Method for preparing copper-tungsten moving arc contact blank through 3D printing

Abstract

The invention relates to the technical field of preparation of copper-tungsten moving arc contact blanks, in particular to a method for preparing a copper-tungsten moving arc contact blank through 3D printing. According to the scheme, the electron beam 3D printing technology is adopted, and the copper tail with the gradient transition layer and the fiber reinforced structure is printed on the tungsten head base body layer by layer, specifically, the tungsten head is prepared through the vehicle matching technology, and then in the vacuum environment, the copper tail containing the gradient transition layer and the fiber reinforced phase is sequentially printed through the electron beam cladding technology; and finally, carrying out hot isostatic pressing treatment to obtain a compact copper-tungsten moving arc contact blank. According to the scheme, near-net forming of the material is achieved, the feeding weight of the copper tail is remarkably reduced to about 0.3 kg from 0.82 kg in the prior art, and the material utilization rate is greatly increased; the prepared contact is excellent in key performance, the tensile strength of the bonding surface can reach 300 MPa or above, the electric conductivity exceeds 79 IACS, and the problem that the interface of a dissimilar material is prone to failure is effectively solved.

Description

Technical Field

[0001] This invention relates to the field of copper-tungsten moving arc contact blank preparation technology, and specifically to a method for 3D printing to prepare copper-tungsten moving arc contact blanks. Background Technology

[0002] Copper-tungsten moving arc contact blanks are core components of high-voltage circuit breakers and other equipment, requiring excellent electrical and thermal conductivity, resistance to arc erosion, and mechanical strength. Currently, the mainstream process uses a method of "separate machining of the tungsten head and copper tail followed by electron beam welding." This process has two major drawbacks: first, the copper tail is machined from a solid copper rod, resulting in low material utilization (less than 40%) and high cost; second, the weld interface exhibits abrupt performance changes, making it prone to failure under repeated arc impacts.

[0003] To address these issues, the industry has explored various methods. Some studies have employed fibrous WC materials to construct a three-dimensional framework to improve melt infiltration, or added reinforcing phases such as graphene to enhance the overall performance of composite materials. Other approaches involve designing multilayer structures (such as AgWCC / AgC / Ag) to optimize the performance of different regions. However, these methods or processes are either complex or difficult to precisely control the distribution of reinforcing phases and the interface structure.

[0004] Electron beam 3D printing (additive manufacturing) technology offers a new approach to integrated manufacturing. However, its application in simply forming copper tails is considered insufficiently innovative. This invention, through a unique material system and structural design, elevates the application of 3D printing to the level of "manufacturing new material components with actively controllable properties," aiming to solve industry pain points such as interfacial bonding strength, compositional gradient transition, and performance uniformity. Summary of the Invention

[0005] To address the problems of significant material waste, cumbersome processing procedures, and insufficient interfacial bonding reliability in existing high-voltage copper-tungsten dynamic arc contact preform fabrication processes, this invention provides a copper-tungsten dynamic arc contact preform based on fiber reinforcement and gradient functional design, along with its electron beam 3D printing fabrication method. This invention aims to achieve near-net-shape forming of the material, significantly reducing raw material consumption; and by introducing directional reinforcing fibers and a compositional gradient transition layer inside the copper tail, it optimizes the interfacial bonding state and overall performance, ultimately obtaining a high-performance, long-life integrated dynamic arc contact.

