A copper-chromium contact and a method for producing the same

Abstract

The application discloses a copper-chromium contact and a preparation method thereof, and belongs to the technical field of alloy contacts. The preparation method takes electrolytic copper and chromium powder as raw materials, prepares CuCr rod material with a taper structure, and then carries out electrode induction gas atomization treatment to obtain CuCr alloy powder with high sphericity, uniform particle size and small organization, and then obtains the copper-chromium contact through 3D printing technology. Through the method, the performance of the copper-chromium contact, such as arc ablation resistance, welding resistance and conductivity, can be effectively improved, and the problems of component segregation, Cr phase agglomeration, un-fusion and porosity defects existing in the printing components of the existing copper-chromium contact are solved.

Description

Technical Field

[0001] This invention relates to the field of alloy contact technology, and in particular to a copper-chromium contact and its preparation method. Background Technology

[0002] Copper-chromium contacts are core electrical contact components in power equipment such as medium- and high-voltage vacuum switches and SF6 circuit breakers. Their performance directly determines the breaking capacity, withstand voltage stability, service life, and operational safety of these devices, making them indispensable key components in power transmission and distribution systems. The quality of copper-chromium contacts depends primarily on the purity, compositional uniformity, and morphological characteristics of the alloy raw materials, as well as the ability of the forming process to control the microstructure, density, and structural precision.

[0003] Currently, the main method for manufacturing copper-chromium contacts is 3D printing. The manufacturing processes primarily include direct 3D printing using a mixture of copper and chromium powders, and 3D printing using pre-alloyed copper-chromium powders. However, direct 3D printing using a mixture of copper and chromium powders can result in defects such as component segregation, Cr phase agglomeration, and even incomplete fusion and porosity. Using pre-alloyed copper-chromium powders, on the other hand, can lead to a significant decrease in conductivity and ablation resistance due to the powder's poor flowability, high oxygen content, and poor sphericity. Summary of the Invention

[0004] The main objective of this invention is to provide a copper-chromium contact and its preparation method, aiming to solve the problems of component segregation, Cr phase agglomeration, lack of fusion, porosity, and low conductivity and ablation resistance of copper-chromium contact printed components obtained by the prior art.

[0005] To achieve the above objectives, the present invention provides a method for preparing a copper-chromium contact, the method comprising: Electrolytic copper and chromium powder are mixed at a weight ratio of 1:25-50 to prepare tapered CuCr rods. The tapered CuCr bar is subjected to electrode induction gas atomization treatment to obtain CuCr alloy powder; Based on the CuCr alloy powder and preset parameters, 3D printing is performed to obtain the copper-chromium contact.

[0006] Optionally, the particle size of the electrolytic copper is ≤200 mesh.

[0007] Optionally, the diameter of the obtained tapered CuCr bar is 60mm-70mm and the length is 750mm-850mm.

[0008] Optionally, the method for 3D printing based on the CuCr alloy powder and preset parameters includes: The CuCr alloy powder is loaded into a 3D printing device, with the powder thickness set to 0.01mm-0.04mm, power set to 400W-500W, scanning speed set to 1000mm / s-1600mm / s, and spot spacing set to 0.08mm-0.1mm. The 3D printing process is then started to obtain the copper-chromium contact.

[0009] Optionally, the method for 3D printing based on the CuCr alloy powder and preset parameters includes: Using 3D printing equipment, the copper-chromium contact is printed in sections, including printing the core area and printing the edge area.

[0010] Optionally, the preset parameters include: The core area has a printing power of 450W-500W and a scanning speed of 1000mm / s-1200mm / s. The edge area has a printing power of 400W-430W and a scanning speed of 1400mm / s-1600mm / s.

[0011] Optionally, the core region includes an internal region ≥ 0.5 mm to 2.0 mm from the outer contour of the copper-chromium contact; the edge region includes the area 0.1 mm to 2.0 mm inward from the outer contour of the copper-chromium contact.

[0012] Optionally, the method for 3D printing based on the CuCr alloy powder and preset parameters further includes: Ar with a purity >99.9% is continuously introduced into the 3D printing equipment, while the O2 content in the molding chamber is continuously kept <0.1%.

[0013] Optionally, after obtaining the copper-chromium contact, the preparation method further includes: The copper-chromium contacts were sequentially subjected to magnetic grinding, cleaning, drying, and vacuum sealing.

[0014] To achieve the above objectives, the present invention also provides a copper-chromium contact, which is prepared by the above-described preparation method.

