Copper-chromium alloy preparation method and copper-chromium alloy printed part

Abstract

The application provides a copper-chromium alloy preparation method and a copper-chromium alloy printed part. The copper-chromium alloy preparation method comprises the following steps: mechanically mixing copper powder and chromium powder to form mixed powder, and baking the mixed powder; performing powder laying work on the mixed powder to form a powder layer, the powder layer comprising a contour area and a filling area, and the contour area being arranged around the edge of the filling area; scanning the filling area by a first laser and scanning the contour area by a second laser to obtain a printed layer; and repeating the powder laying work and the scanning work until a plurality of the printed layers are stacked to form the copper-chromium alloy printed part.

Description

Technical Field

[0001] This application relates to the field of alloy preparation technology, and in particular to a method for preparing copper-chromium alloy and copper-chromium alloy printed parts. Background Technology

[0002] Copper-chromium alloys, such as CuCr30, are commonly used as electrical contact structures in vacuum switchgear, and are mostly produced using either casting or powder infiltration methods. Casting directly molds the alloy by melting a mixture of copper and chromium, resulting in lower costs, but the copper-chromium alloy has lower density. Powder infiltration involves uniformly mixing copper and chromium powders, followed by a high-temperature infiltration process to diffuse the chromium into the copper matrix, resulting in a denser copper-chromium alloy; however, this method has higher production costs. Summary of the Invention

[0003] This application provides a method for preparing copper-chromium alloys and copper-chromium alloy printed parts, in order to solve the problem that the preparation of copper-chromium alloys in known technologies cannot simultaneously achieve both density performance and production cost.

[0004] This application provides a method for preparing a copper-chromium alloy, comprising the following steps: mechanically mixing copper powder and chromium powder to form a mixed powder, and baking the mixed powder; performing a powder spreading operation with the mixed powder to form a powder layer, the powder layer comprising a contour region and a filling region, the contour region being disposed around the edge of the filling region; scanning the filling region with a first laser and scanning the contour region with a second laser to obtain a printing layer; repeating the powder spreading operation and scanning operation until multiple printing layers are stacked to form a copper-chromium alloy printed part.

[0005] In one possible implementation, the power of the first laser is 300 to 450 W, the scanning speed of the first laser is 400 to 800 mm / s, and the scanning spacing of the first laser is 0.07 to 0.09 mm.

[0006] In one possible implementation, the first laser employs strip scanning, and the strip width of the first laser is 100 times the scanning spacing of the first laser.

[0007] In one possible implementation, the power of the second laser is 350 to 400 W, and the scanning speed of the second laser is 500 to 900 mm / s.

[0008] In one possible implementation, the spot diameters of the first laser and the second laser are 30 to 50 μm.

[0009] In one possible implementation, the mixed powder has a mass ratio of copper powder to chromium powder of 7:3 by mass percentage.

[0010] In one possible implementation, the baking temperature of the mixed powder is 100 to 110°C, and the baking time of the mixed powder is 4 to 5 hours.

[0011] In one possible embodiment, the copper-chromium alloy preparation method further includes: heat-treating the copper-chromium alloy printed part; wherein the step of heat-treating the copper-chromium alloy printed part includes:

[0012] The copper-chromium alloy printed part is placed in a heat treatment furnace, and the heat treatment furnace is evacuated.

[0013] The heat treatment furnace is heated to a first temperature and held at the first temperature for a first time.

[0014] The heat treatment furnace is cooled to a second temperature, and the copper-chromium alloy printed part is then removed.

[0015] In one possible implementation, the heat treatment furnace is evacuated to 10... -3 Pa, the heating rate of the heat treatment furnace is 4.2℃ / min to 5℃ / min, the first temperature is 500 to 600℃, the first time is 2.5 to 3.5h, and the second temperature is 80 to 95℃.

[0016] This application also provides a copper-chromium alloy printed part, which is prepared by the above-described copper-chromium alloy preparation method, and the density of the copper-chromium alloy printed part is greater than 99%.

