CN115028459B - Method and device for preparing high-purity superfine aluminum nitride powder by using plasma - Google Patents
Method and device for preparing high-purity superfine aluminum nitride powder by using plasma Download PDFInfo
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Abstract
The invention discloses a method and a device for preparing high-purity superfine aluminum nitride powder by using plasmas, wherein discharge gas is sent into a plasma generator and ionized under the action of a power supply to form high-temperature argon/nitrogen mixed gas thermal plasma jet or nitrogen thermal plasma jet, and the high-temperature argon/nitrogen mixed gas thermal plasma jet and nitrogen thermal plasma jet flow into a plasma high-temperature reactor; the simple substance aluminum powder is quantitatively fed into a plasma high-temperature reactor through a powder feeder and is rapidly liquefied and gasified, and liquefied aluminum and/or gasified aluminum react with high-temperature nitrogen in the plasma high-temperature reactor to generate aluminum nitride powder precursor; the aluminum nitride powder precursor enters an aluminum nitride powder purity lifting chamber to further improve the purity; then the aluminum nitride powder enters a grain size screening chamber, and is cooled and condensed into superfine aluminum nitride powder; the superfine aluminum nitride powder enters a gas-solid separator for separation, and the superfine aluminum nitride powder obtained in each region of a sieve chamber and the gas-solid separator with the particle size of the aluminum nitride powder is respectively collected, so that the superfine aluminum nitride powder has the advantages of uniform particle size and high purity.
Description
Technical Field
The invention relates to the field of preparation of metal ceramic materials, in particular to a method and a device for preparing high-purity superfine aluminum nitride powder by using argon/nitrogen or nitrogen plasma.
Background
With the rapid development of microelectronics and semiconductor technology, chips, electronic components and motors are gradually entering the times of miniature, lightweight, high energy density and high power. This allows a significant increase in the heat generation density inside the chip, electronic component or high power IGBT. In order to keep the electronic device operating stably, this heat needs to be conducted away quickly.
The aluminum nitride ceramic is taken as a typical representative of the third-generation semiconductor material, has the characteristics of high heat conductivity, high temperature resistance, close thermal expansion coefficient to that of silicon, high mechanical strength, good chemical stability, environmental protection, no toxicity, small dielectric constant and the like, and is considered as an ideal material for packaging a new-generation heat dissipation substrate and an electronic device.
Aluminum nitride ceramic device production mainly comprises two processes. Firstly, preparing aluminum nitride powder, and secondly, forming and sintering to obtain the aluminum nitride ceramic device. Of the two, aluminum nitride powder preparation is the most critical. At present, the traditional production method of aluminum nitride powder mainly comprises the following steps:
1. direct nitridation process
The direct nitriding method uses metal aluminum powder to directly react with nitrogen at high temperature to synthesize aluminum nitride powder, and the reaction formula is as follows:
2Al+N 2 →2AlN；
2. carbothermal reduction process
The carbothermal reduction method is to react alumina powder and carbon powder with nitrogen at high temperature to generate aluminum nitride powder, and the reaction formula is as follows:
Al 2 O 3 +3C+N 2 →3CO+2AlN；
3. self-propagating high-temperature synthesis method
The reaction of aluminum and nitrogen is a strong exothermic reaction, no other heat source is needed once the reaction is ignited, and the combustion speed is high; the self-propagating high-temperature synthesis method utilizes heat released by the aluminum nitride reaction to initiate self-sustaining reaction of aluminum and nitrogen, and the method is similar to a direct nitriding method, and has the following reaction formula:
2Al+N 2 →2AlN；
4. chemical vapor deposition method
Chemical Vapor Deposition (CVD) is to react a vapor compound of aluminum with a nitrogen-containing gas under high-temperature gaseous conditions to produce aluminum nitride powder, and the reaction formula is as follows:
AlCl 3 +NH 3 →AlN+3HCl。
besides the traditional preparation method, the hydro-thermal plasma method can also be used for preparing high-purity nano aluminum nitride powder, such as CN108059134A, in a plasma generator, nitrogen and hydrogen are used as discharge gas, the discharge gas is led into the plasma generator, so that the discharge gas generates plasma jet under the high-temperature condition, then the plasma jet is led into a straight tube type reactor and reacts with vaporized high-purity aluminum powder, thus obtaining aluminum nitride powder, the yield of the aluminum nitride powder can reach up to 70%, the purity can reach 99.02%, the average particle size is about 300-400 meshes, and the diameter of most particles is 50-200 nm.
