Sintering coupling rolling preparation method for force-electricity synergistic enhancement of copper-silver alloy

Abstract

The invention discloses a sintering coupling rolling preparation method for force-electricity synergistic enhancement of a copper-silver alloy, and relates to the technical field of alloy preparation. The method comprises the following steps: S1, carrying out ball milling on copper powder and silver powder, then carrying out spark plasma sintering, and cooling to room temperature to obtain a sintered sample; s2, the sintered sample is sequentially subjected to gradient grinding, polishing and cleaning, annealing treatment is conducted after drying, furnace cooling is conducted to the room temperature, and an annealed sample is obtained; and S3, the annealed sample is subjected to multi-pass small-deformation cold rolling, the deformation of each time is 10%-15%, the total deformation is 70%, annealing is conducted again, and the copper-silver alloy with force-electricity synergistic enhancement is obtained. According to the method, microstructure uniformity improvement, grain refinement, conductivity-hardness synergistic strengthening of the copper-silver alloy and strengthening of material current-carrying frictional wear performance are achieved, and the problems of mechanical-electrical property antagonism, poor microstructure uniformity, insufficient working condition adaptability and the like in the prior art are effectively solved.

Description

Technical Field

[0001] This invention relates to the field of alloy preparation technology, specifically to a sintering-coupled rolling preparation method for copper-silver alloys with synergistic mechanical and electrical enhancement. Background Technology

[0002] Copper-silver (Cu-Ag) alloys, possessing both the excellent conductivity of copper and the strengthening properties of silver, are a core candidate material for conductive slip rings in spacecraft, widely used in critical components of spacecraft energy and signal transmission. As a core component of spacecraft, the operational reliability of conductive slip rings directly determines the overall service performance and mission success or failure. They must withstand extreme conditions such as vacuum, temperature fluctuations, high current, and load coupling over extended periods. Especially during the dynamic contact process between the brush and the contact material, they face multiple failure risks, including Joule heating and frictional heat accumulation, thermal stress-induced crack initiation and propagation, increased wear due to debris accumulation, and arc damage. However, existing Cu-Ag alloys still exhibit core performance bottlenecks under these extreme conditions: mechanical strength and conductivity show a significant negative correlation, with strength increases often accompanied by decreased conductivity; surface hardness and wear resistance are insufficient, leading to surface peeling and wear failure; and the tribological properties and service stability under vacuum current-carrying conditions are insufficient to meet the requirements of next-generation spacecraft for highly reliable, long-life conductive slip rings.

[0003] To optimize the overall performance of Cu-Ag alloys, scholars both domestically and internationally have conducted research on various preparation and modification processes, but all have significant limitations. Casting and vacuum melting processes can achieve homogenization of alloy composition, but they are prone to forming coarse grains and segregation structures, resulting in poor synergy between mechanical properties and electrical conductivity, and making subsequent processing difficult. Single plastic deformation processes (such as cold rolling and equal-channel corner extrusion) can improve strength through dislocation strengthening, but they are prone to introducing internal stress, which can lead to stress relaxation under long-term service, and the negative impact on electrical conductivity is difficult to control. Traditional powder metallurgy sintering processes have high preparation efficiency, but sintered bodies are prone to porosity defects and insufficient interfacial bonding strength, making it impossible to achieve both density and performance synergy. Although coating technologies such as physical vapor deposition (PVD) and chemical vapor deposition (CVD) can improve surface wear resistance, the coating-substrate adhesion is weak and the deposition rate is low, making it difficult to meet the large-area uniform strengthening requirements of complex morphological components such as conductive slip rings. Even though existing research employs a composite process of powder metallurgy and plastic deformation, two major problems remain: First, coarse microstructures and segregation are easily formed during sintering, leading to a mismatch between the mechanical properties of the coating and the substrate; second, there is insufficient research on the friction and wear mechanism under vacuum-current coupling conditions, making it difficult to verify the actual service adaptability of the modified alloy. Summary of the Invention

[0004] The purpose of this invention is to provide a sintering-coupled rolling preparation method for copper-silver alloys with synergistic mechanical and electrical enhancement. This method improves the uniformity of microstructure, refines grains, enhances the synergistic strengthening of the electrical conductivity and hardness of the copper-silver alloy, and strengthens the material's current-carrying tribological wear resistance. It effectively solves the problems of antagonistic mechanical and electrical properties, poor microstructure uniformity, and insufficient adaptability to working conditions in existing methods.

