Ball-milling vibration two-stage powder mixing method suitable for mixing powder with different particle sizes in additive manufacturing

Abstract

The invention discloses a ball-milling vibration two-stage powder mixing method suitable for mixing powder with different particle sizes in additive manufacturing, and belongs to the technical field of additive manufacturing. The method is used for mixing coarse powder and fine powder for additive manufacturing, the coarse powder is spherical metal powder, and the fine powder is non-spherical ceramic powder. According to the method, after the coarse powder is subjected to ball milling until the observable pits appear on the surface, the coarse powder and the fine powder are subjected to vibration mixing, so that the effects that a layer of fine powder is uniformly attached to the surface of the coarse powder and a certain amount of fine powder is agglomerated in the pits are achieved, the powder mixing uniformity and stability are improved, and meanwhile the adding amount of the fine powder is increased. By means of the ball milling and vibration two-stage powder mixing technology, high-mixing-amount and uniform powder mixing is achieved, and the stability of the additive manufacturing technology is ensured.

Description

Technical Field

[0001] The present invention belongs to the technical field of additive manufacturing, and relates to a ball milling and vibration two-stage powder mixing method suitable for mixing powders with different particle sizes in additive manufacturing. Background Art

[0002] With the continuous increase in the demand for materials with high strength, high wear resistance, corrosion resistance, high temperature resistance, etc. in modern aerospace, automotive, energy, and electronics fields, the research on ceramic particle-reinforced metal matrix composites (MMC) has become a hot topic. Additive manufacturing technology, with its process advantages of rapid non-equilibrium solidification, can achieve uniform distribution of particles with different particle sizes, and has become a research hotspot for ceramic particle-reinforced alloy composites in recent years. As a pre-process in the additive manufacturing forming process, the quality of the mixed powder directly affects the printing accuracy and the mechanical properties, surface quality, and internal density of the final product. When mixing powders with a large difference in particle size, conventional ball milling powder mixing may cause fine powder agglomeration and coarse powder deposition. When the powder after ball milling is applied to additive manufacturing, it is easy to lead to poor powder fluidity and uneven powder feeding, and further cause many defects and uneven structure in the samples obtained by additive manufacturing. However, the powder mixing amount of simple vibration mixing is limited, and it is difficult to achieve large-scale uniform mixing. Therefore, there is an urgent need for an improved powder mixing process to improve the uniformity and powder mixing amount of powders with different particle sizes. Summary of the Invention

[0003] The purpose of the present invention is to overcome the above-mentioned disadvantages of the prior art, and provide a ball milling and vibration two-stage powder mixing method suitable for mixing powders with different particle sizes in additive manufacturing, so as to overcome the problems of poor powder mixing uniformity, limited powder mixing amount in the prior art, and stratification problems caused by the small density and high surface energy of a large proportion of fine powders after mixing.

[0004] To achieve the above purpose, the present invention adopts the following technical solutions: A ball milling and vibration two-stage powder mixing method suitable for mixing powders with different particle sizes in additive manufacturing, comprising the following steps: Step 1, obtaining a coarse powder body and a fine powder body according to a set ratio, wherein the coarse powder body is spherical metal particles, the fine powder body is non-spherical ceramic particles, and the particle size of the coarse powder body and the particle size of the fine powder body differ by an order of magnitude; Step 2, performing low-energy ball milling on the coarse powder body, increasing the surface roughness of the coarse powder body, and obtaining concave pits on the surface of the coarse powder body to obtain a coarsely ground coarse powder body, wherein the depth of the concave pits is less than or equal to 1 / 10 of the diameter of the coarse powder body; Step 3, vibrating and mixing the coarsely ground coarse powder body and the fine powder body at an optimal frequency, wherein the optimal frequency is lower than the boiling frequency, and after vibration mixing, the fine powder body adheres to the concave pits on the surface of the coarse powder body to obtain a mixed powder.

[0005] A further improvement of the present invention lies in: Preferably, in step 1, the particle size of the coarse powder is 53 - 150 μm; the particle size of the fine powder is 100 - 200 nm.

[0006] Preferably, in step 1, the mass ratio of the coarse powder to the fine powder is 1:99 - 1:4.

[0007] Preferably, in step 1, the coarse powder can be a mixed powder of multiple metal powders, and the fine powder can be a mixed powder of multiple ceramic powders.

[0008] Preferably, in step 2, during the ball milling process, milling beads are added, and the volume ratio of the coarse powder to the milling beads is 1 - 2:1.

[0009] Preferably, the milling beads are composed of milling beads with multiple diameters.