The electronic grade aluminum nitride powder is required to have controllable particle size distribution and high purity, and the use requirement of aluminum nitride powder with the D50 (median diameter) of 1-1.5 mu m and the purity of more than 99.2% (w/w) is increased, so that the existing preparation process of the aluminum nitride powder in China also has the problem that the particle size and the purity are difficult to control.
Disclosure of Invention
Aiming at the problems of severe conditions, difficult control of particle size and purity and the like of the traditional aluminum nitride powder preparation process, the invention provides a brand-new preparation method with controllable particle size and high aluminum nitride powder purity and a device for implementing the method.
In order to solve the technical problems, one embodiment of the present invention adopts the following technical scheme:
an apparatus for preparing high purity superfine aluminum nitride powder by using plasma, the structure of the apparatus comprises: the device comprises a plasma generator, a powder feeder, a plasma high-temperature reactor, an aluminum nitride powder purity improving chamber, an aluminum nitride powder particle size screening chamber and a gas-solid separator. These components are organically combined, and the production of the high-purity superfine aluminum nitride powder is completed together. The powder feeder is a powder feeder with controllable powder feeding amount.
The lower end of the plasma generator is connected with the powder feeder, the lower end of the powder feeder is connected with the plasma high-temperature reactor, one side of the plasma high-temperature reactor is connected with the aluminum nitride powder purity lifting chamber, one side of the aluminum nitride powder purity lifting chamber is connected with the aluminum nitride powder particle size screening chamber, and the tail end of the aluminum nitride powder particle size screening chamber is connected with the gas-solid separator.
A water chilling unit is arranged on the outer surface of the device for preparing the high-purity superfine aluminum nitride powder by using the plasmas, and the whole device or part of the device can be water-cooled. The water chiller can be a cold water jacket.
The plasma generator can be driven by direct current, high frequency (MHz) and microwave (GHz) power supplies, and ionizes and breaks down the fed argon and/or nitrogen to form argon-nitrogen plasma jet or nitrogen plasma jet with the center temperature of ten thousands K and the average temperature of more than 3000 ℃. At this temperature, the nitrogen gas is cleaved into highly reactive nitrogen atoms and flows into the plasma high temperature reactor. The input power and input gas flow of the plasma generator are adjustable.
The powder feeder with controllable powder feeding amount uses nitrogen, argon or ammonia as carrier gas to feed high-purity aluminum powder into the reactor in a fluidization mode. The particle size of the aluminum powder which can be conveyed by the powder conveying device is 1-100 microns, including but not limited to 1 micron, 5 microns, 10 microns, 15 microns, 20 microns, 30 microns, 40 microns, 50 microns, 60 microns, 70 microns, 80 microns, 90 microns, 100 microns or the aluminum powder enters the powder conveying device according to a certain particle size distribution range. The high-purity aluminum powder is powder having an aluminum content of 99% (w/w) or more.
The plasma high temperature reactor continuously receives both a high Wen Yadan plasma jet (or high temperature nitrogen plasma jet) from a plasma generator and aluminum powder from a powder feeder. The aluminum powder can complete liquefaction, gasification and nitridation processes in the plasma high-temperature reactor to generate a precursor of the condensable aluminum nitride powder. The plasma high Wen Tiqi reactor is a hot wall channel space with high temperature resistant (above 3000 ℃) material as the inner wall.
The aluminum nitride powder purity enhancement chamber corresponds to a subsequent reactor. The aluminum nitride powder purity lifting chamber uses high temperature resistant material as the hot wall channel space of the inner wall, and keeps the average temperature above 3000 ℃ through heat preservation (using high temperature resistant material above 3000 ℃ as the inner wall) and reheating measures (plasma high temperature reaction), so that the aluminum powder possibly not reacted in the precursor can continuously complete the reaction in the flowing process.
