WO2020063620A1 - 一种逐液滴离心雾化法高效制备低熔点球形金属粉末的装置及方法 - Google Patents

一种逐液滴离心雾化法高效制备低熔点球形金属粉末的装置及方法 Download PDF

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Publication number
WO2020063620A1
WO2020063620A1 PCT/CN2019/107697 CN2019107697W WO2020063620A1 WO 2020063620 A1 WO2020063620 A1 WO 2020063620A1 CN 2019107697 W CN2019107697 W CN 2019107697W WO 2020063620 A1 WO2020063620 A1 WO 2020063620A1
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Prior art keywords
crucible
droplet
turntable
induction heating
melting
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PCT/CN2019/107697
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English (en)
French (fr)
Inventor
董伟
许富民
孟瑶
朱胜
王晓明
白兆丰
王延洋
韩阳
李国斌
赵阳
石晶
韩国峰
王思捷
常青
任智强
滕涛
孙瑜
Original Assignee
大连理工大学
王晓明
朱胜
赵阳
王思捷
韩国峰
石晶
常青
任智强
滕涛
孙瑜
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Application filed by 大连理工大学, 王晓明, 朱胜, 赵阳, 王思捷, 韩国峰, 石晶, 常青, 任智强, 滕涛, 孙瑜 filed Critical 大连理工大学
Priority to AU2019351409A priority Critical patent/AU2019351409A1/en
Publication of WO2020063620A1 publication Critical patent/WO2020063620A1/zh

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F9/00—Making metallic powder or suspensions thereof
    • B22F9/02—Making metallic powder or suspensions thereof using physical processes
    • B22F9/06—Making metallic powder or suspensions thereof using physical processes starting from liquid material
    • B22F9/08—Making metallic powder or suspensions thereof using physical processes starting from liquid material by casting, e.g. through sieves or in water, by atomising or spraying
    • B22F9/10—Making metallic powder or suspensions thereof using physical processes starting from liquid material by casting, e.g. through sieves or in water, by atomising or spraying using centrifugal force

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  • the invention belongs to the technical field of preparing ultrafine spherical microparticles, and in particular, particularly relates to a device and method for efficiently preparing a low melting point spherical metal powder by using a droplet-by-drop centrifugal atomization method.
  • spherical metal powder As an important industrial raw material, spherical metal powder has been widely used in 3D printing, electronic packaging, semiconductor integrated circuits, new energy and other fields. With the development of equipment miniaturization and high precision, the above fields have put forward higher requirements on spherical powder and its preparation technology, especially in the field of rapid molding of metal powder.
  • the powder produced by the atomization method has a wide particle size distribution. It must be screened multiple times to obtain a powder that meets the requirements, and the yield is low.
  • the atomized powder contains a large number of satellite droplets, which reduces its fluidity and spreadability.
  • the melt temperature and rotation speed are too high, the melt is prone to side slip, which seriously affects the atomization efficiency.
  • the powder produced by the pulse microporous spraying method has high sphericity and uniform particle size, the method is not efficient in preparing small particle size particles, and its application range is limited.
  • a device for efficiently preparing low-melting spherical metal powder by a droplet-by-drop centrifugal atomization method and method mainly combines the two methods of pulsed microporous droplet spraying method and centrifugal atomization method, and simultaneously designs the structure of the turntable and inductively heats the surface of the disc, so that the molten metal liquid breaks through the traditional molten metal splitting mode.
  • a fibrous splitting method that can be achieved only when the atomizing medium is an aqueous or organic solution is compared with the existing centrifugal atomizing technology.
  • the powder obtained by atomizing in this linear splitting mode can be ultra-fine.
  • a device for efficiently preparing a low melting point spherical metal powder by a droplet-by-drop centrifugal atomization method comprising a casing, a crucible disposed in the casing, and a powder collection region, the powder collection region being placed at the bottom of the casing,
  • the crucible is placed at the upper part of the powder collection area.
  • the crucible is provided with a transmission rod connected to a piezoelectric ceramic provided outside the casing. The lower end of the transmission rod faces the center of the bottom of the crucible.
  • a hole with a gasket with a small hole at the bottom of the center hole; a thermocouple inside the crucible and a ring resistance heater outside the crucible;
  • the shell is provided with a crucible air inlet pipe that extends into the crucible, and a side wall of the shell is further provided with a mechanical pump and a diffusion pump that communicate with the crucible, and the shell is further provided with With cavity air inlet and cavity exhaust valve;
  • the powder collection area includes a collection tray provided at the bottom of the housing and a turntable connected to a motor for atomizing metal droplets, which is provided above the collection tray;
  • the turntable includes a base body, an atomizing plane and a vent hole;
  • the longitudinal section of the base body composed of the upper receiving part and the lower supporting part is similar to a "T-shaped" main structure, and the upper surface of the receiving part is provided with a circular groove with a certain radius coaxial with the center of the circle;
  • the base body is made of a material having a thermal conductivity of less than 20W / m / k;
  • the atomizing plane is a disc structure, the disc structure matches the circular groove and interference fit with the circular groove, and the atomizing plane adopts a wetting angle with the atomized metal droplet smaller than 90 ° made of material;
  • the vent hole is disposed through the receiving portion and the support portion, an upper end surface of the vent hole is in contact with a lower end surface of the atomizing plane, and a lower end of the vent hole is in communication with the outside;
  • the axis position of the turntable is disposed through the receiving portion and the support portion, an upper end surface of the vent hole is in contact with a lower end surface of the atomizing plane, and a lower end of the vent hole is in communication with the outside; The axis position of the turntable.
  • An induction heating coil is also provided on the periphery of the turntable.
  • the height of the base body is 10-20 mm, and the height of the support portion should not be too high, and it should be smaller than the height of the receiving portion.
  • the upper end surface of the atomizing plane protrudes from the upper end surface of the receiving portion, and the protruding range is 0.1-0.5 mm.
  • the protruding height only needs to meet the requirement that the discrete metal droplets do not contact the substrate and fly directly into the chamber and fall into the collection tray.
  • the diameter of the receiving portion ranges from 10 to 100 mm, and the diameter of the circular groove ranges from 5 to 90 mm.
  • the substrate is made of zirconium dioxide ceramic, silica glass, or stainless steel, and is not limited to the foregoing materials, as long as it meets a material with a thermal conductivity of less than 20 W / m / k.
  • the upper end face of the vent hole is less than or equal to the lower end face of the atomization plane.
  • the purpose of the vent hole is to clean the gas in the turntable when the vacuum is drawn, and it is safer when the turntable is rotating at high speed. The larger the contact area between the upper end surface of the air hole and the lower end surface of the atomizing plane, the better the stability of the atomizing plane when the vacuum is evacuated.
  • the volume of the shell should be sufficient for the droplets to fall to the bottom of the collecting tray after centrifugal crushing, to ensure that they will not solidify on the inner wall of the shell, and the area of the collecting tray must be large enough to collect powder. .
  • the diameter of the central hole at the bottom of the crucible is larger than the diameter of the small hole of the gasket with the small hole, and the diameter of the small hole of the gasket with the small hole ranges from 0.02 mm to 2.0 mm.
  • the wetting angle between the material of the gasket with small holes and the melt placed in the crucible is greater than 90 °.
  • the rotation speed of the turntable is 10,000 rpm to 50,000 rpm.
  • the heating thickness range of the induction heating coil is between 5-20mm, and it is connected to a frequency converter and a regulated power supply provided outside the casing, and the voltage control range of the regulated power supply is between 0-50V. between.
  • the piezoelectric ceramic, the transmission rod, the crucible, the ring-shaped resistance heater, the gasket, the turntable, and the induction are located on the same axis.
