Electron beam melting-ultrasonic atomization powder production system and method

Abstract

The present application relates to a kind of electron beam smelting-ultrasonic atomization powder system and method, belong to the preparation technical field of metal powder material, solve the problem such as high melting point metal powder difficult preparation in the existing metal powder preparation technology, medium introduction leads to low powder purity and high cost, powder sphericity is low, particle size is uncontrollable etc.The electron beam smelting-ultrasonic atomization powder system includes: electron beam system, vacuum system, cooling system, ultrasonic powder system and powder collection system.The system can realize powder preparation under high vacuum condition, avoid medium introduction and promote impurity removal, be beneficial to obtain low-oxygen ultra-pure powder;The energy density of electron beam is high, and the preparation of high melting point metal powder can be successfully realized;Ultrasonic atomization makes metal powder high sphericity, particle size is controllable, defect is less, especially suitable for the preparation of refractory metal (such as W, Mo, Ta) and active metal (such as Ti, Nb, Co, V) ultra-pure powder.

Description

Technical Field

[0001] The present invention relates to the technical field of metal powder material preparation, and in particular to an electron beam melting-ultrasonic atomization powder making system and method. Background Art

[0002] Metal powder is an important raw material for powder near-net-shape forming technologies such as additive manufacturing, powder metallurgy, surface coating, and injection molding. Its own properties have a significant impact on the stability of the molding process and the performance of the product. Spherical powder has good fluidity and uniformity, better filling and compaction properties during the molding process, and can produce high-precision, high-performance products. It can also reduce powder waste and agglomeration, thereby improving process efficiency. Currently, the commonly used methods for preparing spherical metal powders include vacuum induction atomization powder production, electrode induction atomization powder production, plasma rotating electrode atomization powder production, plasma atomization powder production, water atomization powder production, radio frequency plasma spheroidization powder production, and ultrasonic atomization powder production.

[0003] However, vacuum induction atomization powder production requires a crucible to hold the molten metal during the metal melting process, which is prone to introducing contaminants; the powder obtained by electrode induction atomization has satellite balls (large balls sticking to small balls), and there may be holes inside the powder. In addition, it is more difficult to prepare powders of ultra-high melting point metals (W, Mo, Ta, etc.); the powder obtained by plasma atomization has a large particle size, and the raw material for preparation needs to be wire, which is limited in the applicable metals, and plasma rotating electrode atomization powder production also has the disadvantage of large powder particle size; the powder shape obtained by water atomization is difficult to control, the loose packing ratio is low, the fluidity is poor, and the active metal is easy to react with the atomization medium water at high temperature, reducing the purity of the product; the radio frequency plasma spheroidization method is not suitable for the preparation of low melting point metal powder, and the spheroidization process has limited effect on the removal of impurities. Ultrasonic atomization powder production is a process in which the molten metal is atomized into tiny droplets through the high-frequency vibration generated by ultrasound, and solidified into metal powder after cooling. The prepared powder has good sphericity, controllable particle size, and a narrow particle size range. However, existing ultrasonic atomization powder production methods all use induction or arc plasma as a heat source to melt the metal raw materials. The vacuum degree of the powder production process is not high, and the impurity removal effect is limited. It is difficult to prepare powders of high-melting-point refractory metals using induction as a heat source. When arc plasma is used as a heat source, the vacuum degree is low. Due to the use of high-purity argon, the cost of powder preparation is high.

[0004] In view of the shortcomings of the existing technology, a new method and system for preparing spherical metal powder is needed to avoid the introduction of argon, plasma or other media (such as high-pressure water) during the powder making process to improve the purity of the metal powder, and to achieve the preparation of refractory metal spherical powder, improve the performance of the metal powder and reduce costs. Summary of the Invention

[0005] In view of the above analysis, the embodiments of the present application aim to provide an electron beam melting-ultrasonic atomization powder preparation system and method to solve at least one of the problems in the prior art, such as difficulty in preparing high-melting-point metal powder, low powder purity and high cost caused by medium introduction, low powder sphericity, uncontrollable particle size, and many metallurgical defects.

[0006] In a first aspect, the embodiments of the present application provide an electron beam melting-ultrasonic atomization powder preparation system, which comprises:

[0007] a furnace body 2;

[0008] an electron beam system comprising an electron gun 12 for generating and emitting an electron beam 13 to melt a metal material 14 to form metal droplets and heat a metal atomization plate 5;

[0009] a vacuum system comprising an electron gun vacuum system and a furnace body vacuum system for providing a vacuum environment for the generation of the electron beam 13 and a vacuum environment for the use of the electron beam 13, respectively;

[0010] an ultrasonic powder preparation system for atomizing the metal droplets to form metal microdroplets 4;

[0011] a cooling system for cooling the furnace body 2, the amplitude transformer 6, and the metal powder 11;

[0012] a powder collection system for collecting the prepared metal powder 11;

[0013] The electron beam system is arranged above the furnace body 2; the ultrasonic powder preparation system is arranged in the furnace body 2; the electron gun vacuum system is connected to the electron beam system, the furnace body vacuum system is arranged on the furnace body 2, the cooling system is arranged on the inner wall of the furnace body 2, around the amplitude transformer 6, and on the side wall and bottom of the powder collection tank 10; and the powder collection system is arranged below the furnace body 2.