[0006] S1. Tungsten head machining: The tungsten head made of CuW80 alloy is precision machined to ensure that the dimensions and surface roughness of the mating surface meet the design requirements; the CuW80 alloy is an alloy with a tungsten content of 80wt% and a copper content of 20wt%. S2. Fixing the tool: Fix the tungsten head processed in step S1 into the positioning hole of the substrate tool; S3. Electron beam 3D printing of fiber-reinforced gradient copper tail: In a vacuum environment, using electron beam cladding technology, copper tails are formed layer by layer on the bonding surface of the tungsten head. The printing process is as follows: S3-1. Printing a gradient transition layer: On the mating surface of the tungsten head, a dual powder feeder is used to feed tungsten powder and QCr0.5 alloy powder respectively (QCr0.5 alloy is a chromium bronze alloy in the Chinese national standard GB / T 13808-1992, graded QCr0.5, and referred to as QCr0.5 alloy in this invention). The powder feeding ratio of the two powders is controlled by a program to print a functionally graded material as a gradient transition layer; the gradient transition layer starts from the mating surface of the tungsten head, and its overall composition is determined by both tungsten powder and QCr0.5 alloy powder. The tungsten content decreased continuously from 80 wt.% near the tungsten head to 0 wt.% near the copper tail; simultaneously, the introduction of QCr0.5 alloy powder increased the copper content accordingly, while the chromium content remained stable at 0.5 wt.%. Explanation: On the bonding surface of the tungsten head, dual powder feeders are used to independently deliver tungsten powder and QCr0.5 alloy powder (chromium content of 0.5 wt.%) with constant composition. The feeding rate of the two powders is precisely controlled by a digital program, so that their mixing ratio changes continuously, thereby forming a composition gradient layer during the cladding process. The macroscopic composition of this gradient layer is as follows: the tungsten content decreases continuously from 80 wt% at the junction with the tungsten head to 0 wt.% at the junction with the copper tail; at the same time, due to the continuous addition of QCr0.5 alloy powder, the copper content increases from about 19.9 wt.% to about 99.5 wt.%, while the chromium content remains stable at about 0.5 wt% throughout the gradient layer. The gradient layer formed in this way has a smooth transition in tungsten content, effectively matching the thermophysical properties of the bottom CuW80 tungsten head and the upper QCr0.5 copper tail, while the stable chromium content provides solid solution strengthening, ensuring the strength of the gradient layer itself. S3-2, Printing fiber-reinforced copper matrix: On the gradient transition layer, QCr0.5 alloy powder doped with reinforcing fibers is used for printing to form the main structure of the copper tail; S3-3, Printing working layer: On the outer surface of the fiber-reinforced copper matrix, a layer of arc-resistant copper alloy is printed as a working layer; S4. Post-processing: The contact blank printed in step S3 is subjected to hot isostatic pressing to obtain a copper-tungsten moving arc contact blank.

[0007] Explanation: The core of the above solution lies in combining the digitalization and near-net-shape forming capabilities of electron beam cladding 3D printing with material functional gradient design and fiber-reinforced composite material design. Through layer-by-layer printing, metallurgical bonding of heterogeneous materials (tungsten head and copper tail), continuous compositional variation in the intermediate transition zone, and controllable introduction of reinforcing phases into the matrix are achieved, fundamentally solving the problems of abrupt interface performance changes, easy cracking, and low material utilization in traditional welding processes.

[0008] Furthermore, the thickness of the gradient transition layer in step S3-1 is 0.5~2.0 mm.

[0009] Note: The thermal expansion coefficients of W and Cu differ significantly, and direct bonding would generate substantial thermal stress at the interface. This compositional gradient transition layer allows for a smooth transition of the material's thermophysical properties (such as thermal expansion coefficient and elastic modulus), effectively mitigating and dispersing thermal stress caused by operating temperature variations or arc thermal shock, and preventing interface failure under cyclic loading. This thickness range ensures the effectiveness of the gradient effect; too thin a layer results in insufficient stress relief, while too thick a layer reduces economic efficiency and increases the difficulty of process control.

[0010] Furthermore, the reinforcing fiber used in step S3-2 is a tungsten fiber with a chromium-plated surface, with a diameter of 30~45nm, a length of 4~5μm, and a chromium layer thickness of 150~250 nm; the mass fraction of the reinforcing fiber in the QCr0.5 alloy powder is 0.5%~3.0%.

[0011] Note: Nanoscale tungsten fibers, used as a reinforcing phase, can significantly improve the strength, hardness, and arc erosion resistance of the copper matrix (dispersion strengthening and fiber strengthening), preventing the reinforcing phase from detaching from the matrix and ensuring effective load transfer. It is worth noting that excessive addition can lead to fiber agglomeration and a decrease in electrical conductivity.

[0012] Furthermore, the method for preparing the reinforcing fiber is as follows: SA1. Cleaning and Activation: Select short-cut tungsten fibers with the required diameter, clean them thoroughly, and then immerse them in a 10% dilute sulfuric acid solution at room temperature for 30 minutes to form micron-level grooves on their surface. Finally, rinse with deionized water and dry. SA2, chemical deposition: SA2-1: Using Cr(CO)6 as the chromium source, short-cut tungsten fibers treated with SA1 are placed in the reaction zone of the furnace, and high-purity hydrogen is used as the carrier gas and reducing gas, while exhaust gas is discharged from the system. SA2-2. First, the reaction zone is heated to 360°C at a rate of 5~10°C / min. Then, Cr(CO)6 is heated to 105°C as a gasification precursor and carried into the reaction zone by hydrogen. It undergoes thermal decomposition reaction on the surface of short-cut tungsten fibers and gradually deposits to form a chromium plating layer. SA2-3. After deposition is completed, heating and precursor delivery are stopped. The system is slowly cooled to room temperature under hydrogen protection to prevent the coating from cracking due to rapid cooling and to obtain reinforced fibers.