  • the purpose is that the droplets can be dropped in the center of the turntable, and the plane can be spread and atomized better under the action of centrifugal force.
  • the invention discloses a method for efficiently preparing a low-melting-point spherical metal powder by using the above-mentioned device drop-by-drop centrifugal atomization method, which is characterized by including the following steps,
  • Induction heating using a motor to make the turntable rotate at a high speed at a preset speed, and then using an induction heating coil to heat the upper surface of the turntable rotating at a high speed above the melting point temperature of the metal material;
  • Powder preparation First, manually adjust the position of the transmission rod to a preset distance between the transmission rod and the gasket with a small hole; second, through the crucible set on the casing and protruding into the crucible.
  • the gas pipe passes in a high-purity inert protective gas, so that a positive pressure difference is formed between the inside and outside of the crucible, so that the melt fills the central hole at the bottom of the crucible; finally, a certain waveform pulse signal is input to the piezoelectric ceramic, and the pressure
  • the electric ceramic generates a downward displacement, and is transmitted to the melt in the area near the center hole by a transmission rod connected to the piezoelectric ceramic, so that the melt is ejected from a gasket with a small hole at the bottom of the center hole to form a uniform liquid droplet;
  • Uniform droplets fall freely on a high-speed rotating turntable.
  • the uniform droplets In the molten state, the uniform droplets first drop in the center of the turntable. Due to the small centrifugal force at this time, the droplets will not be dispersed immediately, but will be round. Spread on the turntable. When the centrifugal force is sufficiently large in a certain range, the spreading metal will be dispersed on the turntable in the form of fiber lines to the edge of the turntable under the action of the centrifugal force. Finally, it will split into tiny droplets and fly out. In the process of falling, no container solidifies, forms metal powder, and drops onto the collecting tray, and at the same time restores the transmission rod to its original state.
  • the metal powder is collected by a collection tray provided at the bottom of the casing.
  • the average length of the raw materials is 3mm-10mm, and the amount of the raw materials is 1 / 4-3 / 4 of the volume of the crucible.
  • manually adjusting the position of the induction heating coil is 1-2 mm higher than the turntable.
  • an induction heating voltage range of the induction heating coil is 0-50V, and an induction heating time is 5-15min.
  • the high-purity inert protective gas is argon or helium, and the gas is filled into the shell, so that the pressure in the shell is 0.1 MPa, and the heat preservation time is 15-20 after the metal material is completely melted. Minutes; the pressure difference between the crucible and the shell is 0-200kPa.
  • the present invention has the following beneficial effects:
  • the invention designs a device for combining pulsed microporous spraying method and centrifugal atomization method to efficiently produce ultrafine metal spherical powder in a fibrous splitting mode.
  • the molten metal material in the crucible is subjected to differential pressure and pulse disturbance. Under the action, it sprays out through the small holes at the bottom of the crucible to form uniform droplets.
  • the droplets land on the rotating disc that rotates at high speed. Due to the effect of induction heating, the uniform droplets are still molten when they reach the upper surface of the disc. It has good wettability with the material on the surface of the turntable.
  • the droplet metal can be completely spread on the atomized surface without being ejected.
  • the uniform droplets Under the action of centrifugal force, the uniform droplets will spread on the turntable in a fibrous shape and on the edge of the turntable. Discrete into smaller droplets, fly out along the path of fibrous spread, and the flying micro-droplets solidify to form metal powder after free fall.
  • the particle size of the metal particles produced by the traditional pulse micro-hole spraying method is controllable, but the production of particles produced by a single hole is insufficient to meet the increasing demand.
  • the invention combines the pulse micro-hole spraying method and the centrifugal atomization method, and simultaneously performs structural design on the rotating disk, selects a material that has good wettability with metal materials as the atomization plane, and adds an induction heating device to enable the molten metal to be realized.
  • the fibrous splitting method is adopted. This splitting method effectively reduces the diameter of the powder obtained by atomization, and greatly improves the productivity of the metal powder. Therefore, the combination of the two methods results in a fine and small particle size of the metal powder.
  • the diameter distribution range is narrow, the sphericity is high, the particle size distribution is controllable, the thermal history is consistent, and the fine powder yield is high, which meets the requirements of industrial production.
  • the control method of the invention has strong controllability, which is manifested in the following points: the heating temperature of the crucible can be accurately controlled by the ring resistance heater, and the pressure difference between the crucible and the casing can be controlled by passing an inert gas into the crucible and the casing; The size of the small holes of the gasket with small holes at the bottom of the crucible can control the size of uniform droplets; the induction heating coil can control the temperature of the surface of the turntable to prevent the surface temperature of the turntable from lowering due to high-speed rotation, so that the molten metal solidifies in advance; The controllable rotation speed can control the fibrous splitting effect of the molten metal, which can further control the particle size distribution of the metal fine particles; the adjustable and controllable process parameters can obtain spherical metal powders with different particle size and distribution to meet different requirements , And high production efficiency.
  • the invention can efficiently prepare metal powder that meets the requirements of 3D printing through fibrous splitting of molten metal, with controllable particle size, fine particle size, narrow particle size distribution range, high sphericity, no satellite drops, and good fluidity and spreadability.
  • the thermal history is consistent, the production efficiency is very high, the production cost is low, and it can be used for industrial production.
  • FIG. 1 is a schematic structural diagram of the present invention.
  • FIG. 2 is a schematic structural diagram of a turntable of the present invention.
  • FIG. 3 is a comparison diagram of the powder prepared by the device and method of the present invention and the powder prepared by the unmodified device, wherein (a) is a powder prepared by the present invention, and (b) is a powder prepared by the prior art.
  • Fig. 4 is a comparison diagram of the surface of the turntable of the present invention after the experiment with that of the original turntable, wherein (a) is the surface of the turntable with fibrous splits, and (b) is the surface of the turntable in the prior art.
  • FIG. 5 is a liquid flow line diagram on the surface of the turntable of the present invention, wherein (a) is a liquid flow line in the middle portion of the turntable, and (b) is a liquid flow line on the edge of the turntable.
  • orientation words such as “front, back, up, down, left, right", “horizontal, vertical, vertical, horizontal”, “top, bottom” and the like indicate the orientation Or the positional relationship is usually based on the orientation or positional relationship shown in the drawings, only for the convenience of describing the present invention and simplifying the description. Unless otherwise stated, these orientation words do not indicate and imply the device or element referred to. It must have a specific orientation or be constructed and operated in a specific orientation, so it cannot be understood as a limitation on the scope of protection of the present invention: the orientation words “inside and outside” refer to the inside and outside relative to the outline of each component itself.
  • spatially relative terms such as “above”, “above”, “above”, “above”, etc. can be used here to describe as shown in the figure Shows the spatial position relationship between one device or feature and other devices or features. It should be understood that spatially relative terms are intended to encompass different orientations in use or operation in addition to the orientation of the device as described in the figures. For example, if a device in the figure is turned over, devices described as “above” or “above” other devices or constructions will be positioned “below the other devices or constructions” or “below” Under its device or structure. " Thus, the exemplary term “above” may include both directions “above” and “below”. The device can also be positioned in other different ways (rotated 90 degrees or at other orientations), and the relative description of space used here is explained accordingly.
  • the present invention provides a device for efficiently preparing a low melting point spherical metal powder by a droplet-by-drop centrifugal atomization method, which includes a casing 12, a crucible 4 disposed in the casing 12, and a powder collection area.
  • the powder collection area is placed on the bottom of the housing 12, the crucible 4 is placed on the upper part of the powder collection area, and the crucible 4 is provided with a piezoelectric ceramic 1 provided outside the housing 12.