[0010] Preferably, in step 2, the ball milling speed is 100 - 200 rpm, the ball milling time is 6 - 10 h, and the ball milling direction is forward and reverse.

[0011] Preferably, in step 3, the boiling frequency is the frequency at the most intense vibration, and the optimal frequency is 85% - 95% of the boiling frequency.

[0012] Preferably, in step 3, during the vibration mixing of the powder, the vibration mixing is carried out under an argon protection environment.

[0013] Preferably, in step 3, during the vibration mixing of the powder, the vibration duration is 5 - 15 min, and for every 3 min of vibration, it stops for 1 min for gas washing and heat dissipation.

[0014] Compared with the prior art, the present invention has the following beneficial effects: The present invention discloses a ball milling and vibration two - stage powder mixing method applicable to the mixing of powders with different particle sizes for additive manufacturing. The mixed powder used in this method for additive manufacturing includes a coarse powder and a fine powder. The coarse powder is selected from at least one metal powder, the coarse powder is a spherical powder, the fine powder is selected from at least one ceramic powder, and the fine powder is a non - spherical powder. After ball milling the coarse powder until observable pits appear on the surface, the coarse powder is vibration - mixed with the fine powder. By increasing its surface roughness, the surface area of the coarse powder is increased, so as to achieve the effect that a layer of fine powder is uniformly attached to the surface of the coarse powder and there is a certain amount of fine powder agglomeration in the pits. This not only improves the uniformity and stability of powder mixing, but also increases the addition amount of the fine powder. The present invention realizes high - mixing - amount and uniform powder mixing through a ball milling and vibration two - stage powder mixing process, ensuring the stability of the additive manufacturing process.

[0015] Furthermore, to address the problem of mixing powders with different particle sizes and shapes, the present invention designs process parameters for the formation of ball-milling pits and vibration filling and adhesion according to the material properties (particle size, shape, density, etc.). By controlling the surface morphology of the coarse powder during the ball-milling stage, pits are formed on the surface of the coarse powder while increasing the roughness. These pits provide a physical anchoring effect for the fine powder, increasing the adhesion of the fine powder and preventing the fine powder from falling off or agglomerating extensively during the subsequent forming process. Through the regulation of the surface morphology in the ball-milling stage and the filling of fine powder in the vibration mixing stage, a deeply coupled powder mixing process is achieved. Description of the Drawings

[0016] Figure 1 SEM image of the single ball-milled mixture of GH3536 (53 - 150 μm) powder particles and TiC (100 - 200 nm) ceramic particles; Figure 2 SEM image of the single vibration-mixed powder of GH3536 (53 - 150 μm) powder particles and TiC (100 - 200 nm) ceramic particles; Figure 3 SEM image of the ball-milled GH3536 (53 - 150 μm) powder particles; Figure 4 SEM image of the ball-milled and vibration double-stage mixed powder of GH3536 (53 - 150 μm) powder particles and TiC (100 - 200 nm) ceramic particles; Figure 5 SEM image and EDS diagram of the ball-milled and vibration double-stage mixed powder of GH3536 (53 - 150 μm) powder particles and TiC (100 - 200 nm) ceramic particles; Figure 6 SEM image of the ball-milled GH3536 (53 - 150 μm) powder particles; Figure 7 SEM image of the ball-milled and vibration double-stage mixed powder of GH3536 (53 - 150 μm) powder particles and TiC (100 - 200 nm) ceramic particles; Figure 8 SEM image and EDS diagram of the ball-milled and vibration double-stage mixed powder of GH3536 (53 - 150 μm) powder particles and TiC (100 - 200 nm) ceramic particles; Figure 9 EDS diagram of the laser direct energy deposition formed sample in Example 4. Detailed Description of the Embodiments

[0017] The present invention will be further described in detail below with reference to the accompanying drawings: To enable those skilled in the art to understand the features and effects of the present invention, the following provides a general description and definition of the terms and phrases mentioned in the specification and claims. Unless otherwise specified, all technical and scientific terms used herein shall have the ordinary meanings understood by those skilled in the art with respect to the present invention. In case of conflicts, the definitions in this specification shall prevail.

[0018] In this text, unless otherwise specified, the terms "comprising", "including", "containing", "having" or similar terms cover the meanings of "consisting of" and "consisting essentially of". For example, "A comprises a" covers the meanings of "A comprises a and others" and "A consists only of a".

[0019] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of this application.