[0014] Further, the electron gun vacuum system comprises a molecular pump 1 and a first mechanical pump 3-1.

[0015] Further, the furnace body vacuum system comprises a diffusion pump 16, a secondary Roots pump 17, a primary Roots pump 18, and a second mechanical pump 3-2.

[0016] Further, the ultrasonic powder preparation system comprises the metal atomization plate 5, an ultrasonic wave generating device, and a feeding mechanism 15, the feeding mechanism 15 is used to feed the metal material 14 so that the melted end face of the metal material 14 is located above the metal atomization plate 5, and the ultrasonic wave generating device is arranged below the metal atomization plate 5.

[0017] Further, the metal material 14 does not completely block the emission path of the electron beam, so that the electron beam simultaneously acts on the metal atomization plate 5.

[0018] Further, the metal atomization plate 5 has the same material as the metal material 14.

[0019] Further, the distance between the electron gun 12 and the metal atomization plate 5 is adjustable in the range of 500-1500mm.

[0020] Further, the distance between the metal material 14 and the metal atomization plate 5 is adjustable in the range of 50-500mm.

[0021] In the second aspect, the embodiment of the present application provides a preparation method of metal powder, and the method comprises the following steps:

[0022] (1) pretreating the metal material to obtain clean metal material to be treated;

[0023] (2) under a vacuum state, performing electron beam melting on the metal material to be treated to obtain metal droplets;

[0024] (3) performing ultrasonic atomization on the metal droplets to form atomized metal microdroplets;

[0025] (4) cooling and solidifying the atomized metal microdroplets in the movement process, collecting and obtaining metal powder.

[0026] Further, in step (2), the pressure of the vacuum state is 1x10 -3 -8x10 -3 Pa.

[0027] Further, the method further comprises: further cooling the collected metal powder.

[0028] Compared with the prior art, the present application can achieve at least one of the following beneficial effects:

[0029] 1. The system of the present application melts the metal material by using electron beam, the energy density of the electron beam is high, and can melt high melting point metals (W, Mo, Ta, etc.), and can prepare various metal powders with different melting points by adjusting the electron beam power;

[0030] The melted metal droplets fall on the metal atomization plate to form a micro-melt pool, and then under the action of ultrasonic waves, the liquid metal produces sputtering to form a metal mist, and after cooling and solidification, metal powder is obtained. Compared with gas atomization, the metal powder prepared by ultrasonic atomization has good sphericity (>0.95), high fine powder yield (powder below 75μm accounts for more than 60%), and there is no swirling airflow in ultrasonic atomization, reducing the probability of particle collision and avoiding the generation of hollow powder and satellite powder;

[0031] The application is used for powder making under high vacuum condition, the high vacuum condition is beneficial to remove gas impurities (O, N, etc.) in the molten drop, meanwhile, the pollution caused by the introduction of medium (such as argon, plasma, high pressure water, etc.) is avoided, which is beneficial to obtain low-oxygen ultra-pure powder, especially suitable for the preparation of active metal (such as Ti, Nb, Co, V) ultra-pure powder, and the cost is reduced.

[0032] 2、The application controls the movement of the metal material through the horizontal feeding mechanism, ensures that the melting end face of the metal material is located in the electron beam bombardment range above the metal atomization plate, and the metal material does not completely shield the transmission path of the electron beam, so that part of the electron beam bombards the metal atomization plate, and the purposes of melting the metal and heating the metal atomization plate are achieved, the temperature required for atomization powder making is ensured, the metal molten drop is promoted to form metal micro-droplets, and the application is especially suitable for the preparation of high melting point and even refractory metal powder; a single electron beam heat source is adopted, and the structure of the powder making system is simplified.

[0033] 3、The metal atomization plate used in the application has the same material as the metal material, and a crucible is not needed, so that the introduction of pollutants is avoided, and high-purity metal powder is obtained.

[0034] 4、The powder making system and method of the application realize the preparation of metal powder with a melting point range of 200-3500 DEG C by adjusting the electron beam power (5-500 kW), and the application is suitable for a large variety of materials; the raw material is metal rod or metal strip, which is easy to obtain and beneficial to industrialization promotion; high-purity argon is not used in the powder making process, and a single heat source system is adopted, so that the system structure is effectively simplified, and the production cost is reduced.

