Particle-reinforced copper alloy powder and preparation and application thereof

Abstract

The invention discloses particle reinforced copper alloy powder and preparation and application thereof. The powder comprises copper or copper alloy particles with the surfaces coated with nanocrystalline carbide powder, and the nanocrystalline carbide powder is carbide which is formed by metal powder and graphite powder and has the particle size smaller than 5 micrometers and the grain size not larger than 1000 nm. The preparation method of the powder comprises the steps that metal powder and graphite powder are mixed and then subjected to high-energy ball milling, and nanocrystalline carbide powder is obtained; carrying out ball-milling mixing on the nanocrystalline carbide powder and copper or copper alloy powder to obtain intermediate powder; and the intermediate powder is subjected to annealing treatment, and the particle-enhanced copper alloy powder is obtained. The superfine nanocrystalline carbide powder is used as a reinforcing phase in the 3D printing copper alloy, the reinforcing efficiency of the 3D printing copper alloy can be improved, the dispersity of the reinforcing phase is improved, and meanwhile agglomeration and segregation are avoided. Meanwhile, due to the high activity, diffusion alloying in the printing process is facilitated, and therefore the good strengthening effect is achieved.

Description

Technical Field

[0001] The present invention relates to a 3D printing powder raw material and preparation and application thereof, and in particular to a particle-enhanced copper alloy powder and preparation and application thereof in 3D printing. Background Art

[0002] Traditional copper and its alloys have some limitations in 3D printing applications, such as insufficient strength, poor toughness and wear resistance. With the increasing demand for high-performance materials in industries such as electronics, aerospace, and medical devices, the development of particle-reinforced copper alloys has become an important solution. By introducing reinforcing particles (such as carbides, ceramics, or other high-performance metal particles), the mechanical properties, thermal conductivity, and corrosion resistance of copper-based materials can be significantly improved. Particle-reinforced materials improve their performance by adding high-strength reinforcing phases (such as ceramic particles as dispersed phases) to the base metal (copper alloy). The reinforcing particles form a complex phase structure in the matrix, which can effectively improve the strength and hardness of the material while maintaining good electrical and thermal conductivity. Carbides (such as TiC, WC, etc.) are dispersed in copper alloys as reinforcing phases, which can effectively prevent the movement of dislocations, thereby improving the strength and hardness of the material. The melting point of carbides is usually higher than that of the copper matrix, so they are more stable in high temperature environments, enhancing the thermal stability of copper alloys while significantly improving the wear resistance of copper-based alloys.

[0003] At present, carbide powder is usually added directly into molten metal for mixed smelting to obtain reinforced metal particles. However, the dispersion of carbides in the reinforced metal particles thus obtained is poor, and they are prone to agglomeration and segregation, which greatly reduces the strengthening efficiency of carbides and limits the performance improvement of the reinforced metal particle products. Summary of the invention

[0004] Purpose of the invention: The purpose of the present invention is to provide a particle-reinforced copper alloy powder to solve the problem that the strength and hardness of existing reinforced copper metal particles are only slightly improved by carbides. Another purpose of the present invention is to propose a method for preparing particle-reinforced copper alloy powder to solve the problem of how to prepare particle-reinforced copper alloy powder. The third purpose of the present invention is to propose the application of particle-reinforced copper alloy powder in 3D printing to solve the problem of how to perform 3D printing using particle-reinforced copper alloy powder as raw material.

[0005] Technical solution: The particle-enhanced copper alloy powder described in the present invention includes copper or copper alloy particles whose surfaces are coated with nanocrystalline carbide powder. The nanocrystalline carbide powder is a carbide formed by metal powder and graphite powder with a particle size less than 5 μm and a grain size not exceeding 1000 nm.

[0006] Preferably, the material of the metal powder is at least one of Ti, W, Cr and Mo.

[0007] The second aspect of the present invention discloses a method for preparing the above-mentioned particle-enhanced copper alloy powder, comprising the following steps:

[0008] (1) mixing metal powder and graphite powder and then subjecting them to high-energy ball milling to obtain nanocrystalline carbide powder;

[0009] (2) ball-milling the nanocrystalline carbide powder and the copper or copper alloy powder to obtain an intermediate powder;

[0010] (3) The intermediate powder is annealed to obtain a particle-enhanced copper alloy powder.

