Metal powder suitable for additive manufacturing and preparation method thereof

Abstract

The present invention relates to the technical field of additive manufacturing, and specifically to a metal powder suitable for additive manufacturing and a preparation method thereof. The metal powder suitable for additive manufacturing of the present invention comprises the following preparation steps: (1) modifying cobalt-based alloy powder; (2) mixing the modified cobalt-based alloy powder with a ceramic reinforcement; (3) ball milling and screening. The metal powder suitable for additive manufacturing of the present invention has excellent sphericity, and its alloy manufactured by additive manufacturing has excellent hardness and wear resistance, and still has excellent oxidation resistance in a high temperature environment, especially at 1000°C. The metal powder suitable for additive manufacturing of the present invention, its alloy can meet the requirements of long-term use in a high temperature environment.

Description

Technical Field

[0001] The present invention relates to the technical field of additive manufacturing, and in particular to a metal powder suitable for additive manufacturing and a preparation method thereof. Background Art

[0002] Laser Additive Manufacturing (LAM) is an advanced manufacturing technology that uses lasers to melt or solidify powder materials and stack them layer by layer to build a three-dimensional entity. Compared with traditional manufacturing methods such as cutting and casting, it has the advantages of high flexibility, high molding accuracy, and no need for molds. It is widely used in many fields, such as aerospace, automobile manufacturing, medical equipment, etc.

[0003] High-temperature alloys refer to a type of metal material that can work for a long time at temperatures above 600°C and under certain stresses and maintain a stable organizational structure. The production of high-temperature alloys is closely related to the development of the aerospace industry and is generally used in high-temperature hot end components of aircraft engines, rocket engines and gas turbines.

[0004] Patent technical document CN201910644371.6 discloses an ECY768 cobalt-based alloy powder and its preparation method and application. The invention adopts vacuum smelting technology to obtain ECY768 cobalt-based alloy powder through ultrasonic vibration screening and airflow classification. The ECY768 cobalt-based alloy powder prepared by the present invention has high purity, low oxygen content, high sphericity, uniform particle size distribution, high loose density, good fluidity, and can meet the use requirements of selective laser melting technology, greatly reducing production costs and pollution. However, the prints obtained by printing the powder are easily oxidized under high temperature conditions. Summary of the invention

[0005] In view of this, the purpose of the present invention is to propose a metal powder suitable for additive manufacturing and a preparation method thereof, so as to provide a metal powder suitable for additive manufacturing, wherein the alloy obtained by additive manufacturing still has excellent oxidation resistance at 1000°C.

[0006] Based on the above purpose, the present invention provides a metal powder suitable for additive manufacturing, comprising the following preparation steps:

[0007] S1: mixing, ball-milling, smelting, atomizing and pulverizing the cobalt-based alloy powder and silicon carbide, and sieving to obtain a modified cobalt-based alloy powder;

[0008] S2: In an argon atmosphere, the modified cobalt-based alloy powder, chromium carbide and chromium silicide are mixed, ball-milled, and sieved to obtain a metal powder with a particle size of 15-53 μm suitable for additive manufacturing.

[0009] Preferably, in step S1, the ball milling speed is 300-500 rpm, and the ball milling time is 1-3 h.

[0010] Preferably, the cobalt-based alloy powder in step S1 is Co-Mo-Cr-Si alloy powder with a particle size of 30-50 μm.

[0011] Preferably, the particle size of the silicon carbide in step S1 is 600-800 nm.

[0012] Preferably, in step S1, the weight ratio of the cobalt-based alloy powder to silicon carbide is 80-95:5-20.

[0013] Preferably, the smelting in step S1 is vacuum smelting, the smelting temperature is 1600-1700°C, and the vacuum degree is less than 1.0×10 -2 Pa.

[0014] Preferably, the atomization pressure of the atomization powder making in step S1 is 2.0-3.5 MPa.

[0015] Preferably, the particle size of the modified cobalt-based alloy powder in step S1 is 60-80 μm.

[0016] Preferably, the particle size of the chromium carbide in step S2 is 80-100 nm.

[0017] Preferably, in step S2, the weight ratio of the modified cobalt-based alloy powder, chromium carbide and chromium silicide is 89-94.5:5-10:0.5-1.

[0018] Preferably, the particle size of the chromium silicide in step S2 is 0.5-5 μm.

[0019] Preferably, in step S2, the ball milling speed is 40-60 r / min, and the ball milling time is 8-10 h.

[0020] Furthermore, the present invention also provides a metal powder suitable for additive manufacturing, which is prepared by the above-mentioned method for preparing the metal powder suitable for additive manufacturing.

