TWI603793B - A hybrid atomization device - Google Patents

Description

Hybrid atomization device

The invention provides a hybrid atomization device, in particular to a liquid metal output after being atomized and cooled.

According to the metal powder, it can be directly used as a metallurgical material. Therefore, it can be applied in a wide range of fields, from general household products to technology industries, transportation products and aerospace, and even to laminated manufacturing. The field of Additive Manufacturing, AM); and for the improvement of the level of technology, the precision and quality requirements for metal powders are also increasing; there are many methods for making metal powders, such as reduction, electrolysis, atomization. Method, mechanical mincing, carbonyl method and direct method, wherein the metal powder obtained by the atomization method has a better yield and shape, and the cost of the process is relatively low, so the atomization method is now made of metal The core technology of powder.

The nozzle 10 for atomizing the metal powder, as shown in Fig. 1, comprises: a nozzle 10 provided with a furnace 101 having a flow passage 102 for natural output of the liquid metal 20, An atomizing device 103 is disposed on both sides of the outside of the flow channel 102. The atomizing device 103 outputs high-pressure gas below the flow channel 102, so that the liquid metal 20 is output from the flow channel 102, that is, the atomized by the high-pressure gas; In addition, a restrictive atomizing nozzle 30 is provided, as shown in FIG. 2, which comprises: a nozzle 30, which is provided with a furnace 301 having a tapered flow channel 302 in the flow channel 302. An atomizing device 303 is disposed on both sides of the flow channel 302. The atomizing device 303 outputs high-pressure gas along the wall surface of the flow channel 302, so that the high-pressure gas generates a reflow at the opening of the flow channel 302, thereby atomizing the liquid metal 20 Regardless of the conventionally known atomizing nozzles 10, 30 as shown in Fig. 1 or Fig. 2, as shown in Fig. 3, the heated molten metal 20 is placed in the preheated crucible 40. , by introducing the atomizing gas spraying device 10, 30 to atomize, and atomizing the liquid metal 20 Into a cooling chamber 50 filled with an inert gas, whereby the atomized liquid metal 20 is solidified to form a metal powder 201, and the powder of the dissimilar particle size can be sieved by centrifugal force by the powder classifying device 501 in the cooling compartment. The powder 201 is stored in a collecting bottle 502 at the bottom of each powder classifying device 501.

However, the cooling efficiency of the droplets of the liquid metal 20 has a negative correlation with the particle diameter, for example, the metal droplets have a uniform temperature distribution, and the cooling process of the droplets can be regarded as a Newton cooling condition, and In the state where the Bi (Biot number) system of the droplet and gas interface heat conduction is less than 0.1, the cooling rate of the metal droplet can be described by the following Mathematical Formula 1: [Math 1]

among them For the cooling rate, For the original temperature of the metal droplet, For the cooling temperature of the gas, For the density of metal droplets, For the heat capacity of the metal droplets, Is the particle size of the metal droplets, and It can be obtained by the Ranz-Marshall formula, as shown in the following Mathematical Formula 2: [Math 2]

among them, For gas thermal conductivity, Reynolds number for metal droplets, Is the Prandtl number of the metal droplet, and and It can be obtained from the following Mathematical Formula 3 and Mathematical Formula 4: [Math 3] [Math 4]

among them, For gas density, For the relative velocity between the droplet and the gas, It is the dynamic viscosity of the gas.

Thereby, the stainless steel metal droplets, the output gas is nitrogen, and the various condition parameters are satisfied. For 1973 K, For 298 K, for , For 565 , For 600 Under the conditions and the thermal physical properties of nitrogen, for , for , for , For 1.15 , when the metal droplet size is less than 100μm and the cooling rate As shown in Fig. 4, it can be clearly seen that the cooling efficiency of the metal droplets has a negative correlation with the particle diameter, and the smaller the particle diameter of the metal droplets, the higher the cooling rate.

The surface of the conventionally produced metal powder 201 was observed by SEM (Scanning Electron Microscope) as shown in Fig. 5, wherein the metal powder 201 of Fig. 5(a) has a particle size of 74. Mm, Fig. 5(b) is an enlarged view of Fig. 5(a), the metal powder 201 of Fig. 5(c) has a particle diameter of 53 to 62 μm, and Fig. 5(d) is a fifth figure (c). In the enlarged view, the metal powder 201 of Fig. 5(e) has a particle diameter of 38 to 45 μm, and the metal powder 201 of Fig. 5(f) has a particle diameter of less than 25 μm, and the smaller the particle diameter of the metal powder 201 is, the smaller The smoother the surface will be, because the cooling rate is faster, so segregation is less likely to occur during the cooling process, and the segregation phenomenon does not cause the main cause of the surface roughness of the metal powder 201, which will greatly affect its mechanical properties, so it can be seen that If the particle size of the metal powder 201 is 25 μm or more, segregation occurs.

