Gradient structure Cu-Cr-Nb / Cu composite material and preparation method thereof

Abstract

This invention discloses a method for preparing a gradient structure Cu-Cr-Nb / Cu composite material, specifically including the following steps: Step 1, preparing precursor powders by mixing Cu-4Cr-2Nb with pure Cu powder in different proportions; Step 2, pressing the precursor powders prepared in Step 1 into compacts; Step 3, sintering the powder treated in Step 2; Step 4, subjecting the sintered product from Step 3 to hot deformation treatment; Step 5, subjecting the product from Step 4 to cold deformation treatment; Step 6, annealing the product from Step 5 to obtain the final product. This invention also discloses a gradient structure Cu-Cr-Nb / Cu composite material, solving the problem that traditional Cu-Cr-Nb composite materials cannot simultaneously possess high heat transfer efficiency and high mechanical properties.

Description

Technical Field

[0001] This invention belongs to the field of copper-based composite material technology, and relates to gradient structure Cu-Cr-Nb / Cu composite material. This invention also relates to a method for preparing gradient structure Cu-Cr-Nb / Cu composite material. Background Technology

[0002] Cu-Cr-Nb composites, due to their excellent thermal conductivity, high-temperature resistance, fatigue resistance, and high-temperature creep resistance, hold significant promise for applications in reusable rocket engine combustion chamber liners. However, existing Cu-Cr-Nb lining materials are primarily homogeneous, and their overall performance often falls short when facing multiple performance requirements. This is especially true in rocket engine linings, where regenerative cooling designs are commonly employed. The outer side of the lining material directly faces the combustion gas flow, requiring excellent thermal conductivity to maintain the structure at an acceptable temperature level; the inner side needs propellant flow channels, and the increased pressure after propellant absorbs heat necessitates high material strength to withstand this pressure. Clearly, traditional homogeneous Cu-Cr-Nb composites have limitations in meeting these performance requirements. For example, the strength improvement of homogeneous Cu-Cr-Nb composites mainly depends on the Cr2Nb phase; however, a high Cr2Nb phase content reduces the material's heat transfer efficiency, while a low Cr2Nb phase content leads to insufficient strength. To overcome the dilemma of homogeneous materials having both thermal conductivity and strength, it is necessary to develop gradient CuCrNb composite lining materials. Summary of the Invention

[0003] The purpose of this invention is to provide a method for preparing gradient structure Cu-Cr-Nb / Cu composite materials, which solves the problem that traditional Cu-Cr-Nb composite materials cannot simultaneously possess high heat transfer efficiency and high mechanical properties.

[0004] Another object of the present invention is to provide a gradient structure Cu-Cr-Nb / Cu composite material.

[0005] The first technical solution adopted in this invention is a method for preparing a gradient structure Cu-Cr-Nb / Cu composite material, which specifically includes the following steps: Step 1: Prepare precursor powders by mixing Cu-4Cr-2Nb with pure Cu powder in different proportions; Step 2: Press the precursor powders prepared in different proportions in Step 1 into compacts; Step 3: Sinter the powder processed in Step 2; Step 4: Perform heat deformation treatment on the product sintered in step 3; Step 5: Perform cold deformation treatment on the product after step 4; Step 6: Anneal the product processed in step 5 to obtain the final product.

[0006] The first technical solution of this invention is further characterized by: The specific process of step 1 is as follows: Atomized spherical Cu-4Cr-2Nb powder and pure Cu powder were mixed in a mass ratio of 9:1 to 2:8 to obtain mixed precursor powders with different Cr2Nb contents.

[0007] In step 1, the mass fraction of Cr2Nb in the mixed precursor powder is 1.1~5.7 wt.%.

[0008] The specific process of step 2 is as follows: the mixed powders with different Cr2Nb contents obtained in step 1 are spread in order from high to low Cr2Nb powder content, and the powders are filled into the mold by layer-by-layer spreading. The powders are pressed into a compact by holding the pressure at 10~30 MPa for 5~60 s on a four-column hydraulic press. In step 3, the sintering temperature is 700 ºC to 1050 ºC, the holding time is 20 to 90 min, and the sintering pressure is 20 to 60 MPa.

[0009] In step 4, the heat deformation amount is 10~90%, and the heat deformation temperature is 800~950 ℃.