  • the lower end of the transmission rod 2 faces the center hole at the bottom of the crucible 4, and a gasket 6 with a small hole is installed at the bottom of the center hole;
  • the crucible 4 is provided with a ring-shaped resistance heater 5 outside; the diameter of the central hole at the bottom of the crucible 4 is larger than the diameter of the small hole 6 of the gasket 6, and the diameter of the small hole of the small hole 6 is in the range of Between 0.02mm-2.0mm.
  • the wetting angle of the material of the gasket 6 with small holes and the melt 3 placed in the crucible is greater than 90 °.
  • the casing 12 is provided with a crucible gas inlet pipe 20 that extends into the crucible 4, and the side wall of the casing 12 is also provided with a mechanical pump 16 and a diffusion pump 17 that communicate with the crucible 4.
  • the housing 12 is further provided with a cavity air inlet 15 and a cavity exhaust valve 18;
  • the powder collection area includes a collection tray 11 provided at the bottom of the casing and a turntable 8 for atomizing metal droplets 14 connected to the motor 9 and disposed above the collection tray 11;
  • the turntable 8 includes a base, an atomizing plane 23 and a vent hole 24;
  • the longitudinal section of the base body composed of the upper receiving portion 21 and the lower supporting portion 22 is similar to a “T-shaped” main structure.
  • the upper surface of the receiving portion 21 is provided with a circular recess having a certain radius coaxial with the center of the circle.
  • the atomizing plane 23 is a disc structure.
  • the disc structure matches the circular groove and interference fits with the circular groove.
  • the atomizing plane 23 uses droplets that are atomized with metal. 14 Made of materials with a wetting angle of less than 90 °;
  • the ventilation hole 24 is penetrated and provided in the receiving portion 21 and the support portion 22.
  • the upper end surface of the ventilation hole 24 is in contact with the lower end surface of the atomizing plane 23.
  • the lower end of the ventilation hole 24 is outside.
  • the height of the base body is 10-20 mm, and the height of the support portion 22 should not be too high, and it should be smaller than the height of the receiving portion 21.
  • the upper end surface of the atomizing plane 23 protrudes from the upper end surface of the receiving portion 21, and the protruding range is 0.1-0.5 mm. As long as the protruding height is satisfied, the molten liquid droplets 14 that are favorable for discreteness do not touch the substrate, and directly fly into the chamber and fall into the collection tray.
  • the diameter of the receiving portion 21 ranges from 10 to 100 mm, and the diameter of the circular groove ranges from 5 to 90 mm.
  • the volume of the casing 12 should be sufficient for the molten droplets 14 to fall to the bottom of the collection pan 11 after centrifugal crushing, to ensure that they will not solidify on the inner wall of the casing 12, and the area of the collection pan 11 must be sufficient It is sufficient to be able to collect the metal powder 10.
  • the substrate is made of zirconium dioxide ceramic, silica glass, or stainless steel, and is not limited to the foregoing materials, as long as it meets a material with a thermal conductivity of less than 20 W / m / k.
  • the upper end face of the vent hole 24 is less than or equal to the lower end face of the atomizing plane 23.
  • the purpose of the vent hole 24 is to make the gas in the gap inside the turntable 8 cleaner when the vacuum is drawn. It is safer, so the larger the contact area between the upper end surface of the vent hole 24 and the lower end surface of the atomizing plane 23 is, the better the stability of the atomizing plane 23 is when the vacuum is evacuated.
  • An induction heating coil 13 is also provided on the periphery of the turntable 8.
  • the rotation speed of the turntable 8 is 10,000 rpm-50,000 rpm.
  • the heating thickness range of the induction heating coil 13 is between 5-20mm. It is connected to a frequency converter and a regulated power supply provided outside the casing 12, and the voltage control range of the regulated power supply is between 0-50V. between.
  • the piezoelectric ceramic 1, the transmission rod 2, the crucible 4, the ring-shaped resistance heater 5, the gasket 6, the turntable 8 and The induction heating coils 13 are located on the same axis.
  • the purpose is that the droplets can be dropped in the center of the turntable, and the plane can be spread and atomized better under the action of centrifugal force.
  • the mechanical pump 16 and the diffusion pump 17 are used to evacuate the shell 12 and the crucible 4; the bottom of the crucible 4 is equipped with a gasket 6 with small holes, and the ring-shaped resistance heater 5 is used to process the raw materials to be prepared in the crucible 4.
  • high purity inert protective gas such as helium, argon
  • molten liquid droplets 14 are generated near the small hole 6 with a small hole; the molten liquid droplets 14 generated near a small hole with a small hole 6 fall freely at high speed.
  • the induction heating coil 13 on the periphery of the turntable 8 keeps the upper surface temperature of the turntable 8 above the melting point of the metal material to be prepared, and the uniform molten droplets 14 in the molten state fall freely in the center of the turntable 8.
  • the centrifugal force is small, the droplets 14 will not be dispersed immediately, but will spread on the turntable 8 in a circle.
  • the spreading metal When the centrifugal force is spread to a certain range, the spreading metal will be under the action of the centrifugal force on the turntable 8 Fiber-like discrete At the edge of the turntable 8, it finally splits into tiny liquid droplets that fly out. During the falling process, the fine liquid droplets are solidified without a container, forming a metal powder 10, and landing on the collecting disk 11, and at the same time, the transmission rod 2 is restored to the initial state.
  • the invention also discloses a method for efficiently preparing a low-melting-point spherical metal powder by using the above-mentioned device, a droplet-by-drop centrifugal atomization method, including the following steps,
  • Resistance heating set the heating temperature of the ring resistance heater 5 to 220-300 ° C and the heating rate to 10-30 ° C / min, and monitor the temperature in the crucible 4 in real time through the thermocouple set in the crucible 4, After the metal material is completely melted, a melt 3 is obtained and kept for 10-20 minutes;
  • Induction heating use the motor 9 to rotate the turntable 8 at a high speed at a preset speed, and then use an induction heating coil 13 to heat the surface of the high speed rotating turntable 8 to a temperature above the melting point of the metal material.
  • the turntable is a copper-inlaid stainless steel disc.
  • the speed is 10000rpm-50000rpm, the induction heating voltage range is 0-50V, and the induction heating time is 5-15min;
  • 5Powder preparation manually adjust the position of the transmission rod 2 so that the transmission rod 2 and the gasket 6 with small holes are 2-5 mm away from each other, through the crucible air inlet pipe provided on the casing 12 and protruding into the crucible 20 Pass in a high-purity inert protective gas, so that a positive differential pressure of 0-200 kPa is generated in the crucible 4 and the casing 12, so that the melt 3 fills the central hole at the bottom of the crucible 4; input to the piezoelectric ceramic 1
  • the pulse signal of a certain waveform causes the piezoelectric ceramic 1 to generate a downward displacement, and the transmission rod 2 connected to the piezoelectric ceramic 1 is transmitted to the melt 3 in the vicinity of the center hole, so that the melt 3 passes from the bottom of the center hole.
  • the gasket 6 with small holes is ejected to form a uniform droplet 14;
  • the homogeneous droplets 14 land freely on the rotating disc 8 which rotates at a high speed. Under the action of centrifugal force, the homogeneous droplets 14 in the molten state will spread on the disc 8 in a fibrous shape, split into tiny droplets and fly out. During the dropping process, no container solidifies to form the metal powder 10 and land on the collecting tray 11.
  • the metal powder 10 is collected by a collection tray 11 provided at the bottom of the casing 12.