In addition, as for the microscopic structure, since the stainless steel powder is subjected to X-ray diffraction (XRD), as shown in Fig. 6, the stainless steel has BCC (body-centered cubic crystal) δ and FCC (face core). a cubic crystal) mixture of γ, and the equation for its volume percentage can be expressed by the following mathematical formula 5: [Math 5]

among them, Is the volume percentage of BCC, For the volume percentage of the FCC, Is the bulk strength of the BCC diffraction peak (the crystal surface is 110 in Figure 6), It is the volume strength of the FCC diffraction peak (the crystal surface is 111 in Figure 6), and R is the diffraction angle 2θ, thereby obtaining the volume percentage of BCC and FCC under different powder particle sizes, such as the seventh As shown in the figure, it can be known that the volume percentage of BCC is negatively correlated with the particle size of the powder, and the volume percentage of FCC is positively correlated with the particle size of the powder. Therefore, segregation occurs in the alloy phase, which is the main cause of the surface roughness of the powder. This will cause a drop in mechanical properties and instability.

Therefore, if it is applied to a device that can vibrate (such as a carrier), the conventionally produced metal powder 201 can only use a non-directional Amorphous metal, and if a crystal system or alloy is used. The metal and vibrating device will also be prone to quality defects due to metal segregation, which will result in extremely limited material application.

In view of this, our inventors are concentrating on further research on the manufacture of metal powders, and proceeding with research and development and improvement, with a better design to solve the above problems, and after continuous trial and modification, the present invention is come out.

Therefore, the object of the present invention is to solve the conventional metal powder prepared by the atomization method. Because the cooling rate is too slow, the metal powder of a larger particle size is liable to cause segregation, which affects the mechanical properties and causes application. When the device is shaken, it is easy to cause defects such as quality defects.

In order to achieve the above object, the inventors provide a hybrid atomization device comprising: a nozzle provided with a discharge end, the discharge end being gradually expanded from the inside and outside of the nozzle, and the The nozzle is sequentially disposed with a main flow channel, an atomization flow channel, a cooling flow channel and a cooling vortex flow channel; the main flow channel, the atomization flow channel and the cooling flow channel are coaxially arranged, and the main flow channel, The openings of the atomizing flow channel, the cooling flow channel and the cooling vortex flow channel are respectively located at the wall surface of the discharge end; wherein the main flow prop has an axis, and the atomization flow channel and the cooling flow channel are input to the axis a gas flow, the cooling vortex flow channel is fed with a gas flow toward the tangent of the discharge end; and the atomization flow channel outputs a high temperature and high pressure gas flow, and the cooling flow channel output temperature is lower than the cooling of the main flow channel and the atomization flow channel The air flow, and the cooling vortex flow path is used to generate a vortex air flow corresponding to the discharge end.

According to the hybrid atomization device described above, the discharge end is slightly tapered.

According to the hybrid atomization device described above, wherein the direction of the cooling vortex flow path is slightly perpendicular to the axis, and the cooling vortex flow path is offset from the axis by a distance, thereby generating the vortex air flow. .

According to the hybrid atomization device described above, the temperature between the main flow channel, the atomization flow channel, the cooling flow channel and the cooling vortex flow channel is sequentially from high to low: the main flow channel, the atomization flow channel, Cooling runners, cooling vortex runners.

According to the hybrid atomization device described above, the temperature of the cooling flow output cooling passage is between -196 ° C and 25 ° C.

The hybrid atomizing device according to the above, further comprising a first heating device and a second heating device, the first heating device is disposed between the main flow channel and the atomizing flow channel, thereby using a constant mainstream channel Temperature; the second heating device is disposed on the atomizing flow path to thereby constant the temperature of the atomizing flow path.

According to the hybrid atomization device described above, a feed end is connected to the main flow channel, and the temperature of the feed end is greater than or equal to the main flow channel.

According to the hybrid atomization device described above, a third heating device is further disposed at the feed end to thereby constant the temperature of the feed end.

According to the hybrid atomization device described above, the main flow channel is for outputting a liquid metal.