The aluminum nitride powder particle size screening chamber adopts a dust separation principle. The reacted aluminum nitride powder precursor grows at reduced temperature and is condensed, and then passes through a channel embedded with a plurality of sedimentation lattices at a certain flow rate. And settling the agglomerated powder with larger particle size into a first lattice, and analogizing to realize screening control of the particle size of the product.
The gas-solid separator is the terminal end of the device. The powder which is not settled after passing through the powder particle size screening is completely collected, and the collection mode is cloth bag vacuumizing or electrostatic adsorption.
The whole system can be controlled by a PLC or manually from a plasma generator, a powder feeder and a plasma high-temperature reactor to pressure feedback, and the intelligent degree of the reaction device is high.
In addition, the invention also provides a method for preparing high-purity superfine aluminum nitride powder by using plasma, which comprises the following steps: argon and nitrogen are used as discharge gases or nitrogen is used as discharge gases, the discharge gases are sent into the plasma generator and ionized under the action of a power supply to form high-temperature (average temperature is more than 3000 ℃) argon/nitrogen mixed gas thermal plasma jet or nitrogen thermal plasma jet, and the high-temperature argon/nitrogen mixed gas thermal plasma jet and the nitrogen thermal plasma jet flow into a plasma high-temperature reactor; the simple substance aluminum powder is quantitatively fed into a plasma high-temperature reactor (2000-4000 ℃) through a powder feeder and is rapidly liquefied and gasified, and liquefied aluminum and/or gasified aluminum react with high-temperature nitrogen in the plasma high-temperature reactor to generate aluminum nitride powder precursor; the aluminum nitride powder precursor enters an aluminum nitride powder purity lifting chamber to further improve the purity; then the aluminum nitride powder enters a grain size screening chamber, and is cooled (finally cooled to the temperature below the condensation temperature to the room temperature) and condensed into superfine aluminum nitride powder; the superfine aluminum nitride powder enters a gas-solid separator for separation, and the superfine aluminum nitride powder obtained in each region of a sieve chamber and the gas-solid separator with the particle size of the aluminum nitride powder is respectively collected, so that the superfine aluminum nitride powder has the advantages of uniform particle size (narrow distribution) and high purity.
When argon and nitrogen are used as discharge gases, the volume flow ratio of the argon to the nitrogen is 1:2-10.
The temperature and flow rate of the plasma jet entering the lower-end plasma high-temperature reactor can be controlled by adjusting the discharge power of the plasma generator and the flow rate of the discharge gas. Preferably, the output power of the plasma generator is 30-200kW, and the flow rate of the discharge gas is 5-20m 3 And/or hours. The output power is 30-200kW, including but not limited to 30kW, 40kW, 50kW, 60kW, 70kW, 80kW, 90kW, 100kW, 120kW, 150kW, 160kW, 180kW, 200kW. The discharge gas flow rate is 5-20m 3 Per hour, including but not limited to 5m 3 Per hour, 7m 3 Per hour, 9m 3 Per hour, 12m 3 Per hour, 15m 3 Per hour, 18m 3 Per hour, 20m 3 Per hour。
The powder feeder uses nitrogen or argon or ammonia as carrier gas to feed high-purity aluminum powder into the plasma high-temperature reactor in a fluidization mode. The mass of the aluminum powder fed into the reactor in unit time can be freely adjusted by matching the carrier gas flow and the aluminum powder particle size. Preferably, the grain diameter of the aluminum powder is 10-100 microns, and the flow rate of the carrier gas is 0.5-5m 3 And/h, carrying the aluminum powder by 200-3000g/h. Aluminum powder particle sizes of 10-100 microns including, but not limited to, 10, 30, 50, 80, 100 microns; carrier gas flow rate 0.5-5m 3 /h, including but not limited to 0.5, 1, 2, 3, 4, 5m 3 /h; the carrying amount of the aluminum powder is 200-3000g/h, including but not limited to 200, 500, 800, 1200, 1800, 2300, 2700 and 3000g/h.