  • the ring resistance heater 5 is used to heat the crucible 4 at a heating temperature of 300 ° C., a heating speed of 15 ° C./min, and a heat preservation of 10 minutes, so that all the metal materials in the crucible 4 are melted into the melt 3;
  • the motor 9 is used to make the speed of the turntable 8 24000r / min, and then the induction heating voltage of the induction heating coil 13 is set to 21V, the induction heating current is 8A, and the induction heating time is 10min.
  • the surface of the high speed rotating turntable 8 is heated to a metal material.
  • the melting temperature is above 183 °C;
  • the inert gas of purity inert gas, argon, is passed, so that a positive differential pressure of 50 kPa is generated in the crucible 4 and the casing 12 to cause the molten metal 3 to fill the central hole at the bottom of the crucible 4;
  • a pulse signal, and the frequency is set to 100 Hz, so that the piezoelectric ceramic 1 generates a downward displacement, and the transmission rod 2 connected to the piezoelectric ceramic 1 is transmitted to the molten metal 3 in the area near the center hole, so that the molten metal 3 passes from the center hole
  • the gasket 6 with a small hole at the bottom sprays out to form a uniform droplet 14; the uniform droplet 14 drops freely on the rotating disc 8 that rotates at a high speed.
  • the uniform droplet 14 in the molten state will be on the disc 8 under the action of centrifugal force.
  • Spread in a fibrous shape split into tiny droplets and fly out, and the micro-droplets solidify without a container during the falling process, forming a metal powder 10, and landing on a collecting tray 11;
  • the particle diameter of the powder produced in the prior art is relatively coarse and there are hemispheres
  • (a) is a powder prepared by the method of the present invention, and the particle diameter of the powder is obviously ,
  • the particle size meets the requirements for use, and the sphericity becomes higher, and the surface morphology of the powder becomes better, and no hemisphere is generated.
  • (b) is an atomizing disc obtained by atomizing in the prior art. Because the wettability of the atomizing disc material and the prepared metal powder material is too small, and the temperature of the turntable is too low during the atomization process, As a result, the liquid is split into membranes, and a thicker solidified liquid film appears on the atomized surface. The surface of the liquid film is very rough, which is not conducive to the further atomization of subsequent metal droplets, which will seriously affect the atomization effect and atomization efficiency. (a) For the atomized surface obtained by the method of the present invention, it can be seen that the atomization mode is changed into an obvious fibrous split mode, and the linear split mode greatly improves the miniaturization and production efficiency of the metal powder.
  • (a) is the fluid flow line in the middle part of the turntable. From the figure, the width of the fluid flow lines is less than 50 ⁇ m, which can explain that the reason for the fineness of the powder produced by this method is due to the fine fibers. Formed like a liquid stream.
