High-strength corrosion-resistant copper-based composite material and preparation process thereof

Abstract

The application discloses a high-strength corrosion-resistant copper-based composite material and a preparation process thereof. The composite material comprises a continuous copper matrix, a plurality of reinforcing belts extending along a first direction and being distributed at intervals, and an interface barrier region. The reinforcing belt comprises a ceramic reinforcing phase, and the surface of the ceramic reinforcing phase is provided with an interface modification layer containing nickel and rare earth elements. The interface barrier region is distributed in an interface region between the continuous copper matrix and the reinforcing belt and in the continuous copper matrix between adjacent reinforcing belts, and comprises a rare earth graphene composite sheet, a Ni-rich interface region and interface rare earth oxide particles. The preparation process comprises surface activation of the ceramic reinforcing phase, deposition of the interface modification layer, mixing and coordination of the oxidized graphene and the rare earth salt, reduction treatment, preparation of a composite suspension, directional freezing, freeze-drying, copper liquid infiltration, densification treatment and aging treatment. The application can balance the strength, electrical conductivity and salt mist corrosion resistance of the material at a lower ceramic reinforcing phase content.

Description

Technical Field

[0001] This invention belongs to the field of copper-based composite materials and their preparation technology, specifically relating to a high-strength corrosion-resistant copper-based composite material and its preparation process. Background Technology

[0002] Copper has good electrical and thermal conductivity and is easy to process, and is often used in electrical contacts, conductive connectors, heat dissipation structures, and wear-resistant conductive parts. However, pure copper has limited strength and wear resistance, and is prone to problems such as plastic deformation, surface wear, pitting corrosion, and interface corrosion under salt spray, humid heat, friction, or impact environments.

[0003] To improve the strength and wear resistance of copper materials, existing technologies often employ ceramic particles, carbon materials, or alloying elements to reinforce the copper matrix. For example, adding ceramic reinforcing phases such as SiC and Al2O3 to copper can improve the material's hardness and load-bearing capacity; adding sheet materials such as graphene to copper can improve its barrier properties; and adding elements such as nickel and rare earth elements can also improve the corrosion resistance and interfacial stability of copper materials.

[0004] However, existing copper-based composite materials still have some problems. The wettability between the ceramic reinforcing phase and the copper matrix is ​​poor, and pores or unbonded regions easily form at the interface, allowing corrosive media and cracks to easily propagate along this interface. Graphene tends to agglomerate in the copper matrix and is difficult to stably distribute at locations where it needs to block corrosive media and crack propagation. If nickel and rare earth elements are simply added randomly to the copper matrix, it is also difficult to form a stable barrier structure at the interface between the ceramic reinforcing phase and the copper matrix. On the other hand, if a large amount of ceramic reinforcing phase is added to improve strength, it can easily reduce the continuous conductivity of the copper matrix.

[0005] Therefore, there is a need to provide a copper-based composite material and its preparation process, which enables the reinforcing phase, graphene, nickel and rare earth components to be distributed in predetermined positions, thereby improving the strength and corrosion resistance of the material while maintaining the continuous conductive channels of the copper matrix. Summary of the Invention

[0006] The purpose of this invention is to provide a high-strength and corrosion-resistant copper-based composite material and its preparation process, which can improve the problems of insufficient bonding between the ceramic reinforcing phase and the copper matrix, unstable graphene distribution, and difficulty in effectively enriching nickel and rare earth components at the interface in existing copper-based composite materials.

[0007] The above-mentioned technical objective of the present invention is achieved through the following technical solution: a high-strength corrosion-resistant copper-based composite material, comprising a continuous copper matrix, a reinforcing strip, and an interface barrier region; There are multiple reinforcing strips, which are spaced apart in the continuous copper matrix. The reinforcing strips extend along a first direction, and the continuous copper matrix fills the space between two adjacent reinforcing strips. The reinforcing strip comprises a ceramic reinforcing phase, and the surface of the ceramic reinforcing phase is provided with an interface modification layer containing nickel and rare earth elements; The interface blocking region is distributed in the interface region between the continuous copper substrate and the reinforcing strip, and in the continuous copper substrate between adjacent reinforcing strips. The interface barrier region includes a rare earth graphene composite sheet, a Ni-rich interface region, and interface rare earth oxide particles.

[0008] Furthermore, based on the total volume of the high-strength corrosion-resistant copper-based composite material, the volume fraction of the ceramic reinforcing phase is 1.5–5 vol%; based on the total mass of the high-strength corrosion-resistant copper-based composite material, the graphene content is 0.15–0.60 wt%, the total nickel content is 0.3–1.0 wt%, and the total rare earth element content is 0.03–0.20 wt%.

[0009] Furthermore, the ceramic reinforcing phase is selected from one or more of SiC, Al2O3, TiC, WC, and ZrO2; the rare earth element is selected from one or more of Y, Ce, La, and Nd.