[0015] Compared with the prior art, the beneficial effects that the present invention can achieve are as follows: 1. The method for preparing copper-chromium contacts disclosed in this invention uses electrolytic copper and chromium powder as raw materials to prepare CuCr rods with a tapered structure. During the crucibleless induction melting stage of electrode induction gas atomization, this CuCr rod structure improves the melt flow state and heating uniformity, avoiding local overheating or undercooling, thus promoting the initial uniform mixing of Cu and Cr elements and reducing large Cr agglomeration. During the high-pressure gas atomization stage, the alloy melt can be broken into fine droplets and rapidly condensed to obtain CuCr alloy powder with high sphericity, uniform particle size, and fine microstructure. This CuCr alloy powder has excellent flowability and loose packing density. Then, the CuCr alloy powder is printed into complex, irregularly shaped copper-chromium contacts using 3D printing technology. Furthermore, under preset printing parameters, the CuCr alloy powder can rapidly melt and solidify, further refining the alloy microstructure.

[0016] 2. This invention discloses a method for preparing copper-chromium contacts, which can significantly reduce macroscopic and microscopic compositional segregation in CuCr alloys, thereby improving the compositional uniformity of copper-chromium contacts. Simultaneously, it can effectively suppress Cr phase agglomeration, obtaining dispersed fine Cr strengthening phases, thus significantly improving the uniformity of the copper-chromium contact structure. Furthermore, it can significantly reduce interlayer and interparticle fusion defects, significantly reducing the internal porosity of copper-chromium contacts, thereby improving the density and structural integrity of copper-chromium contacts and reducing stress concentration and performance degradation caused by porosity. Ultimately, it effectively improves the arc erosion resistance, weld resistance, and conductivity of copper-chromium contacts, solving the problems of compositional segregation, Cr phase agglomeration, fusion defects, and porosity defects present in existing copper-chromium contact printed components. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the preparation method of the copper-chromium contact disclosed in this invention; Figure 2 The image shows a CuCr alloy powder electron microscope scan image obtained in Example 1. Figure 3 This is a metallographic microstructure of the copper-chromium contact obtained in Example 3. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] To address the problems of component segregation, Cr phase agglomeration, lack of fusion, porosity, and low conductivity and ablation resistance in copper-chromium contact printed components obtained by existing technologies, this invention provides a method for preparing copper-chromium contacts, such as... Figure 1 As shown, the preparation method includes: S10. Electrolytic copper and chromium powder are mixed at a weight ratio of 1:25-50 to prepare tapered CuCr rods; S20. The tapered CuCr bar is subjected to electrode induction gas atomization treatment to obtain CuCr alloy powder; S30. Based on the CuCr alloy powder and preset parameters, perform 3D printing to obtain the copper-chromium contact.

[0020] Optionally, the particle size of the chromium powder can be 100-300 mesh.

[0021] Optionally, the particle size of the CuCr alloy powder can be 15μm-60μm.

[0022] Optionally, the purity of the electrolytic copper can be ≥99.9%.

[0023] Alternatively, the above-mentioned Cr powder can be prepared by the aluminothermic method.

[0024] It should be understood that the above-mentioned aluminothermic method refers to a metallurgical method of producing metallic chromium by reducing chromium oxide (Cr2O3) with metallic aluminum as a reducing agent at high temperature.

[0025] It should be understood that the aforementioned tapered CuCr bar refers to CuCr bar with a tapered structure, meaning that the diameter or cross-sectional dimension of the bar is not a constant value along the length direction, but rather decreases linearly and uniformly from one end to the other, forming a frustum or truncated cone shape, rather than a standard cylinder. For example, when the length of the CuCr bar is 750mm, the diameter of the thicker end is 70mm, and the diameter of the thinner end is 60mm, then from the diameter of 60mm to the diameter of 70mm, the diameter will decrease uniformly and linearly along the length direction.

[0026] Alternatively, the above method for preparing tapered CuCr rods based on electrolytic copper and chromium powder can be as follows: electrolytic copper and chromium powder are mixed in a certain proportion and then prepared by cold isostatic pressing and sintering.

[0027] Optionally, the above-mentioned cold isostatic pressing process can be as follows: the electrolytic copper powder and chromium powder, which are mixed evenly according to the ratio, are loaded into a flexible mold with a tapered inner cavity, sealed, and placed in a high-pressure liquid medium, such as water, at room temperature. Under these conditions, a uniform high pressure is applied to the flexible mold by a hydraulic device, such as 100MPa-300MPa, so that the mixed powder is uniformly compacted in three dimensions to form a tapered CuCr rod with a certain strength, density, and regular shape.

[0028] Optionally, the above sintering treatment method can be as follows: the tapered CuCr rod obtained by cold isostatic pressing is placed in a vacuum or protective atmosphere furnace and heated to a temperature below the melting point of Cu, but sufficient to cause powder metallurgy bonding, such as 800℃-1050℃, and then held at that temperature for a certain time, so that the powder particles achieve metallurgical bonding through atomic diffusion, neck-like connection and grain boundary migration, and finally obtain a dense, high-strength, and uniformly composed tapered CuCr rod.