[0035] The above technical solutions can be combined with each other to realize more preferred combination solutions. Other features and advantages of the application will be described in the subsequent specification, and some advantages will become apparent from the specification, or will be understood by implementing the application. The purpose and other advantages of the application can be realized and obtained from the contents specifically pointed out in the specification and the drawings. BRIEF DESCRIPTION OF DRAWINGS

[0036] The accompanying drawings are included to provide a further understanding of the application and are incorporated herein and constitute a part of the application. The drawings illustrate embodiments of the application and, together with the description, serve to explain the principles of the application. In the drawings:

[0037] Figure 1 It is a schematic diagram of the electron beam melting-ultrasonic atomization powder making system of the application;

[0038] Figure 2 It is a flow chart of the electron beam melting-ultrasonic atomization powder making process of the application;

[0039] Reference signs:

[0040] 1 - molecular pump; 2 - furnace body; 3 - 1 - first mechanical pump; 3 - 2 - second mechanical pump; 4 - atomized metal microdroplets; 5 - metal atomization plate; 6 - amplitude lever; 7 - ultrasonic transducer; 8 - 1 - cooling system inlet / outlet; 8 - 2 dust collection system cooling water; 8 - 3 amplitude lever cooling water; 9 - ultrasonic generator; 10 - dust collection tank; 11 - metal powder; 12 - electron gun; 13 - electron beam; 14 - metal material; 15 - feeding mechanism; 16 - diffusion pump; 17 - secondary Roots pump; 18 - primary Roots pump; 19 - flapper valve. DETAILED DESCRIPTION

[0041] The preferred embodiments of the present application will be described in detail below with reference to the drawings, which form a part of this description, and together with the description illustrate the principles of the application. The application is not limited to the embodiments disclosed but is applied to any alternative embodiments.

[0042] The commonly used preparation methods of spherical metal powder in the prior art include vacuum induction gas atomization, electrode induction gas atomization, plasma rotating electrode atomization, plasma atomization, water atomization, radio frequency plasma spheroidization, induction / arc ultrasonic atomization, etc. However, one or more of the following problems may occur in the powder preparation process of the existing methods: the crucible is used to hold the metal melt, which is easy to introduce contaminants; the prepared powder has large particle size and many defects (hollow powder, satellite powder); it is difficult to prepare powder of ultra-high melting point metals (W, Mo, Ta, etc.); the prepared powder has large particle size (D50 is greater than 100 μm); the preparation raw material needs to be a wire, and the applicable metals are limited; the shape of the prepared powder is difficult to control, the loose packing ratio is low, and the flowability is poor; the active metal is easy to react with the atomization medium or impurities at high temperature, reducing the product purity; the powder preparation process has limited effect on the removal of impurities; the equipment structure is complex; and the cost is high.

[0043] Therefore, the present application provides an electron beam melting-ultrasonic atomization powder preparation system, which is a metal powder preparation system based on electron beam heating and ultrasonic atomization, as shown in Figure 1 The system comprises:

[0044] a furnace body 2;

[0045] an electron beam system comprising an electron gun 12 for generating and emitting an electron beam 13 to melt a metal material 14 to form metal droplets and heat a metal atomization plate 5;

[0046] a vacuum system comprising an electron gun vacuum system and a furnace body vacuum system for providing a vacuum environment for the generation of the electron beam 13 and a vacuum environment for the use of the electron beam 13, respectively;

[0047] an ultrasonic powder preparation system for atomizing the metal droplets to form metal microdroplets 4;

[0048] A cooling system is arranged to cool the furnace body 2, the amplitude lever 6 and the metal powder 11.

[0049] A powder collecting system is arranged to collect the prepared metal powder 11.

[0050] The electron beam system is arranged above the furnace body 2; the ultrasonic powder preparation system is arranged in the furnace body 2; the electron gun vacuum system is connected with the electron beam system; the furnace body vacuum system is arranged on the furnace body 2; the cooling system is arranged on the inner wall of the furnace body 2, the periphery of the amplitude lever 6 and the side wall and bottom of the powder collecting tank 10; and the powder collecting system is arranged below the furnace body 2.

[0051] According to a preferred embodiment of the present application, the electron gun vacuum system comprises a molecular pump 1 and a first mechanical pump 3-1, which are connected to vacuumize the gun body of the electron gun; a valve is arranged on the pipeline connecting the electron gun 12 and the molecular pump 1; and a valve is arranged on the pipeline connecting the molecular pump 1 and the first mechanical pump 3-1.

[0052] According to a preferred embodiment of the present application, the vacuum system comprises a diffusion pump 16, a two-stage Roots pump 17, a one-stage Roots pump 18 and a second mechanical pump 3-2, which are used to vacuumize the furnace body 2.

[0053] Specifically, one end of the diffusion pump 16 is connected with the furnace body 2, and the other end is connected with the two-stage Roots pump 17; one end of the two-stage Roots pump 17 is also connected with the furnace body 2 through a gas pipeline, and the other end is connected with the one-stage Roots pump 18; the other end of the one-stage Roots pump 18 is connected with the second mechanical pump 3-2; and pneumatic valves are arranged on the pipelines between the diffusion pump 16 and the furnace body 2, between the diffusion pump 16 and the two-stage Roots pump 17 and between the two-stage Roots pump 17 and the furnace body 2. Through the joint action of the diffusion pump 16, the two-stage Roots pump 17, the one-stage Roots pump 18 and the second mechanical pump 3-2, the high vacuum state in the furnace body 2 is ensured.