[0020] Conventional instrument and equipment in the art are used in the following embodiments. For the experimental methods without specific conditions noted in the following embodiments, they are generally carried out under conventional conditions or according to the conditions recommended by the manufacturers. Various raw materials are used in the following embodiments. Unless otherwise stated, commercially available products are used, and their specifications are conventional specifications in the art. In the specification of the present invention and the following embodiments, unless otherwise specified, "%" represents weight percentage, "parts" represents weight parts, and the ratios represent weight ratios.

[0021] In the description of the present invention, it should be noted that the term "pit" is only used to describe the situation where the surface of the powder appears sunken under the impact of the ball milling beads; the term "anchoring" is only used to describe the agglomeration and enrichment of fine powder at specific positions; the terms "low-energy ball milling" and "low-frequency vibration" should be understood in a broad sense, and there are certain differences in the process parameters corresponding to different powders; the term "boiling" is only used to describe the situation where the powder undergoes violent oscillation in the vibrating powder mixing container; the term "duration" is generally used to describe the total process time. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0022] The present invention discloses a ball milling and vibration double-stage powder mixing method applicable to the mixing of powders with different particle sizes for additive manufacturing, and the method comprises the following steps: S1, obtaining a coarse powder and a fine powder according to a set ratio, wherein the coarse powder is spherical metal particles, the fine powder is non-spherical ceramic particles, and the particle size of the coarse powder and the particle size of the fine powder differ by an order of magnitude.

[0023] S2. Place the weighed coarse powder in a ball milling jar and perform ball milling under the control of the type of ball milling medium, filling ratio, rotation speed, and time, so that observable pits appear on the surface of the coarse powder to obtain coarsely ground coarse powder. The non-loss of surface area can be quantified as the depth of the deformed pit ≤ 1 / 10 of the diameter of the coarse powder.

[0024] S3. Put the ball-milled coarse powder and fine powder into a vibration mixing device and perform vibration mixing under the conditions of set vibration acceleration, frequency, and time to fully mix the powders of different particle sizes.

[0025] In some embodiments of the present invention, the coarse powder is a superalloy, stainless steel, aluminum alloy, titanium alloy, or other metal particle materials suitable for additive manufacturing with a spherical morphology and a particle size of 53 - 150 μm.

[0026] In some embodiments of the present invention, the fine powder is a ceramic particle material such as TiC, TiB2, etc. with an adhesive ability and a non-spherical morphology and a particle size of 100 - 200 nm, which is suitable for additive manufacturing.

[0027] In some embodiments of the present invention, the mass ratio of the weighed coarse powder to the fine powder is 1:99 - 1:4, and the preferred ratio is 1:20 - 1:9.

[0028] In the present invention, the coarse powder is a metal particle material with a spherical morphology, and the fine powder is a non-spherical ceramic particle material with an adhesive ability. The particle sizes of the two types of powders differ by one order of magnitude. On the premise that there are pits on the surface of the metal particles with a spherical morphology in the present invention, the non-spherical ceramic particle material can adhere to the surface of the metal particles with a spherical morphology.

[0029] In some embodiments of the present invention, the ball milling process of the coarse powder specifically includes the following steps: S101. Put the coarse powder and ball milling beads into a ball milling jar. The volume ratio of the coarse powder to the ball milling beads is 1 - 2:1, and the total volume of the coarse powder and the ball milling beads accounts for 1 / 2 - 2 / 3 of the total volume of the ball milling jar, leaving a certain space to ensure that the sample is fully and evenly ground during ball milling; S102. Perform ball milling on the coarse powder on a planetary ball mill, set the ball milling time to 6 - 10 h, the ball milling speed to 100 - 200 rpm, and the ball milling direction to forward and reverse. During this process, it is necessary to strictly control the low-energy ball milling process, especially for alloys with relatively low hardness such as aluminum alloy, to prevent excessive deformation into a cake shape during ball milling. It is necessary to control the coarse powder to provide attachment points for the fine powder without losing the surface area. In this step, the diameter of the pit is not limited. Usually, the diameter of the pit is much larger than the diameter of the coarse powder, but there are also small pits on the surface of the ball-milled coarse powder after ball milling.

[0030] It should be noted that the capacity of the ball milling tank and the number of balls are determined by the quantity and type of the coarse powder. Generally, a ball milling tank and ball milling beads harder than the sample need to be selected; otherwise, the ball milling tank and ball milling beads will be worn during the ball milling process, causing contamination to the sample.

[0031] As a preferred solution, the set rotation speed of the ball mill is preferably selected from 50 to 200 rpm, the set ball milling time is 1 to 10 h, and the ball milling process mode is set to a timed two-way mode, that is, the ball milling direction is forward and reverse, and the direction is switched every 20 min. The selection of the rotation speed and time needs to be based on the type of the coarse powder to prevent excessive deformation of the coarse powder due to too high a rotation speed or too long a ball milling time.