[0011] The present invention selects graphite powder, Ti / W / Cr / Mo and other metal powders that can form carbides for high-energy ball milling to obtain highly active and ultrafine carbide mixed powder. The powder particles are broken during high-energy ball milling, but they are not completely alloyed, and there are a large number of carbide particles with a high specific surface area.

[0012] Nanocrystalline carbide powder is mixed with copper or copper alloy powder and mechanically mixed in a ball mill. During this process, ultrafine carbide powder particles are adsorbed and bonded to the surface of copper / copper alloy powder under high-speed collision to form uniform particle-enhanced copper / copper alloy powder. Grinding time and parameters need to be adjusted according to the needs of the powder.

[0013] The intermediate powder is annealed by a heat treatment process to further improve the organizational structure and performance of the intermediate powder, increase the bonding strength of the nanocrystalline carbide powder, and ensure the uniform distribution of the spherical copper / copper alloy particles and improve the strength.

[0014] Preferably, in step (1), the mass ratio of the metal powder to the graphite powder is 1:0.05-1.5, depending on the metal carbide formation ratio.

[0015] Preferably, in step (1), the high-energy ball milling method is: placing metal powder, graphite powder and grinding balls in a ball milling jar, and milling at a ball milling speed of not less than 500 rpm under vacuum conditions for at least 1 hour. The vacuum condition is a vacuum degree of less than 0.1 Pa. Under a vacuum environment, graphite powder and metal powders such as Ti / W / Cr / Mo that can form carbides are subjected to high-speed ball milling, and the powder is more likely to obtain high-density dislocations, and while carbonization occurs, a carbide powder with high activity and finer powder particle size is obtained.

[0016] Preferably, the mass ratio of the grinding balls to the total weight of the metal powder and the graphite powder is 1:15-1:30. The grinding balls are made of ceramic grinding balls, including inorganic materials such as oxides, carbides and agate, with a diameter of 20-125 mm. The ceramic grinding balls can be selected according to the diameter of the powder particles.

[0017] Preferably, in step (2), the mass ratio of nanocrystalline carbide powder to copper or copper alloy powder is 0.01-0.5:1, and the copper or copper alloy powder is spherical copper powder or spherical copper alloy powder with a particle size of 15-60 μm.

[0018] Preferably, in step (2), the ball milling mixing conditions are a ball milling speed of 200-500 r / min and a ball milling time of 30-60 min.

[0019] Preferably, in step (3), the annealing condition is annealing at 350-550° C. for 0.5-3 h in an inert atmosphere. The inert atmosphere may be N 2 atmosphere or helium atmosphere.

[0020] Since a large number of dislocations are generated during the crushing process of the particles during ball milling, the surface energy of the powder is high and unstable, and it is easy to oxidize and agglomerate, which ultimately affects the performance of the powder. Therefore, heating annealing treatment is carried out at a certain temperature.

[0021] The third aspect of the present invention discloses the application of the above-mentioned particle-enhanced copper alloy powder in 3D printing.

[0022] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages:

[0023] The present invention selects graphite powder, Ti / W / Cr / Mo and other metal powders that can form carbides for high-energy ball milling. During the high-energy ball milling, the raw material powder particles are crushed and the metal elements are carbonized to generate ultrafine carbide particles with a high specific surface area. The use of ultrafine nanocrystalline carbide powder as a reinforcing phase in 3D printed copper alloys can improve its strengthening efficiency and the dispersibility of the reinforcing phase, while avoiding agglomeration and segregation. At the same time, due to its high activity, it is conducive to diffusion alloying during the printing process, thereby playing a good strengthening role, so that the performance of preparing 3D printed copper alloys is improved.