The high-temperature plasma reactor is a hot wall channel space with high-temperature resistant material as the inner wall, and the temperature of the inner space is kept at 2000-4000 ℃ and can simultaneously receive high Wen Yadan plasma jet (or nitrogen plasma jet) from the plasma generator and continuous aluminum powder from the powder feeder. The diameter and the length of the matched channel can be used for adjusting the residence time of the aluminum powder in the reactor, so that the aluminum powder can be ensured to finish the processes of liquefying, gasifying and nitriding, and the reaction rate is improved. Preferably, the temperature of the inner space of the plasma high-temperature reactor is kept above 3000 ℃, the diameter is 2-8cm, and the length is 10-50cm. And (3) a sufficient residence time to generate a precursor of the agglomerated aluminum nitride powder.
The aluminum nitride powder purity improving chamber uses high temperature resistant material as the hot wall channel space of the inner wall, and keeps the temperature above 3000 ℃ through the measures of temperature and reheating, so that the aluminum powder from the incomplete reaction of the reactor continuously completes the reaction in the flowing process. The heat preservation method is the same as that of a plasma high-temperature reactor (the inner wall is made of high-temperature resistant materials), and the heating method is the same as that of a plasma generator. Preferably, the plasma discharge power is 15-100kW.
The method comprises the steps of arranging a plurality of lattices capable of selectively settling or blocking aluminum nitride powder with different particle sizes in a flow channel, cooling, growing and agglomerating aluminum nitride powder precursors which are completely reacted from a purity lifting chamber, and settling agglomerated powder with larger particle sizes into a first lattice when the agglomerated powder passes through an embedded channel (such as 3-5 conical powder blockers connected in series) at a certain flow rate, so that the product particle size screening control is realized.
The gas-solid separator adopts a cloth bag or filter element type vacuumizing gas-solid separation mode. The air resistance generated by the two methods can be gradually increased, and the normal pressure of the whole system is maintained by using a pressure feedback type vacuum pump. Preferably, the absolute pressure of the whole system is 0.9X10 5 Pa-1.4×10 5 Pa。
Compared with the prior art, the invention has at least the following beneficial effects: can realize the rapid preparation of the superfine high-purity aluminum nitride powder with the particle size of 200-500nm,500-800nm and 800-1500 nm. The highest yield of the aluminum nitride powder can be close to 100%, the purity of the product can reach 99.5%, the DN50 is about 800-1200nm, the purity of the product is obviously higher than that of the product obtained by the traditional process method, and the particle size is controllable.
Compared with the existing plasma process, the process has no environmental pollution, is easy to enlarge the device and is easier to produce in large scale. The aluminum nitride powder prepared by the method can be applied to chips, high-power IGBT module substrates and packaging materials; the method can be applied to the fields of 5G base stations, new energy automobile electronics, high-speed rail electronics, aerospace, military communication and the like.
Drawings
FIG. 1 is a schematic diagram of an apparatus for preparing high purity ultrafine aluminum nitride powder by plasma.
Detailed Description
The present invention will be described in further detail with reference to the following examples in order to make the objects, technical solutions and advantages of the present invention more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.
Example 1
The schematic diagram of the device for preparing high-purity superfine aluminum nitride powder by using the plasmas is shown in fig. 1. The structure of the device comprises: the device comprises a plasma generator, a powder feeder, a plasma high-temperature reactor, an aluminum nitride powder purity lifting chamber, an aluminum nitride powder particle size screening chamber and a gas-solid separator. The components are organically combined, and the high-purity superfine aluminum nitride powder production is completed together. The powder feeder is a powder feeder with controllable powder feeding quality. The lower end of the plasma generator is connected with the powder feeder, the lower end of the powder feeder is connected with the plasma high-temperature reactor, one side of the plasma high-temperature reactor is connected with the aluminum nitride powder purity lifting chamber, one side of the aluminum nitride powder purity lifting chamber is connected with the aluminum nitride powder particle size screening chamber, and the tail end of the aluminum nitride powder particle size screening chamber is connected with the gas-solid separator.
The plasma generator is driven by a direct current power supply, and the argon and nitrogen fed in are ionized and broken down to form argon-nitrogen plasma jet with the center temperature of ten thousands K and the average temperature of 3000 ℃. At this temperature, the nitrogen gas is cleaved into highly reactive nitrogen atoms and flows into the plasma high temperature reactor. The powder feeder uses nitrogen as carrier gas to feed high-purity aluminum powder into the reactor in a fluidization mode. The particle size of the aluminum powder which can be conveyed by the powder conveyer is distributed between 1 and 100 microns. High purity aluminum powder refers to a powder having an aluminum content of 99% (w/w).