[0017] The copper-chromium alloy preparation method of this application involves mechanically mixing copper powder and chromium powder to form a mixed powder. This mechanical mixing method improves the uniformity of powder distribution, thereby enhancing subsequent printing results, and it is also less expensive. Furthermore, this application uses a method of first scanning the filled area and then scanning the contour area to form each printing layer, which improves the density and surface properties of the prepared copper-chromium alloy printed parts. The laser printing method is also less expensive, further reducing the overall production cost of the copper-chromium alloy. Attached Figure Description

[0018] Figure 1 This is a schematic flowchart of the copper-chromium alloy preparation method of this application in one embodiment.

[0019] Figure 2 This is a schematic diagram of the mixed powder state in one embodiment of the copper-chromium alloy preparation method of this application.

[0020] Figure 3 Images of square copper-chromium alloy blocks printed from samples 1 to 25 in one embodiment of the copper-chromium alloy preparation method of this application.

[0021] Figure 4Images of square copper-chromium alloy blocks printed from samples 26 to 40 in one embodiment of the copper-chromium alloy preparation method of this application.

[0022] Figure 5 Metallographic photograph of sample 11 in one embodiment of the copper-chromium alloy preparation method of this application.

[0023] Figure 6 Metallographic photograph of sample 26 in one embodiment of the copper-chromium alloy preparation method of this application.

[0024] Figure 7 Metallographic photograph of sample 33 in one embodiment of the copper-chromium alloy preparation method of this application.

[0025] Explanation of key component symbols: 100, preparation method of copper-chromium alloy.

[0026] The following detailed description, in conjunction with the accompanying drawings, will further illustrate this application. Detailed Implementation

[0027] The following description will refer to the accompanying drawings to provide a more complete picture of the present application. The drawings illustrate exemplary embodiments of the present application. However, the present application may be implemented in many different forms and should not be construed as limited to the exemplary embodiments set forth herein. These exemplary embodiments are provided to make the present application thorough and complete, and to fully convey the scope of the present application to those skilled in the art. The same reference numerals denote the same or similar components.

[0028] The terminology used herein is for the purpose of describing particular exemplary embodiments only and is not intended to limit the application. As used herein, unless the context clearly indicates otherwise, the singular forms “a,” “an,” and “the” are intended to also include the plural forms. Furthermore, when used herein, “comprising” and / or “including” and / or “having,” integers, steps, operations, components, and / or components, but does not exclude the presence or addition of one or more other features, regions, integers, steps, operations, components, and / or groups thereof.

[0029] Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. Furthermore, unless expressly defined herein, terms such as those defined in a general dictionary should be interpreted as having the same meaning as they have in the relevant art and in the content of this application, and will not be interpreted as having an idealized or overly formal meaning.

[0030] The specific embodiments of this application will be further described in detail below with reference to the accompanying drawings.

[0031] like Figure 1As shown, this embodiment provides a method 100 for preparing a copper-chromium alloy, including the following steps:

[0032] S1. Mechanically mix copper powder and chromium powder to form a mixed powder, and then bake the mixed powder;

[0033] S2. A powder spreading operation is performed using mixed powder to form a powder layer, the powder layer including a contour area and a filling area, the contour area being disposed around the edge of the filling area;

[0034] S3. The first laser scans the filled area, and the second laser scans the outline area to obtain the printing layer;

[0035] S4. Repeat the powder spreading and scanning operations until multiple printing layers are stacked to form a copper-chromium alloy print.

[0036] Thus, the copper-chromium alloy preparation method 100 of this application forms a mixed powder by mechanically mixing copper powder and chromium powder. Mechanical mixing improves the uniformity of powder distribution, thereby enhancing subsequent printing results, and is also less expensive. Furthermore, this application uses a method of first scanning the filling area and then scanning the contour area to form each printing layer, which improves the density and surface properties of the prepared copper-chromium alloy printed parts. The laser printing method is also less expensive, further reducing the overall production cost of the copper-chromium alloy.

[0037] In this embodiment, for step S1, the copper powder is a spherical powder made of pure copper, the chromium powder is a spherical powder made of pure chromium, and the mass ratio of the mixed powder to the copper powder is 7:3 by mass percentage.

[0038] In addition, both copper and chromium powders use standard powders with diameters ranging from 15 to 53 μm, and the composition of the standard powders is approximately D10=15 μm and D90=53 μm.