[0010] In step 5, the product obtained in step 4 is subjected to cold deformation treatment at room temperature; the room temperature deformation amount in step 5 is 10~90%.

[0011] In step 6, the annealing temperature is 400~600 ℃, and the holding time is 30~120 min.

[0012] The second technical solution adopted in this invention is a gradient structure Cu-Cr-Nb / Cu composite material, which is prepared by the above-mentioned method for preparing gradient structure Cu-Cr-Nb / Cu composite material.

[0013] The beneficial effects of this invention are as follows: (1) This invention combines multiple preparation techniques, and by precisely controlling the composition ratio of Cr2Nb phase and Cu, and by using a specific preparation process, prepares Cr2Nb gradient structure copper-based composite material, which can obtain high-performance copper-based composite material with high inner strength and good thermal conductivity on the outer side.

[0014] (2) The gradient copper-based composite material of the present invention has excellent thermal conductivity on the outer side, and the composite material also has excellent mechanical properties after deformation. This material has high strength, high electrical conductivity and good thermal conductivity, and is suitable for applications under various high load and high temperature environments. Attached Figure Description

[0015] Figure 1 This is a gradient structure metallographic diagram of Example 1 of the preparation method of the gradient structure Cu-Cr-Nb / Cu composite material of the present invention. Detailed Implementation

[0016] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0017] This invention relates to a gradient structure Cu-Cr-Nb / Cu composite material, comprising an inner material and an outer material; the inner material consists of a Cu matrix and a high-content (5.7 wt.%) Cr2Nb precipitate, while the outer material consists of a Cu matrix and a low-content (1.1 wt.%) Cr2Nb precipitate. The Cr2Nb precipitate decreases in a gradient from the inner to the outer side, forming a Cr2Nb gradient composite material. In this gradient structure Cu-Cr-Nb / Cu composite material, based on a 100% mass percentage, the mass percentage of Cr is 0-5 wt.%, the mass percentage of Nb is 0-5 wt.%, and the balance is Cu. The Cr2Nb phase decreases in gradient from the inside to the outside, specifically as the mixing ratio of Cu-4Cr-2Nb powder and pure Cu powder changes from 9:1 to 2:8 (specifically, the mass percentage ratio of Cu-4Cr-2Nb powder to pure Cu powder gradually transitions to 9:1, 8:2, 7:3, 6:4, 5:5, 4:6, 3:7, and 2:8, forming a gradient structure). The Cr2Nb precipitate is obtained from the in-situ spontaneous generation of Cr and Nb elements.

[0018] The gradient structure Cu-Cr-Nb / Cu composite material of the present invention is prepared by dispersing Cr2Nb particles in a copper matrix and controlling the Cr2Nb particle content to change in a gradient from the inside to the outside, thus forming a composite material with a Cr2Nb content gradient.

[0019] This invention also provides a method for preparing a gradient-structured Cu-Cr-Nb / Cu composite material, specifically comprising: mixing or ball milling precursor Cu-4Cr-2Nb powder and pure Cu powder in a specified ratio, hot pressing sintering, deformation heat treatment, etc. The composite material prepared by this invention overcomes the difficulty of achieving both high-temperature strength and thermal conductivity in traditional homogeneous materials. It achieves higher thermal conductivity through a low Cr2Nb content design on the outer side, while obtaining higher high-temperature strength through a high Cr2Nb content design on the inner side. Furthermore, a rocket engine liner material with excellent comprehensive performance is prepared through continuous gradient changes.

[0020] The method for preparing the gradient structure Cu-Cr-Nb / Cu composite material of the present invention includes the following steps: Step 1, Precursor Powder Mixing: Atomized spherical Cu-4Cr-2Nb powder (commercial) and pure Cu powder are mixed in a mass ratio of 9:1 to 2:8 (e.g., 9:1, 8:2, 7:3, 6:4, 5:5, 4:6, 3:7, 2:8) to obtain 4 to 8 mixed powders with different Cr2Nb contents (Cr2Nb content is 1.1 to 5.7 wt.%). Step 2, Powder processing: The mixed powders with 4 to 8 different Cr2Nb contents obtained in Step 1 are spread in order of Cr2Nb content from high to low, and then filled into the mold by layer-by-layer spreading. The powder is pressed into a compact by pressing it on a four-column hydraulic press with a pressure of 10 to 30 MPa for 5 to 60 seconds. Step 3, sintering: The product obtained in step 2 is subjected to hot pressing sintering; the sintering temperature is 700 ºC~1050 ºC, the holding time is 20~90 min, and the sintering pressure is 20~60 MPa.