[0010] Furthermore, the average spacing of the reinforcing strips is 20–80 μm; within a 100 μm × 100 μm cross-sectional observation area, the proportion of reinforcing strips whose extension direction is at an angle of less than 15° to the first direction is not less than 60%.

[0011] Furthermore, the thickness of the interface modification layer is 50–500 nm, and the coverage of the interface modification layer on the surface of the ceramic reinforcing phase is not less than 60%. When the interface between the continuous copper matrix and the reinforcing strip is crossed by EDS line scan, the peak atomic percentage of Ni element within 1 μm on both sides of the interface is more than twice the average atomic percentage of Ni element in the continuous copper matrix region more than 5 μm away from the interface, and the peak atomic percentage of rare earth element within 1 μm on both sides of the interface is more than twice the average atomic percentage of rare earth element in the continuous copper matrix region more than 5 μm away from the interface.

[0012] This invention also provides a preparation process for a high-strength, corrosion-resistant copper-based composite material, the preparation process comprising the following steps: S1, Surface activation of ceramic reinforced phase; S2. An interface modification layer containing nickel and rare earth elements is deposited on the surface of the ceramic reinforcing phase to obtain the modified ceramic reinforcing phase; S3, graphene oxide and rare earth salt solution mixed coordination; S4. Reduction treatment to obtain rare earth graphene composite sheets; S5. The modified ceramic reinforcing phase, rare earth graphene composite sheet and nickel powder are dispersed in a freezing medium to obtain a composite suspension. S6. Directional freezing to form a layered frozen body; S7. Freeze-dry to obtain a layered porous preform; S8. Copper liquid is melted and infiltrated to obtain a copper-based composite billet; S9. Densification treatment, wherein the densification treatment is hot pressing or hot isostatic pressing; S10. Aging treatment, which causes the nickel elements in the interface modification layer and the nickel elements provided by the nickel powder to segregate in the interface region between the continuous copper matrix and the reinforcing strip, and form a Ni-rich interface region and interface rare earth oxide particles. S11, a high-strength and corrosion-resistant copper-based composite material was obtained.

[0013] Furthermore, in step S1, the ceramic reinforcing phase is ultrasonically cleaned in ethanol for 10-30 minutes, then treated with a 5-10% hydrofluoric acid or sodium hydroxide solution for 3-10 minutes. After cleaning until neutral, it is sensitized and activated, and then dried at 60-90°C for 2-6 hours.

[0014] Furthermore, in step S2, the activated ceramic reinforcing phase is added to the electroless plating solution, which includes nickel salt, rare earth salt, complexing agent, reducing agent and pH adjuster; the concentration of nickel salt is 0.03-0.15 mol / L, the concentration of rare earth salt is 0.001-0.010 mol / L, the pH of the electroless plating solution is 8.0-10.0, the reaction temperature is 60-85℃, and the reaction time is 10-60 min.

[0015] Further, in step S3, graphene oxide is dispersed in deionized water or a water / ethanol mixed solvent, a rare earth nitrate solution is added, the pH is adjusted to 5-7, and the mixture is stirred at 40-70°C for 1-4 hours; in step S4, ascorbic acid or glucose is added as a reducing agent, and the mixture is reacted at 70-95°C for 1-4 hours to obtain the rare earth graphene composite sheet.

[0016] Furthermore, in step S6, the bottom temperature of the directional freezing is -80 to -20℃, the upper temperature is -10 to 10℃, the temperature gradient is 5 to 30℃ / cm, and the freezing rate is 1 to 20μm / s; in step S7, the freeze-drying temperature is -60 to -30℃, the vacuum degree is below 50Pa, and the drying time is 12 to 36h; in step S8, the copper melt infiltration temperature is 1088 to 1130℃, and the infiltration time is 5 to 30min; in step S9, the hot pressing temperature is 750 to 900℃, the pressure is 20 to 60MPa, and the holding time is 0.5 to 2h, or the hot isostatic pressing temperature is 750 to 900℃, the pressure is 80 to 150MPa, and the holding time is 1 to 3h; in step S10, the aging temperature is 350 to 500℃, and the holding time is 0.5 to 4h.

[0017] Compared with the prior art, the present invention has at least the following beneficial effects: 1. The present invention uses multiple reinforcing bands extending along a first direction to be distributed at intervals in a continuous copper matrix, so that the material can change the crack propagation path when under stress, thereby improving the crack resistance of the material.

[0018] 2. This invention improves the bonding between the ceramic reinforcing phase and the continuous copper matrix by setting an interface modification layer containing nickel and rare earth elements on the surface of the ceramic reinforcing phase, thereby reducing interface porosity and interface debonding.