It is obvious from the above description and setting that the present invention has the following several advantages and effects, which are detailed as follows:

1. After the liquid metal is outputted from the main channel, the liquid metal is atomized by the high-pressure airflow output from the atomizing channel, and then the cooling airflow output from the cooling channel is initially cooled and cooled in the process. The vortex flow system generates a vortex flow to produce a mixed cooling effect, so that the liquid metal can be atomized and rapidly solidified to form a metal powder in the discharge end of the nozzle, thereby avoiding the metal of the crystalline during the cooling process. The phenomenon of segregation occurs, and the surface of the metal powder of various particle sizes is smoother, thereby improving the precision, and the mechanical properties and strength after metallurgy or product making, so as to improve the applicability of the metal powder.

The invention will be described in detail below with reference to the drawings.

Please refer to FIG. 8 first, the present invention is a hybrid atomization device comprising:

a nozzle 1 is provided with a discharge end 11 which is gradually expanded from the inside of the nozzle 1 , and the nozzle 1 is sequentially disposed with a main flow channel 12 and an atomization flow path from the center. 13. A cooling flow passage 14 and a cooling vortex flow passage 15; the main flow passage 12, the atomization flow passage 13 and the cooling flow passage 14 are coaxially disposed, and the main flow passage 12, the atomization flow passage 13, and the cooling flow The openings of the channel 14 and the cooling vortex channel 15 are respectively located on the wall surface of the discharge end 11;

The main flow channel 12 has an axis A, and the atomizing flow channel 13 and the cooling flow channel 14 are connected to the axis A with an air flow, and the cooling vortex flow channel 15 is connected to the tangential line of the discharge end 11 to receive a gas flow; The atomizing flow channel 13 outputs a high-temperature high-pressure airflow, and the cooling flow channel 14 outputs a cooling airflow having a temperature lower than the main flow channel 12 and the atomizing flow channel 13, and the cooling vortex flow channel 15 is used to generate a corresponding The vortex airflow of the discharge end 11; in an embodiment, the discharge end 11 is slightly tapered, and the cooling vortex flow passage 15 is offset from the axis A by a distance d, thereby being like the ninth Figure and Figure 10, which in turn can improve the performance of the vortex flow;

a first heating device 2 and a second heating device 3, the first heating device 2 is disposed between the main flow channel 12 and the atomizing flow channel 13 to thereby maintain the temperature of the main flow channel 12; the second heating device 3 is disposed in the atomizing flow path 13 to thereby constant the temperature of the atomizing flow path 13; a receiving end 16 is coupled and fed to the main flow channel 12, in a preferred embodiment, the the infeed end 16 of the temperature T _1, the temperature of the main flow channel 12 of T _2, the temperature of the flow channel 13 of the atomizing T _3, the temperature T of the cooling flow passage 14 swirl the cooling flow _{passage. 4} and T ₅ 15 temperature, the line with T ₁ ≧T ₂ > T ₃ > T ₄ > T ₅ ;

A third heating device 4 is disposed at the feed end 16 to thereby maintain the temperature of the feed end 16.

Thereby, the metal can be preheated according to its melting point to form the liquid metal 5 to be added to the feed end 16, and the temperature of the feed end 16 is constant by the third heating device 4, so that the liquid metal 5 is maintained at the temperature of the melting point of the metal. Above, or directly into the feed end 16 to form a liquid metal 5, after which the liquid metal 5 will flow out through the main flow channel 12, in order to prevent metal solidification during the outflow, preferably, the first heating The device 2 is configured to keep the temperature of the main flow channel 12 above the melting point of the metal, and according to the characteristics of the metal, control whether the temperature of the main flow channel 12 needs to be less than or equal to the feeding end 16, which is due to the liquid in the liquid metal 5. The droplet is a uniform temperature distribution, and the cooling process of the droplet can be regarded as a Newton cooling condition, and the cooling rate of the metal droplet can be borrowed when the Bi (Biot number) system of the droplet and gas interface heat conduction is less than 0.1. It is expressed by the following Mathematical Formula 6: [Math 6]

among them For the cooling rate, For the original temperature of the metal droplet, For the cooling temperature of the gas, For the density of metal droplets, For the heat capacity of the metal droplets, Is the particle size of the metal droplets, and It can be obtained by the Ranz-Marshall formula, as shown in the following Mathematical Formula 7: [Math 7]

among them, For gas thermal conductivity, Reynolds number for metal droplets, Is the Prandtl number of the metal droplet, and and It can be obtained from the following Mathematical Formula 8 and Mathematical Formula 9 respectively: [Math 8] [Math 9]

among them, For gas density, For the relative velocity between the droplet and the gas, It is the dynamic viscosity of the gas.