[0021] Step 4, heat deformation treatment: The product obtained in step 3 is subjected to heat deformation treatment; the heat deformation amount in step 4 is 10~90%, and the heat deformation temperature is 800~950 ℃.

[0022] Step 5, cold deformation treatment: The product obtained in step 4 is subjected to cold deformation treatment at room temperature; the room temperature deformation amount in step 5 is 10~90%.

[0023] Step 6, Annealing: The product obtained in Step 5 is annealed. The annealing temperature in Step 6 is 400~600 ℃, and the holding time is 30~120 min.

[0024] Example 1 In this embodiment, the gradient structure is a unidirectional gradient structure with 9 gradient layers. The preparation method of this gradient structure Cu-Cr-Nb / Cu composite material specifically includes the following steps: Step 1, Precursor Powder Mixing: Spherical Cu-4Cr-2Nb powder and pure Cu powder are mixed in different proportions to obtain more mixed powders with different Cr2Nb contents. Step 2, Precursor Powder Processing: Cu-4Cr-2Nb and pure Cu powder were mixed in ratios of 9:1, 8:2, 7:3, 6:4, 5:5, 4:6, 3:7, and 2:8 to obtain eight different mixed powders with Cr2Nb contents of 5.1 wt.%, 4.6 wt.%, 4.0 wt.%, 3.4 wt.%, 2.9 wt.%, 2.3 wt.%, 1.7 wt.%, and 1.1 wt.%. According to the gradient design model (as shown in Table 1, Example 1), the powder was layered from high to low Cr2Nb content, with each layer being 0.5 mm thick, for a total of nine layers. The powder was then pressed into a blank in a mold under a pressure of 20 MPa and held for 10 s on a four-column hydraulic press.

[0025] Step 3: The pre-pressed block is placed in a graphite crucible for hot pressing and sintering. The sintering process is carried out under a vacuum degree lower than 6.0 × 10⁻⁶. - 3 The process was carried out under Pa conditions, followed by pressurization, which was increased to 30 MPa within 10 min. Then, heating and sintering were started, which was heated to 950 °C within 60 min, and then held at that temperature for 30 min. Finally, the temperature was lowered to obtain a gradient structure Cu-Cr-Nb / Cu composite material in hot-pressed sintered state. Step 4: Hot-roll the composite material obtained in Step 3 at 900 °C by 30%; Step 5: The composite material obtained in Step 4 is further cold-rolled at room temperature by 90%. Step 6: Anneal the composite material obtained in Step 5 at 450 °C for 60 min to obtain the final product; The gradient-structured copper-based composite material obtained in this embodiment has an inner hardness of 163 HBW and an outer hardness of 139 HBW. Its thermal conductivity at room temperature is 301.6 W / (m·K), at 200℃ it is 287.7 W / (m·K), and at 400℃ it is 278.7 W / (m·K). The variation in gradient layer thickness in this embodiment is shown in Table 1, Example 1.

[0026] Example 2 The only difference between this embodiment and the one in Example 1 is the thickness of the gradient layer, which is 0.3 mm. All other preparation processes are the same. The variation of the gradient layer thickness in this embodiment is shown in Table 1, Example 2.

[0027] The gradient structure copper-based composite material obtained in this embodiment has an inner hardness of 154 HBW and an outer hardness of 126 HBW. Its thermal conductivity at room temperature is 311.6 W / (m·K), at 200℃ it is 298.7 W / (m·K), and at 400℃ it is 284.4 W / (m·K).

[0028] Example 3 The only difference between this embodiment and the one in Example 1 is the thickness of the gradient layer, which is 0.2 mm. All other preparation processes are the same. The variation of the gradient layer thickness in this embodiment is shown in Table 1, Example 3.