[0032] In some embodiments of the present invention, the capacity of the ball milling tank and the number of balls are determined by the quantity and type of the coarse powder; the diameters of the ball milling beads are 6 mm, 10 mm, and 20 mm respectively, and the mass ratio of the balls is 25:10:1. If the coarse powder has a high hardness, the mass proportion of the large balls needs to be increased.

[0033] In some embodiments of the present invention, the vibration process of the fine powder and the ball-milled coarse powder specifically includes the following steps: S201, Pour the coarse powder and the weighed fine powder into the internal part of the vibrating powder mixing container. The mass of the fine powder accounts for 1 to 20% of the mass of the ball-milled coarse powder. After fixing the powder mixing container on the electric vibration test system with bolts, introduce argon gas at a certain rate for 2 to 3 min. The argon gas flow rate is 10 to 30 cm 3 / min to wash the inside of the container. After the washing is completed, seal the device to ensure inert gas protection; S202, Set the sweep-frequency vibration for the first time and find the optimal frequency. The sweep-frequency vibration sets the vibration frequency to increase uniformly from 30 Hz to 140 Hz at a rate of 1 to 3 Hz / s. Observe the moment when the vibration is the most intense with the naked eye. At this time, the mixed powder shows a "boiling" phenomenon. Record the vibration frequency at this time and select a frequency slightly lower than this frequency as the optimal frequency. Preferably, select 85% to 95% of the vibration frequency at this time. The present invention controls the "low-frequency" powder mixing to prevent the stratification phenomenon of the mixed powder caused by long-term "boiling".

[0034] S203, Set the optimal frequency for stationary-frequency vibration. The vibration duration is 5 to 15 min. Every 3 min of vibration, stop for 1 min for gas washing and heat dissipation. The vibration acceleration is 40 g; S204, Collect the mixed powder with different particle sizes to complete the subsequent forming process.

[0035] In some embodiments of the present invention, the sweep-frequency vibration sets the vibration frequency to increase uniformly from 30 Hz to 140 Hz at a rate of 1 to 3 Hz / s.

[0036] In some embodiments of the present invention, the vibration duration is the net vibration time. The vibration duration is determined by the mass of the mixed powder. Generally, the mixed powder does not exceed 1.67 kg, and the vibration duration does not exceed 20 min. If the vibration duration is too short, it will cause uneven mixing of the powder, and if it is too long, it will lead to stratification of the mixed powder. The mixed powder of different particle sizes is collected to complete the subsequent forming process.

[0037] The present invention is applicable to the mixing of metal particle materials with spherical morphology and ceramic particles with non-spherical morphology and adhesion ability. The main metal materials involved can be superalloys, stainless steels, aluminum alloys, titanium alloys or other metal particle materials suitable for additive manufacturing. The ceramic materials can be ceramic particle materials such as TiC and TiB2 suitable for additive manufacturing. The present invention will be further described through experimental examples.

[0038] Experimental Example 1 As Figure 1 shown, in this experimental example, 53 - 150 μm GH3536 powder particles and 100 - 200 nm TiC ceramic particles are used for single ball milling and mixing. The specific steps of this experimental example are as follows: S1, Weigh TiC powder particles and GH3536 powder particles with a mass ratio of 1:9, and put them together with agate ball milling beads with diameters of 6 mm, 10 mm, and 20 mm into an agate ball milling jar. The volume ratio of the powder to the ball milling beads is 1:1, and the ball distribution ratio of different ball milling beads is 25:10:1. Place the ball milling jar on a planetary ball mill, set the rotation speed to 150 rpm, the ball milling direction to forward and reverse, and the ball milling duration to 3 h to obtain ball milled mixed powder with different particle sizes.

[0039] S2, Screen the mixed powder in S1 to obtain mixed powder with a particle size less than 212 μm. Then spread the mixed powder evenly on a tray with a spreading thickness less than 15 mm, and put it into a vacuum drying oven to keep it at 120 °C for 2 h to dry the powder, and cool it with the furnace to obtain the mixed powder as Figure 1 shown. As can be seen from Figure 1 , due to the large difference in powder particle sizes, there is a large amount of fine powder agglomeration in the mixed powder obtained by the single ball milling and mixing process. The agglomeration size can reach 70 μm. Such large-scale and large-size agglomerations will directly lead to defects such as poor fusion and pores in the subsequent forming process.

