Equipment for surface modification and enhanced transplantation of nickel-based powder in additive manufacturing

Abstract

The utility model relates to the technical field of additive manufacturing, and provides equipment for additive manufacturing nickel-based powder surface modification and enhanced transplantation, the equipment comprises a shell, an inner container, an upper cover, a cooling device, an inert gas flow compression device and a high-frequency oscillation device, the inner container and the upper cover are connected in a sealed mode to form a forming cavity, and the high-frequency oscillation device is arranged at the inner bottom of the shell; the inner container is arranged in the shell, the cooling device is connected with the shell, and the inert airflow compression device is connected with the forming cavity. An airflow field is generated in the forming cavity through the inert airflow compression device, so that the powder obtains corresponding kinetic energy, satellite particles are eliminated through collision among the powder, and the surface appearance of the powder is improved; uniformly dispersing and refining the nano reinforced particles through a high-frequency oscillation device; and the nano-particles are attached to the surface of the base powder under the action of the airflow field, so that surface modification and reinforced particle transplantation of the base powder are carried out under the coupling action of the airflow field and the ultrasonic field, and preparation of the high-quality composite powder of the core-shell structure is achieved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of additive manufacturing, and more particularly relates to an equipment for surface modification and strengthening implantation of nickel-based powder for additive manufacturing. BACKGROUND

[0002] Metal additive manufacturing (metal AM) technology is considered to be an ideal processing option for preparing nickel-based alloys due to its high degree of freedom in shaping and the ability to realize rapid shaping of complex structures. However, most studies show that the low degree of densification, anisotropy of microstructure and other defects restrict the mechanical properties of nickel-based alloys prepared by additive manufacturing. Therefore, many researchers have explored the regulation mechanism between performance defects and related factors in the additive manufacturing process. The latest research shows that the characteristics of raw materials play an important role in inhibiting defects and also significantly affect the final performance of the metal AM parts.

[0003] In recent years, many researchers have solved the problem of uneven distribution of columnar crystals and phases in nickel-based alloys by using nano inoculants, and pointed out that the use of nano inoculants can not only inhibit the anisotropy of the microstructure, but also hinder the expansion of micro-cracks.

[0004] However, some studies have pointed out that particles with a particle size less than 10 pm will cause serious agglomeration due to the van der Waals force between particles, which reduces the flowability and apparent density of the powder, thereby affecting the continuity, uniformity and stability of the powder during the conveying process. Most metal AM equipment uses spherical powder prepared by gas atomization technology as raw material. The satellite powder commonly found in gas atomized powder increases the interlocking and friction inside the powder, which greatly reduces the flowability and apparent density. In the metal AM process, the reduction of flowability and apparent density not only affects the uniformity and stability of the powder during continuous conveying, but also seriously reduces the density and microstructure uniformity of the formed parts.

[0005] Currently, researchers only improve the nickel-based alloy powder for additive manufacturing from a single aspect. Due to the limitations of the improvement method, the mechanical properties of the nickel-based alloy prepared by additive manufacturing still have deficiencies. Therefore, it is necessary to develop a new surface modification metal powder manufacturing process for additive manufacturing. CONTENT OF THE INVENTION

[0006] In view of the deficiencies of the prior art, the purpose of the embodiments of the present application is to provide an equipment for surface modification and strengthening implantation of nickel-based powder for additive manufacturing, which combines the advantages of airflow mill and ultrasonic disperser, and uses the coupling effect of airflow field and ultrasonic oscillation field to realize the formation of a spherical core-shell structure powder (nano inoculant as shell and nickel-based powder as core).

[0007] To achieve the above object, the technical scheme adopted by the present application is: provide a kind of for the equipment of additive manufacturing nickel-based powder surface modification and strengthening grafting, including: shell, inner container, upper cover, cooling device, inert gas flow compression device and high-frequency oscillation device, the inner container and upper cover detachable seal connection and form forming cavity, the high-frequency oscillation device is arranged in the inner bottom of the shell, the inner container is located in the shell, the cooling device is connected with the shell, the inert gas flow compression device is connected with the forming cavity.

