface of the copper-chromium contact material with a cloth; finally, ultrasonically clean the copper-chromium contact material in deionized water for 3-10 minutes, controlling the temperature at 30-50℃ and the frequency at 60-80 kHz.

6. The rapid hot pressing sintering forming process for copper-chromium contact materials according to claim 1, characterized in that, The temperature in the electrolytic cell is 20~40℃, the stirring intensity is 600r / min, and the current density is controlled at 2~6A / dm³. 2 The electrodeposition treatment time is 0.5~2h.

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