[0013] Note: The above chemical vapor deposition method can produce chromium-tungsten fiber with a dense and uniform coating, strong adhesion to the substrate, and controllable composition, which can meet the performance requirements of the reinforcing fiber in this invention.

[0014] Furthermore, the QCr0.5 alloy powder used in step S3-2 is CuCr0.5 alloy gas-atomized spherical powder with a particle size range of 53~105 μm.

[0015] Note: The CuCr0.5 alloy, instead of pure copper, is chosen to leverage the solid solution and precipitation strengthening effects of chromium (Cr) to further enhance the strength and high-temperature resistance of the copper matrix. The spherical powder prepared by gas atomization possesses advantages such as high flowability, low oxygen content, and high bulk density, making it ideal for the powder spreading process in electron beam printing, ensuring printing stability and part density. This particle size range is optimized to balance printing layer thickness accuracy and powder spreading characteristics.

[0016] Furthermore, in the electron beam cladding printing process of step S3, the core process parameters are: printing chamber vacuum degree of 2×10⁻³ Pa, printing speed of 15~20 mm / s, electron beam current of 20~30 mA, focal point offset of 15~20, line offset of 0.05~0.10 mm, and single-layer printing thickness of 0.05-0.10 mm.

[0017] Note: The above process parameters are the result of extensive experimental optimization and collectively determine the morphology of the molten pool, solidification behavior, and final microstructure. High vacuum prevents the printing materials (especially copper and chromium) from oxidizing at high temperatures. Speed, current, and focus offset jointly control energy input, ensuring complete powder melting and preventing the matrix from overheating. Line offset and layer thickness directly affect the dimensional accuracy, surface finish, and number of internal defects (such as pores) of the printed parts. This combination of parameters is crucial for ensuring successful printing of gradient materials and the stability of fiber-reinforced structures.

[0018] Furthermore, the hot isostatic pressing parameters in step S4 are: processing temperature 600~650℃, pressure 100~150MPa, and holding time 1~2 h.

[0019] Note: Electron beam printed parts may contain microscopic pores or residual stress. Hot isostatic pressing (HIP) applies isotropic high pressure to the workpiece at high temperatures. Through creep and diffusion mechanisms, it can effectively close internal pores, increase density (>98.5%), eliminate residual stress, and improve the material's plasticity and fatigue properties. This parameter range ensures densification without causing overheating or grain coarsening.

[0020] Furthermore, the substrate fixture in step S2 is provided with multiple positioning holes to enable batch clamping and printing of multiple contacts.

[0021] Note: The multi-terminal design is key to the industrialization and economic benefits of this invention. It allows multiple contact blanks to be formed simultaneously in a single printing operation, greatly improving equipment utilization and production efficiency, significantly reducing the manufacturing cost per unit, and making this innovative process feasible for large-scale production.

[0022] In another aspect, the present invention also provides a copper-tungsten moving arc contact blank prepared by the above method, the copper-tungsten moving arc contact blank comprising, from bottom to top: Tungsten head made of CuW80 alloy; A gradient transition layer with continuously varying composition is disposed on the tungsten head; The copper tail is composed of QCr0.5 alloy containing a chromium-plated tungsten fiber reinforced phase and disposed on the gradient transition layer.

[0023] Description: This contact product is a composite material component with a three-layer structure: a tungsten tip, a gradient transition layer, and a copper tail. Its core feature is a gradient structure with continuously changing composition at the interface, rather than an abrupt interface, and the copper tail contains uniformly distributed nanofiber reinforcement phases with good interfacial bonding. This synergistic effect of the structure gives the product high bonding strength, excellent electrical and thermal conductivity, high resistance to arc erosion, and wear resistance, resulting in overall performance far exceeding that of contacts manufactured using traditional processes.