[0019] 3. This invention improves the salt spray corrosion resistance of the material by using rare earth graphene composite sheets, Ni-rich interface regions, and rare earth oxide particles in the interface barrier region to prevent the corrosive medium from spreading along the interface between the continuous copper matrix and the reinforcing strip.

[0020] 4. This invention controls the overall content of the ceramic reinforcing phase and maintains the continuous interconnected structure of the copper matrix, so that the material can maintain good electrical conductivity while improving its strength and corrosion resistance. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the layered structure of the high-strength corrosion-resistant copper-based composite material of the present invention; Figure 2 The images show the microstructure of the high-strength corrosion-resistant copper-based composite material of the present invention, wherein (a) is a low-magnification cross-sectional morphology image and (b) is a magnified morphology image of the interface region. Figure 3 The image shows the SEM and EDS elemental distribution of the high-strength corrosion-resistant copper-based composite material of the present invention, used to show the distribution of Cu, Si, C, Ni, and Y elements in the layered structure and interface region. According to EDS line scan analysis, the peak atomic percentage content of Ni and Y elements within 1 μm on both sides of the interface in Example 1 is more than twice the average atomic percentage content of the corresponding elements in the continuous copper matrix 1 region more than 5 μm away from the interface.

[0022] Figure 4 This is a flowchart of the preparation process of the high-strength corrosion-resistant copper-based composite material of the present invention.

[0023] In the figure: 1. Continuous copper substrate; 2. Reinforcing band; 3. Interface barrier region. Detailed Implementation

[0024] The following is combined with Figures 1 to 4 The specific embodiments of the present invention will be described below. The high-strength corrosion-resistant copper-based composite material of the present invention includes a continuous copper matrix 1, reinforcing bands 2, and an interface barrier region 3. The continuous copper matrix 1 is the main metallic phase in the material, used to maintain the material's conductive channels and plastic deformation capability. There are multiple reinforcing bands 2, which are spaced apart in the continuous copper matrix 1 and extend along a first direction. The spaces between adjacent reinforcing bands 2 are still filled by the continuous copper matrix 1. The interface barrier region 3 is located in the interface region between the continuous copper matrix 1 and the reinforcing bands 2, and may also be distributed within the continuous copper matrix 1 between adjacent reinforcing bands 2. The interface barrier region 3 includes rare earth graphene composite sheets, Ni-rich interface regions, and interface rare earth oxide particles.

[0025] Figure 1 The diagram illustrates the layered structure of the material. In the figure, the continuous copper substrate 1 is located between adjacent reinforcing bands 2, which are distributed in an intermittent banded pattern. The interface barrier region 3 is located near the boundary of the reinforcing bands 2. This schematic diagram is used to illustrate the positional relationship between the components and does not imply that each component must have perfectly straight boundaries. In actual materials, the boundaries of the reinforcing bands 2 may have slight undulations, and the interface barrier region 3 may be locally continuous or semi-continuous.

[0026] This implementation method adopts Figure 4 The process shown is used to prepare the material. This process includes S1 to S11. S1 is surface activation of the ceramic reinforcing phase. S2 is depositing an interface modification layer containing nickel and rare earth elements on the surface of the ceramic reinforcing phase to obtain a modified ceramic reinforcing phase. S3 is mixing and coordinating graphene oxide with a rare earth salt solution. S4 is reduction treatment to obtain a rare earth graphene composite sheet. S5 is dispersing the modified ceramic reinforcing phase, the rare earth graphene composite sheet, and nickel powder in a freezing medium to obtain a composite suspension. S6 is directional freezing to form a layered frozen body. S7 is freeze-drying to obtain a layered porous preform. S8 is copper melt infiltration to obtain a copper-based composite preform. S9 is densification treatment. S10 is aging treatment to cause nickel elements to segregate in the interface region between the continuous copper matrix 1 and the reinforcing band 2, forming a Ni-rich interface region and interface rare earth oxide particles. S11 yields a high-strength, corrosion-resistant copper-based composite material.

[0027] Example 1: A copper-based composite material with SiC as the ceramic reinforcing phase and Y as the rare earth element was prepared.

[0028] SiC particles with a D50 diameter of approximately 3 μm were selected as the ceramic reinforcing phase. The SiC particles were added to ethanol and ultrasonically cleaned for 20 min to remove oil and loose deposits from the particle surface. Subsequently, they were treated with a 5% hydrofluoric acid solution for 5 min. This treatment primarily removes the surface contaminant layer and makes the particle surface more suitable for subsequent deposition. After treatment, the particles were repeatedly rinsed with deionized water until near neutral, followed by sensitization and activation treatment, and then dried at 80 °C for 4 h.