[0029] Optionally, the above method for electrode induction gas atomization treatment of tapered CuCr rods can be as follows: the tapered CuCr rods are used as consumable electrodes and vertically clamped in the electrode induction gas atomization device; the atomization chamber is evacuated to a vacuum degree ≤ 5 × 10⁻⁶. -3 The process begins by filling the cavity with high-purity argon gas (≥99.999%) to maintain a slightly positive pressure environment. A high-frequency induction heating device is then activated, controlling the induction power to continuously and uniformly melt the lower end of the CuCr rod, forming a stable molten metal flow. The axial feeding speed of the rod is controlled at 0.5 mm / s-3 mm / s to ensure the molten flow stably enters the atomization zone. High-purity argon gas at a pressure of 6 MPa-10 MPa can be used as the atomization medium, and the molten metal flow is impacted and broken by a supersonic annular nozzle, causing the metal droplets to rapidly solidify and spheroidize in an inert atmosphere. Finally, after cyclone grading and sieving, spherical CuCr alloy powder with a particle size range of 15 μm-53 μm can be obtained.

[0030] Optionally, in the above method for preparing CuCr alloy powder using electrode induction gas atomization treatment, the induction heating temperature can be controlled at 1350℃-1550℃ to fully melt the lower end of the CuCr rod and form a continuous and stable molten metal flow.

[0031] In the above-mentioned electrode induction gas atomization process, by controlling the induction heating temperature at 1350℃-1550℃, the CuCr rod material can be fully melted without overheating, the melt fluidity is moderate, and the molten metal flow is continuous, stable and does not splash. This can effectively avoid chromium element burn-off and component segregation, reduce the oxygen content of the powder, and ensure the sphericity and purity of the powder. This results in the subsequent 3D printed copper-chromium contacts having high density, uniform structure, and excellent conductivity and ablation resistance.

[0032] Through the above-mentioned electrode-induced gas atomization treatment, a product with sphericity ≥0.92, oxygen content ≤120ppm, flowability ≤25s / 50g, and loose pack density ≥4.8g / cm³ can be obtained. 3 The CuCr alloy powder is uniform and free from segregation, ceramic inclusions or crucible contamination, and has a smooth particle surface without obvious defects. In the subsequent 3D printing process, the CuCr alloy powder is evenly spread and the molding is stable, resulting in a copper-chromium contact density of ≥99.2%.

[0033] In one possible implementation, the particle size of the electrolytic copper is ≤200 mesh, and the electrolytic copper and chromium powder are mixed according to CuCr... 25-50 The proportions are determined.

[0034] It should be understood that the above-mentioned electrolytic copper and chromium powder are processed according to CuCr... 25-50 The proportions are determined by mixing, i.e., the mass fraction of Cr in the copper-chromium alloy powder is 25%-50%.

[0035] It should be noted that in the above technical solution, when the particle size of electrolytic copper is ≤200 mesh, that is, when the particle size of electrolytic copper powder is ≤74μm, it can not only be matched with Cr powder prepared by the aluminothermic method, thus significantly reducing the tendency of segregation caused by particle size difference; but also, during powder mixing, electrolytic copper can fully separate and encapsulate Cr powder particles, achieving initial uniform dispersion of the Cr phase in the Cu matrix. Furthermore, in the process of preparing tapered CuCr rods, the electrolytic copper powder can not only fully fill the gaps between Cr particles, significantly improving the compaction density, but also fully rearrange, resulting in uniform density of the obtained CuCr rods and avoiding the problem of density gradients.

[0036] Furthermore, the tapered CuCr rods prepared by the above method can form an alloy liquid with a consistent melting point and composition during the subsequent electrode induction gas atomization process. Cr particles are uniformly dispersed in the alloy liquid, avoiding the problems of Cr particle sedimentation and large agglomeration, and preventing the occurrence of Cu-rich droplets. During the subsequent rapid solidification process, the uniform structure can be preserved, ultimately yielding a CuCr alloy powder with a uniform composition.

[0037] In one possible implementation, the tapered CuCr bar has a diameter of 60mm-70mm and a length of 750mm-850mm.

[0038] It should be noted that in CuCr alloys, Cr has a high melting point and is prone to sedimentation and segregation, making it extremely sensitive to melting rate and melt flow stability. Therefore, when the diameter of the CuCr rod is 60mm-70mm, under high-frequency induction heating with electrode induction gas atomization treatment, its melting rate is moderate and controllable. It will not cause the melt to tumble and Cr to be difficult to disperse in time due to excessive melting, nor will it cause Cr to settle and agglomerate due to excessive melting. When the length of the CuCr rod is 750mm-850mm, continuous and stable melting of the CuCr rod can be achieved, so that the composition of the resulting alloy liquid remains uniform and the composition fluctuation is significantly reduced, ultimately forming a stable, continuous, and uniformly flowing alloy liquid, which then enters the atomization zone.