[0024] The yield of the particle-enhanced copper alloy powder prepared by the present invention is high. The carbide powder in the obtained particle-enhanced copper alloy powder has a small particle size and the crystal grains are nanocrystalline, which has the advantages of high stability and is not prone to agglomeration and segregation. The preparation method generates submicron high-activity carbide particles on the surface of copper particles through mixing high-energy ball milling and ordinary mechanical ball milling, forming a micro-nano composite particle-enhanced particle structure. The micro-nano enhanced phase particles improve the strength and printing performance of the copper-based composite material. The particle-enhanced copper alloy powder prepared by the method has the advantages of low oxygen content and good sphericity, which is conducive to the uniform spreading of the powder and interlayer bonding during 3D printing, thereby improving the accuracy and quality of the printed parts. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1is a SEM image of the particle-enhanced copper alloy powder prepared in Example 1;

[0026] Figure 2 EDS element distribution spectrum (Cu, Mo) of the particle-enhanced copper alloy powder prepared in Example 1;

[0027] Figure 3 is a SEM image of the particle-enhanced copper alloy powder prepared in Example 2;

[0028] Figure 4 EDS element distribution spectrum (Cu, Cr) of the particle-enhanced copper alloy powder prepared in Example 2;

[0029] Figure 5 is a SEM image of the particle-enhanced copper alloy powder prepared in Example 3;

[0030] Figure 6 The SEM image of the printed product in Example 1 and the EDS spectrum of the molybdenum element therein;

[0031] Figure 7 The following is a SEM image of the finished product printed in Comparative Example 4 and an EDS spectrum of the molybdenum element therein. DETAILED DESCRIPTION

[0032] The technical solution of the present invention is further described below in conjunction with the accompanying drawings.

[0033] Example 1: A particle-enhanced copper alloy powder, such as Figure 1 As shown, it includes spherical copper particles with molybdenum carbide powder coated on the surface, the molybdenum carbide powder has a particle size of less than 5 μm and a grain size of 689 nm, and the copper alloy powder has a particle size of 20-60 μm and good sphericity.

[0034] The preparation method of the particle-enhanced copper alloy powder is as follows:

[0035] (1) Molybdenum powder and graphite powder with a purity of >99% are used as raw materials, and the particle size of the coarse powder after the raw material powder is crushed is -325 mesh. The metal powder, graphite powder and grinding balls are placed in a ball mill at a mass ratio of 1:0.13, and the ball mill is sealed. The vacuum is repeatedly evacuated to ensure that the vacuum degree is less than 0.1 Pa. The ball mill is rotated at 800 rpm and the ball mill is milled for 1.5 hours to obtain nanocrystalline carbide powder; the mass ratio of the grinding balls to the total weight of the metal powder and the graphite powder is 1:20, and the material of the grinding balls is alumina, and the diameter ratio is Φ20 mm:Φ50 mm, which is 4:6.

[0036] (2) mixing the nanocrystalline carbide powder and the spherical copper powder with a particle size of 20-60 μm at a mass ratio of 0.05:1, and then ball milling at a speed of 300 r / min for 45 min to obtain an intermediate powder;

[0037] (3) The intermediate powder was heated at 500°C in N 2 After annealing in atmosphere for 1.5 hours, a particle-enhanced copper alloy powder was obtained. The EDS element distribution spectrum of the particle-enhanced copper alloy powder is shown in FIG. Figure 2 shown.

[0038] Example 2: A particle-enhanced copper alloy powder, such as Figure 3 As shown, it includes copper particles coated with titanium carbide powder on the surface, the particle size of the titanium carbide powder is less than 5μm, the grain size is 815nm, the particle size of the copper alloy powder is 20-50μm, and the sphericity is good.

[0039] The preparation method of the particle-enhanced copper alloy powder is as follows:

[0040] (1) Titanium powder and graphite powder with a purity of >99% are used as raw materials. The raw material powder is crushed to a particle size of -325 mesh. Metal powder, graphite powder and grinding balls are placed in a ball mill at a mass ratio of 1:0.25. The ball mill is sealed and repeatedly evacuated to ensure that the vacuum degree is less than 0.1 Pa. The ball mill is rotated at 500 rpm for 2 hours to obtain nanocrystalline carbide powder by high-energy ball milling. The mass ratio of the grinding balls to the total weight of the metal powder and graphite powder is 1:16. The grinding balls are made of silicon carbide and have a diameter ratio of Φ20 mm:Φ50 mm of 5:5.