[0029] The activated SiC particles were added to a chemical plating solution. The solution consisted of nickel sulfate, yttrium nitrate, sodium citrate, sodium hypophosphite, and a pH adjuster. The concentrations were: nickel sulfate 0.08 mol / L, yttrium nitrate 0.004 mol / L, sodium citrate 0.12 mol / L, and sodium hypophosphite 0.18 mol / L. The pH was controlled at 8.8, the reaction temperature at 75℃, and the reaction time at 30 min. After the reaction, the particles were removed, washed with deionized water and ethanol, and then dried to obtain Ni-Y modified SiC particles.

[0030] The aforementioned electroless plating step is used to form an interface modification layer containing nickel and yttrium on the surface of SiC particles. The nickel component has good compatibility with the copper substrate, which can improve the wetting state during subsequent copper melt infiltration. The yttrium component can participate in the formation of interface rare earth oxide particles during subsequent heat treatment. By controlling the concentration of the plating solution, the reaction temperature, and the reaction time, the thickness of the interface modification layer can be controlled within the range of 50–500 nm, preferably within the range of 100–300 nm. This interface modification layer does not need to be completely uniform in thickness on every particle surface; as long as a identifiable modified region can be formed on the particle surface, the interfacial porosity and unbonded areas between the ceramic reinforcing phase and the continuous copper substrate 1 can be reduced.

[0031] Graphene oxide was dispersed in deionized water at a concentration of 1.5 mg / mL and ultrasonically dispersed for 60 min to obtain a graphene oxide dispersion. Yttrium nitrate solution was added to this dispersion to achieve a Y:O mass ratio of approximately 0.12:1. The pH was adjusted to 6.2, and the mixture was stirred at 60 °C for 2 h. The surface of graphene oxide contains oxygen-containing groups such as hydroxyl, carboxyl, and epoxy groups. Yttrium ions can coordinate with these oxygen-containing groups, resulting in preferential distribution of the yttrium component on the surface and edges of the graphene sheets. Ascorbic acid was then added as a reducing agent, and the reaction was carried out at 85 °C for 2 h. After the reaction, the mixture was centrifuged, washed, and freeze-dried to obtain Y-rGO composite sheets.

[0032] In this step, the rare earth components are not simply added to the copper powder, but are first bonded to the graphene oxide sheets. This process allows the rare earth components to enter the subsequent interlayer and interface regions along with the graphene sheets. The reduction treatment transforms the graphene oxide into reduced graphene oxide sheets, but a small number of oxygen-containing groups remain on the sheets. These groups are beneficial for the fixation of the rare earth components on the sheets.

[0033] Based on the final composition of the composite material, the amount of Ni-Y modified SiC particles added corresponds to a SiC volume fraction of approximately 3 vol%; the graphene content in the Y-rGO composite sheet is approximately 0.35 wt%; additionally, nickel powder with an average particle size of approximately 0.5 μm is added, resulting in a total nickel content of approximately 0.6 wt% and a total Y content of approximately 0.09 wt% in the composite material. The Ni-Y modified SiC particles, Y-rGO composite sheet, and nickel powder are added to deionized water containing 0.4 wt% polyvinyl alcohol, mechanically stirred, then ultrasonically dispersed, and finally degassed under vacuum to obtain a composite suspension.

[0034] Polyvinyl alcohol (PVA) primarily functions to disperse and regulate ice crystal growth in the composite suspension. Modified SiC particles are used to form reinforcing band 2, Y-rGO composite sheets are used to enter the interlayer and interface regions, and nickel powder provides a migratable nickel source for subsequent melting and aging treatments. The nickel powder does not need to retain all its original particle morphology; during melting and aging, some components can enter the copper phase or interface region and participate in the formation of Ni-rich interface zones.

[0035] The composite suspension was injected into a mold with a unidirectional heat-conducting base. The temperature at the bottom of the mold was controlled at -60℃, and the temperature at the top was controlled at 0℃, with a temperature gradient of approximately 15℃ / cm and a freezing rate of approximately 8μm / s. During directional freezing, ice crystals grew along the temperature gradient direction. As the ice crystals grew, they displaced the solid components in the suspension, causing the Ni-Y modified SiC particles, Y-rGO composite sheets, and nickel powder to gradually accumulate in the gaps between the ice crystals. As the ice crystals continued to grow, the solid components formed a layered arrangement extending along the first direction.

[0036] After directional freezing, a layered frozen body is obtained. This layered frozen body is placed in a freeze-drying apparatus and dried at -50℃ and 30Pa vacuum for 24 hours to sublimate the ice crystals, resulting in a layered porous preform. The pores left after ice sublimation provide channels for subsequent copper molten metal ingress. To improve the stability of the layered porous preform, it can be placed in an argon atmosphere and held at 450℃ for 1 hour to remove some organic matter. This pretreatment temperature should not be too high to avoid excessive oxidation of the graphene sheets and to prevent significant sintering between the ceramic reinforcing phases.