[0054] According to a preferred embodiment of the present application, the upper end surface of the furnace body 2 is provided with a flange, the electron gun 12 is connected with the furnace body through the flange, and the emitted electron beam is used to melt the metal material 14.

[0055] It should be noted that the system of the present application adjusts the electron beam to melt the metal material through the electron beam system, and the electron beam has high energy density, which can melt refractory metals (W, Mo, Ta, etc.) and can adjust the electron beam power in the range of 5-500 kW to prepare various metal powders with different melting points; according to the preferred embodiment of the present application, the electron beam power for preparing titanium metal powder is 15-30 kW.

[0056] Preferably, a sealing device is arranged at the connection between the electron gun 12 and the furnace body 2 to ensure the airtightness of the whole furnace body.

[0057] According to a preferred embodiment of the present application, the ultrasonic powdering system comprises a metal atomizing plate 5, an ultrasonic wave generating device and a feeding mechanism 15. The feeding mechanism 15 is used to feed the molten end face of the metal material 14 above the metal atomizing plate 5, and the ultrasonic wave generating device is arranged below the metal atomizing plate 5.

[0058] In the present application, the metal material can be a metal rod material or a metal strip material.

[0059] According to a preferred embodiment of the present application, the ultrasonic wave generating device comprises an ultrasonic wave generator 9, an ultrasonic transducer 7 and a horn 6.

[0060] According to a preferred embodiment of the present application, the horn 6 is connected to the metal atomizing plate 5 through a support rod or a screw, which facilitates the replacement of the metal atomizing plate 5.

[0061] According to a preferred embodiment of the present application, the horn 6 is cooled by a cooling system. During the powdering process, the temperature of the metal atomizing plate 5 is relatively high due to the electron beam, and the horn needs to be cooled to avoid the heat being transferred to the ultrasonic transducer through the horn, which affects the normal operation of the ultrasonic transducer. In addition, the high temperature can also cause the metal atomizing plate to be directly melted, and the atomization efficiency is reduced.

[0062] During the use of the electron beam melting-ultrasonic atomization powdering system of the present application, the metal material 14 is driven by the feeding mechanism 15 to move, so that the molten end face is located in the bombardment range of the electron beam 13. The molten droplets obtained by melting fall on the metal atomizing plate 5, and under the action of the ultrasonic wave generating device, the molten droplets in contact with the metal atomizing plate are broken and sputtered by the ultrasonic waves to produce atomized microdroplets 4. The atomized microdroplets 4 fall and cool when contacting the side wall of the furnace body 2, and solidify to form metal microparticles, which fall into the powder collecting tank 10 connected to the furnace body 2 for collection.

[0063] According to a preferred embodiment of the present application, a cooling system is arranged in the side wall of the furnace body 2. According to a preferred embodiment of the present application, the inlet of the cooling water pipe of the cooling system is located on one side of the furnace body 2, and the outlet of the cooling water pipe is located on the other side of the furnace body 2. The cooling system keeps the inner wall surface of the furnace body 2 in a cooling state (<40℃), so as to preliminarily cool the prepared metal powder.

[0064] Preferably, in order to ensure the sealing property of the furnace body 2, a sealing device is arranged at the inlet and outlet of the cooling water pipe on the furnace body 2.

[0065] Further, the lower end of the furnace body 2 is connected to the powder collecting system.

[0066] According to a preferred embodiment of the present application, the lower end surface of the furnace body 2 is arranged in a conical structure with the upper part larger and the lower part smaller, and the lower part of the cone is connected with the powder collecting system, which is beneficial to the collection of metal powder.

[0067] Specifically, the powder collecting system comprises a plug valve 19 and a powder collecting tank 10, and the side wall surface and the bottom of the powder collecting tank 10 are provided with circulating cooling water to further cool the collected metal powder 11.

[0068] Further, after the collection of the metal powder 11 is completed, the plug valve 19 arranged at the connecting position of the furnace body 2 and the powder collecting system is inserted, the vacuum sealing of the powder tank body is completed, the powder collecting tank 10 is transferred to the powder screening equipment, and the powder is screened to obtain the ultra-pure low-oxygen metal powder.

[0069] The metal melt drops after being melted by the electron beam fall on the metal atomization plate, and then under the action of the ultrasonic wave regulated by the ultrasonic powder preparation system, the liquid melt drops generate sputtering to form metal atomization micro-droplets, and the metal powder is obtained after cooling and solidification. Compared with the gas atomization in the prior art, the metal powder prepared by the ultrasonic atomization has good sphericity (>0.95), high fine powder yield (more than 60% of the powder below 75 μm), and no swirling airflow exists in the ultrasonic atomization, which reduces the particle collision probability and avoids the generation of hollow powder and satellite powder.

[0070] The present application prepares the powder under high vacuum condition, avoids the pollution caused by the introduction of medium (such as argon, plasma, high-pressure water, etc.), is beneficial to obtain the low-oxygen ultra-pure powder, is particularly suitable for the preparation of active metal (such as Ti, Nb, Co, V) ultra-pure powder, and reduces the cost.