[0039] It is understood that the diameters of copper powder and chromium powder can be 15µm, 16µm, 17µm, 18µm, 19µm, 20µm, 21µm, 22µm, 23µm, 24µm, 25µm, 26µm, 27µm, 28µm, 29µm, 30µm, 31µm, 32µm, 33µm, 34µm, 35µm, 36µm, 37µm, 38µm, 39µm, 40µm, 41µm, 42µm, 43µm, 44µm, 45µm, 46µm, 47µm, 48µm, 49µm, 50µm, 51µm, 52µm, 53µm, etc., but are not limited to the values ​​listed above. Other unlisted values ​​within this range are also within the scope of protection of this application.

[0040] In this embodiment, copper powder and chromium powder are mechanically mixed using a double-cone powder mixer. This method utilizes centrifugal force or gravity to ensure thorough mixing of the powders without requiring additional energy input. This not only reduces production costs but also ensures that the powders maintain their original spherical or near-spherical shape (e.g., ...). Figure 2 (As shown).

[0041] Compared to ball milling, the mechanical mixing method described in this application improves the density of subsequent copper-chromium alloy printed parts. Ball milling causes the powder to be subjected to intense compression and impact during the milling process, resulting in the breakage of originally smooth spherical powder, a significant decrease in sphericity, and a noticeable lamellar or broken surface, directly affecting powder flowability and uniformity. Furthermore, the mechanical mixing method described in this application offers high mixing efficiency and is simpler to operate, facilitating large-scale application.

[0042] Figure 2 The medium-dark powder is chromium powder, and the light-colored powder is copper powder. Figure 2 Images were taken using SEM (Scanning Electron Microscopy) at a magnification of 200x. This well-preserved spherical structure gives the mixed powder excellent flowability, significantly improving the uniformity of powder spreading during subsequent 3D printing, reducing friction and agglomeration, thus ensuring uniform and stable powder dispersion and guaranteeing the density and other properties of the subsequently printed copper-chromium alloy parts.

[0043] In this embodiment, the mixed powder is placed in a drying oven for baking. The baking temperature of the mixed powder is 100 to 110°C, and the baking time is 4 to 5 hours. This can keep the mixed powder dry, further improve the flowability of the mixed powder, and ensure the uniformity of subsequent powder spreading.

[0044] It is understood that the baking temperature of the mixed powder can be 100℃, 101℃, 102℃, 103℃, 104℃, 105℃, 106℃, 107℃, 108℃, 109℃, 110℃, etc., but is not limited to the values ​​listed above. Other values ​​not listed within this range are also within the scope of protection of this application.

[0045] It is understood that the baking time of the mixed powder can be 4.0h, 4.1h, 4.2h, 4.3h, 4.4h, 4.5h, 4.6h, 4.7h, 4.8h, 4.9h, 5.0h, etc., but is not limited to the values ​​listed above. Other unlisted values ​​within this range are also within the scope of protection of this application.

[0046] In this embodiment, for steps S2 and S3, this application uses selective laser melting technology to print copper-chromium alloy. First, a three-dimensional model of the copper-chromium alloy to be printed is constructed, and the three-dimensional model is sliced ​​to form multiple layers. Multiple layers correspond to multiple printing layers, so as to form copper-chromium alloy by stacking multiple printing layers.

[0047] In the printing process, powder is first spread and mixed onto the printing substrate to form a first powder layer. This first powder layer is then laser-scanned to form the printed layer. Subsequently, mixed powder is spread on top of the newly formed printed layer to form a second powder layer. This second powder layer is also laser-scanned to form a new printed layer, and the new printed layer is connected to the previously formed printed layer. This process of spreading powder and laser scanning is repeated until a copper-chromium alloy part is printed.

[0048] In this embodiment, the preheating temperature of the printing substrate is 80°C, and the thickness of each powder layer is 30µm.

[0049] In this embodiment, when laying out each powder layer, each powder layer is first divided into a contour area and a filling area. The contour area surrounds the edge of the filling area, and the contour area and the filling area together form a powder layer. Subsequently, during the laser scanning operation, the powder corresponding to the filling area is scanned first to form a filling structure, and then the powder corresponding to the contour area is scanned to form a contour structure. The contour structure and the filling structure are connected to each other and together form the printing layer corresponding to the current powder layer.