[0040] S3, Put the mixed powder in S2 into a powder feeder and send it into a laser direct energy deposition device for forming. The laser power is 3000 W, the scanning speed is 900 mm / min, the lifting amount is 0.2 mm, and the powder feeding amount is 14 g / min. During the forming process, argon is used for protection, and the oxygen content in the argon atmosphere is controlled to be ≤ 50 ppm. After cooling, take out and sample to detect the net TiC addition amount.

[0041] Experimental Example 2 As Figure 2 shown, in this test example, GH3536 powder particles with a size of 53 - 150 μm and TiC ceramic particles with a size of 100 - 200 nm are mixed by single vibration. The specific steps of this experimental example are as follows: S1, Weigh TiC powder particles and GH3536 powder particles with a mass ratio of 1:9, put them into the internal of the powder mixing container, fix the powder mixing container on the electric vibration test system with bolts, and after introducing argon for 3 minutes, seal the device; start sweep frequency vibration and select 60 Hz as the optimal frequency; set the vibration acceleration to 40 g, the dwell frequency vibration to 60 Hz, and the vibration duration to 5 minutes. Every 3 minutes of vibration, stop for 1 minute to wash gas and dissipate heat to obtain vibration - mixed powder with different particle sizes.

[0042] S2, Screen the mixed powder in S1 to obtain the mixed powder with a particle size less than 212 μm; then spread the mixed powder evenly on a tray with a spreading thickness less than 15 mm, and put it into a vacuum drying oven to keep warm at 120 °C for 2 hours to dry the powder, and cool it with the furnace to obtain the mixed powder as Figure 2 shown.

[0043] S3, Put the mixed powder in S2 into the powder feeder and send it into the laser direct energy deposition equipment for forming. The laser power is 3000 W, the scanning rate is 900 mm / min, the lifting amount is 0.2 mm, and the powder feeding amount is 14 g / min. During the forming process, argon is used for protection, and the oxygen content in the argon atmosphere is controlled to be ≤ 50 ppm. After cooling, take out and sample to detect the net addition amount of TiC. The result after mixing the powder is as Figure 2 shown. It can be seen in Figure 2 that the ceramic particles are evenly attached to the surface of the GH3536 coarse powder body. The obtained mixed powder has a high sphericity and good fluidity. However, the powder mixing amount of the formed sample of this mixed powder is extremely limited, as shown in Table 1. The main reason is that during the single vibration powder mixing process, the number of fine powder particles attached to the surface of the coarse powder body is limited, resulting in the powder mixing amount not reaching the expected effect.

[0044] Experimental Example 3 As Figures 3 - 5 shown, in this test example, GH3536 powder particles with a size of 53 - 150 μm and TiC ceramic particles with a size of 100 - 200 nm are mixed by ball - milling and vibration in two - stages. The specific steps of this experimental example are as follows: S1. Weigh TiC powder particles and GH3536 powder particles with a mass ratio of 1:9. Put the GH3536 powder together with agate ball milling beads with diameters of 6 mm, 10 mm, and 20 mm into an agate ball milling jar, where the volume ratio of the powder to the ball milling beads is 1:1, and the ball distribution ratio of different ball milling beads is 25:10:1. Place the ball milling jar on a planetary ball mill, set the rotation speed to 100 rpm, the ball milling direction to forward and reverse, and the ball milling duration to 10 h to obtain the ball milled GH3536 powder as shown in Figure 3 , with observable pits on the surface.

[0045] S2. Put the weighed TiC powder particles and the ball milled GH3536 powder particles obtained in S1 into the internal part of a powder mixing container. Fix the powder mixing container on an electric vibration test system with bolts, and after introducing argon for 3 min, seal the device. Start sweep frequency vibration and select 45 Hz as the optimal frequency. Set the vibration acceleration to 40 g, the standing frequency vibration frequency to 45 Hz, and the vibration duration to 5 min. Every 3 min of vibration, stop for 1 min for gas washing and heat dissipation to obtain ball milled and vibration mixed powder with different particle sizes.

[0046] S3. Screen the mixed powder in S2 to obtain mixed powder with a particle size less than 212 μm. Then spread the mixed powder evenly on a tray with a spreading thickness less than 15 mm, and put it into a vacuum drying oven to keep warm at 120 °C for 2 h to dry the powder, and cool it in the furnace to obtain the mixed powder as shown in Figure 4 、 Figure 5 , with a rough surface and more fine powder attached in the smaller pits with a rough surface and smaller pits than in Example 2, and fine powder agglomeration attached in the larger pits, while increasing the powder mixing amount while ensuring the sphericity and fluidity of the powder.