[0021] Beneficial effects of the present invention:

[0022] (1) The present invention uses a modification treatment method to first ball-mill and mix-smelt the cobalt-based alloy powder with silicon carbide, so that the silicon carbide can be evenly dispersed. During the additive process, it can generate a reinforcing phase in situ with the cobalt-based alloy powder, thereby improving the hardness and wear resistance of the alloy. It can also promote the compatibility between the oxide film generated during the additive process and the matrix, so that the alloy still has relatively excellent antioxidant properties at a high temperature of 1000°C.

[0023] (2) The present invention first modifies the cobalt-based alloy powder and then mixes it with chromium carbide and chromium silicide powders for ball milling to add a reinforcing phase, thereby improving the hardness and wear resistance of the alloy. In addition, the compound use of chromium carbide and chromium silicide powders can further form a reinforcing phase with the modified cobalt-based alloy powder during the additive process, thereby improving the compatibility between the oxide film and the matrix, so that the alloy still has relatively excellent antioxidant properties at a high temperature of 1000°C.

[0024] (3) The present invention can improve the hardness and wear resistance of the alloy by adding chromium carbide and chromium silicide to the modified cobalt-based alloy powder; and there is a synergistic effect between the modified cobalt-based alloy powder and the chromium carbide and chromium silicide, so that the alloy still has excellent high-temperature oxidation resistance at 1000°C. DETAILED DESCRIPTION

[0025] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments.

[0026] The properties of the raw materials used in the examples and comparative examples of the present invention are as follows:

[0027] Co-Mo-Cr-Si alloy powder, particle size 30-50μm, composition as follows:

[0028]

[0029] Embodiment 1: A method for preparing metal powder suitable for additive manufacturing, the specific steps are as follows:

[0030] (1) 80 g of Co-Mo-Cr-Si alloy powder was mixed with 20 g of silicon carbide and ball-milled at 300 rpm for 1 h under a vacuum of 0.8 × 10 -2 Pa, smelting at 1600°C, keeping the temperature for 0.5h, then atomizing and powdering under argon atmosphere and 2.0MPa, sieving to obtain modified cobalt-based alloy powder with a particle size of 60-80μm;

[0031] (2) Under an argon atmosphere, 89 g of modified cobalt-based alloy powder with a particle size of 60-80 μm, 10 g of chromium carbide and 1 g of chromium silicide were mixed, ball-milled at 40 r / min for 8 h, and sieved to obtain a metal powder with a particle size of 15-53 μm suitable for additive manufacturing.

[0032] Embodiment 2: A method for preparing metal powder suitable for additive manufacturing, the specific steps are as follows:

[0033] (1) 87.5 g of Co-Mo-Cr-Si alloy powder was mixed with 12.5 g of silicon carbide and ball-milled at 300 rpm for 1 h under a vacuum of 0.8 × 10 -2 Pa, smelting at 1650 ° C, keeping the temperature for 1 hour, then atomizing and powdering under argon atmosphere and 3 MPa, sieving, and obtaining a modified cobalt-based alloy powder with a particle size of 60-80 μm;

[0034] (2) Under an argon atmosphere, 92 g of modified cobalt-based alloy powder with a particle size of 60-80 μm, 7.2 g of chromium carbide and 0.8 g of chromium silicide were mixed, ball-milled at 50 r / min for 9 h, and sieved to obtain a metal powder with a particle size of 15-53 μm suitable for additive manufacturing.

[0035] Embodiment 3: A method for preparing metal powder suitable for additive manufacturing, the specific steps are as follows:

[0036] (1) 90 g of Co-Mo-Cr-Si alloy powder was mixed with 10 g of silicon carbide and ball-milled at 300 rpm for 1 h under a vacuum of 0.8 × 10 -2 Pa, smelting at 1680°C, keeping the temperature for 0.5h, then atomizing and powdering under argon atmosphere and 2.5MPa, sieving to obtain modified cobalt-based alloy powder with a particle size of 60-80μm;

[0037] (2) Under an argon atmosphere, 93 g of modified cobalt-based alloy powder with a particle size of 60-80 μm, 6.1 g of chromium carbide and 0.9 g of chromium silicide were mixed, ball-milled at 50 r / min for 9 h, and sieved to obtain a metal powder with a particle size of 15-53 μm suitable for additive manufacturing.