  • (b) is the liquid flow line at the edge of the turntable, and the traces left by the small liquid droplets can be seen, so that it can be explained that the metal liquid is dispersed at the edge by complete centrifugal atomization.

Abstract

一种逐液滴（14）离心雾化法高效制备低熔点球形金属粉末（10）的装置及方法。装置包括壳体（12）、设置于壳体（12）内的坩埚（4）和粉末收集区，转盘（8）为镶嵌式结构，主体选择导热性较差的材料，雾化平面（23）选择与液滴（14）的润湿角小于90°的金属材料，在转盘（8）轴线上增加通气孔（24）提高圆盘转动时的稳定性，转盘（8）外设有感应加热线圈（13）。结合脉冲微孔喷射法和离心雾化法，配合转盘（8）结构并对转盘（8）表面感应加热，从而使金属液突破了传统熔融金属的分裂模式，实现了只有当雾化介质为水溶液或有机溶液时才能实现的纤维状分裂方式，在超微细化方面取得飞跃进步，制得圆球度高、有良好流动性和铺展性、无卫星滴的符合使用要求的低熔点超微细金属球形粉末。

Description

一种逐液滴离心雾化法高效制备低熔点球形金属粉末的装置及方法 技术领域
本发明属于超细球形微粒子制备技术领域，具体而言，尤其涉及一种利用逐液滴离心雾化法高效制备低熔点球形金属粉末的装置及方法。
背景技术
球形金属粉末作为一种重要的工业原料，在3D打印、电子封装、半导体集成电路、新能源等领域得到了广泛的应用。随着设备微型化、高精度的发展，上述领域对球形粉末及其制备技术提出了更高的要求，特别是金属粉末快速成型领域。
目前全球对金属材料进行3D打印的需求十分迫切，如不锈钢、钛合金、镍基合金、银和金等，但目前这些打印技术还未能得到快速发展，其中金属粉末制备技术成为制约3D打印技术发展的关键问题之一。3D打印技术要求金属粉末需满足粒径细小、粒度分布窄、球形度高、易铺展、流动性好和松装密度高等性能。但国内所用粉末大部分都依赖进口，远远无法满足3D打印的要求。因此，探索一种制备效率高、粉末质量高的超微细金属球形粉末的制备方法意义重大。
目前国内外生产球形金属粉末的方法主要有：雾化法和近几年新兴的脉冲微孔喷射法。雾化法制得的粉末粒径分布宽，必须经过多次筛选才能得到满足要求的粉末，成品率低；雾化粉末中含有大量的卫星滴，使其流动性和铺展性下降；此外，在传统离心雾化过程中，当熔体温度及转速过高时，熔体极易发生侧滑，严重影响雾化效率。脉冲微孔喷射法制得的粉末虽然球形度高，粒径均一，但是该方法制备小粒径粒子时效率不高，且应用范围受到限制。
因此，这两种方法生产的粉末都无法满足要求，研发一种制备效率高、粉末质量高的超微细金属球形粉末的制备方法意义重大。
发明内容
根据上述提出的3D打印用金属粉末制备过程中存在的流动性及铺展性差、成品率 低、效率低等问题，而提供一种逐液滴离心雾化法高效制备低熔点球形金属粉末的装置及方法。本发明主要结合脉冲微孔液滴喷射法和离心雾化法两种方法，同时对转盘进行结构设计，且对圆盘表面进行感应加热，从而使熔融金属液突破了传统熔融金属的分裂模式，实现了只有当雾化介质为水溶液或有机溶液时才能实现的纤维状分裂方式，与现有的离心雾化技术相比较，这种线状分裂模式下雾化得到的粉末在超微细化方面可取得飞跃进步，从而可以制备得到粒径非常小、粒径分布区间窄且可控、圆球度高、有良好流动性和铺展性、无卫星滴、雾化效率高、细粉收得率非常高的符合3D打印使用要求的超微细金属球形粉末。
本发明采用的技术手段如下：
一种逐液滴离心雾化法高效制备低熔点球形金属粉末的装置，包括壳体、设置于所述壳体内的坩埚和粉末收集区，所述粉末收集区置于所述壳体的底部，所述坩埚置于所述粉末收集区的上部，所述坩埚上设有与设置在所述壳体外部的压电陶瓷相连的传动杆，所述传动杆的下端对着所述坩埚底部的中心孔，所述中心孔底部装有带小孔的垫片；所述坩埚内部设有热电偶，所述坩埚外部设有环形电阻加热器；
所述壳体上设有伸入于所述坩埚内的坩埚进气管，所述壳体的侧壁上还设有与所述坩埚相连通的机械泵和扩散泵，所述壳体上还设有腔体进气口和腔体排气阀；
所述粉末收集区包括设置在所述壳体底部的收集盘和设置于所述收集盘上方的与电机相连的用于雾化金属液滴的转盘；
所述转盘包括基体，雾化平面和通气孔；
所述基体由上部的承接部和下部的支撑部构成的纵截面呈类“T型”的主体结构，所述承接部上表面设有与其圆心同轴的具有一定半径的圆形凹槽；其中，所述基体采用导热性小于20W/m/k的材料制成；
所述雾化平面为圆盘结构，所述圆盘结构与所述圆形凹槽相匹配且与圆形凹槽过盈配合，所述雾化平面采用与雾化金属液滴润湿角小于90°的材料制成；
所述通气孔贯通设置在所述承接部及所述支撑部内，所述通气孔的上端面与所述雾化平面的下端面接触，所述通气孔的下端与外界连通；即通气口设置在转盘的轴线位置。
所述转盘的外围还设有感应加热线圈。
优选地，基体的高度为10-20mm，支撑部的高度不宜太高，小于承接部的高度为宜。 所述雾化平面的上端面凸出于所述承接部上端面，凸出范围为0.1-0.5mm。凸出高度只要满足利于离散的金属液滴不接触基体，直接飞到腔室内落入收集盘内即可。所述承接部的直径范围在10-100mm，所述圆形凹槽的直径范围在5-90mm。
所述基体采用二氧化锆陶瓷、二氧化硅玻璃或不锈钢制成，不局限于上述几种材质，只要满足导热性小于20W/m/k的材料均可。所述通气孔的上端面小于等于所述雾化平面的下端面，通气孔设置的目的是为了在抽真空时可以将转盘内间隙的气体抽的更干净，转盘高速旋转时更加安全，因此通气孔的上端面与雾化平面的下端面的接触面积越大抽真空时雾化平面的稳定性越好。
所述壳体的体积要足够液滴经离心破碎后飞行降落到底部的收集盘内的范围，能够保证不会凝固在壳体的内壁上，收集盘的面积要保证足够大能够收集粉末即可。
进一步地，所述坩埚底部的的中心孔直径大于带小孔的垫片的小孔直径，所述带小孔的垫片的小孔直径范围在0.02mm-2.0mm之间。
进一步地，所述带小孔的垫片的材料与置于所述坩埚内的熔体的润湿角大于90°。
进一步地，所述转盘的转速为10000rpm-50000rpm。
进一步地，所述感应加热线圈的加热厚度范围在5-20mm之间，它与设置在所述壳体外的变频器和稳压电源相连，所述稳压电源的电压控制范围在0-50V之间。
进一步地，在所述装置自上而下的方向上，所述压电陶瓷、所述传动杆、所述坩埚、所述环形式电阻加热器、所述垫片、所述转盘以及所述感应加热线圈位于同一轴线上。目的是为了液滴可以滴落在转盘中心位置，在离心力的作用下可以更好的铺展与雾化平面。
本发明公开了一种采用上述的装置逐液滴离心雾化法高效制备低熔点球形金属粉末的方法，其特征在于包括如下步骤，
①装料：将原材料焊丝剪到预设的平均长度后，装入设置在壳体上部的坩埚内，手动调整高度方向上，感应加热线圈位置至转盘为预设距离后密封壳体；
②抽真空：利用机械泵和扩散泵对所述坩埚和所述壳体抽真空，并充入高纯度惰性保护气体，使壳体内压力达到预设值；
③电阻加热：根据待加热原材料的熔点设定使用环形电阻加热器的加热参数，并通过所述坩埚内设置的热电偶实时监测所述坩埚内的温度，待金属材料完全熔化后保温；
④感应加热：利用电机使所述转盘在预设转速下高速旋转，接着利用感应加热线圈将高速旋转的转盘上表面加热到金属材料的熔点温度以上；
⑤粉末制备：首先，手动调整传动杆的位置至传动杆与带小孔的垫片之间为预设距离；其次，通过设置在所述壳体上并伸入于所述坩埚内的坩埚进气管将高纯度惰性保护气体通入，使所述坩埚内外形成正压力差，促使熔体填满所述坩埚底部的中心孔；最后，给压电陶瓷输入一定波型的脉冲信号，所述压电陶瓷产生向下位移，由与所述压电陶瓷相连的传动杆传递给中心孔附近区域的熔体，使得熔体从中心孔底部的带小孔的垫片喷出形成均匀液滴；