[0050] It is worth noting that the width of the contour area is 0.1 mm to 0.2 mm.

[0051] It is understood that the width of the outline area can be 0.10mm, 0.11mm, 0.12mm, 0.13mm, 0.14mm, 0.15mm, 0.16mm, 0.17mm, 0.18mm, 0.19mm, 0.20mm, etc., but is not limited to the values ​​listed above. Other unlisted values ​​within this range are also within the scope of protection of this application.

[0052] In this way, each printing layer is formed using a two-scan method, scanning the infill area first and then the contour area. This allows the thermal stress generated by the first-formed infill structure to be released in the powder environment surrounding the contour area. After the infill structure stabilizes, the contour area is scanned, thereby reducing the thermal and mechanical stress on the contour area, ensuring forming quality, and improving the density and other properties of the printed copper-chromium alloy parts. In addition, during the subsequent scanning of the contour area, irregular edges of the formed infill structure can be remelted and trimmed, thereby improving surface quality.

[0053] In this embodiment, the first laser and the second laser can share the same laser, or they can each use their own specific lasers, and both lasers are Gaussian lasers. Furthermore, the spot diameters of the first and second lasers are 30 to 50 μm.

[0054] It is understood that the spot diameters of the first and second lasers can be 30µm, 31µm, 32µm, 33µm, 34µm, 35µm, 36µm, 37µm, 38µm, 39µm, 40µm, 41µm, 42µm, 43µm, 44µm, 45µm, 46µm, 47µm, 48µm, 49µm, 50µm, etc., but are not limited to the values ​​listed above. Other unlisted values ​​within this range are also within the scope of protection of this application.

[0055] In this embodiment, the power of the first laser is 300 to 450W, the scanning speed of the first laser is 400 to 800mm / s, and the scanning spacing of the first laser is 0.07 to 0.09mm.

[0056] It is understood that the power of the first laser can be 300W, 310W, 320W, 330W, 340W, 350W, 360W, 370W, 380W, 390W, 400W, 410W, 420W, 430W, 440W, 450W, etc., but is not limited to the values ​​listed above. Other unlisted values ​​within this range are also within the scope of protection of this application.

[0057] It is understood that the scanning speed of the first laser can be 400mm / s, 450mm / s, 500mm / s, 550mm / s, 600mm / s, 650mm / s, 700mm / s, 750mm / s, 800mm / s, etc., but is not limited to the values ​​listed above. Other unlisted values ​​within this range are also within the scope of protection of this application.

[0058] It is understood that the scanning spacing of the first laser can be 0.07mm, 0.08mm, 0.09mm, etc., but is not limited to the values ​​listed above. Other unlisted values ​​within this range are also within the scope of protection of this application.

[0059] In this embodiment, the first laser employs strip scanning, and the strip width of the first laser is 100 times the scanning interval of the first laser, with the strip direction perpendicular to the scanning direction. Thus, by using strip scanning to first scan the filling area, heat distribution becomes more uniform, reducing structural deformation and residual stress. This results in a lower defect rate and more uniform internal structure in the printed copper-chromium alloy, thereby improving the density of the copper-chromium alloy.

[0060] In this embodiment, after the first laser scans the filling area to form the filling structure, a second laser is directly used to scan the contour area. The power of the second laser is 350 to 400 W, and the scanning speed of the second laser is 500 to 900 mm / s.

[0061] It is understood that the power of the second laser can be 350W, 360W, 370W, 380W, 390W, 400W, etc., but is not limited to the values ​​listed above. Other unlisted values ​​within this range are also within the scope of protection of this application.

[0062] It is understood that the scanning speed of the second laser can be 500mm / s, 550mm / s, 600mm / s, 650mm / s, 700mm / s, 750mm / s, 800mm / s, 850mm / s, 900mm / s, etc., but is not limited to the values ​​listed above. Other values ​​not listed within this range are also within the scope of protection of this application.

[0063] Please combine Figure 1 In one embodiment, the copper-chromium alloy preparation method 100 further includes:

[0064] S5. Heat treat the copper-chromium alloy printed parts.

[0065] The heat treatment steps for copper-chromium alloy printed parts include:

[0066] S51. Place the copper-chromium alloy printed part into the heat treatment furnace and evacuate the heat treatment furnace.