[0071] According to a preferred embodiment of the present application, the movement of the metal material 14 is accurately controlled by the feeding mechanism 15, not only ensures that the melting end surface of the metal material 14 is located in the electron beam bombardment range above the metal atomization plate 5, but also does not completely block the emission path of the electron beam, so that part of the electron beam is emitted onto the metal atomization plate 5, and the purposes of melting the metal and heating the metal atomization plate are achieved, the temperature required for the melt atomization powder preparation is ensured, the formation of metal micro-droplets 4 by sputtering of the melt drop is promoted, and the present application is particularly suitable for the preparation of high-melting-point and even refractory metal powder; and the structure of the electron beam melting-ultrasonic atomization powder preparation system is simplified.

[0072] According to a preferred embodiment of the present application, the metal atomization plate 5 is arranged directly below the electron gun 12, and the distance between the metal atomization plate 5 and the electron gun 12 is 500-1500 mm. The distance can ensure that the electron beam has a good heating effect on the metal atomization plate after being focused. If the distance is too large, the electron beam cannot be focused or the focusing radius is too large. If the distance is too small, the space for atomization operation is limited. According to a preferred embodiment of the present application, the distance between the metal atomization plate and the electron gun is 700 mm.

[0073] According to a preferred embodiment of the present application, the metal atomization plate 5 is made of the same material as the metal material 14, and does not need a crucible, thereby avoiding the introduction of pollutants and facilitating the obtaining of high-purity metal powder.

[0074] According to a preferred embodiment of the present application, the metal atomization plate 5 is arranged horizontally.

[0075] It should be noted that the metal atomization plate 5 can be arranged obliquely, and the center of the metal atomization plate is arranged on the central axis of the electron beam. The oblique angle of the metal atomization plate can be adjusted in the range of 0°-60° to the left or right of the horizontal direction, so that the prepared powder can move in one direction, and the powder can be easily collected.

[0076] According to a preferred embodiment of the present application, the distance between the horizontal metal material and the metal atomization plate is 50-500 mm. If the distance is too large, the molten droplets are excessively cooled, and the atomization effect is poor. If the distance is too small, the metal atomization plate is overheated and melted, and the yield of the metal powder is affected. According to a preferred embodiment of the present application, the distance between the horizontal metal material and the metal atomization plate is 100 mm.

[0077] The present application also provides a method for preparing metal powder by electron beam melting-ultrasonic atomization. Figure 2 As shown in the flowchart, the method comprises the following steps:

[0078] (1) The metal material is pretreated to obtain clean metal material to be treated;

[0079] (2) The metal material to be treated is subjected to electron beam melting in a vacuum state to obtain metal molten droplets;

[0080] (3) The metal molten droplets are subjected to ultrasonic atomization to form atomized metal microdroplets;

[0081] (4) The atomized metal microdroplets are cooled and solidified during movement, collected, and metal powder is obtained.

[0082] The preparation method melts metal material by electron beam and heats the metal atomization plate, and under the action of ultrasonic waves, the droplets splashed on the metal atomization plate form mist droplets by sputtering, and the metal powder is obtained after cooling and solidification; the powder is prepared under high vacuum condition, the medium is avoided to be introduced and the impurities are removed, which is beneficial to obtain low-oxygen ultra-pure powder; the energy density of the electron beam is high, the preparation of high-melting-point metal powder is successfully realized from two aspects of melting metal and providing heat source for atomization plate, and the equipment structure is simple; the ultrasonic atomization makes the metal powder have high sphericity, controllable particle size and few defects, and is especially suitable for the preparation of ultra-pure powder of refractory metals (such as W, Mo and Ta) and active metals (such as Ti, Nb, Co and V).

[0083] In some embodiments of the present application, the pretreatment in step (1) includes: checking the surface state of the material, cleaning the surface when the surface has contaminants, confirming that the surface is clean and free of contaminants, and placing the metal raw material in a dry state.

[0084] In order to obtain ultra-pure metal powder in later period, the raw material with high purity is selected as much as possible in step (1); for example, the purity of the selected metal raw material can be 3N-5N level (not including gas impurity content).

[0085] In some embodiments of the present application, step (2) is performed under vacuum state, and the metal material to be treated is melted by electron beam. Specifically, step (2) includes:

[0086] S1: clean the furnace body and the furnace wall of the electron beam smelting furnace, and avoid the introduction of external impurities in the process of droplet melting and ultrasonic atomization;

[0087] S2: place the metal material to be treated 14 into the feeding mechanism, then close the bunker door and the electron beam furnace door; start the cooling system and the vacuum system, and after the diffusion pump 16 is preheated, the furnace body 2 and the gun body are pumped to the target vacuum state (vacuum degree 1x10 -3 ~ 8x10 -3 Pa), and then the electron gun 12 is started to preheat the equipment;

[0088] S3: after preheating, the power of the electron gun 12 is slowly increased, the end of the metal material 14 and the metal atomization plate 5 are preheated in a large beam spot annular scanning mode, and then the ultrasonic generator 9 is started to make the metal atomization plate 5 vibrate at high frequency;

[0089] S4: adjust the parameters of electron beam smelting (beam spot radius and scanning radius, scanning frequency, scanning position, etc.), so that the top end of the metal material 14 starts to melt to form droplets, and the droplets drop to the surface of the metal atomization plate 5 under the action of gravity.