[0038] Embodiment 4: A method for preparing metal powder suitable for additive manufacturing, the specific steps are as follows:

[0039] (1) 95 g of Co-Mo-Cr-Si alloy powder was mixed with 5 g of silicon carbide and ball-milled at 300 rpm for 1 h under a vacuum of 0.8 × 10 -2 Pa, smelting at 1700 ° C, keeping the temperature for 1 hour, then atomizing and powdering in an argon atmosphere at 3.5 MPa, sieving, and obtaining a modified cobalt-based alloy powder with a particle size of 60-80 μm;

[0040] (2) Under an argon atmosphere, 94.5 g of modified cobalt-based alloy powder with a particle size of 60-80 μm, 5 g of chromium carbide and 0.5 g of chromium silicide were mixed, ball-milled at 60 r / min for 10 h, and sieved to obtain a metal powder with a particle size of 15-53 μm suitable for additive manufacturing.

[0041] Comparative Example 1: A method for preparing metal powder, the specific steps are as follows:

[0042] In an argon atmosphere, 92 g of Co-Mo-Cr-Si alloy powder, 7.2 g of chromium carbide and 0.8 g of chromium silicide were mixed, ball-milled at 50 r / min for 9 h, and sieved to obtain a metal powder with a particle size of 15-53 μm suitable for additive manufacturing.

[0043] Comparative Example 2: A method for preparing metal powder, the specific steps are as follows:

[0044] (1) 87.5 g of Co-Mo-Cr-Si alloy powder was mixed with 12.5 g of silicon carbide and ball-milled at 300 rpm for 1 h under a vacuum of 0.8 × 10 -2 Pa, smelting at 1650 ° C, keeping the temperature for 1 hour, then atomizing and powdering under argon atmosphere and 3 MPa, sieving, and obtaining a modified cobalt-based alloy powder with a particle size of 60-80 μm;

[0045] (2) Under an argon atmosphere, 92 g of modified cobalt-based alloy powder and 8 g of chromium carbide were mixed, ball-milled at 50 r / min for 9 h, and sieved to obtain a metal powder with a particle size of 15-53 μm suitable for additive manufacturing.

[0046] Comparative Example 3: A method for preparing metal powder, the specific steps are as follows:

[0047] In an argon atmosphere, 81 g of Co-Mo-Cr-Si alloy powder, 11 g of silicon carbide, 7.2 g of chromium carbide and 0.8 g of chromium silicide were mixed, ball-milled at 50 r / min for 9 h, and sieved to obtain a metal powder with a particle size of 15-53 μm suitable for additive manufacturing.

[0048] Comparative Example 4: A method for preparing metal powder, the specific steps are as follows:

[0049] 100 g of Co-Mo-Cr-Si alloy powder was ball-milled and sieved to obtain a metal powder with a particle size of 15-53 μm suitable for additive manufacturing.

[0050] Performance Testing

[0051] Sphericity: The powders obtained in the examples and comparative examples were tested according to GB / T16418-2008. The test results are shown in Table 1.

[0052] The powders obtained in the embodiment and the comparative example were placed in a vacuum drying furnace at 100°C for drying, 45 steel with a size of 150mm×150mm×30mm was used as a substrate, the substrate was preheated to 500°C, and laser additive manufacturing was performed. The laser power was 1200W, the powder feeding rate was 15g / min, and the protector flow rate was 15L / min. Subsequently, heat treatment (1250°C / 1h AC+800°C / 4h FC) was performed to finally obtain the prints corresponding to the embodiment and the comparative example, and the performance of the prints was tested.

[0053] Microhardness: The microhardness of the printed parts was measured using a Vickers microhardness tester (model: HVS-50 Vickers microhardness tester). The experimental parameters are: loading load 300 g, holding time 15 s, 3 points on the same horizontal plane of the same point were selected for measurement, and the microhardness of each horizontal position was taken as the average value of the three points. The test results are shown in Table 1.

[0054] Friction performance test: The wear resistance test was conducted using a HT-1000 ball-disc high temperature friction and wear tester. The test load was 4N, the test temperature was 25°C, and the test time was 1h. The wear piece was a Si3N4 ceramic ball. Before the experiment, the printed part was polished and cleaned with 1000# sandpaper. The mass of the printed part (m1) was recorded before the friction and wear experiment. After the experiment, the printed part was cleaned and dried again, and its new mass (m2) was recorded again. The test results are shown in Table 2.

[0055] High temperature oxidation experiment: The printed part is divided into several small pieces with certain regular shapes, the surface of the sample is polished with sandpaper, and then it is placed in anhydrous ethanol and cleaned with an ultrasonic oscillator and dried. Each sample is placed in a crucible, and the mass of each sample and the crucible as a whole is recorded (M1). Then the sample is placed in a HMF1400-30 box-type resistance air furnace for high temperature oxidation experiment. The experimental temperature is 1000℃ and the experimental time is 48h. After the experiment, the mass of each sample and the crucible as a whole (M2) is measured again, and the weight gain per unit area is calculated. The results are shown in Table 2.