[0008] In one embodiment, the inert gas flow compression device includes: compressed argon source and argon pipeline, the upper cover is provided with gas inlet and gas outlet, the compressed argon source is provided with argon switch valve, the gas inlet is connected with the argon switch valve by the argon pipeline, the gas inlet is provided with one-way valve, and the gas outlet is provided with electromagnetic switch valve.

[0009] In one embodiment, the upper cover is also provided with air pressure gauge.

[0010] In one embodiment, the gas inlet and the gas outlet are each provided with filter screen with nanoscale pores.

[0011] In one embodiment, the high-frequency oscillation device includes at least one ultrasonic oscillator.

[0012] In one embodiment, the cooling device includes: water inlet pipe, water outlet pipe and refrigeration unit, the shell is provided with circulating water pipe, and the water inlet pipe and the water outlet pipe are connected with the circulating water pipe and the refrigeration unit.

[0013] In one embodiment, the inner container is provided with temperature sensor.

[0014] In one embodiment, the upper cover is threadedly sealed with the inner container.

[0015] The device for additive manufacturing nickel-based powder surface modification and strengthening grafting provided by the present application has the following beneficial effects:

[0016] The inert gas flow compression device generates high-speed rotating airflow field in the forming cavity, so that the powder obtains corresponding kinetic energy, collides, eliminates satellite particles by collision between powders, thereby improving the powder surface morphology; the high-frequency oscillation device utilizes the cavitation effect and mechanical effect of ultrasonic waves to uniformly disperse and refine nano-enhanced particles; and under the action of the airflow field, the nano particles are attached to the surface of the base powder, so as to realize the coupling effect of the airflow field and the ultrasonic field for base powder surface modification and strengthening particle grafting, and realize the preparation of a high-quality composite powder with core-shell structure (nano inoculant as shell and nickel-based powder as core). BRIEF DESCRIPTION OF DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments or prior art description will be briefly introduced. Obviously, the drawings in the following description only constitute some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor.

[0018] Figure 1 The overall connection simplified schematic diagram of the device for surface modification and strengthening transplantation of additive manufacturing nickel-based powder provided by the embodiments of the present application is shown in the figure.

[0019] Figure 2 The middle axis sectional view schematic diagram of the shell in the device for surface modification and strengthening transplantation of additive manufacturing nickel-based powder provided by the embodiments of the present application is shown in the figure.

[0020] Figure 3 The schematic diagram of core-shell powder formation is shown in the figure.

[0021] Figure 4 The geometric characteristics of Inconel718 nickel-based core-shell powder are shown in the figure.

[0022] Figure 5 The comparative diagram of the microstructure of Inconcl718 nanocomposite powder and ordinary Inconel718 nickel-based alloy powder in additive manufacturing is shown in the figure.

[0023] In the figure, various reference signs are as follows:

[0024] 1, shell; 11, circulating water pipe; 2, inner container; 3, upper cover; 31, air inlet; 32, air outlet; 33, filter screen; 4, cooling device; 41, water inlet pipe; 42, water outlet pipe; 43, refrigeration unit; 5, inert gas flow compression device; 51, compressed argon source; 52, argon switch valve; 53, argon pipeline; 54, one-way valve; 55, electromagnetic switch valve; 56, air pressure gauge; 6, high-frequency oscillation device. DETAILED DESCRIPTION

[0025] In order to make the technical problems, technical solutions and beneficial effects of the present application more clearly understood, the present application will be further described in detail below in combination with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and not to limit the present application.

[0026] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

[0027] It should be understood that the terms "length", "width", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate directions or positions based on the directions or positions shown in the drawings and are used for convenience in describing the present application and simplifying the description, and thus cannot be construed as indicating or implying that a device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0028] In addition, the terms "first", "second", "third", etc. are used only for descriptive purposes and cannot be construed as indicating or implying relative importance or an implied indication of the number of technical features indicated. Therefore, the features defined as "first", "second", "third" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise explicitly specified.