[0090] In steps S3 and S4, the large beam spot annular scanning can improve the uniformity of heating.

[0091] In step S2, the metal material 14 is placed in the feeding mechanism 15, and the end face to be melted of the metal material is located in the electron beam bombardment range above the metal atomization plate.

[0092] According to some preferred embodiments of the present application, in step (3), a suitable frequency of the ultrasonic generator 9 is selected in the range of 5-80 kHz (preferably 30-80 kHz), and meanwhile, reasonable electron beam melting parameters are matched, so that the molten droplets falling on the atomization plate are broken and sputtered out by high-frequency vibration, to generate atomized metal microdroplets 4.

[0093] According to some preferred embodiments of the present application, in step (4), the atomized microdroplets 4 are cooled and solidified to form metal spherical powder, which falls into the powder collecting device below under the action of gravity. In order to enable the atomized microdroplets after sputtering to be quickly cooled, the temperature of the inner wall of the furnace body is maintained below 40°C. If the temperature is too high, the cooling speed of the droplets will be slow, which will affect the powder production efficiency. According to the preferred embodiments of the present application, the temperature of the water flowing out of the cold water pipe outlet is 32°C.

[0094] According to some preferred embodiments of the present application, the preparation method further comprises the following steps:

[0095] (5) The feeding mechanism 15 is started to move the metal material 14 horizontally at a slow speed, and the powder production process is continuously carried out through the control of the feeding, electron beam melting and ultrasonic atomization parameters;

[0096] (6) When the horizontal feeding mechanism reaches the maximum stroke, the power of the electron gun is reduced to 0 kW, and the ultrasonic generator 9 is paused, and then the standby feeding mechanism is started;

[0097] (7) Steps S3-S5 in step (2) are repeated;

[0098] (8) When the raw material is completely powdered, the power of the electron gun 12 is reduced to 0 kW, and the ultrasonic generator 9 is paused, and then the electron gun 12 is turned off, so that the metal powder 11 is fully cooled in the powder collecting tank 10;

[0099] (9) After the metal powder 11 is completely cooled, the plug valve 19 is inserted to complete the vacuum sealing of the powder collecting tank 10, and the electron beam melting equipment is turned off after the electron beam equipment is completely cooled. The powder collecting tank 10 is transferred to the powder screening equipment, and the powder is screened to obtain the ultra-pure low-oxygen metal powder.

[0100] Different from the prior art, the raw material of the present application is a metal rod or strip material, which is easy to obtain and conducive to industrialization and popularization; the preparation of metal powder with a melting point ranging from 200 to 3500℃ is realized by adjusting the electron beam power within a certain range, and the application is suitable for a wide variety of materials; and a single heat source system is adopted, effectively simplifying the system structure and reducing the production cost. The electron beam power of the present application ranges from 5 to 500kW, according to the preferred embodiment of the present application, the electron beam power for preparing titanium powder is 20kW, and the morphology and flow rate of the molten droplets of the metal material are optimized by adjusting the electron beam spot radius, scanning frequency, scanning distance, etc.

[0101] In order to avoid the introduction of impurity gas and more effectively remove volatile impurities and gas impurities (such as O, N, etc.) in the metal, the vacuum state during the powder preparation process of the present application is 1×10 -3 -8×10 -3 Pa, which is conducive to obtaining low-oxygen ultra-pure powder; according to the preferred embodiment of the present application, the vacuum state during the powder preparation process is 5×10 -3 Pa.

[0102] Different from the prior art, the entire powder preparation process of the present application does not require the introduction of high-purity argon or other media, which not only helps to improve the purity of the powder, but also effectively simplifies the system structure and reduces the production cost.

[0103] In order to keep the melting end face of the metal material within the bombardment range of the electron beam, and according to the actual preparation needs of the metal powder, the metal material does not completely block the emission path of the electron beam, so that part of the electron beam bombards the metal atomization plate, achieving the purpose of melting the metal and heating the metal atomization plate, the speed of the metal material moving is 5-50mm / min, which not only ensures the melting temperature of the metal material, but also ensures the temperature required for the droplet atomization powder preparation, which is conducive to promoting the sputtering of the droplet to form metal microdroplets, especially suitable for the preparation of high-melting-point and even refractory metal powder; at the same time, the structure of the electron beam melting-ultrasonic atomization powder preparation system is simplified; and by adjusting the melting speed of the metal rod and the falling time of the droplet in combination with the related parameters of the electron beam, the particle size and quality of the prepared powder are controlled.