A plasma high temperature reactor (using a graphite tube reactor) continuously receiving both a high Wen Yadan plasma jet from a plasma generator and aluminum powder from a powder feeder. The aluminum powder can complete liquefaction, gasification and nitridation processes in the plasma high-temperature reactor to generate a precursor of the condensable aluminum nitride powder. The plasma high Wen Tiqi reactor is a hot wall channel space with high temperature resistant (above 3000 ℃) material as the inner wall.
The aluminum nitride powder purity enhancement chamber corresponds to a subsequent reactor. The aluminum nitride powder purity improving chamber uses high temperature resistant material as the hot wall channel space of the inner wall, and is heated by a plasma generator, and the average temperature is kept above 3000 ℃ by a temperature-keeping and reheating measure, so that the aluminum powder possibly not reacted in the precursor continuously completes the reaction in the flowing state.
The aluminum nitride powder particle size screening chamber adopts a dust separation principle. The reacted aluminum nitride powder precursor is cooled to grow and agglomerate, and the reacted aluminum nitride powder precursor is led to flow through the channel with three serially connected conic powder stoppers. And settling the agglomerated powder with larger particle size into a first lattice, and analogizing to realize screening control of the particle size of the product.
The gas-solid separator is a cloth bag vacuum air-solid separator. The pressure feedback of the whole system from the plasma generator, the powder feeder, the plasma high-temperature reactor to the gas-solid separator can be controlled by a PLC automatic control system or manually controlled, and the intelligent degree of the reaction device is high.
Taking direct current arc thermal plasma as an example, the working process of the device is as follows:
1. starting a water chilling unit to enable the outer layer of the whole device to be in a water-cooling state;
2. starting an air source, and replacing the air in the device with nitrogen by utilizing nitrogen through a PLC automatic control system;
3. argon and nitrogen are proportionally input into the plasma generator through the control of the PLC automatic control system, and a plasma power supply and the generator are started to enable plasma discharge to be in a stable state;
4. starting a powder feeder through a PLC automatic control system, enabling aluminum powder to enter the upper part of the graphite tubular reactor in a fluidization mode according to a set quantity and be mixed with high-temperature plasma jet flow, and performing nitriding reaction under the action of nitrogen plasma in the graphite tubular reactor;
5. starting a plasma generator of the purity lifting chamber through a PLC automatic control system, ensuring that incomplete reactants in a front-end plasma high-temperature reactor are subjected to further reaction, and then entering an aluminum nitride powder particle size screening chamber;
6. the screening chamber consists of three conical powder blockers connected in series, and powder with different particle sizes is blocked respectively, so that particle size screening is realized.
7. The gas passing through the sieving chamber also contains superfine aluminum nitride dust, and finally is collected by a cloth bag. When the cloth bags are collected, the rotational speed of the vacuum pump is modulated by the PLC to ensure that the pressure of the system is in a safe operation range;
8. the aluminum nitride powder collected by the powder screening chamber and the cloth bag is analyzed by adopting a scanning electron microscope, a particle size analyzer and other instruments to obtain the granularity of the aluminum nitride.