[0005] The technical solution of this invention to solve the above-mentioned technical problems is as follows: A method for preparing copper-silver alloys through sintering-coupled rolling with synergistic mechanical and electrical reinforcement is provided, comprising the following steps:

[0006] S1. Ball mill the copper powder and silver powder, then perform spark plasma sintering, and cool to room temperature to obtain the sintered sample;

[0007] During spark plasma sintering, the mixed powder after spheroidizing is loaded into a graphite mold, pre-pressed at 20 MPa for 5-8 min, and then heated to 700 ℃ at a rate of 40-60 ℃ / min under vacuum conditions of 20-40 MPa, and then heated to 800 ℃ at a rate of 20-30 ℃ / min, and held for 6-10 min.

[0008] S2. The sintered sample is successively subjected to gradient grinding, polishing and cleaning, dried and then annealed. It is then cooled to room temperature in the furnace to obtain the annealed sample.

[0009] S3. The annealed sample is subjected to multiple small-deformation cold rolling, with each deformation amount being 10%-15%, and the total deformation amount being 70%. It is then annealed again to produce a copper-silver alloy with synergistic enhancement of strength and electrical properties.

[0010] Furthermore, in step S1, the copper powder is electrolytic dendritic copper powder with a purity of 99.99% and a particle size of ≤50 μm, and the silver powder is spherical copper powder with a purity of 99.99% and a particle size of 1-3 μm; the silver powder content is 5-15 wt%.

[0011] Furthermore, the silver powder content is 12.5 wt%.

[0012] Furthermore, in step S1, during ball milling, the ball-to-material ratio is 10:1, the rotation speed is 150-250 rpm, and the milling is paused for 15 minutes every 30 minutes, for a total of 2-4 hours.

[0013] Furthermore, in step S1, during spark plasma sintering, the mixed powder after spheroidizing is loaded into a graphite mold, pre-pressed at 20 MPa for 6 min, and then heated to 700 ℃ at a rate of 50 ℃ / min under vacuum conditions of 20-40 MPa, and then heated to 800 ℃ at a rate of 25 ℃ / min, and held for 8 min.

[0014] Furthermore, in step S2, gradient polishing is performed using 180-2000 grit silicon carbide sandpaper; and ultrasonic cleaning is performed in an ethanol solution.

[0015] Furthermore, in step S2, the temperature is increased to 500 ℃ at a rate of 5-15 ℃ / min and held at that temperature for 1 h.

[0016] Furthermore, in step S2, the temperature is increased to 500 ℃ at a rate of 10 ℃ / min and held at that temperature for 1 h.

[0017] Furthermore, in step S3, annealing is performed at 350-450 ℃ for 1 h.

[0018] Furthermore, in step S3, the annealing is carried out at 400 °C for 1 h.

[0019] The copper-silver alloy sample, which had been annealed to eliminate internal stress, was rolled. To prevent impurities from embedding into the alloy matrix during rolling and affecting the material properties, alcohol was sprayed onto the surface of the rolling rollers first, and then the rollers were thoroughly cleaned with a lint-free cloth to remove any attached impurities. Subsequently, the rolling equipment was adjusted to keep the speed of the upper and lower rollers consistent. After rolling, the sample was annealed again to eliminate work hardening and residual stress caused by material deformation during the rolling process.

[0020] The present invention also provides a mechanically and electrically reinforced copper-silver alloy, which is prepared by the above-described method.

[0021] The present invention has the following beneficial effects:

[0022] 1. Precise control of microstructure to achieve synergistic optimization of material mechanical and electrical properties: This invention, through the coupling of SPS sintering and 70% cold rolling process, can precisely control the morphology and distribution of the silver phase. As the silver content increases, the silver phase gradually evolves from isolated islands into a continuous network structure. Under the synergistic effect of dislocation strengthening and stacking fault energy reduction, a balance is achieved between increased hardness and a gentle decline in electrical conductivity. Furthermore, the cold rolling process further improves the uniformity of the silver phase, making the network structure more continuous, breaking through the performance constraints of traditional processes. Experimental data show that the Cu-12.5Ag alloy prepared by this invention has the best comprehensive performance, with a hardness of 121.4 HV, which is about 48% higher than that of pure copper. At the same time, the electrical conductivity remains at a high level of 91.6% IACS. Compared with the same composition un-cold-rolled alloy prepared by traditional processes, the hardness is increased by more than 20%, and the electrical conductivity is also improved, perfectly meeting the dual core requirements of high wear resistance and high conductivity for conductive slip rings.