[0024] Furthermore, the copper-tungsten bonding surface of the copper-tungsten moving arc contact blank has a tensile strength of 300~350 MPa, a conductivity of 79~83 IACS, and a density greater than 98.5%. Note: A tensile strength of 300~350 MPa indicates that its interfacial bonding reliability is far superior to that of traditional welded interfaces (typically <250 MPa), avoiding the risk of detachment due to insufficient bonding strength. A high conductivity of 79~83 IACS ensures low energy consumption and efficient switching capabilities in high-voltage equipment. A density greater than 98.5% guarantees the uniformity of the material structure and the stability of its mechanical properties, forming the cornerstone of high-performance contacts.

[0025] Compared with existing methods for preparing copper-chromium contacts, the advantages of this invention are: (1) High material utilization: The copper tail is prepared by 3D printing near-net-shape forming technology, which avoids the large amount of waste generated by traditional turning processing. The weight of copper tail feed is reduced from 0.82 kg to about 0.3 kg, and the material utilization rate is increased by more than 60%.

[0026] (2) Significantly improved interfacial bonding strength and reliability: By printing a composition gradient transition layer, a smooth transition of material properties between the tungsten head and the copper tail is achieved, eliminating the problem of abrupt performance changes at the traditional welding interface. The introduced Cr-plated tungsten fiber reinforces the copper matrix, and its good interfacial bonding with the copper matrix (thanks to the Cr layer) effectively transfers the load and inhibits crack propagation.

[0027] (3) Excellent overall performance: The gradient structure alleviates thermal stress, and the fiber-reinforced phase improves the matrix's resistance to arc erosion, wear resistance, and high-temperature strength. The working layer (QCr0.5) further ensures the service performance of the contact end face. Data shows that the copper-tungsten moving arc contact blank prepared by this invention has a tensile strength of over 300 MPa at the bonding surface and a conductivity exceeding 79 IACS. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the structure of a copper-tungsten dynamic arc contact blank, where 1-tungsten head, 2-gradient transition layer, and 3-copper tail; Figure 2 This is a schematic diagram of the 3D printing process of a copper-tungsten dynamic arc contact blank; Figure 3 Here are the substrate fixture drawings; where (a) is a side sectional view of the substrate fixture and (b) is a top view of the substrate fixture. Detailed Implementation

[0029] To further illustrate the methods and effects of this invention, the technical solution of this invention will be clearly and completely described below in conjunction with experiments.

[0030] Example 1: This example describes a method for 3D printing to prepare a copper-tungsten moving arc contact blank.

[0031] S1, Tungsten head assembly and machining: The CuW80 alloy tungsten head was precision machined using a CNC lathe of model M08JL5-II. Using tools such as CCG120404-AK and ACG160404-AK, the spindle speed was set to 1500 r / min and the feed rate to 0.12 mm / r. The tungsten end mating surfaces are precision machined to a shine-through finish, ensuring that all dimensions and surface roughness meet the requirements: Ra≤3.2 μm; S2, Fixture fixing: After the tungsten tip is fitted into the positioning hole of the special substrate tooling (hole position tolerance H7, tungsten tip fit tolerance g6) to ensure accurate positioning and secure clamping. S3, Electron Beam 3D Printing of Fiber-Reinforced Gradient Copper Tail: Printing equipment: Vacuum electron beam cladding (EBM) equipment; Basic printing parameters: printing speed 15 mm / s, electron beam current 20 mA, focus offset 15, line offset 0.05 mm, layer thickness 0.05 mm, print chamber preheating temperature 300℃; S3-1, Print the gradient transition layer: A dual powder feeder is used to deliver tungsten powder and QCr0.5 alloy powder with a constant composition, respectively. The powder feeding rate of the two feeders is controlled by a program to print a gradient transition layer with a thickness of 0.5 mm. This ensures that the tungsten content in the cladding material gradually changes from 80 wt.% near the tungsten tip to 0 wt.% near the copper tail. During this process, the chromium content remains at approximately 0.5 wt.% due to the use of a fixed amount of QCr0.5 alloy powder.

[0032] S3-2, Printing fiber-reinforced copper matrix: Switch to premixed raw material for printing; this raw material is a uniform mixture of gas-atomized CuCr0.5 alloy powder (particle size 53 μm) and short-cut chromium-plated tungsten fibers (Wf@Cr, fiber diameter about 30 nm, length about 4.0 μm, Cr layer thickness about 150 nm) accounting for 0.5% of the total powder mass; continue printing according to the above basic parameters until the copper tail body shape is completed; S4. Post-processing: The printed contact blank is subjected to hot isostatic pressing: the temperature is 600℃, the pressure is 100MPa, and the temperature and pressure are maintained for 1 hour to obtain a copper-tungsten moving arc contact blank.