Example 2
The apparatus of example 1 was used to produce nano aluminum nitride powder using the following process:
argon and nitrogen are used as discharge gases, and the flow rate of the discharge gases is 10m 3 The volume flow ratio of argon to nitrogen is 1:5; the discharge gas is sent into a plasma generator, ionized under the action of a direct current power supply, the output power of the plasma generator is 100kW, and high-temperature (average temperature 3000 ℃) argon/nitrogen mixed gas thermal plasma jet is formed and flows into a plasma high-temperature reactor; the powder feeder takes nitrogen as carrier gas, high-purity aluminum powder (purity 99%) is fed into a plasma high-temperature reactor in a fluidization mode, the particle size of the aluminum powder is distributed at 40-60 micrometers, and the flow rate of the carrier gas is 2.5m 3 And/h, carrying the aluminum powder by 1000g/h. The temperature of the inner space of the plasma high-temperature reactor was kept at 3000 ℃, the diameter was 6cm, and the length was 35cm. The aluminum powder is rapidly liquefied and gasified in the plasma high-temperature reactor, and the liquefied aluminum and/or gasified aluminum reacts with high-temperature nitrogen in the plasma high-temperature reactor to generate aluminum nitride powder precursor. The aluminum nitride powder precursor enters an aluminum nitride powder purity lifting chamber (the internal temperature is 3000 ℃, and the output power of a plasma generator is 100 kW) to further improve the purity; then the mixture enters a grain size screening chamber of aluminum nitride powder, and is cooled (finally cooled to the temperature below the condensation temperature to the room temperature, assisted by a water chilling unit) to be condensed into superfine aluminum nitride powder; the superfine aluminum nitride powder enters a gas-solid separator for separation, and the normal absolute pressure of the whole system is 1.0 multiplied by 10 5 Pa, respectively collecting ultrafine aluminum nitride powder obtained in each region of the aluminum nitride powder particle size screening chamber and the gas-solid separator.
The detection result shows that the dispersibility of the product is relatively good, and the average particle size of the powder of the three conical powder stoppers is respectively about 150-500nm, 500-1000nm and 1-1.5 mu m. The particle size range collected by the cloth bag is 40-140nm. The purity of the aluminum nitride is 99.5 percent. The powder D50 of the three screening chambers is 1.1 mu m, and the yield of the aluminum nitride powder is 99%.
Example 3
The apparatus of example 1 was used to produce nano aluminum nitride powder using the following process:
argon and nitrogen are taken as dischargeAn electric gas, a discharge gas flow rate of 15m 3 The volume flow ratio of argon to nitrogen is 1:6; the discharge gas is sent into a plasma generator, ionized under the action of a direct current power supply, the output power of the plasma generator is 100kW, and high-temperature (average temperature 3000 ℃) argon/nitrogen mixed gas thermal plasma jet is formed and flows into a plasma high-temperature reactor; the powder feeder takes nitrogen as carrier gas, high-purity aluminum powder (purity 99%) is fed into a plasma high-temperature reactor in a fluidization mode, the particle size of the aluminum powder is distributed at 30-50 micrometers, and the flow rate of the carrier gas is 3m 3/ And h, carrying the aluminum powder by 800g/h. The temperature of the inner space of the plasma high-temperature reactor was maintained at 3200 ℃, the diameter was 6cm, and the length was 35cm. The aluminum powder is rapidly liquefied and gasified in the plasma high-temperature reactor, and the liquefied aluminum and/or gasified aluminum reacts with high-temperature nitrogen in the plasma high-temperature reactor to generate aluminum nitride powder precursor. The aluminum nitride powder precursor enters an aluminum nitride powder purity lifting chamber (the internal temperature is 3000 ℃, and the output power of a plasma generator is 100 kW) to further improve the purity; then the mixture enters a grain size screening chamber of aluminum nitride powder, and is cooled (finally cooled to the temperature below the condensation temperature to the room temperature, assisted by a water chilling unit) to be condensed into superfine aluminum nitride powder; the superfine aluminum nitride powder enters a gas-solid separator for separation, and the normal absolute pressure of the whole system is 1.0 multiplied by 10 5 Pa, respectively collecting ultrafine aluminum nitride powder obtained in each region of the aluminum nitride powder particle size screening chamber and the gas-solid separator.
The detection result shows that the dispersibility of the product is relatively good, and the average particle size of the powder of the three conical powder stoppers is respectively about 150-500nm, 500-800nm and 800nm-1.2 mu m. The particle size range collected by the cloth bag is 40-140nm. The purity of the aluminum nitride is 99.6 percent. The powder D50 of the three screening chambers is 1.0 mu m, and the yield of the aluminum nitride powder reaches 99.5 percent.
Although the invention has been described herein with reference to illustrative embodiments thereof, it should be understood that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the scope and spirit of the principles of this disclosure. More specifically, various variations and modifications may be made to the component parts and/or arrangements of the subject combination arrangement within the scope of the disclosure. In addition to variations and modifications in the component parts and/or arrangements, other uses will be apparent to those skilled in the art.