[0023] 2. Significantly improved micro-region mechanical properties and enhanced interfacial bonding stability: Through the synergistic mechanism of "sintering densification-cold rolling strengthening", the mechanical properties of the alloy micro-region and the interfacial bonding strength are significantly improved. Nanoscale scratch testing verifies that the alloy interface is tightly bonded and the scratch depth is uniformly distributed, proving that the cold rolling process can effectively eliminate interface defects, improve interfacial bonding stability, and avoid interface peeling failure during service.

[0024] 3. Optimal Wear Stability and Reliability for Vacuum Current-Carrying Conditions: The Cu-Ag alloy obtained by the method of this invention exhibits wear behavior that can be precisely controlled through atmosphere, rolling process, and silver content, making it suitable for extreme vacuum conditions. The cold rolling process significantly improves the alloy's wear stability by increasing surface hardness and refining the microstructure. The vacuum environment effectively suppresses oxidation-induced delamination wear, greatly reducing wear volume and making the wear morphology more regular. The wear rate of the Cu-12.5Ag alloy is 2.6 × 10⁻⁶. -5 mm 3 / (N•m), which exhibits the best point contact stability, achieving the optimal balance between strengthening effect and tissue stability.

[0025] 4. This invention proposes a sintering-coupled rolling preparation method for copper-silver alloys with synergistic mechanical and electrical enhancement. It utilizes a combination of mechanical ball milling pretreatment, spark plasma sintering (SPS), and cold rolling processes, along with multi-stage annealing control, to construct a high-performance Cu-Ag alloy. SPS sintering technology offers advantages such as high energy density, rapid cooling, and good sintering density, effectively suppressing grain growth and compositional segregation. The cold rolling process, through multi-pass small deformation control, introduces a uniform dislocation structure for strengthening, while annealing eliminates internal stress and optimizes the microstructure. This synergistic coupling of the two processes overcomes the bottleneck of the negative correlation between strength and conductivity in Cu-Ag alloys. Furthermore, by precisely controlling the silver content and process parameters, the uniformity of the alloy's microstructure and interfacial bonding performance are further optimized, simultaneously improving mechanical strength, wear resistance, and conductivity to meet the extreme service requirements of conductive slip rings.

[0026] 5. The Cu-Ag alloy prepared by the process of this invention achieves synergistic enhancement of mechanical strength and electrical conductivity compared with alloys and original matrices prepared by traditional processes. The friction coefficient and wear rate under vacuum current-carrying conditions are significantly reduced. After subsequent rolling and annealing treatment, the microstructure stability and interfacial bonding strength are further improved. This can effectively solve the problem of shortened service life of conductive slip rings caused by surface wear and performance degradation, and provide a reliable technical path for the preparation of high-performance conductive slip ring materials.

[0027] 6. This invention significantly improves the vacuum current-carrying tribological wear performance of copper-silver alloys through the synergistic control of rolling and heat treatment processes, ensuring stable contact resistance output during dynamic sliding contact while drastically reducing wear volume and effectively enhancing the alloy's service reliability. Simultaneously, it achieves a uniform material microstructure, significantly improving the balance between hardness and conductivity of the copper-silver alloy, thus enhancing its vacuum current-carrying tribological wear performance. Attached Figure Description

[0028] Figure 1 The images show the SEM morphology and EDS spectra of the annealed sample Cu-12.5Ag in Example 2; Figure a is the SEM image, Figure b is a magnified view and EDS spots on the sample surface, Figure c is the EDS spectrum of oxygen, Figure d is the EDS spectrum of copper, and Figure e is the EDS spectrum of silver.

[0029] Figure 2 This is a schematic diagram of the EDS results at the interface between the silver-enriched phase and the matrix; Figure a shows the line scan direction of the sample surface, Figure b shows the relative intensities of O, Cu, and Ag elements in the line scan, Figure c shows the relative intensity of copper, and Figure d shows the relative intensity of silver.

[0030] Figure 3 The electrical conductivity test results of the alloys in Examples 1-3 and Comparative Example 1 before and after rolling are shown in Figure a; the eddy current conductivity before and after cold rolling is shown in Figure b; the difference in electrical conductivity between different processes and Examples 1 and 2 is shown in Figure b.