[0104] In order to ensure the melting efficiency of the metal material and simplify the process steps, the diameter of the metal rod is 30-100mm, and the length is 200-2000mm.

[0105] Example 1

[0106] As shown in Figure 1 , an electron beam melting-ultrasonic atomization powder preparation system of the present embodiment includes a furnace body, an electron beam system, a vacuum system, a cooling system, an ultrasonic powder preparation system, and a powder collection system.

[0107] The electron beam system is used for melting the metal material 14 to form the metal droplet by emitting the electron beam, and various low-melting-point and high-melting-point metal powders are prepared by adjusting the power of the electron beam 13. For example, by adjusting the power of the electron beam in the range of 5-500 kW, metal rods with a melting point of 200-3500℃ can be melted.

[0108] As shown in Figure 1 , the vacuum system includes an electron gun vacuum system and a furnace body vacuum system for providing a vacuum environment (vacuum degree of 1×10 -3 -8×10 -3 Pa) for the generation and use of the electron beam 13, avoiding the introduction of medium to cause powder pollution, and promoting the degassing and impurity removal of the melt to obtain low-oxygen ultra-pure powder; wherein the electron gun vacuum system includes a molecular pump 1 and a first mechanical pump 3-1; the furnace body vacuum system includes a diffusion pump 16, a secondary Roots pump 17, a primary Roots pump 18 and a second mechanical pump 3-2.

[0109] As shown in Figure 1 , the ultrasonic powder system includes a metal atomization plate 5, an ultrasonic generating device and a feeding mechanism 15, the feeding mechanism 15 is used to provide the metal material 14, so that the melting end face of the metal material 14 is located above the electron beam bombardment range of the metal atomization plate 5, and the metal material 14 does not completely block the emission path of the electron beam 13, so that part of the electron beam bombards the metal atomization plate 5, to ensure that the metal atomization plate 5 has a relatively high temperature; the ultrasonic generating device is arranged below the metal atomization plate 5 and includes an ultrasonic generator 9, an amplitude transformer 6 and an ultrasonic transducer 7, and is used to atomize the metal droplet to form metal microdroplets 4; wherein the metal atomization plate 5 has the same material as the metal material 14, to reduce the introduction of pollutants; the distance between the electron gun 12 and the metal atomization plate 5 is 700 mm, and the distance between the metal material and the metal atomization plate is 100 mm.

[0110] The inner wall of the furnace body 2 is provided with a cooling system, and the circulating water cooling system is used to keep the inner wall of the furnace body at a relatively low temperature (less than 40℃), which is beneficial to the rapid cooling of the powder; the existing circulating water cooling system can be used.

[0111] The lower end of the furnace body 2 is designed as a cone structure, the lower part of the cone is connected with the powder collecting system, and a plug valve 19 is arranged at the connection position, to realize the vacuum sealing of the powder collecting tank 10 after the preparation of the metal powder 11, to avoid the oxidation of the metal powder 11 and the introduction of impurities.

[0112] The metal material 14 is driven by the feeding mechanism 15 to move so that the molten end face is within the bombardment range of the electron beam. The melted molten liquid falls onto the metal atomizing plate 5. Under the action of the ultrasonic generator, the dripping metal droplets are broken up by the ultrasonic wave and sputtered out to produce atomized micro-droplets 4. The atomized micro-droplets 4 cool down and solidify to form metal particles during movement. After contacting the side wall of the furnace body 2, they are further cooled and fall into the powder collection system connected to the lower end face of the furnace body 2 for collection. By adjusting the frequency of ultrasonic atomization, the power of the electron beam, the powder making speed, etc., different working states are used to adjust the sphericity and particle size of the obtained metal powder and reduce the defects of the metal powder, including hollow powder and satellite powder defects. For example, the frequency of ultrasonic atomization is set to 30-80kHz.

[0113] Example 2

[0114] like Figure 2 As shown in the flowchart, this embodiment is a method for preparing metal Ti powder using an electron beam melting-ultrasonic atomization powder making system, comprising:

[0115] (1) Pretreatment of metal materials: The raw material used in the present invention is metal Ti, which is in the shape of a rod with a diameter of 50 mm, a length of 1500 mm, and a purity of 4N. The surface condition of the rod is checked, the surface is cleaned to ensure that the surface is clean and free of contamination, and the rod is dried at 30°C.