[0067] S52. Heat the heat treatment furnace to a first temperature and keep it at the first temperature for a first time;

[0068] S53. The heat treatment furnace is cooled to the second temperature, and the copper-chromium alloy printed part is removed.

[0069] In this embodiment, the heat treatment furnace is specifically a vacuum heat treatment furnace. In step S51, the heat treatment furnace is evacuated to 10... -3 Pa. In step S52, the heat treatment furnace is heated from room temperature to a first temperature over a period of approximately 2 hours. The heating rate of the heat treatment furnace is 4.2°C / min to 5°C / min, the first temperature is 500 to 600°C, and the first time is 2.5 to 3.5 hours. In step S53, the second temperature is 80 to 95°C.

[0070] It is understood that the first temperature can be 500℃, 510℃, 520℃, 530℃, 540℃, 550℃, 560℃, 570℃, 580℃, 590℃, 600℃, etc., but is not limited to the values ​​listed above. Other unlisted values ​​within this range are also within the scope of protection of this application.

[0071] It is understood that the first time can be 2.5h, 2.6h, 2.7h, 2.8h, 2.9h, 3.0h, 3.1h, 3.2h, 3.3h, 3.4h, 3.5h, etc., but is not limited to the values ​​listed above. Other unlisted values ​​within this range are also within the scope of protection of this application.

[0072] It is understood that the heating rate of the heat treatment furnace may be 4.2℃ / min, 4.3℃ / min, 4.4℃ / min, 4.5℃ / min, 4.6℃ / min, 4.7℃ / min, 4.8℃ / min, 4.9℃ / min, 5.0℃ / min, etc., but is not limited to the values ​​listed above. Other unlisted values ​​within this range are also within the scope of protection of this application.

[0073] It is understood that the second temperature can be 80℃, 81℃, 82℃, 83℃, 84℃, 85℃, 86℃, 87℃, 88℃, 89℃, 90℃, 91℃, 92℃, 93℃, 94℃, 95℃, etc., but is not limited to the values ​​listed above. Other unlisted values ​​within this range are also within the scope of protection of this application.

[0074] This application also provides a copper-chromium alloy printed part, prepared using the aforementioned copper-chromium alloy preparation method 100. The copper-chromium alloy printed part has a density greater than 99%, and can reach a maximum of 99.7%.

[0075] In some implementation methods, the copper-chromium alloy is prepared according to the above-described copper-chromium alloy preparation method 100. The mixed powder (both copper and chromium powders have a D10=15µm and D90=53µm) is placed in a drying oven and baked at 105°C for 4 hours. A Gaussian beam with a spot diameter of 40µm is used as the first and second lasers for subsequent scanning. The preheating temperature of the printing substrate is 80°C, and the powder layer thickness is 30µm. The width of the contour area is 0.15mm. After the first laser scan forms the filling structure, the second laser is used directly to scan and form the contour structure. The powder spreading and scanning operations are repeated until the copper-chromium alloy is printed.

[0076] Subsequently, the cylindrical chromium alloy was placed in a vacuum heat treatment furnace and evacuated to 10°C. -3 Pa, then the vacuum heat treatment furnace is heated from room temperature to 550°C at a heating rate of 4.6°C / min, held at that temperature for 3 hours, and then cooled to 80°C.

[0077] By adjusting the laser power, scanning speed, scanning spacing, and energy density of the first laser, as well as the laser power, scanning speed, and energy density of the second laser, 40 copper-chromium alloy samples were obtained. The density of each copper-chromium alloy sample was then tested (density = 100% - porosity), and the following process parameter test table was obtained.

[0078]

[0079]

[0080] Images of the square copper-chromium alloy blocks printed from samples 1 to 25 in the table are shown below. Figure 3 As shown in the table, the images of the square copper-chromium alloy blocks printed from samples 26 to 40 are as follows: Figure 4 As shown.

[0081] For example, in sample 11, a square copper-chromium alloy block measuring 12×12×12mm was printed. After metallographic polishing, the metallographic image of the copper-chromium alloy block was as follows. Figure 5 As shown, the maximum pore size is 540.5508 μm. According to the porosity statistics, there are 460 pores larger than 30 μm, and the rest are smaller than 30 μm. The porosity is 11.78%, and the density is 88.222%.