[0029] The gradient structure copper-based composite material obtained in this embodiment has an inner hardness of 151 HBW and an outer hardness of 122 HBW. Its thermal conductivity at room temperature is 315.7 W / (m·K), at 200℃ it is 311.9 W / (m·K), and at 400℃ it is 309.3 W / (m·K).

[0030] The gradient layer thicknesses of Examples 1 to 3 are shown in Table 1 below: Table 1

[0031] Example 4 In this embodiment, the gradient structure is a unidirectional gradient structure with 5 gradient layers. The preparation method of this gradient structure Cu-Cr-Nb / Cu composite material specifically includes the following steps: Step 1, Precursor Powder Mixing: Spherical Cu-4Cr-2Nb powder and pure Cu powder are mixed in different proportions to obtain more mixed powders with different Cr2Nb contents. Step 2, Precursor Powder Processing: Cu-4Cr-2Nb and pure Cu powder were mixed in four different ratios of 8:2, 6:4, 4:6, and 2:8 to obtain mixed powders with Cr2Nb contents of 4.6 wt.%, 3.4 wt.%, 2.3 wt.%, and 1.1 wt.%, respectively. Based on the gradient design model, powder was layered from high to low Cr2Nb content, with each layer being 0.5 mm thick. A total of five powder layers were added, including a pure Cu-4Cr-2Nb layer. The powder was pressed into a blank in a mold by applying pressure of 10 MPa and holding the pressure for 5 seconds on a four-column hydraulic press.

[0032] Step 3: The pre-pressed block is placed in a graphite crucible for hot pressing and sintering. The sintering process is carried out under a vacuum degree lower than 6.0 × 10⁻⁶. - 3 The process was carried out under Pa conditions, followed by pressurization, which was increased to 20 MPa within 10 min. Then, heating and sintering were started, which was heated to 850 °C within 20 min, and then held at that temperature for 30 min. Finally, the temperature was lowered to obtain a gradient structure Cu-Cr-Nb / Cu composite material in hot-pressed sintered state. Step 4: Hot-roll the composite material obtained in Step 3 at 800 °C by 10%; Step 5: The composite material obtained in Step 4 is further cold-rolled at room temperature by 10%; Step 6: Anneal the composite material obtained in Step 5 at 400 °C for 30 min to obtain the final product.

[0033] Example 5 In this embodiment, the gradient structure is a unidirectional gradient structure with 5 gradient layers. The preparation method of this gradient structure Cu-Cr-Nb / Cu composite material specifically includes the following steps: Step 1, Precursor Powder Mixing: Spherical Cu-4Cr-2Nb powder and pure Cu powder are mixed in different proportions to obtain more mixed powders with different Cr2Nb contents. Step 2, Precursor Powder Processing: Cu-4Cr-2Nb and pure Cu powder were mixed in four different ratios of 9:1, 7:3, 5:5, and 3:7 to obtain mixed powders with Cr2Nb contents of 5.1 wt.%, 4.0 wt.%, 2.9 wt.%, and 1.7 wt.%, respectively. Based on the gradient design model, powder was layered from high to low Cr2Nb content, with each layer being 0.5 mm thick. A total of five powder layers were added, including a pure Cu-4Cr-2Nb layer. The powder was pressed into a blank in a mold by applying pressure of 30 MPa and holding the pressure for 60 s on a four-column hydraulic press.

[0034] Step 3: The pre-pressed block is placed in a graphite crucible for hot pressing and sintering. The sintering process is carried out under a vacuum degree lower than 6.0 × 10⁻⁶. - 3 The process was carried out under Pa conditions, followed by pressurization, which was increased to 60 MPa within 10 min. Then, heating and sintering were started, which was heated to 1050 °C within 20 min, and then held at that temperature for 30 min. Finally, the temperature was lowered to obtain a gradient structure Cu-Cr-Nb / Cu composite material in hot-pressed sintered state. Step 4: Hot-roll the composite material obtained in Step 3 at 950 °C by 90%; Step 5: The composite material obtained in Step 4 is further cold-rolled at room temperature by 80%. Step 6: Anneal the composite material obtained in Step 5 at 600 °C for 120 min to obtain the final product.