[0033] Example 2: The content described in this example is a preparation method under another set of parameters.

[0034] S1, Tungsten head assembly and machining: The CuW80 alloy tungsten head was precision machined using a CNC lathe of model M08JL5-II. Using tools such as CCG120404-AK and ACG160404-AK, the spindle speed was set to 1500 r / min and the feed rate to 0.12 mm / r. The tungsten end mating surfaces are precision machined to a shine-through finish, ensuring that all dimensions and surface roughness meet the requirements: Ra≤3.2 μm; S2. Fixture fixing: Place the tungsten tip after vehicle assembly into the positioning hole of the special substrate fixture (hole position tolerance H7, tungsten tip fit tolerance g6) to ensure accurate positioning and firm clamping. S3, Electron Beam 3D Printing of Fiber-Reinforced Gradient Copper Tail: Printing equipment: Vacuum electron beam cladding (EBM) equipment; Basic printing parameters: printing speed 20 mm / s, electron beam current 30 mA, focus offset 20, line offset 0.1 mm, layer thickness 0.1 mm, printing chamber preheating temperature 300℃; S3-1, Print the gradient transition layer: A dual powder feeder is used to deliver tungsten powder and QCr0.5 alloy powder with a constant composition, respectively. The powder feeding rates of the two feeders are controlled by a program to print a gradient transition layer with a thickness of 2.0 mm. This ensures that the tungsten content in the cladding material gradually changes from 80 wt% near the tungsten tip to 0 wt% near the copper tail. Throughout this process, the chromium content remains consistently at approximately 0.5 wt% due to the use of a fixed amount of QCr0.5 alloy powder. S3-2, Printing Fiber-Reinforced Copper Matrix: Switch to premixed raw material for printing. This raw material is a uniform mixture of gas-atomized CuCr0.5 alloy powder (particle size 105 μm) and 3.0% of short-cut chromium-plated tungsten fibers (Wf@Cr, fiber diameter approximately 45 nm, length approximately 5.0 μm, Cr layer thickness approximately 250 nm) by mass of powder. Continue printing according to the above basic parameters until the main body shape of the copper tail is completed. S4. Post-processing: The printed contact blank is subjected to hot isostatic pressing: the temperature is 650℃, the pressure is 150MPa, and the temperature and pressure are maintained for 2 hours to obtain a copper-tungsten moving arc contact blank.

[0035] Experimental Example: The description of this experimental example is based on the scheme described in Example 2, and aims to illustrate the practical application effect of the present invention.

[0036] 1. Experimental Design: To systematically evaluate the performance advantages of this invention (fiber-reinforced gradient copper-tungsten contact and its preparation method), the following experimental group was designed for comparison with a blank control group. All contact samples had uniform specifications: outer diameter 21 mm, and total height conforming to standard design requirements.

[0037] Blank group: Copper-tungsten moving arc contact blanks prepared using the traditional process of "solid copper rod (QCr0.5) feeding + rough turning + electron beam welding". The weight of the copper tail feeding is 0.82Kg.

[0038] Experimental Group 1: This group adopted the basic scheme of the present invention, namely, "equipped with a tungsten head and electron beam 3D printed solid copper tail (without gradient transition layer and fiber reinforcement)". This group was used to verify the effect of the near-net-shape 3D printing process itself.

[0039] Experimental Group 2: Based on Experimental Group 1, a 0.5 mm thick functionally graded material transition region (composition gradually changing from CuW80 to QCr0.5) was introduced between the tungsten head and the copper tail. This group was used to verify the effect of the gradient transition structure on improving interface performance.

[0040] Experimental Group 3: Based on Experimental Group 1, 0.5 wt.% of chromium-plated tungsten fiber (Wf@Cr) was incorporated into the copper tail body. This group was used to verify the individual effect of fiber reinforcement.

[0041] Experimental Group 4 (Preferred Embodiment of the Invention): The entire scheme of the present invention is adopted, that is, it simultaneously includes a gradient transition layer (0.5 mm) and fiber reinforcement (0.5 wt% Wf@Cr).

[0042] Experimental Group 5: Based on Experimental Group 4, the fiber content was increased to 3.0 wt.%. This group was used to investigate the ultimate effect of fiber content on performance.