[0056]

[0057] It can be seen from Table 1 that the metal powder suitable for additive manufacturing of the present invention has excellent sphericity and can meet the requirements of additive manufacturing for powder. It can be seen from Examples 1-4 in Table 2 that the metal powder suitable for additive manufacturing of the present invention has excellent hardness and wear resistance, and most importantly, still has excellent antioxidant properties at a high temperature of 1000°C.

[0058] It can be seen from Example 2 and Comparative Examples 1 and 3 in Table 2 that the present invention uses a modification treatment method to first ball-mill the cobalt-based alloy powder and silicon carbide and then mix-smelt the cobalt-based alloy powder so that the silicon carbide can be evenly dispersed. During the additive process, a reinforcing phase can be generated in situ with the cobalt-based alloy powder, so that the hardness and wear resistance of the alloy are improved, and the compatibility between the oxide film generated during the additive process and the matrix can be enhanced, so that the alloy still has relatively excellent antioxidant properties at a high temperature of 1000°C.

[0059] It can be seen from Example 2 and Comparative Examples 2 and 3 in Table 2 that the present invention first modifies the cobalt-based alloy powder and then mixes it with chromium carbide and chromium silicide powders for ball milling to add a reinforcing phase, thereby improving the hardness and wear resistance of the alloy. In addition, the compound use of chromium carbide and chromium silicide powders can further form a reinforcing phase with the modified cobalt-based alloy powder during the additive process, thereby improving the compatibility between the oxide film and the matrix, so that the alloy still has relatively excellent antioxidant properties at a high temperature of 1000°C.

[0060] It can be seen from Example 2 and Comparative Examples 1, 2, 3, and 4 in Table 2 that the modified cobalt-based alloy powder and chromium carbide and chromium silicide can improve the hardness and wear resistance of the alloy; and there is a synergistic effect between the modified cobalt-based alloy powder and chromium carbide and chromium silicide, so that the alloy still has excellent high-temperature oxidation resistance at 1000°C.

[0061] Those skilled in the art should understand that the discussion of any of the above embodiments is merely illustrative and is not intended to imply that the scope of the present invention is limited to these examples. Under the concept of the present invention, the technical features in the above embodiments or different embodiments may be combined, the steps may be implemented in any order, and there are many other variations of the different aspects of the present invention as described above, which are not provided in detail for the sake of simplicity.

[0062] The present invention is intended to cover all such substitutions, modifications and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing metal powder suitable for additive manufacturing, characterized in that: The invention comprises the following preparation steps: S1: mixing cobalt-based alloy powder and silicon carbide, ball milling, smelting, atomizing and pulverizing, screening, and obtaining modified cobalt-based alloy powder; S2: in an argon atmosphere, mixing the modified cobalt-based alloy powder, chromium carbide and chromium silicide, ball milling, and screening, and obtaining a metal powder with a particle size of 15-53 μm suitable for additive manufacturing; the cobalt-based alloy powder in step S1 is a Co-Mo-Cr-Si alloy powder with a particle size of 30-50 μm; the weight ratio of the modified cobalt-based alloy powder, chromium carbide and chromium silicide in step S2 is 89-94.5:5-10:0.5-1; The particle size of the silicon carbide in step S1 is 600-800 nm; The weight ratio of the cobalt-based alloy powder to silicon carbide in step S1 is 80-95:5-20.

2. The method for preparing metal powder suitable for additive manufacturing according to claim 1, characterized in that: The smelting in step S1 is vacuum smelting, the smelting temperature is 1600-1700°C, and the vacuum degree is less than 1.0×10 -2 Pa.

3. The method for preparing metal powder suitable for additive manufacturing according to claim 1, characterized in that: The particle size of the chromium carbide in step S2 is 80-100 nm.

4. The method for preparing metal powder suitable for additive manufacturing according to claim 1, characterized in that: The particle size of the chromium silicide in step S2 is 0.5-5 μm.

5. The method for preparing metal powder suitable for additive manufacturing according to claim 1, characterized in that: In step S2, the ball milling speed is 40-60 r / min, and the ball milling time is 8-10 h.

6. A metal powder suitable for additive manufacturing, characterized in that: The metal powder suitable for additive manufacturing is prepared by the method for preparing the metal powder suitable for additive manufacturing according to any one of claims 1 to 5.

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