[0116] Clean the contaminants on the inner wall of the furnace to avoid the introduction of foreign impurities during the powder making process, and then load the prepared metal bars into the feeding mechanism;

[0117] Start the circulating water cooling system and electron beam melting equipment, and use the vacuum system to reduce the pressure inside the furnace to 5×10 -3 Pa, ensure that the temperature of the water flowing out of the cooling water outlet is below 40℃;

[0118] (2) adjusting the position of the metal rod in the feeding mechanism so that the end face of the metal material to be melted is within the bombardment range of the electron beam and above the metal atomizing plate;

[0119] (3) Start the electron gun with an electron beam power of 5 kW to preheat the end of the rod and the metal atomizing plate so that the end of the rod becomes red hot under the action of the electron beam; start the ultrasonic generator with an ultrasonic frequency of 40 kHz to cause the metal atomizing plate to vibrate at a high frequency;

[0120] (4) Adjust the electron beam power to 20 kW so that the top of the bar begins to melt and form droplets, which then drip onto the surface of the metal atomizing plate under the action of gravity;

[0121] (5) The molten drops on the surface of the metal atomization plate are broken and sputtered out by high-frequency vibration, generating atomized metal micro-droplets, which solidify into spherical metal powder after cooling, and fall into the powder collecting system below;

[0122] The feeding mechanism is started to move the metal rod slowly horizontally at a speed of 20 mm / min, so that the powder preparation process continues;

[0123] (6) When the horizontal feeding mechanism reaches the maximum stroke, the electron gun power is reduced to 0 kW, and the ultrasonic generator is paused; then the standby feeding mechanism is started, the electron gun power is slowly increased, and the rod end and the metal atomization plate are preheated in a large beam spot annular scanning mode; the ultrasonic generator is started to make the metal atomization plate vibrate at high frequency;

[0124] (7) Steps (4)-(6) are repeated, when the raw material rod is completely powdered, the electron gun power is reduced to 0 kW, and the ultrasonic generator is paused, then the electron gun is turned off, so that the powder is fully cooled in the powder collecting tank; the plug valve is inserted to complete the vacuum sealing of the powder tank, and after the electron beam equipment is cooled, the electron beam melting equipment is turned off.

[0125] The obtained powder is passed through a 100-mesh screen to obtain the target section powder; detection shows that the D50 of the prepared powder is 45-50 μm, the particle size distribution range is narrow, the particle size is less than 75 μm, the powder with particle size of 75 μm or less accounts for more than 60%, the sphericity is greater than 0.95, and the oxygen content is 260 ppm.

[0126] The above is only a preferred specific embodiment of the present application, but the protection scope of the present application is not limited thereto, any changes or replacements within the technical range disclosed by the present application can be easily thought by those skilled in the art, which should be covered within the protection scope of the present application.

Claims

1. An electron beam melting-ultrasonic atomization powder making system, characterized in that: The system comprises: furnace body (2); An electron beam system, comprising an electron gun (12) for generating and emitting an electron beam (13) to melt a metal material (14) to form metal droplets and to heat a metal atomizing plate (5); A vacuum system, comprising an electron gun vacuum system and a furnace vacuum system, for respectively providing a vacuum environment for the electron beam (13) to be generated and a vacuum environment for the electron beam (13) to be used; An ultrasonic powder making system for atomizing the metal molten droplets to form metal micro-droplets (4); A cooling system for cooling the furnace body (2), the horn (6) and the metal powder (11); A powder collecting system for collecting the produced metal powder (11); The electron beam system is arranged above the furnace body (2); the ultrasonic powder making system is arranged inside the furnace body (2); the electron gun vacuum system is connected to the electron beam system, the furnace body vacuum system is arranged on the furnace body (2), the cooling system is arranged on the inner wall of the furnace body (2), around the amplitude transformer (6), and the side wall and bottom of the powder collecting tank (10); the powder collecting system is arranged below the furnace body (2); The ultrasonic powder making system comprises a metal atomizing plate (5), an ultrasonic generating device and a feeding mechanism (15), wherein the feeding mechanism (15) is used to feed materials so that the melting end surface of the metal material (14) is located above the metal atomizing plate (5), and the ultrasonic generating device is provided below the metal atomizing plate (5); The metal material (14) does not completely block the emission path of the electron beam (13), so that the electron beam (13) acts on the metal atomization plate (5) at the same time.

2. The system according to claim 1, wherein: The electron gun vacuum system comprises a molecular pump (1) and a first mechanical pump (3-1); The furnace body vacuum system includes a diffusion pump (16), a secondary Roots pump (17), a primary Roots pump (18) and a second mechanical pump (3-2).

3. The system according to claim 1, wherein: The metal atomizing plate (5) has the same material as the metal material (14).

4. The system according to claim 1, wherein: The distance between the electron gun (12) and the metal atomization plate (5) is adjustable within the range of 500-1500 mm.

5. The system according to claim 1, wherein: The distance between the metal material (14) and the metal atomizing plate (5) is adjustable within a range of 50-500 mm.

6. A method for preparing metal powder using the electron beam melting-ultrasonic atomization powder making system according to any one of claims 1 to 5, characterized in that: The method comprises: (1) Pre-treating the metal material to obtain clean metal material to be processed; (2) Under vacuum conditions, the metal material to be processed is subjected to electron beam melting to obtain metal droplets; (3) ultrasonically atomizing the metal droplets to form atomized metal micro-droplets; (4) The atomized metal droplets are cooled and solidified during the movement, and are collected to obtain metal powder.

7. The method according to claim 6, characterized in that In step (2), the pressure in the vacuum state is 1×10 -3 -8×10 -3 Pa.

8. The method according to claim 6, characterized in that The method further includes further cooling the collected metal powder.

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