[0082] For example, in sample 26, a square copper-chromium alloy block measuring 12×12×12mm was printed. After metallographic polishing, the metallographic image of the copper-chromium alloy block was as follows. Figure 6 As shown, the maximum pore size is 124.7838 μm. According to the porosity statistics, there are 23 pores larger than 30 μm, and the others are smaller than 30 μm. The porosity is 0.3%, and the density is 99.700%.

[0083] For example, in sample 33, a square copper-chromium alloy block measuring 12×12×12mm was printed. After metallographic polishing, the metallographic image of the copper-chromium alloy block was as follows. Figure 7 As shown, the maximum pore size is 179.3389 μm. According to the porosity statistics, there are 41 pores larger than 30 μm, and the others are smaller than 30 μm. The porosity is 0.45%, and the density is 99.551%.

[0084] It is evident that by controlling the power and scanning speed of the first and second lasers, and controlling the scanning spacing of the first laser, combined with the two-stage scanning method of internal scanning followed by contour scanning adopted in this application, the density of the formed copper-chromium alloy 30 can be significantly improved.

[0085] The specific embodiments of this application have been described above with reference to the accompanying drawings. However, those skilled in the art will understand that various changes and substitutions can be made to the specific embodiments of this application without departing from the scope of this application. All such changes and substitutions fall within the scope defined by this application.

Claims

1. A method for preparing a copper-chromium alloy, characterized in that, Includes the following steps: Copper powder and chromium powder are mechanically mixed to form a mixed powder, and the mixed powder is then baked. The mixed powder is used to perform a powder spreading operation to form a powder layer, the powder layer including a contour region and a filling region, the contour region being disposed around the edge of the filling region; The filling area is scanned with a first laser, and the contour area is scanned with a second laser to obtain a printing layer; the power of the first laser is 300 to 450W, the first laser adopts strip scanning, and the strip width of the first laser is 100 times the scanning interval of the first laser. Repeat the powder spreading and scanning operations until multiple printing layers are stacked to form a copper-chromium alloy print.

2. The method for preparing copper-chromium alloy as described in claim 1, characterized in that, The scanning speed of the first laser is 400 to 800 mm / s, and the scanning spacing of the first laser is 0.07 to 0.09 mm.

3. The method for preparing copper-chromium alloy as described in claim 1, characterized in that, The power of the second laser is 350 to 400W, and the scanning speed of the second laser is 500 to 900mm / s.

4. The method for preparing copper-chromium alloy as described in claim 1, characterized in that, The spot diameters of the first laser and the second laser are 30 to 50 μm.

5. The method for preparing copper-chromium alloy as described in claim 1, characterized in that, The mixed powder, by mass percentage, has a copper powder to chromium powder ratio of 7:

3.

6. The method for preparing copper-chromium alloy as described in claim 1, characterized in that, The baking temperature of the mixed powder is 100 to 110°C, and the baking time of the mixed powder is 4 to 5 hours.

7. The method for preparing copper-chromium alloy as described in claim 1, characterized in that, The method for preparing the copper-chromium alloy further includes: heat-treating the copper-chromium alloy printed part; wherein the step of heat-treating the copper-chromium alloy printed part includes: The copper-chromium alloy printed part is placed in a heat treatment furnace, and the heat treatment furnace is evacuated. The heat treatment furnace is heated to a first temperature and held at the first temperature for a first time. The heat treatment furnace is cooled to a second temperature, and the copper-chromium alloy printed part is then removed.

8. The method for preparing copper-chromium alloy as described in claim 7, characterized in that, The heat treatment furnace was evacuated to 10°C. -3 Pa, the heating rate of the heat treatment furnace is 4.2℃ / min to 5℃ / min, the first temperature is 500 to 600℃, the first time is 2.5 to 3.5h, and the second temperature is 80 to 95℃.

9. A copper-chromium alloy printed part, characterized in that, The copper-chromium alloy printed part is prepared by any one of the copper-chromium alloy preparation methods as described in claims 1 to 8, and the density of the copper-chromium alloy printed part is greater than 99%.

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