[0037] A layered porous preform and pure copper raw material were placed in a graphite mold. The mixture was heated to 1105℃ under a hydrogen / argon mixed atmosphere and held for 15 minutes, with an auxiliary pressure of 2 MPa applied to allow molten copper to penetrate into the pores of the layered porous preform. After entering the pores, the molten copper forms a continuous copper matrix 1. Because a Ni-Y interface modification layer has already formed on the surface of the SiC particles, the wetting state of the ceramic reinforcing phase within the reinforcing band 2 is improved. After cooling, a copper-based composite preform is obtained.

[0038] The copper-based composite preform was hot-pressed at 850℃ and 40MPa for 1 hour to reduce residual porosity and improve the contact tightness between the continuous copper matrix 1 and the reinforcing strip 2. It was then aged at 450℃ for 2 hours. During aging, nickel elements in the interface modification layer and those provided by nickel powder can locally segregate in the interface region between the continuous copper matrix 1 and the reinforcing strip 2, forming a Ni-rich interface region. Yttrium elements can form interface rare earth oxide particles near the interface. The Y-rGO composite sheet, the Ni-rich interface region, and the interface rare earth oxide particles together constitute the interface barrier region 3.

[0039] The material obtained in Example 1 was observed by cross-sectional SEM, and the results are as follows: Figure 2 As shown. Figure 2 (a) is a low-magnification cross-sectional topography image, showing multiple banded regions extending along the first direction. Adjacent banded regions are connected by relatively continuous copper substrate areas. Observation using the 50μm scale in the image shows that the spacing of reinforcing band 2 is on the order of tens of micrometers, consistent with a structural range of 20–80μm. Figure 2 (b) is a magnified morphology diagram of the interface region. It can be seen that there are lamellar structures and fine granular structures near the interface, indicating that the interface region is not a simple direct contact between copper and ceramic, but a transition region formed by lamellar components and interface particles.

[0040] The material obtained in Example 1 was subjected to SEM and EDS elemental surface distribution analysis, and the results are as follows: Figure 3 As shown. Figure 3 In the results, Cu signals are mainly distributed in the continuous copper matrix 1 region; Si signals are mainly concentrated in the reinforcement zone 2 region, indicating that SiC particles participated in the formation of reinforcement zone 2; C signals can be observed near reinforcement zone 2 and within the continuous copper matrix 1 between adjacent reinforcement zones 2, indicating that the rare earth graphene composite sheet is not only present inside reinforcement zone 2, but can also be distributed in the interlayer copper matrix region and the interface region; Ni and Y signals are more obvious near the boundary of reinforcement zone 2, indicating that nickel and rare earth elements have an enrichment trend near the interface between the continuous copper matrix 1 and reinforcement zone 2. These results are consistent with... Figure 1 The structural relationships of the continuous copper substrate 1, the reinforcing band 2, and the interface barrier region 3 shown correspond to each other.

[0041] for Figure 3The distribution of Ni and Y elements in the sample can be further quantitatively analyzed using EDS linear scanning. The linear scanning path can start from the continuous copper matrix 1 region, cross the boundary of reinforcement zone 2, and enter the reinforcement zone 2 region. By comparing the peak atomic percentage of Ni or rare earth elements within 1 μm on both sides of the interface with the average atomic percentage of the corresponding elements within the continuous copper matrix 1 region at a distance of more than 5 μm from the interface, the enrichment factor of the interface can be evaluated. Using relative factors rather than a single absolute content helps to reduce the influence of sample surface condition, test conditions, and instrument differences on the interpretation results.

[0042] Example 2 describes the preparation of a highly conductive oriented copper-based composite material. The preparation steps are basically the same as in Example 1, except that: the SiC volume fraction is controlled at 1.5–2 vol%, the graphene content in the Y-rGO composite sheet is controlled at 0.20–0.25 wt%, the total nickel content is controlled at 0.4–0.5 wt%, and the total Y content is controlled at 0.06–0.08 wt%. The directional freezing rate can be controlled at 8–12 μm / s, the copper melt infiltration temperature can be controlled at 1095–1105 °C, and the aging temperature can be controlled at 420–440 °C.

[0043] In this embodiment, the content of the ceramic reinforcing phase is relatively low, and the connectivity of the continuous copper matrix 1 is good, making it suitable for components with high conductivity requirements. Because directional freezing is still used, reinforcing bands 2 extending along the first direction can still be formed in the material. Since Y-rGO composite sheets and nickel powder are still added, and the Ni-Y interface modification layer is retained, interface blocking regions 3 can still be formed near the boundaries of the reinforcing bands 2. Compared to Example 1, the number of reinforcing bands 2 in this embodiment is relatively small, and the interlayer continuous copper matrix 1 region is relatively wide.