[0035] Example 6 In this embodiment, the gradient structure is a unidirectional gradient structure with 7 gradient layers. The preparation method of this gradient structure Cu-Cr-Nb / Cu composite material specifically includes the following steps: Step 1, Precursor Powder Mixing: Spherical Cu-4Cr-2Nb powder and pure Cu powder are mixed in different proportions to obtain more mixed powders with different Cr2Nb contents. Step 2, Precursor Powder Processing: Cu-4Cr-2Nb and pure Cu powder were mixed in six different ratios of 8:2, 7:3, 6:4, 4:6, 3:7, and 2:8 to obtain mixed powders with Cr2Nb contents of 4.6 wt.%, 4.0 wt.%, 3.4 wt.%, 2.3 wt.%, 1.7 wt.%, and 1.1 wt.%, respectively. Based on a gradient design model, powder was layered from high to low Cr2Nb content, with each layer being 0.5 mm thick. A total of seven powder layers were added, including a pure Cu-4Cr-2Nb layer. The powder was then pressed into a blank in a mold under a pressure of 30 MPa and held for 60 s on a four-column hydraulic press.

[0036] Step 3: The pre-pressed block is placed in a graphite crucible for hot pressing and sintering. The sintering process is carried out under a vacuum degree lower than 6.0 × 10⁻⁶. - 3 The process was carried out under Pa conditions, followed by pressurization, which was increased to 60 MPa within 10 min. Then, heating and sintering were started, which was heated to 1050 °C within 20 min, and then held at that temperature for 30 min. Finally, the temperature was lowered to obtain a gradient structure Cu-Cr-Nb / Cu composite material in hot-pressed sintered state. Step 4: Hot-roll the composite material obtained in Step 3 at 850 °C for 90% of its thickness; Step 5: The composite material obtained in Step 4 is further cold-rolled at room temperature by 80%. Step 6: Anneal the composite material obtained in Step 5 at 600 °C for 120 min to obtain the final product.

Claims

1. A method for preparing gradient structure Cu-Cr-Nb / Cu composite materials, characterized in that: Specifically, the steps include the following: Step 1 involves preparing precursor powders by mixing Cu-4Cr-2Nb with pure Cu powder in different proportions; the specific process of Step 1 is as follows: Atomized spherical Cu-4Cr-2Nb powder and pure Cu powder were mixed in a mass ratio of 9:1 to 2:8 to obtain mixed precursor powders with different Cr2Nb contents; the mass fraction of Cr2Nb in the mixed precursor powders of step 1 was 1.1 to 5.7 wt.%. Step 2: Press the precursor powders prepared in different proportions in Step 1 into compacts; Step 3: Sinter the powder processed in Step 2; Step 4: Perform heat deformation treatment on the product sintered in step 3; Step 5: Perform cold deformation treatment on the product after step 4; Step 6: Anneal the product processed in step 5 to obtain the final product.

2. The method for preparing the gradient structure Cu-Cr-Nb / Cu composite material according to claim 1, characterized in that: The specific process of step 2 is as follows: the mixed powders with different Cr2Nb contents obtained in step 1 are spread in order from high to low Cr2Nb powder content, and the powders are filled into the mold by layer-by-layer spreading. The powders are then pressed into a compact by applying a pressure of 10~30MPa for 5~60s on a four-column hydraulic press.

3. The method for preparing the gradient structure Cu-Cr-Nb / Cu composite material according to claim 2, characterized in that: In step 3, the sintering temperature is 700 ºC to 1050 ºC, the holding time is 20 to 90 min, and the sintering pressure is 20 to 60 MPa.

4. The method for preparing the gradient structure Cu-Cr-Nb / Cu composite material according to claim 3, characterized in that: In step 4, the heat deformation amount is 10~90%, and the heat deformation temperature is 800~950 ℃.

5. The method for preparing the gradient structure Cu-Cr-Nb / Cu composite material according to claim 4, characterized in that: In step 5, the product obtained in step 4 is subjected to cold deformation treatment at room temperature; the room temperature deformation amount in step 5 is 10~90%.

6. The method for preparing the gradient structure Cu-Cr-Nb / Cu composite material according to claim 5, characterized in that: In step 6, the annealing temperature is 400~600 ℃ and the holding time is 30~120 min.

7. A gradient structure Cu-Cr-Nb / Cu composite material, prepared by the method for preparing a gradient structure Cu-Cr-Nb / Cu composite material as described in any one of claims 1 to 6.

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