[0039] In one possible implementation, the above-described method for 3D printing based on CuCr alloy powder and preset parameters includes: The CuCr alloy powder is loaded into the 3D printing equipment, and the powder thickness is set to 0.01mm-0.04mm, the power to 400W-500W, the scanning speed to 1000mm / s-1600mm / s, and the spot spacing to 0.08mm-0.1mm.

[0040] Alternatively, SolidWorks modeling can be used in the 3D printing process described above.

[0041] Optionally, in the above 3D printing process, the printing substrate can be a brass substrate.

[0042] It should be noted that during the aforementioned 3D printing, when the powder layer thickness is 0.01mm-0.04mm, the powder layer is extremely thin, allowing sufficient laser energy penetration depth to completely penetrate the powder layer and achieve good metallurgical bonding with the underlying solidified layer, significantly reducing interlayer incomplete fusion. Simultaneously, a powder layer thickness of 0.01mm-0.04mm results in better powder uniformity and higher powder bed density, reducing internal voids in the powder layer and thus lowering printing porosity, while preventing powder dragging, accumulation, and layer breaks. When the power is 400W-500W and the scanning speed is 1000mm / s-1600mm / s, sufficient energy is provided to avoid an excessively shallow molten pool and insufficient melting. It also prevents overheating of the molten pool, which could lead to boiling and splashing of the Cu liquid phase into spheroids during the holding process. Under these conditions, sufficient melting is ensured while suppressing Cr phase precipitation and agglomeration, preventing component segregation. When the spot spacing is 0.08mm-0.1mm, the molten pool can be made transversely continuous, resulting in a more uniform temperature field in the entire molten pool area, reducing local thermal stress and cracking tendency, and significantly improving the overall density of the printed component.

[0043] Furthermore, in the aforementioned 3D printing process, if the powder layer thickness is too thick, for example, 0.05mm-1.0mm, energy cannot penetrate completely, resulting in ineffective metallurgical bonding between layers, leading to incomplete fusion defects, metallurgical pores, and process pores, thus significantly reducing density. If the power is too low, for example, <400W, the molten pool temperature will be insufficient, the Cr phase will not melt sufficiently, and a large number of unmelted Cr particles will agglomerate, resulting in a rough solidification structure, reduced density, and increased porosity. If the power is >500W, the molten pool will overheat, causing Cu liquid to evaporate and splash, exacerbating component segregation, and thermal stress will increase sharply, making the contacts prone to deformation and cracking. Therefore, in the aforementioned 3D printing process, the printing parameters need to be matched. If the printing parameters deviate from the above settings, the performance of the resulting copper-chromium contacts may be significantly reduced.

[0044] In one possible implementation, the above-described method for 3D printing based on CuCr alloy powder and preset parameters includes: Using 3D printing equipment, copper-chromium contacts are printed in sections, including printing the core area and printing the edge area.

[0045] In one possible implementation, in the above-mentioned 3D printing process based on CuCr alloy powder and preset parameters, the preset parameters include: The core area mentioned above has a printing power of 450W-500W and a scanning speed of 1000mm / s-1200mm / s. For the aforementioned edge areas: printing power is 400W-430W, and scanning speed is 1400mm / s-1600mm / s.

[0046] In one possible implementation, the core region includes an internal region ≥ 0.5 mm to 2.0 mm from the outer contour of the copper-chromium contact; the edge region includes 0.1 mm to 2 mm inward from the outer contour of the copper-chromium contact.

[0047] It should be understood that the aforementioned core area refers to the solid main body area inside the cross-section of the copper-chromium contact, far from the outer contour, i.e., the main internal area of ​​the copper-chromium contact, corresponding to the working body of the copper-chromium contact, requiring high density, uniform structure, smooth conductivity, and stable resistance to ablation. The edge area refers to the strip-shaped area of ​​a certain width extending inward from the outer contour boundary of the copper-chromium contact, corresponding to the control area for the copper-chromium contact's shape contour, dimensional accuracy, and surface quality.

[0048] It should be noted that during the aforementioned partitioned printing, when printing the core area, a printing power of 450W-500W and a scanning speed of 1000mm / s-1200mm / s result in higher energy density, a deeper and more stable molten pool, ensuring complete melting of the CuCr alloy without any unfused phases or internal pores, and uniform dispersion of the Cr phase, thus avoiding Cr agglomeration and compositional segregation issues. The resulting printed component has higher density, a complete continuous conductive path for Cu, higher and more stable conductivity, and a uniform and fine microstructure. Under the action of the electric arc, the ablation is uniform, avoiding the problem of localized concentrated erosion, and the resistance to welding is stronger. When printing edge areas, with a printing power of 400W-430W and a scanning speed of 1400mm / s-1600mm / s, the energy density is reduced, which can avoid edge overheating, burning, splattering, and spheroidization. At the same time, fast scanning can reduce heat accumulation, significantly reducing thermal stress and deformation tendency. Edge melting is more controllable, resulting in higher dimensional accuracy, smoother surface, and reduced machining allowance. It can also prevent Cu loss and Cr segregation due to edge overheating, ensuring stable edge performance.