Therefore, since the temperature of the liquid metal 5 will affect its density, and the density of the liquid metal 5 will directly affect its cooling rate, the first heating device 2 can control the actual flow of the liquid metal 5 required by the main flow channel 12. After the liquid metal 5 is output from the main flow channel 12, first, it will be excited by the atomizing flow channel 13 toward the axis A to output a high-temperature high-pressure gas stream to atomize to form metal droplets, wherein the atomizing flow channel 13 The temperature can be controlled by the second heating device 3, and to facilitate atomization, the temperature of the atomizing channel 13 is between the main channel 12 and the cooling channel 14; wherein the atomizing channel 13 outputs high temperature and high pressure gas. The temperature of the metal droplets can be controlled according to the particle size of the desired metal droplets; and the temperature of the cooling channel 14 to the cooling axis of the axis A is between -196 ° C and 25 ° C, so that the atomization can be quickly The metal droplets are cooled and solidified, and are cooled and solidified through a cooling vortex flow path 15 which is disposed perpendicularly to the axis A and is offset from the axis A by a distance d, and is slightly tapered with the discharge end. The setting, in order to facilitate the generation of vortex airflow, The shape of the swirling airflow can be easily controlled by the shape of the discharge end to generate a path change of the swirling motion, and the temperature of the swirling airflow is lower than the cooling flow passage 14, so that the metal droplets are as shown in FIG. In the process, the original swirling radius R _{1 is} gradually increased to a radius R ₂ to generate a mixed cooling effect by the swirling motion, thereby improving the cooling efficiency, so that the metal droplets can be quickly solidified to form the metal powder 51 and The output from the nozzle 1 is not easy to cause segregation; and for the collection of the metal powder 51, a cooling chamber (not shown) corresponding to the vortex flow generated by the cooling vortex flow path 15 is provided at the opening of the nozzle 1, By means of collecting and cooling the metal powder, a powder classifying device may be provided at the bottom of the cooling compartment to screen the metal powder 51 of a specific particle size, but it is not limited thereto.

Therefore, in the embodiment, the metal portion is made of stainless steel, and the air flow portion is made of nitrogen gas, but is not limited thereto, so that the metal produced by the embodiment is as shown in FIGS. 10 to 14 The powder 51 has a particle diameter of 10 to 20 μm, 20 to 30 μm, 30 to 40 μm, 40 to 50 μm, and 50 to 60 μm, respectively, and FIG. 15 is produced in the present embodiment. The metal powder 51 is observed by an SEM (Scanning Electron Microscope) overview, and the 16th to 18th views of the SEM are observed in the SEM. The particle diameter of the produced metal powder 51 is less than 10 μm, The observation chart of 10 to 20 μm and 30 to 40 μm can be observed that the smaller the particle diameter of the metal powder 51 is, the smoother the surface is, and the metal powder 51 produced in this embodiment can be clearly seen regardless of the particle size. And regardless of whether the metal powder 51 is an amorphous metal, a crystalline or an alloy, it has a smoother surface than the conventional one, and represents that the metal droplets hardly generate during cooling and solidification. Segregation, which in turn can indeed raise gold 51 were powders of accuracy.

In summary, the technical means disclosed by the present invention can effectively solve the problems of the prior knowledge, achieve the intended purpose and efficacy, and are not found in the publication before publication, have not been publicly used, and have long-term progress, The invention referred to in the Patent Law is correct, and the application is filed according to law, and the company is invited to give a detailed examination and grant a patent for invention.

The above is only the preferred embodiments of the present invention, and the scope of the present invention is not limited thereto, that is, the equivalent changes and modifications made by the scope of the invention and the contents of the invention are all It should remain within the scope of this invention.

[study]
10, 30‧‧‧ nozzle
101, 302‧‧‧ furnace
102, 302‧‧‧ runners
103, 303‧‧‧ atomizing device
20‧‧‧Liquid metal
201‧‧‧Metal powder
40‧‧‧ Shabu-shabu
50‧‧‧Cooling cabin
501‧‧‧Powder classifier
502‧‧‧Collection bottle (present invention)
1‧‧‧ nozzle
11‧‧‧Drawing end
12‧‧‧mainstream
13‧‧‧Atomized flow channel
14‧‧‧Cooling runner
15‧‧‧Cooling vortex runner
16‧‧‧ Feeding end
2‧‧‧First heating unit
3‧‧‧Second heating device
4‧‧‧ Third heating device
5‧‧‧Liquid metal
51‧‧‧Metal powder