[0031] Figure 4 This is a schematic diagram showing the coupling changes of eddy current conductivity and Vickers hardness of the alloys before and after rolling in Examples 1-3 and Comparative Example 1; Figure a shows the changes before cold rolling, and Figure b shows the changes after cold rolling.

[0032] Figure 5 The images show SEM images of the alloys in Examples 1-3 and Comparative Example 1 before and after rolling; image a shows Cu-10Ag before cold rolling, image b shows Cu-12.5Ag before cold rolling, image c shows Cu-15Ag before cold rolling, image d shows Cu-10Ag after cold rolling, image e shows Cu-12.5Ag after cold rolling, and image f shows Cu-15Ag after cold rolling.

[0033] Figure 6 The diagram shows the results of nano-scratch testing of the alloys in Examples 1-3 and Comparative Example 1; Figure a is Cu, Figure b is Cu-10Ag, Figure c is Cu-12.5Ag, and Figure d is Cu-15Ag.

[0034] Figure 7The following are the test results of the current-carrying tribological wear properties of the alloys in Examples 1-3 and Comparative Example 1; Figure a shows the friction coefficient before cold rolling, Figure b shows the contact resistance before cold rolling, Figure c shows the friction coefficient after cold rolling, and Figure d shows the contact resistance after cold rolling.

[0035] Figure 8 Figure 1 shows the three-dimensional contours of scratches and wear amounts of the alloys in Examples 1-3 and Comparative Example 1; Figure a shows the three-dimensional cross-section of Cu, Figure b shows the three-dimensional cross-section of Cu-10Ag, Figure c shows the three-dimensional cross-section of Cu-12.5Ag, Figure d shows the three-dimensional cross-section of Cu-15Ag, and Figure e shows the wear amount. Detailed Implementation

[0036] The present invention will be further illustrated below with reference to specific embodiments, but the embodiments do not limit the present invention in any way. Unless otherwise specified, the reagents, methods, and equipment used in the present invention are conventional reagents, methods, and equipment in this technical field.

[0037] Example 1:

[0038] A method for preparing copper-silver alloys through sintering-coupled rolling with synergistic mechanical and electrical enhancement includes the following steps:

[0039] S1. Electrolytic dendritic copper powder (purity 99.99%, particle size ≤50 μm) and spherical copper powder (purity 99.99%, particle size 1-3 μm) are ball-milled with a silver powder content of 10 wt%. Then, they are subjected to spark plasma sintering and cooled to room temperature to obtain sintered samples.

[0040] During ball milling, the ball-to-material ratio was 10:1, the rotation speed was 200 rpm, and the milling was paused for 15 minutes every 30 minutes for 3 hours. During spark plasma sintering, the mixed powder after ball milling was loaded into a graphite mold, pre-pressed at 20 MPa for 6 minutes, and then heated to 700 ℃ at a rate of 50 ℃ / min under a vacuum of 30 MPa, and then heated to 800 ℃ at a rate of 25 ℃ / min, and held for 8 minutes.

[0041] S2. The sintered sample was polished with 180-2000 grit silicon carbide sandpaper in a gradient. After polishing, it was placed in an ethanol solution for ultrasonic cleaning. After drying, the temperature was increased to 500℃ at a rate of 10℃ / min and kept at a constant temperature for 1 h. The sample was then cooled to room temperature in the furnace to obtain the annealed sample.

[0042] S3. The annealed sample is subjected to multiple small deformation cold rolling, with each deformation amount being 10%-15% and the total deformation amount being 70%. The sample is then annealed at 400 ℃ for 1 h to obtain a copper-silver alloy with synergistic enhancement of strength and electrical properties.

[0043] Example 2:

[0044] A method for preparing copper-silver alloys through sintering-coupled rolling with synergistic mechanical and electrical enhancement includes the following steps:

[0045] S1. Electrolytic dendritic copper powder (purity 99.99%, particle size ≤50 μm) and spherical copper powder (purity 99.99%, particle size 1-3 μm) are ball-milled to a silver powder content of 12.5 wt%. Then, they are subjected to spark plasma sintering and cooled to room temperature to obtain sintered samples.