[0029] Please refer to Figure 1 and Figure 2 , a device for additive manufacturing of nickel-based powder surface modification and strengthening transplantation provided by the embodiments of the present application will be described. The device comprises a shell 1, an inner container 2, an upper cover 3, a cooling device 4, an inert gas flow compression device 5 and a high-frequency oscillation device 6. The inner container 2 and the upper cover 3 are detachably sealed and connected to form a forming cavity, and the forming cavity is a reaction site. The inner container 2 and the upper cover 3 are both made of hard alloy steel, which is to prevent the doping of impurities during the friction and collision of the powder and the inoculant with the inner wall of the forming cavity, thereby affecting the purity of the spherical core-shell powder. The high-frequency oscillation device 6 is arranged at the inner bottom of the shell 1; the inner container 2 is arranged in the shell 1, the cooling device 4 is connected with the shell 1 for controlling the temperature of the inner container 2, the inert gas flow compression device 5 is connected with the forming cavity for providing high-speed inert gas flow into the forming cavity to form a gas field.

[0030] Specifically, the inert gas flow compression device 5 comprises a compressed argon source 51 and an argon pipeline 53. The upper cover 3 is provided with an air inlet 31 and an air outlet 32. The compressed argon source 51 is provided with an argon switch valve 52. The air inlet 31 is connected with the argon switch valve 52 through the argon pipeline 53. A one-way valve 54 is arranged at the air inlet 31. An electromagnetic switch valve 55 is arranged at the air outlet 32. When the work starts, the electromagnetic switch valve 55 is opened, and the argon switch valve 52 is opened. The high-pressure argon in the compressed argon source 51 enters the forming cavity through the argon pipeline 53 and the one-way valve 54, and then flows out through the electromagnetic switch valve 55. In order to improve the pressure in the forming cavity, the outflow of the electromagnetic switch valve 55 is less than the inflow of the one-way valve 54. In order to adjust the pressure in the forming cavity, the upper cover 3 is further provided with a gas pressure gauge 56. The opening degree of the electromagnetic switch valve 55 is adjusted through the gas pressure gauge 56, which is to accurately control the gas pressure value in the device to ensure the formation of the spherical core-shell structure powder.

[0031] In order to prevent the powder from running out of the forming cavity during the working process, the filter screen 33 with nano-level pores is arranged in the air inlet 31 and the air outlet 32, and the pore size of the filter screen 33 is smaller than the diameter of the powder, specifically less than 100 nm.

[0032] Preferably, the high-frequency oscillation device 6 at least comprises one ultrasonic oscillator, and according to specific requirements, a plurality of ultrasonic oscillators can be arranged in an array. The high-frequency oscillation device is arranged at the bottom of the inner container 2, and the purpose is to strengthen the cavitation effect of the ultrasonic wave, so that the nickel-based powder and the nano inoculant can be better dispersed and refined.

[0033] In the embodiment, the cooling device 4 is a conventional device, and specifically, the cooling device 4 comprises a water inlet pipe 41, a water outlet pipe 42 and a refrigeration unit 43. The outer shell 1 is provided with a circulating water pipe 11, the water inlet pipe 41 and the water outlet pipe 42 are connected with the circulating water pipe 11 and the refrigeration unit 43, and the refrigeration unit 43 generates cooling water which enters the circulating water pipe 11 through the water inlet pipe 41 to cool the outer shell 1, thereby maintaining the temperature of the inner container 2. After heat exchange, the cooling water flows back to the refrigeration unit 43 through the water outlet pipe 42, and the cycle is repeated to ensure the reaction temperature of the inner container 2. In order to monitor the reaction temperature of the inner container 2, a temperature sensor is arranged on the inner container 2.

[0034] Preferably, the upper cover 3 is threadedly and sealingly connected with the inner container 2, so as to facilitate adding powder into the inner container 2 or taking out the material in the inner container 2. In other modes, the upper cover 3 and the inner container 2 can also be sealingly connected in a detachable manner by arranging a sealing ring on the abutting surface and through a circle of bolts. Of course, other detachable modes can also be used as long as the upper cover 3 and the inner container 2 can be sealed and detached.

[0035] Specifically, as shown in FIG. 4, the device is used for manufacturing, and the specific method and process parameters are as follows: Figures 3-5

[0036] 1. Pretreatment: Inconel718 (15-25 μm) and inoculant (100-200 nm) are sieved through a 100-mesh sieve and placed in a vacuum dryer for drying for 240-300 min.