[0041] (2) mixing nanocrystalline carbide powder and spherical copper powder with a particle size of 20-50 μm at a mass ratio of 0.1:1, and then ball milling at a speed of 250 r / min for 30 min to obtain an intermediate powder;

[0042] (3) The intermediate powder was heated at 400 °C in N 2 After annealing in atmosphere for 2 hours, particle-enhanced copper alloy powder was obtained. The EDS element distribution spectrum of particle-enhanced copper alloy powder is shown in Figure 4 shown.

[0043] Embodiment 3: A particle-enhanced copper alloy powder, such as Figure 5 As shown, it includes copper particles coated with chromium carbide powder on the surface, the chromium carbide powder has a particle size of less than 5 μm and a grain size of 897 nm, and the copper alloy powder has a particle size of 30-100 μm and good sphericity.

[0044] The preparation method of the particle-enhanced copper alloy powder is as follows:

[0045] (1) Using chromium powder and graphite powder with a purity of >99% as raw materials, crushing the raw powder to a particle size of -325 mesh, placing metal powder, graphite powder and grinding balls in a ball mill at a mass ratio of 1:0.1, sealing the ball mill, repeatedly evacuating to ensure that the vacuum degree is less than 0.1 Pa, and performing high-energy ball milling at a ball mill speed of 700 rpm for 1 hour to obtain nanocrystalline carbide powder; the mass ratio of the grinding balls to the total weight of the metal powder and graphite powder is 1:18, the grinding balls are made of silicon carbide, and the diameter ratio is Φ20 mm:Φ50 mm, which is 4:6.

[0046] (2) mixing nanocrystalline carbide powder particles and 30-100 μm spherical copper powder at a mass ratio of 0.2:1, and then ball milling at a speed of 300 r / min for 40 min to obtain an intermediate powder;

[0047] (3) The intermediate powder was annealed at 350° C. in a N 2 atmosphere for 3 h to obtain a particle-reinforced copper alloy powder.

[0048] Comparative Example 1: The rest is the same as Example 1, except that:

[0049] Replace graphite with fullerenes.

[0050] Comparative Example 2: The rest is the same as Example 1, except that:

[0051] Replace graphite with amorphous carbon.

[0052] Comparative Example 3: The rest is the same as Example 1, except that:

[0053] Commercial molybdenum carbide powder with an average particle size of 10 μm and spherical copper powder are directly ball-milled and mixed according to the method of steps (2)-(3), and then annealed to obtain enhanced copper alloy powder.

[0054] Comparative Example 4: The rest is the same as Example 1, except that:

[0055] According to the mass ratio of molybdenum carbide powder to copper being 0.08:1, molybdenum carbide powder with an average particle size of 5 μm is added into molten copper water and mixed, and then cooled to obtain a copper alloy. The copper alloy is crushed and ball-milled to a particle size of about 20-60 μm to obtain an enhanced copper alloy powder.

[0056] The enhanced copper alloy powders prepared in Example 1 and Comparative Example 4 were used for 3D printing respectively, and the methods were as follows:

[0057] Electron beam selected melting molding (SEBM) was used, with an electron beam current of 15 mA (with a fluctuation of plus or minus 0.2 mA), a powder layer thickness of 50 μm, a scanning line spacing of 0.1 mm, and a scanning speed of 3-3.5 m / s.

[0058] The strength and hardness of the 3D printed material samples were tested, and the agglomeration and segregation of carbides inside the material were observed. The results are as follows: Figure 6 As shown, the left picture is the SEM picture of the printed product, and the right picture is the EDS spectrum of the molybdenum element, which represents the distribution of the molybdenum element. The control group used 20-60μm spherical copper powder for 3D printing. The test data is shown in Table 1. This group also observed whether there was agglomeration and segregation of carbides inside the material. The results are shown in Figure 7 The left picture is the SEM picture of the printed product, and the right picture is the EDS spectrum of the molybdenum element, which represents the distribution of the molybdenum element. It can be clearly observed that there is agglomeration of large-sized molybdenum elements / particles.