均匀液滴自由降落在高速旋转的转盘上，熔融状态下的均匀液滴，先滴落在转盘的中心，由于此时离心力较小，液滴不会被马上离散出去，而是会呈圆形铺展在转盘上，当铺展到一定范围离心力足够大时，铺展的金属会在离心力的作用下，在转盘上呈纤维线状离散至转盘边缘，最后分裂成微小的液滴飞出，微液滴在下落过程中无容器凝固，形成金属粉末，降落至收集盘上，同时将传动杆恢复初始状态。
⑥粒子收集：用设置于所述壳体底部的收集盘收集金属粉末。
进一步地，所述原材料的平均长度为3mm-10mm，原材料放入量为所述坩埚容积的1/4-3/4。
进一步地，手动调整感应加热线圈位置比转盘高1-2mm。
进一步地，所述感应加热线圈的感应加热电压范围为0-50V，感应加热时间为5-15min。
进一步地，所述高纯度惰性保护气体为氩气或氦气，将该气体充入壳体内，使所述壳体内抽真空后的压力达到0.1MPa，金属材料完全熔化后保温时间为15-20分钟；所述坩埚与所述壳体内产生的差压为0-200kPa。
与现有技术相比，本发明具有以下有益效果：
本发明设计了一种脉冲微孔喷射法与离心雾化法相结合使金属液滴在纤维状分裂模式下高效制备超细金属球形粉末的装置，坩埚中熔化的金属材料在差压和脉冲扰动的作用下，通过坩埚底部的小孔喷出，形成均匀液滴，液滴降落在高速旋转的转盘上，由于感应加热的作用，均匀液滴到达转盘上表面时还处于熔融状态，由于液滴金属与转盘上表面材料有较好的润湿性，液滴金属能完全铺展在雾化表面而不被弹出，在离心力的作用下，均匀液滴会在转盘上呈纤维状铺展，并在转盘边缘离散成更加微小的液滴，沿纤 维状铺展的轨迹飞出，飞出的微液滴经自由降落凝固形成金属粉末。传统的脉冲微孔喷射法生产的金属粒子粒径可控，但单孔制备粒子的产量不足以满足日益增加的需求量。本发明将脉冲微孔喷射法与离心雾化法相结合，同时对旋转圆盘进行结构设计，选择与金属材料润湿性好的材料作为雾化平面，且增加了感应加热装置，使熔融金属实现了纤维状分裂方式，这种分裂方式有效地减小了雾化所得粉末的直径，且极大地提高了金属粉末的生产率，因此，通过两种方法的结合，得到的金属粉末粒径细小、粒径分布区间窄、球形度高、粒径分布可控、热履历一致，细粉收得率高，满足工业生产的要求。
本发明的工艺方法可控性强，表现在如下几点：通过环形电阻加热器可精确控制坩埚的加热温度，通过向坩埚与壳体内通入惰性气体，可控制坩埚与壳体内的压力差；坩埚底部带小孔的垫片的小孔的尺寸可以控制均匀液滴的尺寸；感应加热线圈可以控制转盘表面的温度，防止转盘因高速旋转而导致的表面温度降低，使熔融金属提前凝固；转盘的转速可控，可以控制熔融金属的纤维状分裂效果，从而可以进一步控制金属微粒子的粒径分布；工艺参数的可调节与可控制，可以得到满足不同要求的粒径尺寸及分布的球形金属粉末，且生产效率高。
本发明可以通过熔融金属的纤维状分裂高效制备出满足3D打印要求的金属粉末，粒径可控、粒径细小、粒径分布区间窄，球形度高、无卫星滴、流动性与铺展性良好、热履历一致，生产效率非常高，生产成本低，可以用于工业生产。
附图说明
为了更清楚地说明本发明实施例或现有技术中的技术方案，下面将对实施例或现有技术描述中所需要使用的附图做以简单地介绍，显而易见地，下面描述中的附图是本发明的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动性的前提下，还可以根据这些附图获得其他的附图。
图1为本发明的结构示意图。
图2为本发明转盘的结构示意图。
图3为采用本发明装置及方法制备的粉末与未改进的装置制得的粉末的对比图，其中，(a)为本发明制备的粉末，(b)为现有技术制备的粉末。
图4为本发明的转盘在实验后其表面与原转盘实验后的表面对比图，其中，(a)为 呈纤维状分裂的转盘表面，(b)为现有技术中转盘表面。
图5为本发明的转盘表面液流线图，其中，(a)为转盘中间部位液流线，(b)为转盘边缘液流线。
图中：1、压电陶瓷；2、传动杆；3、熔体；4、坩埚；5、环形电阻加热器；6、带小孔的垫片；7、腔体；8、转盘；9、电机；10、金属粉末；11、收集盘；12、壳体；13、感应加热线圈；14、液滴；15、腔体进气管；16、机械泵；17、扩散泵；18、腔体排气阀；19、坩埚腔；20、坩埚进气管；21、承接部；22、支撑部；23、雾化平面；24、通气孔。
具体实施方式
需要说明的是，在不冲突的情况下，本发明中的实施例及实施例中的特征可以相互组合。下面将参考附图并结合实施例来详细说明本发明。
为使本发明实施例的目的、技术方案和优点更加清楚，下面将结合本发明实施例中的附图，对本发明实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例仅仅是本发明一部分实施例，而不是全部的实施例。以下对至少一个示例性实施例的描述实际上仅仅是说明性的，决不作为对本发明及其应用或使用的任何限制。基于本发明中的实施例，本领域普通技术人员在没有做出创造性劳动前提下所获得的所有其他实施例，都属于本发明保护的范围。
需要注意的是，这里所使用的术语仅是为了描述具体实施方式，而非意图限制根据本发明的示例性实施方式。如在这里所使用的，除非上下文另外明确指出，否则单数形式也意图包括复数形式，此外，还应当理解的是，当在本说明书中使用术语“包含”和/或“包括”时，其指明存在特征、步骤、操作、器件、组件和/或它们的组合。
除非另外具体说明，否则在这些实施例中阐述的部件和步骤的相对布置、数字表达式和数值不限制本发明的范围。同时，应当清楚，为了便于描述，附图中所示出的各个部分的尺寸并不是按照实际的比例关系绘制的。对于相关领域普通技术人员己知的技术、方法和设备可能不作详细讨论，但在适当情况下，所述技术、方法和设备应当被视为授权说明书的一部分。在这里示出和讨论的所有示例中，任向具体值应被解释为仅仅是示例性的，而不是作为限制。因此，示例性实施例的其它示例可以具有不同的值。应 注意到：相似的标号和字母在下面的附图中表示类似项，因此，一旦某一项在一个附图中被定义，则在随后的附图中不需要对其进行进一步讨论。
在本发明的描述中，需要理解的是，方位词如“前、后、上、下、左、右”、“横向、竖向、垂直、水平”和“顶、底”等所指示的方位或位置关系通常是基于附图所示的方位或位置关系，仅是为了便于描述本发明和简化描述，在未作相反说明的情况下，这些方位词并不指示和暗示所指的装置或元件必须具有特定的方位或者以特定的方位构造和操作，因此不能理解为对本发明保护范围的限制：方位词“内、外”是指相对于各部件本身的轮廓的内外。
为了便于描述，在这里可以使用空间相对术语，如“在……之上”、“在……上方”、“在……上表面”、“上面的”等，用来描述如在图中所示的一个器件或特征与其他器件或特征的空间位置关系。应当理解的是，空间相对术语旨在包含除了器件在图中所描述的方位之外的在使用或操作中的不同方位。例如，如果附图中的器件被倒置，则描述为“在其他器件或构造上方”或“在其他器件或构造之上”的器件之后将被定位为“在其他器件或构造下方”或“在其位器件或构造之下”。因而，示例性术语“在……上方”可以包括“在……上方”和“在……下方”两种方位。该器件也可以其他不同方式定位(旋转90度或处于其他方位)，并且对这里所使用的空间相对描述作出相应解释。
此外，需要说明的是，使用“第一”、“第二”等词语来限定零部件，仅仅是为了便于对相应零部件进行区别，如没有另行声明，上述词语并没有特殊含义，因此不能理解为对本发明保护范围的限制。
如图1所示，本发明提供了一种逐液滴离心雾化法高效制备低熔点球形金属粉末的装置，包括壳体12、设置于所述壳体12内的坩埚4和粉末收集区，所述粉末收集区置于所述壳体12的底部，所述坩埚4置于所述粉末收集区的上部，所述坩埚4上设有与设置在所述壳体12外部的压电陶瓷1相连的传动杆2，所述传动杆2的下端对着所述坩埚4底部的中心孔，所述中心孔底部装有带小孔的垫片6；所述坩埚4内部设有热电偶，所述坩埚4外部设有环形电阻加热器5；所述坩埚4底部的的中心孔直径大于带小孔的垫片6的小孔直径，所述带小孔的垫片6的小孔直径范围在0.02mm-2.0mm之间。所述带小孔的垫片6的材料与置于所述坩埚内的熔体3的润湿角大于90°。