Fig. 1 is a schematic view showing a nozzle for atomizing a metal powder. Figure 2 is a schematic illustration of a conventional restricted atomizing nozzle. Figure 3 is a schematic view showing the structure and use state of the conventional cooling chamber to form a metal powder. Figure 4 is the particle size of the stainless steel to the cooling rate Line diagram. Fig. 5 is an observation view of a conventionally prepared metal powder by SEM observation. Figure 6 is a graph of the X-ray diffraction pattern of stainless steel powder. Figure 7 is a line graph of the volume fraction of stainless steel powder versus the volume percentage of BCC and FCC. Figure 8 is a schematic view showing the structure of the present invention. Figure 9 is a schematic diagram of the motion path of the metal droplets in the swirling motion to produce a mixed cooling effect. Figure 10 is a schematic diagram of the three-dimensional motion path of the metal droplets in the swirling motion to produce a mixed cooling effect. Figure 11 is a metallographic diagram of a metal powder having a particle size of 10 to 20 μm produced by the present invention. Figure 12 is a metallographic diagram of a metal powder having a particle size of 20 to 30 μm. Figure 13 is a metallographic diagram of a metal powder having a particle size of 30 to 40 μm produced by the present invention. Figure 14 is a metallographic diagram of a metal powder having a particle size of 40 to 50 μm produced by the present invention. Fig. 15 is a metallographic diagram of the present invention for producing a metal powder having a particle diameter of 50 to 60 μm. Fig. 16 is an observation view of the metal powder produced by the present invention observed by SEM observation. Fig. 17 is a view showing the observation of the SEM observation of the metal powder having a particle diameter of less than 10 μm. Fig. 18 is an observation view of the present invention for producing a metal powder having a particle diameter of 10 to 20 μm by SEM observation. Fig. 19 is an observation view of the present invention for producing a metal powder having a particle diameter of 30 to 40 μm by SEM observation.

1‧‧‧ nozzle

11‧‧‧Drawing end

12‧‧‧mainstream

13‧‧‧Atomized flow channel

14‧‧‧Cooling runner

15‧‧‧Cooling vortex runner

16‧‧‧ Feeding end

2‧‧‧First heating unit

3‧‧‧Second heating device

4‧‧‧ Third heating device

5‧‧‧Liquid metal

Claims (7)

A mixing type atomizing device comprises: a nozzle, which is provided with a discharge end, wherein the discharge end is gradually expanded from the inside and the outside of the nozzle, so that the discharge end is slightly tapered, and The nozzle is sequentially disposed with a main flow channel, an atomization flow channel, a cooling flow channel and a cooling vortex flow channel; the main flow channel, the atomization flow channel and the cooling flow channel are coaxially arranged, and the main flow channel The openings of the atomizing flow channel, the cooling flow channel and the cooling vortex flow channel are respectively located at the wall surface of the discharging end; wherein the main flow prop has an axis, and the atomizing flow channel and the cooling flow channel are transmitted toward the axis In the air flow, the direction of the cooling vortex flow path is slightly perpendicular to the axis, and the cooling vortex flow path is offset from the axis by a distance to the tangential line of the discharge end to receive the air flow; and the atomization The flow channel system outputs a high temperature and high pressure gas stream, the cooling channel output temperature is lower than the cooling gas flow of the main flow channel and the atomization flow channel, and the cooling vortex flow channel is used to generate a vortex air flow corresponding to the discharge end. The hybrid atomization device according to claim 1, wherein the temperature between the main flow channel, the atomization flow channel, the cooling flow channel and the cooling vortex flow channel is from high to low in order: the main channel, Atomizing flow channel, cooling flow channel, cooling vortex flow channel. The hybrid atomization device of claim 1, wherein the cooling flow output cooling gas flow has a temperature between -196 ° C and 25 ° C. The hybrid atomizing device of claim 1, further comprising a first heating device and a second heating device, the first heating device being disposed between the main flow channel and the atomizing flow channel, The temperature of the constant main flow channel is set; the second heating device is disposed on the atomization flow path, thereby constanting the temperature of the atomization flow path. The mixing type atomizing device according to claim 1, further comprising a feeding end which is connected and fed to the main flow path, and the temperature of the feeding end is greater than or equal to the main flow path. The hybrid atomization device of claim 5, further comprising a third heating device disposed at the feed end to thereby constant the temperature of the feed end. The hybrid atomization device according to claim 1, wherein the main flow channel is for outputting a liquid metal.