[0046] During ball milling, the ball-to-material ratio was 10:1, the rotation speed was 200 rpm, and the milling was paused for 15 minutes every 30 minutes for 3 hours. During spark plasma sintering, the mixed powder after ball milling was loaded into a graphite mold, pre-pressed at 20 MPa for 6 minutes, and then heated to 700 ℃ at a rate of 50 ℃ / min under a vacuum of 30 MPa, and then heated to 800 ℃ at a rate of 25 ℃ / min, and held for 8 minutes.

[0047] S2. The sintered sample was polished with 180-2000 grit silicon carbide sandpaper in a gradient. After polishing, it was placed in an ethanol solution for ultrasonic cleaning. After drying, the temperature was increased to 500℃ at a rate of 10℃ / min and kept at a constant temperature for 1 h. The sample was then cooled to room temperature in the furnace to obtain the annealed sample.

[0048] S3. The annealed sample is subjected to multiple small deformation cold rolling, with each deformation amount being 10%-15% and the total deformation amount being 70%. The sample is then annealed at 400 ℃ for 1 h to obtain a copper-silver alloy with synergistic enhancement of strength and electrical properties.

[0049] Example 3:

[0050] A method for preparing copper-silver alloys through sintering-coupled rolling with synergistic mechanical and electrical enhancement includes the following steps:

[0051] S1. Electrolytic dendritic copper powder (purity 99.99%, particle size ≤50 μm) and spherical copper powder (purity 99.99%, particle size 1-3 μm) are ball-milled with a silver powder content of 15 wt%. Then, they are subjected to spark plasma sintering and cooled to room temperature to obtain sintered samples.

[0052] During ball milling, the ball-to-material ratio was 10:1, the rotation speed was 200 rpm, and the milling was paused for 15 minutes every 30 minutes for 3 hours. During spark plasma sintering, the mixed powder after ball milling was loaded into a graphite mold, pre-pressed at 20 MPa for 6 minutes, and then heated to 700 ℃ at a rate of 50 ℃ / min under a vacuum of 30 MPa, and then heated to 800 ℃ at a rate of 25 ℃ / min, and held for 8 minutes.

[0053] S2. The sintered sample was polished with 180-2000 grit silicon carbide sandpaper in a gradient. After polishing, it was placed in an ethanol solution for ultrasonic cleaning. After drying, the temperature was increased to 500℃ at a rate of 10℃ / min and kept at a constant temperature for 1 h. The sample was then cooled to room temperature in the furnace to obtain the annealed sample.

[0054] S3. The annealed sample is subjected to multiple small deformation cold rolling, with each deformation amount being 10%-15% and the total deformation amount being 70%. The sample is then annealed at 400 ℃ for 1 h to obtain a copper-silver alloy with synergistic enhancement of strength and electrical properties.

[0055] Comparative Example 1:

[0056] The difference between Comparative Example 1 and Example 1 is that the silver powder content is 0.

[0057] Experimental example:

[0058] 1. Obtain SEM images, magnified morphology, EDS points, and elemental mapping diagrams of the annealed sample (Cu-12.5Ag) after spark plasma sintering and annealing in Example 2, such as... Figure 1 As shown; the elemental composition at each point is shown in Table 1, and the EDS results at the interface between the silver-enriched phase and the matrix are as follows. Figure 2 As shown.

[0059] Table 1. Elemental composition of EDS points

[0060]

[0061] Depend on Figure 1 It can be seen that the Ag phase is uniformly dispersed in the Cu matrix. According to Table 1 and the corresponding EDS spectra of O, Cu and Ag elements, the gray area corresponds to the Cu matrix and the silver area is the Ag phase.

[0062] Depend on Figure 2 It can be seen that the intensity distribution curves of Ag and Cu elements show a continuous and smooth variation in the interface region, indicating that there are no obvious gaps or discontinuities at the Ag-Cu interface, and the interface bonding is good.

[0063] 2. Systematic testing and analysis were conducted on the electrical conductivity properties of the alloys in Examples 1-3 and Comparative Example 1 before and after rolling, and the differences in electrical conductivity between the alloys obtained by different processes and those of Examples 1 (Cu-10Ag) and 2 (Cu-12.5Ag) of this invention were also analyzed. The results are as follows: Figure 3 As shown.