[0044] Example 3 describes the preparation of a high-strength, corrosion-resistant oriented copper-based composite material. SiC particles with a D50 diameter of approximately 2 μm were selected as the ceramic reinforcing phase. Ni-Ce modified SiC particles were obtained through electroless plating using a nickel sulfate and cerium nitrate system. Ce-rGO composite sheets were then prepared. The SiC volume fraction was controlled at 4–5 vol%, the graphene content at 0.45–0.60 wt%, the total nickel content at 0.7–1.0 wt%, and the total Ce content at 0.10–0.20 wt%. The directional freezing rate was controlled at 4–8 μm / s, the copper melt infiltration temperature at 1105–1115 °C, the hot pressing temperature at 830–870 °C, and the aging temperature at 450–470 °C.

[0045] In this embodiment, the reinforcing bands 2 are relatively denser, and the content of the ceramic reinforcing phase and rare earth graphene composite sheet is relatively higher. With the increase in the number of reinforcing bands 2, cracks are more likely to encounter different phase regions and interface regions when propagating in the material, and the crack path may be deflected or bifurcated. Ce elements can form cerium-containing oxide particles near the interface, which, together with the Ni-rich interface region and graphene sheets, participate in interface blocking. Due to the increased proportion of non-copper phase, the effective conductive cross-section of the continuous copper matrix 1 will be reduced accordingly. Therefore, this embodiment is more suitable for applications with high requirements for strength and corrosion resistance and relatively relaxed requirements for conductivity.

[0046] Example 4 illustrates the substitution of other rare earth elements. Yttrium nitrate in Example 1 was replaced with lanthanum nitrate to prepare Ni-La modified SiC particles and La-rGO composite sheets. The remaining steps were the same as in Example 1. The SiC volume fraction could be controlled at 2–4 vol%, the graphene content at 0.20–0.45 wt%, the total nickel content at 0.4–0.8 wt%, and the total La content at 0.05–0.12 wt%. After the same directional freezing, freeze-drying, copper melt infiltration, densification, and aging treatments, a copper-based composite material containing La interfacial components was obtained.

[0047] Replacing lanthanum nitrate with neodymium nitrate can also prepare Ni-Nd modified SiC particles and Nd-rGO composite sheets. The preparation process for the Nd system can follow that of the La system. Both La and Nd can undergo coordination adsorption with oxygen-containing groups on the surface of graphene oxide, forming corresponding rare earth oxide particles during subsequent heat treatment. When using La or Nd, the material can still form a continuous copper matrix 1, reinforcing band 2, and interface barrier region 3. In practical applications, one or more of Y, Ce, La, or Nd can be selected based on raw material costs, interface stability, and application environment.

[0048] Example 5 illustrates alternative methods for replacing other ceramic reinforcing phases. When the SiC particles in Example 1 are replaced with Al2O3 particles, TiC particles, WC particles, or ZrO2 particles, the same or similar surface activation and interface modification steps can be used. For Al2O3 particles, surface activation can be performed by alkaline washing, silane coupling agent pretreatment, or plasma treatment; for TiC, WC, or ZrO2 particles, acid washing, alkaline washing, or plasma treatment can be selected according to the particle surface condition. Subsequently, an interface modification layer is deposited by chemical plating solution containing nickel and rare earth elements, and then a composite suspension is prepared together with rare earth graphene composite sheets and nickel powder.

[0049] Different ceramic reinforcing phases have varying densities, particle sizes, and surface states, resulting in differences in their migration patterns during directional freezing. To obtain clear reinforcing band 2, the solid content of the suspension, the amount of dispersant, the temperature gradient, and the freezing rate can be adjusted. Generally, at lower freezing rates, the ice crystal channels are wider, and the spacing of reinforcing band 2 is larger; at higher freezing rates, the ice crystal channels are narrower, and the spacing of reinforcing band 2 is smaller. By adjusting the freezing rate, the average spacing of reinforcing band 2 can be controlled within the range of 20–80 μm.

[0050] Microstructural testing can be performed as follows: The sample is cut, mounted, polished, and cleaned along a section perpendicular to the extension direction of reinforcement band 2. The cross-sectional morphology is observed using SEM, with at least five fields of view selected for each sample, each field having an area of ​​at least 100 μm × 100 μm. The average spacing of reinforcement bands 2 can be obtained using image processing software or manual measurement. During measurement, multiple measurement lines are selected perpendicular to the extension direction of reinforcement band 2, and the distance between the center lines of adjacent reinforcement bands 2 is statistically analyzed and averaged. The orientation ratio of reinforcement bands 2 can be obtained by statistically analyzing the angle between the extension direction of reinforcement band 2 and the first direction. The proportion of reinforcement bands with an angle less than 15° to the total number of reinforcement bands is the orientation ratio.