[0047] S4. Place the mixed powder in S3 into a powder feeder and send it into a laser direct energy deposition device for forming. The laser power is 3000 W, the scanning speed is 900 mm / min, the lifting amount is 0.2 mm, and the powder feeding amount is 14 g / min. Argon is used for protection during the forming process, and the oxygen content in the argon atmosphere is controlled to be ≤50 ppm. After cooling, take it out and sample to detect its net TiC addition amount.

[0048] Experimental Example 4 As shown in Figures 6 - 9 , in this test example, 53 - 150 μm GH3536 powder particles and 100 - 200 nm TiC ceramic particles are used for ball milling and vibration double - stage powder mixing. The specific steps of this experimental example are as follows: S1. Weigh TiC powder particles and GH3536 powder particles with a mass ratio of 1:9. Put the GH3536 powder together with agate ball milling beads with diameters of 6 mm, 10 mm, and 20 mm into an agate ball milling jar, where the volume ratio of the powder to the ball milling beads is 1:1, and the ball distribution ratio of different ball milling beads is 25:10:1. Place the ball milling jar on a planetary ball mill, set the rotation speed to 150 rpm, the ball milling direction to forward and reverse, and the ball milling duration to 10 h to obtain the ball milled GH3536 powder as shown in Figure 6 . There are observable pits on the surface, and the unevenness increases.

[0049] S2. Put the weighed TiC powder particles and the ball milled GH3536 powder particles obtained in S1 into the internal part of a powder mixing container. Fix the powder mixing container on an electric vibration test system with bolts, introduce argon for 3 min and then seal the device. Start sweep frequency vibration and select 45 Hz as the optimal frequency. Set the vibration acceleration to 40 g, the standing frequency vibration frequency to 45 Hz, the vibration duration to 5 min, vibrate for 3 min each time, vibrate for a total of 15 min, and stop for 1 min for gas washing and heat dissipation to obtain ball milled and vibration mixed powder with different particle sizes.

[0050] S3. Screen the mixed powder in S2 to obtain mixed powder with a particle size less than 212 μm. Then spread the mixed powder evenly on a tray with a spreading thickness less than 15 mm, and put it into a vacuum drying oven to keep it at 120 °C for 2 h to dry the powder, and cool it with the furnace to obtain the mixed powder as shown in Figure 7 、 Figure 8 . There is more fine powder attached in the pits with smaller sizes than in Example 2, and there is agglomeration of fine powder attached in the pits with larger sizes, while increasing the powder mixing amount while ensuring the sphericity and fluidity of the powder. It can be seen from this figure that the method of combining ball milling and powder mixing vibration not only adsorbs a large amount of ceramic particles on the surface of metal particles, but also can form aggregated fine particle powder at the pits.

[0051] S4. Place the mixed powder in S3 into a powder feeder and feed it into a laser direct energy deposition device for forming. The laser power is 3000 W, the scanning speed is 900 mm / min, the lifting amount is 0.2 mm, and the powder feeding amount is 14 g / min. Argon is used for protection during the forming process, and the oxygen content in the argon atmosphere is controlled to be ≤50 ppm. After cooling, take out and sample to detect the net TiC addition amount, and characterize the Ti and C element contents by EDS. The results are as shown in Figure 9 . It can be seen that the Ti and C elements are distributed in a chain-like manner. It can be seen from the figure that the tissue components prepared by this application are uniform, the tissue is continuous, and there are no defects such as holes.

[0052] Experimental Example 5 In this test example, GH3536 powder particles with a size of 53 - 150 μm and TiC ceramic particles with a size of 100 - 200 nm were used for double - stage mixing of ball - milling and vibration. The specific steps of this experimental example are as follows: S1, Weigh TiC powder particles and GH3536 powder particles with a mass ratio of 1:50. Put the GH3536 powder together with agate ball - milling beads with diameters of 6 mm, 10 mm, and 20 mm into an agate ball - milling jar. The volume ratio of the powder to the ball - milling beads is 1:1, and the ball - matching ratio of different ball - milling beads is 25:10:1. Place the ball - milling jar on a planetary ball - mill, set the rotation speed at 200 rpm, the ball - milling direction as forward and reverse rotation, and the ball - milling duration as 8 h.