[0049] Furthermore, compared to zoned printing, printing without zoned printing requires uniform printing parameters. During the printing process, high power and low speed result in good internal density, but also lead to edge overheating, significant deformation, dimensional errors, and a tendency to crack. Conversely, low power and high speed result in good edge precision, but internal issues such as incomplete fusion, porosity, and insufficient density can easily occur. Zoned printing, on the other hand, can satisfy the requirements of high density in the internal area and high precision in the edge area of ​​the copper-chromium contact, while also significantly reducing the risks of cracking, deformation, and warping of the copper-chromium contact.

[0050] In the aforementioned partitioned printing method, if the power is too low or the scanning speed is too fast when printing the core area (e.g., power < 450W or scanning speed > 1200mm / s), the energy will be insufficient, resulting in incomplete fusion and internal unfused areas and porosity, leading to a decrease in density. Simultaneously, it will cause insufficient melting of the Cr phase, Cr agglomeration, and increased component segregation, resulting in decreased conductivity, poorer ablation resistance, and a tendency for localized burn-through of the contacts. If the power is > 500W or the scanning speed is < 1000mm / s, overheating of the molten pool and Cu evaporation and splashing will occur, leading to compositional fluctuations and internal porosity. Simultaneously, cooling will slow down, the Cr phase will coarsen, settle and agglomerate, and thermal stress will increase dramatically, resulting in internal microcracks, deformation, and warping. The resulting copper-chromium contacts will have a coarse structure, and their conductivity and ablation resistance will significantly decrease. When printing edge areas, if the power is <400W or the scanning speed is >1600mm / s, the edge melting will be insufficient, resulting in incomplete fusion, holes, and porosity, leading to low edge strength and problems such as chipping and breakage during use. In addition, the surface will be discontinuous, the arc will easily concentrate and burn at the edge, the contact density will be low, and the edge conductivity will be poor. If the power is >430W or the scanning speed is <1400mm / s, the edge will be overheated and burned, resulting in spheroidization, slag splashing, and rough contours. At the same time, the heat accumulation will be large, leading to edge deformation and warping, excessive melting and loss of Cu, and Cr segregation at the edge, resulting in uneven performance.

[0051] In one possible implementation, the above-described method for 3D printing based on the CuCr alloy powder and preset parameters further includes: Ar gas with a purity >99.9% is continuously supplied to the 3D printing equipment, while the O2 content in the molding chamber is continuously kept <0.1%.

[0052] Optionally, after the 3D printing is completed, the brass sheet can be removed from the substrate using a remover, and then precision wire-cut using single-wire cutting to remove the printing excess, thereby obtaining the copper-chromium contact. Furthermore, the printed copper-chromium contact can be further processed according to the actual required contact structure.

[0053] In one possible implementation, after obtaining the copper-chromium contact, the above preparation method further includes: The copper-chromium contacts were then subjected to magnetic grinding, cleaning, drying, and vacuum sealing in sequence.

[0054] To address the aforementioned technical problems, the present invention also provides a copper-chromium contact, which is prepared by the above-described preparation method.

[0055] The copper-chromium contacts prepared by the above method exhibit uniform composition, no obvious Cr phase agglomeration or component segregation, and significantly reduced internal defects such as porosity and lack of fusion, resulting in high density. They also possess excellent electrical conductivity, resistance to ablation and welding, and a long service life. Furthermore, the partitioned printing process achieves synergistic optimization of internal performance and edge precision, resulting in contacts with high dimensional accuracy, low tendency to deformation and cracking, and superior overall performance and forming quality.