所述壳体12上设有伸入于所述坩埚4内的坩埚进气管20，所述壳体12的侧壁上还 设有与所述坩埚4相连通的机械泵16和扩散泵17，所述壳体12上还设有腔体进气口15和腔体排气阀18；
所述粉末收集区包括设置在所述壳体底部的收集盘11和设置于所述收集盘11上方的与电机9相连的用于雾化金属液滴14的转盘8；
如图2所示，所述转盘8包括基体，雾化平面23和通气孔24；
所述基体由上部的承接部21和下部的支撑部22构成的纵截面呈类“T型”的主体结构，所述承接部21上表面设有与其圆心同轴的具有一定半径的圆形凹槽；其中，所述基体采用导热性小于20W/m/k的材料制成；
所述雾化平面23为圆盘结构，所述圆盘结构与所述圆形凹槽相匹配且与所述圆形凹槽过盈配合，所述雾化平面23采用与雾化金属液滴14润湿角小于90°的材料制成；
所述通气孔24贯通设置在所述承接部21及所述支撑部22内，所述通气孔24的上端面与所述雾化平面23的下端面接触，所述通气孔24的下端与外界连通；
优选地，基体的高度为10-20mm，支撑部22的高度不宜太高，小于承接部21的高度为宜。所述雾化平面23的上端面凸出于所述承接部21上端面，凸出范围为0.1-0.5mm。凸出高度只要满足利于离散的熔融液滴14不接触基体，直接飞到腔室内落入收集盘内即可。所述承接部21的直径范围在10-100mm，所述圆形凹槽的直径范围在5-90mm。
所述壳体12的体积要足够熔融液滴14经离心破碎后飞行降落到底部的收集盘11内的范围，能够保证不会凝固在壳体12的内壁上，收集盘11的面积要保证足够大能够收集金属粉末10即可。
所述基体采用二氧化锆陶瓷、二氧化硅玻璃或不锈钢制成，不局限于上述几种材质，只要满足导热性小于20W/m/k的材料均可。所述通气孔24的上端面小于等于所述雾化平面23的下端面，通气孔24设置的目的是为了在抽真空时可以将转盘8内间隙的气体抽的更干净，转盘8高速旋转时更加安全，因此通气孔24的上端面与雾化平面23的下端面的接触面积越大抽真空时雾化平面23的稳定性越好。
所述转盘8的外围还设有感应加热线圈13。所述转盘8的转速为10000rpm-50000rpm。所述感应加热线圈13的加热厚度范围在5-20mm之间，它与设置在所述壳体12外的变频器和稳压电源相连，所述稳压电源的电压控制范围在0-50V之间。
在所述装置自上而下的方向上，所述压电陶瓷1、所述传动杆2、所述坩埚4、所述 环形式电阻加热器5、所述垫片6、所述转盘8以及所述感应加热线圈13位于同一轴线上。目的是为了液滴可以滴落在转盘中心位置，在离心力的作用下可以更好的铺展与雾化平面。
工作时，机械泵16和扩散泵17用于对壳体12和坩埚4抽真空；坩埚4底部装有带小孔的垫片6，利用环形电阻加热器5对坩埚4中需制备的原材料进行加热，并通过坩埚进气管20和腔体进气管15向坩埚4和壳体12中通入高纯度惰性保护气体，如氦气、氩气，使坩埚4和壳体12之间保持一定的正压力差，在压电陶瓷1和正压力差的共同作用下，熔融液滴14在带小孔的垫片6附近产生；带小孔的垫片6附近产生的熔融液滴14自由降落在高速旋转的转盘8上，转盘8外围的感应加热线圈13使得转盘8的上表面温度保持在要制备的金属材料的熔点以上，熔融状态下的均匀熔融液滴14自由降落在转盘8的中心，由于此时离心力较小，液滴14不会被马上离散出去，而是会呈圆形铺展在转盘8上，当铺展到一定范围离心力足够大时，铺展的金属会在离心力的作用下，在转盘8上呈纤维线状离散至转盘8边缘，最后分裂成微小的液滴飞出，微液滴在下落过程中无容器凝固，形成金属粉末10，降落至收集盘11上，同时将传动杆2恢复初始状态。
本发明还公开了一种采用上述的装置逐液滴离心雾化法高效制备低熔点球形金属粉末的方法，包括如下步骤，
①装料：将原材料焊丝剪成2-10mm的小段，装入设置在壳体12上部的坩埚4内，手动调整高度方向上，感应加热线圈13位置比转盘8高1-2mm后密封壳体12；
②抽真空：利用机械泵16和扩散泵17对所述坩埚4和所述壳体12抽真空，并充入高纯度惰性保护气体氩气，使壳体12内压力达到0.1MPa；
③电阻加热：设置环形电阻加热器5的加热温度为220-300℃，加热速度为10-30℃/min，并通过所述坩埚4内设置的热电偶实时监测所述坩埚4内的温度，待金属材料完全熔化后得到熔体3并保温10-20分钟；
④感应加热：利用电机9使所述转盘8在预设转速下高速旋转，接着使用感应加热线圈13将高速旋转的转盘8表面加热到金属材料的熔点温度以上，转盘为镶铜不锈钢圆盘，转速为10000rpm-50000rpm，感应加热电压范围为0-50V，感应加热时间为5-15min；
⑤粉末制备：手动调节传动杆2的位置，使传动杆2与带小孔的垫片6相距2-5mm，通过设置在所述壳体12上并伸入于所述坩埚内的坩埚进气管20将高纯度惰性保 护气体通入，使坩埚4与所述壳体12内产生0-200kPa的正差压，促使熔体3填满所述坩埚4底部的中心孔；给压电陶瓷1输入一定波型的脉冲信号，使压电陶瓷1产生向下位移，由与所述压电陶瓷1相连的传动杆2传递给中心孔附近区域的熔体3，使得熔体3从中心孔底部的带小孔的垫片6喷出形成均匀液滴14；
均匀液滴14自由降落在高速旋转的转盘8上，熔融状态下的均匀液滴14在离心力的作用下，会在转盘8上呈纤维状铺展，分裂成微小的液滴飞出，微液滴在下落过程中无容器凝固，形成金属粉末10，降落至收集盘11上。
⑥粒子收集：用设置于所述壳体12底部的收集盘11收集金属粉末10。
实施例1
批量制备Sn63Pb37合金球形粉末的具体实施方式：
将Sn63Pb37焊丝剪成5mm左右的小段，进行超声震动清洗后放入坩埚4中，选择小孔直径为350mm的垫片6放置在坩埚4的底部，Sn63Pb37原材料的放入量达到坩埚4容量的3/4，将环形电阻加热器5安装到坩埚4上，坩埚4底部插入热电偶；选择实验用的镶铜不锈钢转盘8安装到电机9上，在转盘8外围安装感应加热线圈13，使得感应加热线圈13位置比转盘8盘高1mm，后密封壳体12；
利用机械泵16将壳体12、坩埚4抽到低真空5Pa以下，再利用扩散泵17将壳体12、坩埚4抽到高真空0.001Pa；利用坩埚进气管20、腔体进气管15通入高纯度惰性保护气体氩气，使壳体12、坩埚4内的压力达到0.1MPa；
利用环形电阻加热器5对坩埚4进行加热，加热温度为300℃，加热速度为15℃/min，保温10min，使坩埚4内的金属材料全部熔化成熔体3；
利用电机9使所述转盘8转速为24000r/min，接着设置感应加热线圈13的感应加热电压为21V，感应加热电流为8A，感应加热时间为10min，将高速旋转的转盘8表面加热到金属材料的熔点温度183℃以上；
手动调节传动杆2的位置，使传动杆2与带小孔的垫片6相距2-5mm，然后通过设置在所述壳体12上并伸入于所述坩埚内的坩埚进气管20将高纯度惰性保护气体氩气通入，使坩埚4与所述壳体12内产生50kPa的正差压，促使熔融金属3填满所述坩埚4底部的中心孔；给压电陶瓷1输入梯形波的脉冲信号，并设置频率为100Hz，使压电陶瓷1 产生向下位移，由与所述压电陶瓷1相连的传动杆2传递给中心孔附近区域的熔融金属3，使得熔融金属3从中心孔底部的带小孔的垫片6喷出形成均匀液滴14；均匀液滴14自由降落在高速旋转的转盘8上，熔融状态下的均匀液滴14在离心力的作用下，会在转盘8上呈纤维状铺展，分裂成微小的液滴飞出，微液滴在下落过程中无容器凝固，形成金属粉末10，降落至收集盘11上；