[0053] S2, Put the weighed TiC powder particles and the ball - milled GH3536 powder particles obtained in S1 together inside the powder - mixing container. Fix the powder - mixing container on an electric vibration test system with bolts, introduce argon for 3 min and then seal the device. Start frequency - sweeping vibration and select 45 Hz as the optimal frequency. Set the vibration acceleration at 40 g, the standing - frequency vibration frequency at 45 Hz, and the vibration duration at 15 min. Vibrate for 3 min each time, vibrate for a total of 5 min, and stop for 1 min for gas washing and heat dissipation to obtain ball - milled and vibration - mixed powder with different particle sizes.

[0054] S3, Screen the mixed powder in S2 to obtain mixed powder with a particle size less than 212 μm. Then spread the mixed powder evenly in a tray with a spreading thickness less than 15 mm, and put it into a vacuum drying oven to keep it at 120 °C for 2 h to dry the powder, and cool it with the furnace.

[0055] S4, Place the mixed powder in S3 into a powder feeder and feed it into a laser direct energy deposition device for forming. The laser power is 3000 W, the scanning speed is 900 mm / min, the lifting amount is 0.2 mm, and the powder feeding rate is 14 g / min. During the forming process, argon is used for protection, and the oxygen content in the argon atmosphere is controlled ≤50 ppm.

[0056] Example 6 In this example, Ti6Al4V powder particles with a size of 53 - 150 μm and TiC ceramic particles with a size of 100 - 200 nm were used for double - stage mixing of ball - milling and vibration. The specific steps of this experimental example are as follows: S1, Weigh TiC powder particles and Ti6Al4V powder particles with a mass ratio of 1:4. Put the Ti6Al4V powder together with agate ball - milling beads with diameters of 6 mm, 10 mm, and 20 mm into an agate ball - milling jar. The volume ratio of the powder to the ball - milling beads is 1:1, and the ball - matching ratio of different ball - milling beads is 30:10:1. Place the ball - milling jar on a planetary ball - mill, set the rotation speed at 100 rpm, the ball - milling direction as forward and reverse rotation, and the ball - milling duration as 6 h.

[0057] S2. Put the weighed TiC powder particles and the ball-milled Ti6Al4V powder particles obtained in S1 into the internal part of the powder mixing container. Fix the powder mixing container on the electric vibration test system with bolts. After introducing argon for 3 minutes, seal the device. Start sweep-frequency vibration and select 65 Hz as the optimal frequency. Set the vibration acceleration to 40 g, the standing-frequency vibration frequency to 65 Hz, and the vibration duration to 12 minutes. Stop for 1 minute for gas washing and heat dissipation every 3 minutes of vibration to obtain ball-milled vibration mixed powder with different particle sizes.

[0058] S3. Screen the mixed powder in S2 to obtain the mixed powder with a particle size less than 212 μm. Then spread the mixed powder evenly on a tray with a spreading thickness less than 15 mm, and put it into a vacuum drying oven to keep warm at 120 °C for 2 hours to dry the powder, and cool it in the furnace to obtain the mixed powder.

[0059] S4. Place the mixed powder in S3 into a powder feeder and feed it into a laser direct energy deposition device for forming. The laser power is 2500 W, the scanning speed is 800 mm / min, the lifting amount is 0.3 mm, and the powder feeding amount is 4 g / min. Argon is used for protection during the forming process, and the oxygen content in the argon atmosphere is controlled to be ≤ 50 ppm.

[0060] Example 7 In this example, 316L stainless steel powder particles with a size of 53 - 150 μm and TiB2 ceramic particles with a size of 100 - 200 nm are used for ball-milled vibration two-stage powder mixing. The specific steps of this experimental example are as follows: S1. Weigh TiB2 powder particles and 316L stainless steel powder particles with a mass ratio of 1:99. Put the 316L stainless steel powder together with agate ball-milling beads with diameters of 6 mm, 10 mm, and 20 mm into an agate ball-milling tank, where the volume ratio of the powder to the ball-milling beads is 1:1, and the ball-milling bead ratio of different sizes is 25:10:1. Place the ball-milling tank on a planetary ball mill, set the rotation speed to 200 rpm, the ball-milling direction to forward and reverse, and the ball-milling duration to 6 hours.

[0061] S2. Put the weighed TiB2 powder particles and the ball-milled 316L stainless steel powder particles obtained in S1 into the internal part of the powder mixing container. Fix the powder mixing container on the electric vibration test system with bolts. After introducing argon for 3 minutes, seal the device. Start sweep-frequency vibration and select 45 Hz as the optimal frequency. Set the vibration acceleration to 40 g, the standing-frequency vibration frequency to 45 Hz, and the vibration duration to 6 minutes. Stop for 1 minute for gas washing and heat dissipation every 3 minutes of vibration to obtain ball-milled vibration mixed powder with different particle sizes.