[0056] Example 1 A method for preparing a copper-chromium contact includes: S10. Based on electrolytic copper and chromium powder, tapered CuCr rods were prepared, specifically as follows: Electrolytic copper powder with a particle size ≤200 mesh and a purity ≥99.95% and chromium powder with a purity ≥99.0% and a particle size of 100-300 mesh prepared by the aluminothermic method were selected, and the CuCr... 40 After proportioning, the mixture is placed in a powder mixer and mixed evenly to obtain a uniform CuCr mixed powder. CuCr mixed powder was loaded into a tapered flexible rubber mold with a large end diameter of 70 mm, a small end diameter of 60 mm, and a length of 800 mm. Cold isostatic pressing was then performed at a pressure of 200 MPa for 20 minutes at room temperature to obtain a tapered CuCr compact. This compact was then placed in a vacuum sintering furnace with a vacuum level controlled at 10... -2 Pa, heated to 950℃, held for 2.5h, and naturally cooled to room temperature to obtain dense, tapered CuCr rods with a large end diameter of 68mm, a small end diameter of 58mm, a length of 780mm, and a density ≥92%; S20. The tapered CuCr bar stock of S10 is subjected to electrode induction gas atomization treatment to obtain CuCr alloy powder, specifically: Tapered CuCr rods are vertically clamped as consumable electrodes, and the atomizing chamber is evacuated to ≤5×10⁻⁶. -3 Pa, high-purity argon gas with a purity ≥99.999% is introduced to form a slightly positive pressure protective atmosphere; the high-frequency induction heating device is started and the heating temperature is controlled at 1350℃ to continuously and uniformly melt the lower end of the CuCr bar; the axial feeding speed is controlled at 0.5mm / s, the molten metal flow enters the atomization zone, and 6MPa high-pressure argon gas is used to impact and break the molten metal flow through a supersonic nozzle. The droplets are rapidly solidified and spheroidized in the inert atmosphere. After classification and sieving, CuCr alloy powder with a size of 15μm-53μm can be obtained. S30. Based on S20 CuCr alloy powder, 3D printing is performed using preset parameters to obtain a copper-chromium contact, specifically: CuCr alloy powder was loaded into an SLM-type 3D printing machine, and the specific parameters were set as follows: powder thickness of 0.02mm, laser power of 450W, scanning speed of 1300mm / s, and spot spacing of 0.09mm. Argon gas protection was used during the printing process to prevent powder oxidation. After printing, the copper-chromium contacts were magnetically ground and cleaned in sequence to obtain the finished copper-chromium contacts.

[0057] The desired copper-chromium contact product is obtained through processes S10-S30.

[0058] Example 2 S10 and S20 in Example 2 are the same as in Example 1; S30. Based on S20 CuCr alloy powder, 3D printing is performed using preset parameters to obtain a copper-chromium contact, specifically: CuCr alloy powder is loaded into an SLM-type 3D printer and printed in sections, divided into core area printing and edge area printing. First, the slicing software of the 3D printer is used to set the slicing range. The core area is the internal area ≥1.0mm away from the outer contour of the copper-chromium contact, and the edge area is the area 0.1mm-2.0mm inward from the outer contour of the copper-chromium contact. The slicing boundary is smooth and there is no obvious boundary. To print the core area, the printing parameters are set as follows: powder thickness is 0.02mm, laser power is 480W, scanning speed is 1100mm / s, and spot spacing is 0.09mm. During the printing process, the molten pool is fully melted to achieve complete metallurgical bonding of the powder. To print the edge areas, the following steps are taken: Set the printing parameters, including a powder thickness of 0.02mm, a laser power of 420W, a scanning speed of 1500mm / s, and a spot spacing of 0.09mm; Control the heat input during printing to avoid overheating and splattering at the edges. The printing process is protected by argon gas. After printing, the copper-chromium contacts are magnetically ground and cleaned in sequence to obtain the finished copper-chromium contacts.

[0059] The desired copper-chromium contact product is obtained through processes S10-S30.

[0060] The physical properties of the CuCr alloy powder obtained in S20 of Examples 1 and 2 were measured, and the results are shown in Table 1.

[0061] Table 1

[0062] Analysis of Table 1 shows that the CuCr alloy powder prepared in the example has an oxygen content of ≤600ppm, indicating high purity; both the loose packing density and tap density meet the printing requirements, ensuring uniform powder spreading, no breaks, and no localized looseness during 3D printing; the Hall flow rate is ≤20s / 50g, enabling continuous and uniform powder feeding and spreading, avoiding problems such as powder feeding jams and uneven powder spreading, and ensuring a stable printing process.

[0063] Electron microscopy was performed on the CuCr alloy powder obtained from S20 in Example 1, and the results are as follows: Figure 2 As shown.

[0064] Through analysis Figure 2 As can be seen from the image, the vast majority of powder particles are complete spheres or near-spheres with a sphericity ≥95%. Judging from the 100μm scale, the powder particle size is mainly concentrated in the 10μm-60μm range, with a continuous overall distribution and no extremely large particles. This particle size range perfectly matches a powder bed thickness of 0.01mm-0.04mm, improving powder bed density and reducing printing porosity. Furthermore, there are no obvious high atomic number inclusions in the backscattered image, indicating high powder purity. The powder's high sphericity and high flowability avoid problems such as incomplete fusion and porosity during printing, enabling efficient printing in different areas.

[0065] The performance of the copper-chromium contact products obtained in Examples 1 and 2 was measured, and the results are shown in Table 2.