[0037] 2. Parameter control: open the upper cover 3, pour the nickel-based alloy powder and the inoculant into the internal forming cavity respectively, start the refrigeration device and close the upper cover 3, open the argon valve, and select 8 MPa for the gas pressure. After the gas pressure is stable for 10 min, start the high-frequency oscillation device, and the ultrasonic frequency is 20 KHz.

[0038] 3. Preparation process: during the preparation process, the gas pressure is always maintained at 8 MPa. After the device is started for 20 min, the ultrasonic frequency is adjusted to 25 KHz for 40 min, and the preparation process is completed.​

[0039] Referring to the drawings Figure 4 As shown in the figure, due to the elimination of satellite powder in the atomized 718 powder, the particle size distribution of the 718 core-shell powder presents a unimodal distribution, the geometric characteristic values (sphericity, aspect ratio, convex envelope) of the core-shell powder are improved, and the flowability of the 718 core-shell powder is effectively improved, which provides a guarantee for obtaining high densification additive manufacturing components.

[0040] Referring to the drawings Figure 5 As shown in the figure, the components prepared based on the nickel-based core-shell powder achieve high densification, and due to the uniform distribution of nano inoculation particles, fine grains are generated, thereby effectively solving the problem of anisotropy in additive manufacturing nickel-based components.

[0041] Experiments show that the flowability of the spherical core-shell powder will not be reduced due to the chain effect of aggregated particles, but will be improved due to the elimination of satellite powder and the uniform dispersion of nano particles, which is the biggest difference and advantage of the device compared with the composite powder prepared by other processes.

[0042] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modifications, equivalent replacements and improvements made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. An apparatus for additive manufacturing of nickel-based powder surface modification and strengthening grafting, characterized in that, It comprises: a shell (1), an inner container (2), an upper cover (3), a cooling device (4), an inert gas flow compression device (5) and a high-frequency oscillation device (6), the inner container (2) and the upper cover (3) are detachably and sealingly connected and form a forming cavity, the high-frequency oscillation device (6) is arranged at the inner bottom of the shell (1), the inner container (2) is arranged in the shell (1), the cooling device (4) is connected with the shell (1), and the inert gas flow compression device (5) is connected with the forming cavity.

2. The apparatus for additive manufacturing of nickel-based powder surface modification and strengthening grafting of claim 1, wherein: The inert gas flow compression device (5) comprises a compressed argon source (51) and an argon pipeline (53), the upper cover (3) is provided with an air inlet (31) and an air outlet (32), the compressed argon source (51) is provided with an argon switch valve (52), the air inlet (31) is connected with the argon switch valve (52) through the argon pipeline (53), a one-way valve (54) is arranged at the air inlet (31), and an electromagnetic switch valve (55) is arranged at the air outlet (32).

3. The apparatus for additive manufacturing of nickel-based powder surface modification and strengthening grafting of claim 2, wherein: The upper cover (3) is further provided with an air pressure gauge (56).

4. The apparatus for additive manufacturing of nickel-based powder surface modification and strengthening grafting of claim 3, wherein: The air inlet (31) and the air outlet (32) are each provided with a filter screen (33) with nanoscale pores.

5. The apparatus for additive manufacturing of nickel-based powder surface modification and strengthening grafting according to any one of claims 1-4, characterized in that: The high-frequency oscillation device (6) at least comprises an ultrasonic oscillator.

6. The apparatus for additive manufacturing of nickel-based powder surface modification and strengthening grafting of claim 5, wherein: The cooling device (4) comprises a water inlet pipe (41), a water outlet pipe (42) and a refrigeration unit (43), the shell (1) is provided with a circulating water pipe (11), the water inlet pipe (41) and the water outlet pipe (42) are connected with the circulating water pipe (11) and the refrigeration unit (43).

7. The apparatus for additive manufacturing of nickel-based powder surface modification and strengthening grafting of claim 6, wherein: The inner container (2) is provided with a temperature sensor.

8. The apparatus for additive manufacturing of nickel-based powder surface modification and strengthening grafting of claim 7, wherein: The upper cover (3) is sealingly connected with the inner container (2) in a threaded manner.

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