[0051] Interface enrichment testing can be performed using EDS linear scanning and EDS area scanning. EDS area scanning is used to observe the spatial distribution of Cu, Si, C, Ni, and rare earth elements. Cu is mainly used to determine the distribution of the continuous copper substrate 1; Si can be used to determine the distribution of the SiC reinforcement band 2; C can be used to determine the approximate location of the graphene sheets; Ni and rare earth elements can be used to determine the enrichment state near the interface. EDS linear scanning can cross the boundary of reinforcement band 2 from the region of continuous copper substrate 1 into the region of reinforcement band 2. By comparing the peak atomic percentage of the target element within 1 μm on both sides of the interface with the average atomic percentage of the same element within the region of continuous copper substrate 1 at a distance of more than 5 μm from the interface, the interface enrichment factor can be obtained.

[0052] When characterizing the material structure, cross-sectional SEM can be used to observe the distribution of reinforcing band 2, and EDS surface scanning can be used to observe the spatial distribution of Cu, Si, C, Ni, and rare earth elements. If necessary, EDS line scanning can be used to confirm the enrichment of Ni and rare earth elements near the interface between the continuous copper matrix 1 and reinforcing band 2. For local phases in the interface barrier region 3, TEM-EDS, XPS, or Raman testing can be used for auxiliary analysis as needed. The above testing methods are used to illustrate the material structure and interface composition and are not intended to limit the preparation process steps of this invention.

[0053] The representations corresponding to Figures 2 and 3 can be summarized as follows:

[0054] From Table 1 and Figure 2 , Figure 3 As can be seen, the material obtained in this embodiment is not a simple randomly dispersed copper-based composite material, but rather a layered structure in which a continuous copper matrix 1, reinforcing bands 2, and interface barrier regions 3 work together. The reinforcing bands 2 provide load-bearing and crack deflection locations, the continuous copper matrix 1 maintains the conductive channels, and the interface barrier regions 3 are located at positions prone to interface corrosion and interface cracking.

[0055] From a process perspective, S1 and S2 form an interface modification layer containing nickel and rare earth elements on the surface of the ceramic reinforcing phase, improving the interfacial bonding during subsequent copper melt infiltration; S3 and S4 bond the rare earth components with the graphene sheets, reducing the disordered agglomeration of graphene in the suspension; S5 to S7 utilize directional freezing and freeze-drying to form a layered porous preform; S8 allows the copper melt to enter the layered porous preform and form a continuous copper matrix 1; S9 reduces residual porosity; S10 further stabilizes the nickel and rare earth components near the interface, forming an interface barrier region 3. Through the above steps, the reinforcing band 2, the rare earth graphene composite sheet, the Ni-rich interface region, and the interface rare earth oxide particles are positioned in locations within the material where crack propagation and corrosive media penetration are more likely to occur.

[0056] In this embodiment, the average spacing of the reinforcing bands 2, the content of the ceramic reinforcing phase, the graphene content, the total nickel content, the total rare earth element content, the freezing rate, the melting and infiltration temperature, and the aging temperature can all be adjusted according to the target performance. When higher conductivity is required, the content of the ceramic reinforcing phase and graphene can be reduced, and the spacing of the reinforcing bands 2 can be appropriately increased. When higher strength and corrosion resistance are required, the content of the ceramic reinforcing phase and rare earth graphene composite sheet can be increased, and the spacing of the reinforcing bands 2 can be appropriately decreased. The above adjustments should be based on maintaining the continuity of the copper matrix 1, the orientation distribution of the reinforcing bands 2, and the formation of the interface barrier region 3 near the interface.

Claims

1. A high-strength, corrosion-resistant copper-based composite material, characterized in that, It includes a continuous copper substrate (1), a reinforcing band (2), and an interface barrier region (3); There are multiple reinforcing strips (2), which are spaced apart in the continuous copper substrate (1). The reinforcing strips (2) extend along a first direction, and the continuous copper substrate (1) fills the space between two adjacent reinforcing strips (2). The reinforcing strip (2) comprises a ceramic reinforcing phase, and the surface of the ceramic reinforcing phase is provided with an interface modification layer containing nickel and rare earth elements; The interface blocking region (3) is distributed in the interface region between the continuous copper substrate (1) and the reinforcing strip (2) and in the continuous copper substrate (1) between adjacent reinforcing strips (2); The interface barrier region (3) includes a rare earth graphene composite sheet, a Ni-rich interface region, and interface rare earth oxide particles.

2. The high-strength, corrosion-resistant copper-based composite material according to claim 1, characterized in that, Based on the total volume of the high-strength corrosion-resistant copper-based composite material, the volume fraction of the ceramic reinforcing phase is 1.5–5 vol%; based on the total mass of the high-strength corrosion-resistant copper-based composite material, the graphene content is 0.15–0.60 wt%, the total nickel content is 0.3–1.0 wt%, and the total rare earth element content is 0.03–0.20 wt%.

3. The high-strength, corrosion-resistant copper-based composite material according to claim 1, characterized in that, The ceramic reinforcing phase is selected from one or more of SiC, Al2O3, TiC, WC, and ZrO2; the rare earth element is selected from one or more of Y, Ce, La, and Nd.