[0066] Table 2

[0067] Analysis of Table 2 shows that in Example 1, the uniform printing parameters cannot simultaneously ensure internal fusion and edge heat control. Therefore, the resulting copper-chromium contacts exhibit slight incomplete fusion, which blocks the continuous conductive path of Cu. Cr phase agglomeration also damages the conductive network, leading to low conductivity and other performance degradation. In contrast, Example 2 uses partitioned printing, ensuring complete fusion of the core area, eliminating internal porosity and incomplete fusion, and avoiding splashing and loosening caused by overheating in the edge area. This achieves high density across the entire region. The high density and fine, dispersed Cr phase of the resulting copper-chromium contacts ensure continuous conductivity of the Cu matrix while minimizing Cr phase electron scattering. Furthermore, the absence of oxide inclusions significantly improves conductivity. Moreover, the copper-chromium contacts obtained in Example 2 are significantly superior to those in Example 1 in terms of mechanical properties and ablation resistance.

[0068] Example 3 A method for preparing a copper-chromium contact includes: S10. Based on electrolytic copper and chromium powder, tapered CuCr rods were prepared, specifically as follows: Electrolytic copper powder with a particle size ≤200 mesh and a purity ≥99.95% and chromium powder with a purity ≥99.0% and a particle size of 100-300 mesh prepared by the aluminothermic method were selected, and the CuCr... 25 After proportioning, the mixture is placed in a powder mixer and mixed evenly to obtain a uniform CuCr mixed powder. CuCr mixed powder was loaded into a tapered flexible rubber mold with a large end diameter of 70 mm, a small end diameter of 60 mm, and a length of 850 mm. Cold isostatic pressing was then performed at a pressure of 200 MPa for 20 minutes at room temperature to obtain a tapered CuCr compact. This compact was then placed in a vacuum sintering furnace with the vacuum level controlled at 10... -2 Pa, heated to 950℃, held for 2.5h, and naturally cooled to room temperature to obtain dense, tapered CuCr rods with a large end diameter of 68mm, a small end diameter of 58mm, a length of 850mm, and a density ≥92%; S20. The tapered CuCr bar stock of S10 is subjected to electrode induction gas atomization treatment to obtain CuCr alloy powder, specifically: Tapered CuCr rods are vertically clamped as consumable electrodes, and the atomizing chamber is evacuated to ≤5×10⁻⁶. -3 Pa, high-purity argon gas with a purity ≥99.999% is introduced to form a slightly positive pressure protective atmosphere; the high-frequency induction heating device is started and the heating temperature is controlled at 1550℃ to continuously and uniformly melt the lower end of the CuCr bar; the axial feeding speed is controlled at 3.0mm / s, the molten metal flow enters the atomization zone, and 10MPa high-pressure argon gas is used to impact and break the molten metal flow through a supersonic nozzle. The droplets are rapidly solidified and spheroidized in the inert atmosphere. After classification and sieving, CuCr alloy powder with a size of 15μm-53μm can be obtained. S30. Based on S20 CuCr alloy powder, 3D printing is performed using preset parameters to obtain a copper-chromium contact, specifically: CuCr alloy powder is loaded into an SLM-type 3D printer and printed in sections, divided into core area printing and edge area printing. First, the slicing software of the 3D printer is used to set the slicing range. The core area is the internal area ≥0.5mm away from the outer contour of the copper-chromium contact, and the edge area is the area 0.1mm-2.0mm inward from the outer contour of the copper-chromium contact. The slicing boundary is smooth and there is no obvious boundary. To print the core area, the printing parameters are set as follows: powder thickness is 0.04mm, laser power is 450W, scanning speed is 1200mm / s, and spot spacing is 0.08mm. During the printing process, the molten pool is fully melted to achieve complete metallurgical bonding of the powder. To print the edge areas, the following steps are taken: Set the printing parameters, including a powder thickness of 0.04mm, a laser power of 400W, a scanning speed of 1600mm / s, and a spot spacing of 0.08mm; Control the heat input during printing to avoid overheating and splattering at the edges. The printing process is protected by argon gas. After printing, the copper-chromium contacts are magnetically ground and cleaned in sequence to obtain the finished copper-chromium contacts.

[0069] The desired copper-chromium contact product is obtained through processes S10-S30.

[0070] Metallographic scanning was performed on the copper-chromium contact product obtained in Example 3, and the results are as follows: Figure 3 As shown.