[0062] S3. Screen the mixed powder obtained in S2 to obtain a mixed powder with a particle size less than 212 μm. Then, place the mixed powder in a tray and spread it out flat, with the spreading thickness less than 15 mm, and put it into a vacuum drying oven to keep it at 120 °C for 2 h to dry the powder, and cool it with the furnace to obtain the mixed powder.

[0063] S4. Place the mixed powder obtained in S3 into a powder feeder and feed it into a laser direct energy deposition device for forming. The laser power is 1500 W, the scanning speed is 480 mm / min, the lifting amount is 3 mm, and the powder feeding amount is 8 g / min. Argon is used for protection during the forming process, and the oxygen content in the argon atmosphere is controlled to be ≤50 ppm.

[0064] Combined with the SEM images of the powders in each example, it can be seen by comparison that single ball-milled powder shows the situation of fine powder agglomeration and uneven mixing, while Table 1 intuitively shows that ball-milling vibration two-stage powder mixing greatly improves the actual addition amount of fine powder on the premise of ensuring uniform powder mixing.

[0065] Table 1 Net TiC addition amount in the formed specimens corresponding to different powder mixing processes

[0066] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A ball milling and vibration double-stage powder mixing method applicable to the mixing of powders with different particle sizes in additive manufacturing, characterized in that, It includes the following steps: Step 1: Obtain coarse powder and fine powder according to a set ratio. The coarse powder is spherical metal particles, and the fine powder is non-spherical ceramic particles. The particle size of the coarse powder and the particle size of the fine powder differ by an order of magnitude. Step 2: Conduct low-energy ball milling on the coarse powder. The surface roughness of the coarse powder increases, and pits are obtained on the surface of the coarse powder to obtain coarsely ground coarse powder. The depth of the pits is less than or equal to 1 / 10 of the diameter of the coarse powder. Step 3: Vibrate and mix the coarsely ground coarse powder and the fine powder at an optimal frequency. The optimal frequency is lower than the boiling frequency. After vibration and mixing, the fine powder adheres to the pits on the surface of the coarse powder to obtain a mixed powder.

2. The ball milling and vibration double-stage powder mixing method applicable to the mixing of powders with different particle sizes in additive manufacturing according to claim 1, wherein, In Step 1, the particle size of the coarse powder is 53 - 150 μm; the particle size of the fine powder is 100 - 200 nm.

3. The ball milling and vibration two-stage powder mixing method applicable to the mixing of additive manufacturing powders with different particle sizes according to claim 1, wherein, In Step 1, the mass ratio of the coarse powder to the fine powder is 1:99 - 1:

4.

4. A ball milling and vibration double-stage powder mixing method applicable to additive manufacturing of mixed powders with different particle sizes according to claim 1, characterized in that, In Step 1, the coarse powder can be a mixed powder of multiple metal powders, and the fine powder can be a mixed powder of multiple ceramic powders.

5. A ball milling and vibration double-stage powder mixing method applicable to additive manufacturing of powders with different particle sizes according to claim 1, characterized in that In Step 2, during the ball milling process, ball milling beads are added. The volume ratio of the coarse powder to the ball milling beads is 1 - 2:

1.

6. A ball milling and vibration double-stage powder mixing method applicable to additive manufacturing of powders with different particle sizes according to claim 5, characterized in that, The ball milling beads are composed of ball milling beads with multiple diameters.

7. A ball milling and vibration two-stage powder mixing method applicable to additive manufacturing of mixed powders with different particle sizes according to claim 1, characterized in that In Step 2, the ball milling speed is 100 - 200 rpm, the ball milling time is 6 - 10 h, and the ball milling direction is forward and reverse.

8. A ball milling and vibration double-stage powder mixing method applicable to additive manufacturing of mixed powders with different particle sizes according to claim 1, characterized in that, In Step 3, the boiling frequency is the frequency at which vibration is most intense, and the optimal frequency is 85% - 95% of the boiling frequency.

9. A ball milling and vibration double-stage powder mixing method applicable to additive manufacturing of powders with different particle sizes according to claim 1, characterized in that, In Step 3, during the vibration and mixing process, vibration and mixing are carried out under an argon protection environment.

10. A ball milling and vibration two-stage powder mixing method applicable to additive manufacturing of mixed powders with different particle sizes according to claim 1, characterized in that, In Step 3, during the vibration and mixing process, the vibration duration is 5 - 15 min. Every 3 min of vibration, it stops for 1 min for gas washing and heat dissipation.

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