[0043] 2. Performance Test Results and Analysis: Table 1: Comparison of Interface and Basic Physical Properties

[0044] As can be seen, compared with the control group, the tensile strength and density of experimental group 1 have been slightly improved, proving that the 3D printing process itself can obtain a denser metallurgical bonding interface. The material utilization rate has increased significantly from 38% to 85%, directly demonstrating the huge advantages of near-net-shape forming.

[0045] The tensile strength of experimental group 2 (with only gradient layer) was significantly higher than that of experimental group 1, indicating that the gradient transition layer effectively alleviated the thermal stress concentration at the copper-tungsten interface, avoided abrupt performance changes, and improved the bonding strength by about 15.7%.

[0046] The strength of experimental group 3 (fiber only) was also better than that of experimental group 1, indicating that the fiber-reinforced phase played a role in pinning and load transfer, thus strengthening the copper matrix.

[0047] Experimental group 4 (Example 1) exhibited the best overall performance, with a tensile strength 38.3% higher than the control group, indicating that the synergistic effect of the gradient structure and fiber reinforcement is significantly better than either single measure. The high conductivity also benefited from good interfacial bonding and a dense structure.

[0048] Experimental group 5 showed a slight improvement in strength, but a slight decrease in conductivity, indicating that the increase in excessive fiber content has a slight negative impact on conductivity.

[0049] Table 2: Results of Arc Ablation Performance Test (Test Conditions: DC 40A, 10 cycles)

[0050] As can be seen, the arc erosion resistance of all experimental groups was better than that of the control group. Experimental group 4 (Example 1) showed the most outstanding performance, with a 36.5% reduction in mass loss and a 47.1% reduction in ablation pit depth compared to the control group.

[0051] The reasons for the above phenomena are: 1) The gradient transition layer avoids cracking and peeling caused by severe thermal stress at the interface; 2) The high-melting-point, high-strength tungsten fiber can effectively support the matrix under the action of electric arc, suppressing the splashing and evaporation of molten copper, and playing a "skeleton" role; 3) The addition of fibers improves the thermal stability of the material. The lowest contact resistance change rate indicates that the contact of the present invention can still maintain excellent conductive contact after multiple arc ablations.

[0052] Table 3. Test results of wear resistance (reciprocating friction and wear test, load 50 N, frequency 5 Hz, duration 2 h)

[0053] As can be seen, abrasion resistance is closely related to hardness. Experimental groups 3, 4, and 5 showed a significant increase in hardness due to the reinforcement effect of the fibers.

[0054] The wear rate of experimental group 4 (Example 1 of this invention) was reduced by 43.5% compared with the control group, and the coefficient of friction was also significantly reduced. This is because the uniformly distributed tungsten fibers can effectively resist the plowing effect on the workpiece during friction and play a role in reducing friction. The gradient structure ensures the support strength below the interface and avoids premature failure of the surface material due to excessive plastic deformation.

[0055] 3. Single-factor influence analysis: 3-1. With a fixed fiber addition amount of 0.5 wt.%, the gradient layer thickness was varied, and the results are shown in Table 4: Table 4 Influence of interfacial tensile strength

[0056] As can be seen, the tensile strength initially increases and then slightly decreases with increasing gradient layer thickness. The strength is highest at a thickness of 1.0 mm, but excessive thickness may cause the gradient layer itself to become a weak point. The range of 0.5 to 1.5 mm shows significant effects.

[0057] 3-2. The combined effect of fiber addition amount on abrasion resistance and electrical conductivity With the gradient layer thickness fixed at 0.5 mm, the fiber addition amount was varied, and the results are shown in Table 7: Table 7. Effect of abrasion resistance on conductivity

[0058] As can be seen, abrasion resistance continuously improves with increasing fiber content, but conductivity shows a slight decreasing trend after exceeding 1.5%. This indicates the existence of an optimal range (0.5%~1.5%), within which abrasion resistance can be significantly improved while maintaining extremely high conductivity.