[0071] like Figure 3 The image shows a metallographic microstructure of a copper-chromium contact. The light orange matrix represents the continuous Cu matrix, the conductive phase of the copper-chromium contact. The dispersed, fine, dark dots or short strips represent the Cr strengthening phase, providing resistance to ablation and welding. The image shows that the Cr phase, in the form of fine particles ranging from 1μm to 3μm, is uniformly and dispersed within the Cu matrix, without any large Cr agglomerates, localized Cr enrichment, or significant component segregation. This fine, dispersed Cr phase does not disrupt the continuous conductive path of Cu and provides uniform resistance to arc erosion. The image also shows that the Cu matrix is ​​continuous and dense, without obvious defects such as porosity, looseness, lack of interlayer fusion, or cracks. The continuous and intact Cu matrix combined with the fine, dispersed Cr phase maximizes the preservation of the Cu's conductive path, minimizes electron scattering, significantly improves conductivity, and significantly enhances matrix strength, wear resistance, and weld resistance. In addition, the uniformly dispersed Cr phase ensures uniform arc erosion without localized concentrated erosion; the high melting point and high temperature strength of Cr effectively resist arc erosion and extend the life of copper-chromium contacts.

[0072] Comparative Example 1 Comparative Example 1 is set up in Example 3.

[0073] In Comparative Example 1, S10 and S20 are the same as in Example 3. In S30, the printing method of the core area is as follows: the powder thickness is 0.04 mm, the laser power is 420 W, the scanning speed is 1500 mm / s, the spot spacing is 0.08 mm, and the molten pool is fully melted during the printing process to achieve complete metallurgical bonding of the powder. The printing method for the edge area is as follows: powder thickness is 0.04mm, laser power is 480W, scanning speed is 1100mm / s, and spot spacing is 0.08mm; heat input is controlled during printing to avoid overheating and splashing at the edges; the remaining processes and parameters are the same as those in Example 3.

[0074] The copper-chromium contacts obtained in Example 3 and Comparative Example 1 were measured respectively, and the results are shown in Table 3.

[0075] Table 3

[0076] Analysis of Table 3 shows that when using the same printing method as in Example 3, if the printing parameters disclosed in this invention are deviated from, for example, low-power high-speed printing is used when printing the core area, or high-power low-speed printing is used when printing the edge area, defects such as internal porosity, lack of fusion, Cr phase agglomeration, and component segregation will occur in the copper-chromium contacts. At the same time, the core performance such as conductivity, ablation resistance, and hardness will be significantly degraded, and the dimensional accuracy and surface quality will be greatly reduced, which will not meet the requirements for the use of high-voltage, high-capacity vacuum switches.

[0077] The above are merely preferred embodiments of the present invention and do not limit the scope of the patent. Any equivalent structural or procedural transformations made based on the description and drawings of the present invention, or direct or indirect applications in other related technical fields, are similarly included within the scope of patent protection of the present invention.

Claims

1. A method for preparing a copper-chromium contact, characterized in that, The preparation method includes: Electrolytic copper and chromium powder are mixed at a mass ratio of 1:25-50 to prepare tapered CuCr rods. The tapered CuCr bar is subjected to electrode induction gas atomization treatment to obtain CuCr alloy powder; Based on the CuCr alloy powder and preset parameters, 3D printing is performed to obtain the copper-chromium contact.

2. The preparation method according to claim 1, characterized in that, The electrolytic copper has a particle size of ≤200 mesh.

3. The preparation method according to claim 1, characterized in that, The obtained tapered CuCr rod has a diameter of 60mm-70mm and a length of 750mm-850mm.

4. The preparation method according to claim 1, characterized in that, The method for 3D printing based on the CuCr alloy powder and preset parameters includes: The CuCr alloy powder is loaded into a 3D printing device, with the powder thickness set to 0.01mm-0.04mm, power set to 400W-500W, scanning speed set to 1000mm / s-1600mm / s, and spot spacing set to 0.08mm-0.1mm, for 3D printing.

5. The preparation method according to claim 1, characterized in that, The method for 3D printing based on the CuCr alloy powder and preset parameters includes: Using 3D printing equipment, the copper-chromium contact is printed in sections, including printing the core area and printing the edge area.

6. The preparation method according to claim 5, characterized in that, The preset parameters include: The core area has a printing power of 450W-500W and a scanning speed of 1000mm / s-1200mm / s. The edge area has a printing power of 400W-430W and a scanning speed of 1400mm / s-1600mm / s.

7. The preparation method according to claim 6, characterized in that, The core region includes an internal region ≥ 0.5 mm - 2.0 mm from the outer contour of the copper-chromium contact; the edge region includes an area 0.1 mm - 2.0 mm inward from the outer contour of the copper-chromium contact.

8. The preparation method according to claim 4 or 5, characterized in that, The method for 3D printing based on the CuCr alloy powder and preset parameters further includes: Ar with a purity >99.9% is continuously introduced into the 3D printing equipment, while the O2 content in the molding chamber is continuously kept <0.1%.

9. The preparation method according to claim 1, characterized in that, After obtaining the copper-chromium contact, the preparation method further includes: The copper-chromium contacts were sequentially subjected to magnetic grinding, cleaning, drying, and vacuum sealing.

10. A copper-chromium contact, characterized in that, The copper-chromium contact is prepared by the preparation method according to any one of claims 1-9.

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