[0064] Depend on Figure 3As can be seen from the eddy current conductivity results, the conductivity of both the samples before and after cold rolling shows a decreasing trend with increasing silver content. A similar trend has been reported in previous studies, mainly attributed to the addition of silver particles. The introduction of silver increases defects such as lattice distortion and grain interfaces, thereby hindering dislocation movement and thus increasing the alloy's strength. Simultaneously, these defects act as scattering centers for free electrons, increasing conductivity and decreasing electrical conductivity. Notably, the cold rolling process significantly improved the eddy current conductivity of Cu-Ag alloys across all compositions; the conductivity of the Cu-15Ag alloy increased by 33.1%, reaching 84% IACS.

[0065] The results showing differences in conductivity across different processes demonstrate that the preparation method significantly impacts the conductivity of Cu-Ag alloys. Alloys produced using powder metallurgy or casting processes ( Figure 3 The region to the left of b typically exhibits electrical conductivity within 80-95% of the IACS (International Copper Association Copper Alloy Classification System) range. In contrast, alloys prepared solely through plastic deformation processes ( Figure 3 The region to the right of b exhibits lower electrical conductivity. The hybrid process combines powder metallurgy with plastic deformation (…). Figure 3 Combining the intermediate region (b) with other methods can typically produce alloys with superior conductivity compared to those obtained using either method alone. In this invention, Cu-10Ag and Cu-12.5Ag alloys prepared by spark plasma sintering (SPS) and then subjected to cold rolling processes achieved eddy current conductivity levels of 98.9% IACS and 91.6% IACS, respectively, placing them among the Cu-Ag alloys reported to date. These results not only confirm the advantages of hybrid powder metallurgy-plastic deformation processes in improving the conductivity of Cu-Ag alloys but also provide theoretical and technical guidance for developing Cu-Ag-based conductive materials that simultaneously possess high strength and high conductivity.

[0066] 3. The coupling changes in eddy current conductivity and Vickers hardness of the alloys in Examples 1-3 and Comparative Example 1 before and after rolling, and their SEM images, are shown below. Figure 4 and Figure 5 As shown.

[0067] Depend on Figure 4 and Figure 5It is observed that the hardness decreases significantly when the Ag content reaches 15 wt%. In the initial state, the Ag phase in the Cu-10Ag alloy exhibits a relatively dispersed, island-like distribution. In contrast, higher Ag contents (Cu-12.5Ag and Cu-15Ag) lead to more concentrated and partially interconnected Ag-rich regions, accompanied by an increase in the density of microstructural defects. These defects and heterogeneous phase interfaces promote local strain accumulation during deformation, thereby increasing hardness. Simultaneously, they also increase the likelihood of electron scattering at interfaces and defects, leading to a decrease in electrical conductivity. Notably, the hardness decreases significantly when the Ag content increases from 12.5% ​​to 15%. This phenomenon can be attributed to the significant aggregation and partial interconnection of Ag-rich regions at high Ag contents, as observed by SEM. Figure 5 c was thus revealed. This interconnected Ag phase reduces the dispersion strengthening effect and contributes to local strain tolerance, thereby weakening the load-bearing capacity of the Cu matrix.

[0068] Meanwhile, after rolling deformation, although a certain degree of trade-off still exists between strength and conductivity, the overall balance between the two has been significantly improved; that is, the material's hardness increases while its electrical conductivity also improves. For example... Figure 5 d- Figure 5 The SEM observations shown in f reveal that rolling deformation significantly promotes microstructure refinement and induces the silver phase to extend along the rolling direction, while simultaneously reducing defect size and improving interface continuity. The more uniform and ordered distribution of the silver phase facilitates electron transport by providing a less tortuous conductive path. At the same time, the increased dislocation density and refined microstructure contribute to improved hardness observed after rolling. Furthermore, the grain refinement induced by rolling shortens the effective electron scattering length, thereby reducing the probability of electron scattering and improving conductivity. Therefore, rolling deformation, to some extent, mitigates the inherent negative correlation between hardness and conductivity in Cu-Ag alloys.

[0069] 4. Nanoscale scratch tests were performed on the alloys obtained in Examples 1-3 and Comparative Example 1. The test conditions included the original sample surface before cold rolling, the sample surface after cold rolling, and the cross-section of the sample after cold rolling. The results are as follows: Figure 6 As shown.