[0059] In summary, this invention demonstrates, with detailed data, the comprehensive advantages of the fiber-reinforced gradient copper-tungsten dynamic arc contact preform described herein compared to traditional processes: 3D printing near-net-shape forming technology significantly increases the utilization rate of copper tail material from ~38% to over 85%, achieving cost reduction and efficiency improvement; by introducing a W-Cu functional gradient material transition zone, the tensile strength of the bonding surface is increased by more than 38%, solving the pain point of easy failure of traditional interfaces; thanks to the synergistic effect of the gradient structure and chromium-plated tungsten fiber reinforcement, the arc erosion resistance and wear resistance of the contact are improved by 36.5% and 43.5% respectively, significantly extending the service life; the gradient layer thickness and fiber addition amount can be used as key parameters to regulate and optimize the mechanical and electrical properties of the contact to meet the specific needs of different application scenarios.

Claims

1. A method for 3D printing a copper-tungsten moving arc contact blank, characterized in that, Includes the following steps: S1. Tungsten head machining: The tungsten head made of CuW80 alloy is precision machined to ensure that the dimensions and surface roughness of the mating surface meet the design requirements; S2. Fixing the tool: Fix the tungsten head processed in step S1 into the positioning hole of the substrate tool; S3. Electron beam 3D printing of fiber-reinforced gradient copper tail: In a vacuum environment, using electron beam cladding technology, copper tails are formed layer by layer on the bonding surface of the tungsten head. The printing process is as follows: S3-1. Printing a gradient transition layer: On the bonding surface of the tungsten head, a dual powder feeder is used to deliver tungsten powder and QCr0.5 alloy powder respectively. The powder feeding ratio of the two powders is controlled by a program to print a functionally graded material as a gradient transition layer. The gradient transition layer starts from the bonding surface of the tungsten head, and its overall composition is determined by both tungsten powder and QCr0.5 alloy powder: the tungsten content continuously decreases from 80 wt.% near the tungsten head to 0 wt.% near the copper tail; at the same time, the introduction of QCr0.5 alloy powder increases the copper content accordingly, while the chromium content remains stable at 0.5 wt.%. S3-2, Printing fiber-reinforced copper matrix: On the gradient transition layer, QCr0.5 alloy powder doped with reinforcing fibers is used for printing to form the main structure of the copper tail; S3-3, Printing working layer: On the outer surface of the fiber-reinforced copper matrix, a layer of arc-resistant copper alloy is printed as a working layer; S4. Post-processing: The contact blank printed in step S3 is subjected to hot isostatic pressing to obtain a copper-tungsten moving arc contact blank.

2. The method for 3D printing a copper-tungsten moving arc contact blank as described in claim 1, characterized in that, The thickness of the gradient transition layer in step S3-1 is 0.5~2.0 mm.

3. The method for 3D printing a copper-tungsten moving arc contact blank as described in claim 1, characterized in that, The reinforcing fiber used in step S3-2 is a tungsten fiber with a chromium-plated surface, with a diameter of 30~45 nm, a length of 4~5 μm, and a chromium layer thickness of 150~250 nm; the mass fraction of the reinforcing fiber in the QCr0.5 alloy powder is 0.5%~3.0%.

4. The method for 3D printing a copper-tungsten moving arc contact blank as described in claim 3, characterized in that, The QCr0.5 alloy powder used in step S3-2 is an atomized spherical powder with a particle size range of 53~105 μm.

5. The method for 3D printing a copper-tungsten moving arc contact blank as described in claim 1, characterized in that, In the electron beam cladding printing process of step S3, the core process parameters are: printing chamber vacuum degree of 2×10⁻³ Pa, printing speed of 15~20 mm / s, electron beam current of 20~30 mA, focal offset of 15~20, line offset of 0.05~0.10 mm, and single-layer printing thickness of 0.05-0.10 mm.

6. The method for 3D printing a copper-tungsten moving arc contact blank as described in claim 1, characterized in that, The hot isostatic pressing parameters in step S4 are: processing temperature 600~650℃, pressure 100~150 MPa, and holding time 1~2 h.

7. The method for 3D printing a copper-tungsten moving arc contact blank as described in claim 1, characterized in that, The substrate fixture in step S2 is provided with multiple contact positioning holes to enable batch clamping and printing of multiple contacts.

8. A copper-tungsten moving arc contact blank prepared by the method according to any one of claims 1 to 7, characterized in that, The copper-tungsten dynamic arc contact blank comprises, from bottom to top: Tungsten head made of CuW80 alloy (1); A gradient transition layer (2) is disposed on the tungsten head and has a continuously varying composition. The copper tail (3) is composed of QCr0.5 alloy containing a chromium-plated tungsten fiber reinforced phase and disposed on the gradient transition layer.

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