4. The high-strength, corrosion-resistant copper-based composite material according to claim 1, characterized in that, The average spacing of the reinforcing strips (2) is 20 to 80 μm; in a cross-sectional observation area of ​​100 μm × 100 μm, the proportion of reinforcing strips whose extension direction is less than 15° with respect to the first direction is not less than 60%.

5. The high-strength, corrosion-resistant copper-based composite material according to claim 1, characterized in that, The thickness of the interface modification layer is 50-500 nm, and the coverage of the interface modification layer on the surface of the ceramic reinforcement phase is not less than 60%. When the interface between the continuous copper substrate (1) and the reinforcement band (2) is crossed by EDS line scan, the peak atomic percentage of Ni element within 1 μm on both sides of the interface is more than twice the average atomic percentage of Ni element in the continuous copper substrate (1) region more than 5 μm away from the interface, and the peak atomic percentage of rare earth element within 1 μm on both sides of the interface is more than twice the average atomic percentage of rare earth element in the continuous copper substrate (1) region more than 5 μm away from the interface.

6. A preparation process for a high-strength, corrosion-resistant copper-based composite material, characterized in that, The preparation process for the high-strength, corrosion-resistant copper-based composite material according to any one of claims 1 to 5 includes the following steps: S1, Surface activation of ceramic reinforced phase; S2. An interface modification layer containing nickel and rare earth elements is deposited on the surface of the ceramic reinforcing phase to obtain the modified ceramic reinforcing phase; S3, graphene oxide and rare earth salt solution mixed coordination; S4. Reduction treatment to obtain rare earth graphene composite sheets; S5. The modified ceramic reinforcing phase, rare earth graphene composite sheet and nickel powder are dispersed in a freezing medium to obtain a composite suspension; S6. Directional freezing to form a layered frozen body; S7. Freeze-dry to obtain a layered porous preform; S8. Copper liquid is melted and infiltrated to obtain a copper-based composite billet; S9. Densification treatment, wherein the densification treatment is hot pressing or hot isostatic pressing; S10. Aging treatment, which causes the nickel elements in the interface modification layer and the nickel elements provided by the nickel powder to segregate in the interface region between the continuous copper matrix (1) and the reinforcing band (2), and form a Ni-rich interface region and interface rare earth oxide particles. S11, a high-strength and corrosion-resistant copper-based composite material was obtained.

7. The preparation process of a high-strength corrosion-resistant copper-based composite material according to claim 6, characterized in that, In step S1, the ceramic reinforcing phase is ultrasonically cleaned in ethanol for 10-30 min, then treated with a 5-10% hydrofluoric acid or sodium hydroxide solution for 3-10 min. After cleaning until neutral, it is sensitized and activated, and then dried at 60-90°C for 2-6 h.

8. The preparation process of a high-strength corrosion-resistant copper-based composite material according to claim 6, characterized in that, In step S2, the activated ceramic reinforcing phase is added to a chemical plating solution, which includes nickel salt, rare earth salt, complexing agent, reducing agent, and pH adjuster; the concentration of the nickel salt is 0.03–0.15 mol / L, the concentration of the rare earth salt is 0.001–0.010 mol / L, the pH of the chemical plating solution is 8.0–10.0, the reaction temperature is 60–85℃, and the reaction time is 10–60 min.

9. The preparation process of a high-strength corrosion-resistant copper-based composite material according to claim 6, characterized in that, In step S3, graphene oxide is dispersed in deionized water or a water / ethanol mixed solvent, rare earth nitrate solution is added, the pH is adjusted to 5-7, and the mixture is stirred at 40-70°C for 1-4 hours; in step S4, ascorbic acid or glucose is added as a reducing agent, and the mixture is reacted at 70-95°C for 1-4 hours to obtain the rare earth graphene composite sheet.

10. The preparation process of a high-strength corrosion-resistant copper-based composite material according to claim 6, characterized in that, In step S6, the bottom temperature of the directional freezing is -80 to -20℃, the top temperature is -10 to 10℃, the temperature gradient is 5 to 30℃ / cm, and the freezing rate is 1 to 20μm / s; in step S7, the freeze-drying temperature is -60 to -30℃, the vacuum degree is below 50Pa, and the drying time is 12 to 36h; in step S8, the copper melt infiltration temperature is 1088 to 1130℃, and the infiltration time is 5 to 30min; in step S9, the hot pressing temperature is 750 to 900℃, the pressure is 20 to 60MPa, and the holding time is 0.5 to 2h, or the hot isostatic pressing temperature is 750 to 900℃, the pressure is 80 to 150MPa, and the holding time is 1 to 3h; in step S10, the aging temperature is 350 to 500℃, and the holding time is 0.5 to 4h.

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