[0070] Depend on Figure 6As can be seen, all curves show a significant peak depth in the initial sliding phase, followed by a rapid decrease in the range of approximately 10 to 20 micrometers, eventually reaching a near-steady state after 40 to 60 micrometers. This behavior can be attributed to the initial contact indentation, plastic flow / accumulation of the material, and the evolution of contact conditions caused by debris and adhesion during the scratching process. Compared to the original sample before cold rolling, the scratch depth of the cold-rolled sample was significantly reduced on both the surface and cross-section, indicating that the strain hardening and high dislocation density generated during cold rolling significantly improved the resistance of the surface and subsurface layers to deformation. Notably, the cross-section after cold rolling showed the lowest scratch depth throughout the sliding process, indicating the existence of a hardening gradient from the surface to the interior. This is likely due to the retention of more plastic accumulation or a denser microstructure in the cross-sectional region, thereby enhancing the resistance to indentation and plastic shear.

[0071] Furthermore, analysis of Cu-12.5Ag revealed that the addition of silver further reduced the depth of the quasi-steady-state scratch, reflecting an improvement in scratch resistance. This effect stems from two mechanisms: solid solution strengthening and the presence of dispersed silver-rich precipitates that impede dislocation movement. When the silver phase is distributed in the form of fine dispersed particles, it enhances local shear strength and suppresses large-scale plastic flow. Among these three states, Cu-12.5Ag exhibited the smallest difference and the lowest overall scratch depth, indicating that at this composition, an optimal balance was achieved between precipitation strengthening and plastic distribution.

[0072] 5. The alloys from Examples 1-3 and Comparative Example 1 were subjected to current-carrying tribological wear performance tests under vacuum conditions. The results are as follows: Figure 7 As shown.

[0073] Depend on Figure 7 It is evident that under vacuum conditions, the overall coefficient of friction (COF) is significantly reduced, and large-scale fluctuations in contact resistance (CR) are largely suppressed. The extremely low oxygen content in the rapidly formed copper oxide film under vacuum constraints promotes direct metal-to-metal contact between the indenter and the alloy surface, making the friction process primarily influenced by adhesion and alloy transfer layer mechanisms. Therefore, the steady-state COF decreases significantly. However, the COF of the original sample before cold rolling exhibits a trend of large fluctuations, while the COF of the sample after rolling shows a trend of stability and small fluctuations. This behavior is particularly critical for conductive slip rings in aerospace applications. In these applications, minimizing fluctuations and avoiding high COF values ​​in the short term are essential to ensuring long-term electrical contact stability.

[0074] Regarding contact resistance stability, such as Figure 7 b and Figure 7As shown in Figure d, the stability of contact resistance directly affects the current-carrying reliability of the conductive slip ring. Before cold rolling, the contact resistance of pure Cu in the original samples fluctuated, while the contact resistance of the silver-containing copper-silver alloy showed a smaller fluctuation trend during the wear process. All original samples exhibited large fluctuations in contact resistance. After rolling, the stability of contact resistance in all samples significantly improved, with a substantial reduction in fluctuation amplitude. Furthermore, the contact resistance level of the silver-containing alloy further decreased; for example, the contact resistance of the rolled silver-containing sample stabilized at around 50 mΩ. This is mainly attributed to the rolling process densifying the alloy structure and refining the grains, forming a more continuous and stable conductive path. This results in a low and stable contact resistance during current-carrying friction, meeting the high conductivity reliability requirements of aerospace conductive slip rings.

[0075] 6. Obtain the three-dimensional contours of scratches and wear amounts of the alloys in Examples 1-3 and Comparative Example 1 under vacuum conditions, such as... Figure 8 As shown in Table 2, its wear rate is as follows.

[0076] Table 2 Wear rate of alloys with different silver contents before and after cold rolling under vacuum conditions

[0077]

[0078] Depend on Figure 8 It can be seen that the wear scratches of the original sample before cold rolling have a deeper depth (H) and a larger width (D). The wear scratches of the original Cu-15Ag sample have a depth of 6.361 μm and a width of 164.5 μm, corresponding to a wear volume as high as 33580.86 μm. 3 After rolling, the depth and width of wear scratches on each alloy were significantly reduced. The wear scratch depth of the Cu-12.5Ag rolled sample decreased to 2.0085 μm, and the width decreased to 114 μm; the wear scratch depth of the Cu-15Ag rolled sample decreased to 2.141 μm, and the width decreased to 182.4 μm. The wear volume was also significantly reduced compared to the original state, with the wear volume of the Cu-15Ag rolled sample being only 9193.95 μm. 3 The wear volume decreased by 72.6%, with the Cu-12.5Ag rolled sample exhibiting the lowest wear volume at only 4044.56 μm. 3 This indicates that rolling treatment, by refining grains and improving alloy hardness and microstructure uniformity, effectively inhibits material loss during the wear process and significantly enhances the wear resistance of the alloy.