[0059] Table 1 Performance test results of different enhanced copper alloy powders

[0060] Group Sample tensile strength Sample hardness Example 1 458.7MPa HB115 Example 2 441.5MPa HB109 Example 3 457.9MPa HB112 Comparative Example 1 381.1MPa HB69 Comparative Example 2 377.7MPa HB77 Comparative Example 3 379.5MPa HB93 Comparative Example 4 383.6MPa HB96 Control group 372.1MPa HB82

[0061] It can be seen from the above data that the agglomeration and segregation of carbides occurred in the materials obtained by 3D printing using the enhanced copper alloy powder prepared in Comparative Examples 1-4, resulting in a small improvement in the strength and hardness of the materials, while the carbides in the materials obtained by 3D printing using Examples 1-4 had good dispersion, and the strength and hardness of the materials were greatly improved. Comparison of Example 1 with Comparative Examples 1-2 shows that carbide powders such as molybdenum powder can only form carbide powders with high activity and nanocrystalline state when subjected to high-energy ball milling with graphite, and similar carbide powders cannot be formed when subjected to high-energy ball milling with other carbon allotropes, resulting in poor dispersion of carbides, affecting the physical properties of 3D printed materials. Comparative Example 3 shows that when commercial molybdenum carbide powder is directly ball milled with spherical copper powder, since commercial carbides do not have the nanocrystalline structure and high activity of carbides obtained by high-energy ball milling, molybdenum carbide powders not only cannot effectively adhere to the surface of spherical copper particles, but also have poor dispersion, resulting in a small improvement in the physical properties of 3D printed materials. Comparative Example 4 shows that when carbide powder is directly smelted with copper, the agglomeration and segregation problem of carbides cannot be solved, resulting in poor performance of the enhanced copper alloy powder, poor printing process, and a large number of pores and agglomerations in the sample. Comparative Examples 3 and 4 show that the high-energy ball milling step directly affects the dispersibility of carbides, and the present invention relies on the high-energy ball milling step to improve the performance of the enhanced copper alloy powder.

Claims

1. A particle-enhanced copper alloy powder, characterized in that: The invention comprises copper or copper alloy particles whose surfaces are coated with nanocrystalline carbide powder. The nanocrystalline carbide powder is carbide formed by metal powder and graphite powder, and the particle size is less than 5 μm and the grain size is not more than 1000 nm.

2. The particle-enhanced copper alloy powder according to claim 1, characterized in that: The material of the metal powder is at least one of Ti, W, Cr and Mo.

3. The method for preparing the particle-enhanced copper alloy powder according to claim 1 or 2, characterized in that: The steps include: (1) mixing metal powder and graphite powder and then subjecting them to high-energy ball milling to obtain nanocrystalline carbide powder; (2) ball-milling the nanocrystalline carbide powder and the copper or copper alloy powder to obtain an intermediate powder; (3) The intermediate powder is annealed to obtain a particle-enhanced copper alloy powder.

4. The method for preparing the particle-enhanced copper alloy powder according to claim 3, characterized in that: In step (1), the mass ratio of the metal powder to the graphite powder is 1:0.05-1.

5.

5. The method for preparing the particle-enhanced copper alloy powder according to claim 3, characterized in that: In step (1), the high-energy ball milling method is: placing metal powder, graphite powder and grinding balls in a ball milling jar, and ball milling at a ball milling speed of not less than 500 rpm under vacuum conditions for at least 1 hour.

6. The method for preparing the particle-enhanced copper alloy powder according to claim 5, characterized in that: The mass ratio of the grinding balls to the total weight of the metal powder and the graphite powder is 1:15-30. The grinding balls are made of ceramic grinding balls with a diameter of 20-125 mm.

7. The method for preparing the particle-enhanced copper alloy powder according to claim 3, characterized in that: In step (2), the mass ratio of nanocrystalline carbide powder to copper or copper alloy powder is 0.01-0.5:1, and the copper or copper alloy powder is spherical copper powder or spherical copper alloy powder with a particle size of 15-60 μm.

8. The method for preparing the particle-enhanced copper alloy powder according to claim 3, characterized in that: In step (2), the ball milling mixing conditions are ball milling speed of 200-500 r / min and ball milling for 30-60 min.

9. The method for preparing the particle-enhanced copper alloy powder according to claim 3, characterized in that: In step (3), the annealing treatment condition is annealing treatment at 350-550° C. in an inert atmosphere for 0.5-3 h.

10. Use of the particle-enhanced copper alloy powder according to claim 1 or 2 in 3D printing.

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