待制备结束后，停止向压电陶瓷1施加梯形波脉冲信号，即停止液滴喷射；停止高速电机9，从而转盘8停止旋转；关闭环形电阻加热器5及感应加热线圈13，待温度降至室温，取出收集盘11中的金属粉末10；最后关闭腔体进气管15和坩埚进气管20，用机械泵16将坩埚4和壳体12抽到低真空5Pa以下，以便使设备在停用时处于真空状态。
如图3所示，从(b)可看出现有技术制得的粉末粒径较粗，且有半球产生，而(a)为通过本发明的方法制备得到的粉末，粉末粒径得到了明显的微细化，粒度大小满足使用要求，且球形度变高，粉末表面形貌也变好，没有半球产生。
如图4所示，(b)为现有技术雾化后得到的雾化盘，由于雾化盘材料与制备的金属粉末材料润湿性太小，且在雾化过程中转盘温度太低，导致液体呈膜状分裂，且雾化表面会出现较厚的已凝固液膜，该液膜表面十分粗糙，不利于后续金属液滴的进一步雾化，会严重影响雾化效果和雾化效率。(a)为通过本发明方法得到的雾化表面，可以看出雾化模式转变为明显的纤维状分裂模式，线状的分裂模式大大提高了金属粉末的微细化和生产效率。
如图5所示，(a)为转盘中间部位的液流线，从图中可以液流线的宽度都小于50μm，从而可以说明通过该方法制得的粉末微细化的原因就是由于微细的纤维状液流雾化形成的。(b)为转盘边缘的液流线，可以看到有小液滴流出后留下的痕迹，从而可以说明金属液都是经过完全的离心雾化在边缘处离散出去的。
最后应说明的是：以上各实施例仅用以说明本发明的技术方案，而非对其限制；尽管参照前述各实施例对本发明进行了详细的说明，本领域的普通技术人员应当理解：其依然可以对前述各实施例所记载的技术方案进行修改，或者对其中部分或者全部技术特征进行等同替换；而这些修改或者替换，并不使相应技术方案的本质脱离本发明各实施例技术方案的范围。

Claims (10)

  1. 一种逐液滴离心雾化法高效制备低熔点球形金属粉末的装置，包括壳体(12)、设置于所述壳体(12)内的坩埚(4)和粉末收集区，所述粉末收集区置于所述壳体(12)的底部，所述坩埚(4)置于所述粉末收集区的上部，所述坩埚(4)上设有与设置在所述壳体(12)外部的压电陶瓷(1)相连的传动杆(2)，所述传动杆(2)的下端对着所述坩埚(4)底部的中心孔，所述中心孔底部装有带小孔的垫片(6)；所述坩埚(4)内部设有热电偶，所述坩埚(4)外部设有环形电阻加热器(5)；
    所述壳体(12)上设有伸入于所述坩埚(4)内的坩埚进气管(20)，所述壳体(12)的侧壁上还设有与所述坩埚(4)相连通的机械泵(16)和扩散泵(17)，所述壳体(12)上还设有腔体进气口(15)和腔体排气阀(18)；
    所述粉末收集区包括设置在所述壳体底部的收集盘(11)和设置于所述收集盘(11)上方的与电机(9)相连的用于雾化金属液滴(14)的转盘(8)；其特征在于：
    所述转盘(8)包括基体，雾化平面(23)和通气孔(24)；
    所述基体是由上部的承接部(21)和下部的支撑部(22)构成的纵截面呈类“T型”的主体结构，所述承接部(21)上表面设有与其圆心同轴的具有一定半径的圆形凹槽；其中，所述基体采用导热性小于20W/m/k的材料制成；
    所述雾化平面(23)为圆盘结构，所述圆盘结构与所述承接部的圆形凹槽相匹配且与所述圆形凹槽过盈配合，所述雾化平面(23)采用与雾化金属液滴(14)润湿角小于90°的材料制成；
    所述通气孔(24)贯通设置在所述承接部(21)及所述支撑部(22)内，所述通气孔(24)的上端面与所述雾化平面(23)的下端面接触，所述通气孔(24)的下端与外界连通；
    所述转盘(8)的外围还设有感应加热线圈(13)。
  2. 根据权利要求1所述的逐液滴离心雾化法高效制备低熔点球形金属粉末的装置，其特征在于，所述坩埚(4)底部的的中心孔直径大于带小孔的垫片(6)的小孔直径，所述带小孔的垫片(6)的小孔直径范围在0.02mm-2.0mm之间。
  3. 根据权利要求1所述的逐液滴离心雾化法高效制备低熔点球形金属粉末的装置，其特征在于，所述带小孔的垫片(6)的材料与置于所述坩埚内的熔体(3)的润湿角大于 90°。
  4. 根据权利要求1所述的逐液滴离心雾化法高效制备低熔点球形金属粉末的装置，其特征在于，所述转盘(8)的转速为10000rpm-50000rpm。
  5. 根据权利要求1所述的逐液滴离心雾化法高效制备低熔点球形金属粉末的装置，其特征在于，所述感应加热线圈(13)的加热厚度范围在5-20mm之间，它与设置在所述壳体(12)外的变频器和稳压电源相连，所述稳压电源的电压控制范围在0-50V之间。
  6. 根据权利要求1所述的逐液滴离心雾化法高效制备低熔点球形金属粉末的装置，其特征在于，在所述装置自上而下的方向上，所述压电陶瓷(1)、所述传动杆(2)、所述坩埚(4)、所述环形式电阻加热器(5)、所述垫片(6)、所述转盘(8)以及所述感应加热线圈(13)位于同一轴线上。
  7. 一种采用如权利要求1-6任意一项权利要求所述的装置逐液滴离心雾化法高效制备低熔点球形金属粉末的方法，其特征在于包括如下步骤，
    ①装料：将原材料焊丝剪到预设的平均长度后，装入设置在壳体(12)上部的坩埚(4)内，手动调整高度方向上，感应加热线圈(13)位置至转盘(8)为预设距离后密封壳体(12)；
    ②抽真空：利用机械泵(16)和扩散泵(17)对所述坩埚(4)和所述壳体(12)抽真空，并充入高纯度惰性保护气体，使壳体(12)内压力达到预设值；
    ③电阻加热：根据待加热原材料的熔点设定使用环形电阻加热器(5)的加热参数，并通过所述坩埚(4)内设置的热电偶实时监测所述坩埚内的温度，待金属材料完全熔化后得到熔体(3)，保温；
    ④感应加热：利用电机(9)使所述转盘(8)在预设转速下高速旋转，接着利用感应加热线圈(13)将高速旋转的转盘(8)上表面加热到金属材料的熔点温度以上；
    ⑤粉末制备：首先，手动调整传动杆(2)的位置至传动杆(2)与带小孔的垫片(6)之间为预设距离；其次，通过设置在所述壳体(12)上并伸入于所述坩埚(4)内的坩埚进气管(20)将高纯度惰性保护气体通入，使所述坩埚(4)内外形成正压力差，促使熔体(3)填满所述坩埚(4)底部的中心孔；最后，给压电陶瓷(1)输入一定波型的脉冲信号，所述压电陶瓷(1)产生向下位移，由与所述压电陶瓷(1)相连的传动杆(2)传递给中心孔附近区域的熔体(3)，使得熔体(3)从中心孔底部的带小孔的垫片(6)喷出形成均匀液滴(14)；
    均匀液滴(14)自由降落在高速旋转的转盘(8)上，熔融状态下的均匀液滴(14)，先滴落在转盘(8)的中心，由于此时离心力较小，液滴(14)不会被马上离散出去，而是会呈圆形铺展在转盘(8)上，当铺展到一定范围离心力足够大时，铺展的金属会在离心力的作用下，在转盘(8)上呈纤维线状离散至转盘(8)边缘，最后分裂成微小的液滴飞出，微液滴在下落过程中无容器凝固，形成金属粉末(10)，降落至收集盘(11)上，同时将传动杆(2)恢复初始状态。
    ⑥粒子收集：用设置于所述壳体(12)底部的收集盘(11)收集金属粉末(10)。
  8. 根据权利要求7所述的逐液滴离心雾化法高效制备低熔点球形金属粉末的方法，其特征在于，手动调整感应加热线圈(13)位置比转盘(8)高1-2mm。
  9. 根据权利要求7所述的逐液滴离心雾化法高效制备低熔点球形金属粉末的方法，其特征在于，所述感应加热线圈(13)的感应加热电压范围为0-50V，感应加热时间为5-15min。
  10. 根据权利要求7所述的逐液滴离心雾化法高效制备低熔点球形金属粉末的方法，其特征在于，所述高纯度惰性保护气体为氩气或氦气，将该气体充入壳体(12)内，使所述壳体(12)内抽真空后的压力达到0.1MPa，金属材料完全熔化后保温时间为15-20分钟；所述坩埚(4)与所述壳体(12)内产生的差压为0-200kPa。
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