[0079] As shown in Table 2, the wear rates of the original samples Cu-10Ag, Cu-12.5Ag, and Cu-15Ag before cold rolling were 1.6 × 10⁻⁶. −4 mm 3 / (N·m), 7.6×10 −5 mm3 / (N·m) 2.2×10 −4 mm 3 / (N·m), after cold rolling treatment according to the present invention, its wear rate is reduced to 4.9×10. −5 mm 3 / (N·m), 2.6×10 −5 mm 3 / (N·m), 6.0×10 −5 mm 3 / (N·m), the wear rate decreased by 69.4%-72.7%; although the wear rate of the pure Cu sample in Comparative Example 1 changed slightly, the wear rate of the silver alloy was significantly reduced, which fully proves that the discharge plasma sintering coupled rolling process of the present invention can effectively improve the vacuum current-carrying tribological wear performance of copper-silver alloy.

[0080] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing copper-silver alloys through sintering-coupled rolling with synergistic mechanical and electrical reinforcement, characterized in that, Includes the following steps: S1. Ball mill the copper powder and silver powder, then perform spark plasma sintering, and cool to room temperature to obtain the sintered sample; During spark plasma sintering, the mixed powder after spheroidizing is loaded into a graphite mold, pre-pressed at 20 MPa for 5-8 min, and then heated to 700 ℃ at a rate of 40-60 ℃ / min under vacuum conditions of 20-40 MPa, and then heated to 800 ℃ at a rate of 20-30 ℃ / min, and held for 6-10 min. S2. The sintered sample is successively subjected to gradient grinding, polishing and cleaning, dried and then annealed. It is then cooled to room temperature in the furnace to obtain the annealed sample. S3. The annealed sample is subjected to multiple small-deformation cold rolling, with each deformation amount being 10%-15%, and the total deformation amount being 70%. It is then annealed again to produce a copper-silver alloy with synergistic enhancement of strength and electrical properties.

2. The method for preparing copper-silver alloy by sintering-coupled rolling with synergistic mechanical-electrical reinforcement according to claim 1, characterized in that, In step S1, the copper powder is electrolytic dendritic copper powder with a purity of 99.99% and a particle size of ≤50 μm, and the silver powder is spherical copper powder with a purity of 99.99% and a particle size of 1-3 μm; the silver powder content is 5-15 wt%.

3. The method for preparing copper-silver alloys by sintering-coupled rolling with synergistic mechanical-electrical reinforcement according to claim 1, characterized in that, In step S1, during ball milling, the ball-to-material ratio is 10:1, the rotation speed is 150-250 rpm, and the milling is paused for 15 minutes every 30 minutes for 2-4 hours.

4. The method for preparing copper-silver alloys by sintering-coupled rolling with synergistic mechanical-electrical reinforcement according to claim 1, characterized in that, In step S1, during spark plasma sintering, the mixed powder after spheroidizing is loaded into a graphite mold, pre-pressed at 20 MPa for 6 min, and then heated to 700 ℃ at a rate of 50 ℃ / min under vacuum conditions of 20-40 MPa, and then heated to 800 ℃ at a rate of 25 ℃ / min, and held for 8 min.

5. The method for preparing copper-silver alloys by sintering-coupled rolling with synergistic mechanical-electrical reinforcement according to claim 1, characterized in that, In step S2, gradient polishing is performed using 180-2000 grit silicon carbide sandpaper; ultrasonic cleaning is then performed in an ethanol solution.

6. The method for preparing copper-silver alloys by sintering-coupled rolling with synergistic mechanical-electrical reinforcement according to claim 1, characterized in that, In step S2, the temperature is increased to 500 ℃ at a rate of 5-15 ℃ / min and held at that temperature for 1 h.

7. The method for preparing copper-silver alloys by sintering-coupled rolling with synergistic mechanical-electrical reinforcement according to claim 1, characterized in that, In step S3, annealing is performed at 350-450 ℃ for 1 h.

8. A copper-silver alloy with synergistic mechanical and electrical enhancement, characterized in that, It is prepared by the method described in any one of claims 1-7.

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