Claims (7)
1. The device for preparing high-purity superfine aluminum nitride powder by using plasma is characterized by comprising the following structure: the device comprises a plasma generator, a powder feeder, a plasma high-temperature reactor, an aluminum nitride powder purity lifting chamber, an aluminum nitride powder particle size screening chamber and a gas-solid separator; the lower end of the plasma generator is connected with a powder feeder, the lower end of the powder feeder is connected with a plasma high-temperature reactor, one side of the plasma high-temperature reactor is connected with an aluminum nitride powder purity lifting chamber, one side of the aluminum nitride powder purity lifting chamber is connected with an aluminum nitride powder particle size screening chamber, and the tail end of the aluminum nitride powder particle size screening chamber is connected with a gas-solid separator; the powder feeder feeds high-purity aluminum powder into the reactor in a fluidization mode, and the aluminum nitride powder particle size screening chamber consists of 3-5 channels of conical powder blockers connected in series or channels embedded with a plurality of sedimentation lattices; the aluminum powder completes liquefying, gasifying and nitriding processes in a plasma high-temperature reactor to generate a precursor of the condensable aluminum nitride powder, the aluminum nitride powder purity lifting chamber is equivalent to a subsequent reactor, the aluminum nitride powder purity lifting chamber uses a material with the temperature resistance of more than 3000 ℃ as a hot wall channel space of the inner wall, and is heated by a plasma generator, and the average temperature is kept to be more than 3000 ℃ through a temperature-keeping and reheating measure, so that the aluminum powder which does not complete the reaction in the precursor continuously completes the reaction in the flowing process.
2. The apparatus for preparing high purity ultrafine aluminum nitride powder by using plasma according to claim 1, wherein the plasma generator is driven by a direct current, high frequency or microwave power supply, and the argon and/or nitrogen fed by ionization breakdown forms an argon-nitrogen plasma jet or a nitrogen plasma jet with a center temperature of ten thousand K and an average temperature of more than 3000 ℃.
3. The apparatus for preparing high purity ultrafine aluminum nitride powder by using plasma according to claim 1, wherein the powder feeder uses nitrogen, argon or ammonia as a carrier gas.
4. The apparatus for preparing high purity ultrafine aluminum nitride powder by using plasma according to claim 1, wherein the high temperature reactor of the plasma simultaneously and continuously receives high Wen Yadan plasma jet or high temperature nitrogen plasma jet from a plasma generator and aluminum powder from a powder feeder; the plasma high Wen Tiqi reactor is a hot wall channel space with a material resistant to 3000 ℃ or more as an inner wall.
5. The apparatus for preparing high purity ultrafine aluminum nitride powder by using plasma according to claim 1, wherein the gas-solid separator is a bag-type vacuum or electrostatic adsorption gas-solid separator.
6. A method for preparing high purity ultrafine aluminum nitride powder by plasma, characterized in that it is carried out in the apparatus according to any one of claims 1 to 5, comprising the steps of:
argon and nitrogen are used as discharge gases or nitrogen is used as discharge gases, the discharge gases are sent into a plasma generator and ionized under the action of a power supply to form argon/nitrogen mixed gas thermal plasma jet or nitrogen thermal plasma jet with average temperature of more than 3000 ℃ and flow into a plasma high-temperature reactor;
the simple substance aluminum powder is quantitatively fed into a plasma high-temperature reactor with the internal temperature of 2000-4000 ℃ through a powder feeder, and is rapidly liquefied and gasified, and liquefied aluminum and/or gasified aluminum react with high-temperature nitrogen in the plasma high-temperature reactor to generate aluminum nitride powder precursor;
the aluminum nitride powder precursor enters an aluminum nitride powder purity lifting chamber to further improve the purity; then the aluminum nitride powder enters a grain size screening chamber, and is cooled and condensed into superfine aluminum nitride powder;
and separating the superfine aluminum nitride powder in a gas-solid separator, and collecting the superfine aluminum nitride powder obtained in each region of the aluminum nitride powder particle size screening chamber and the gas-solid separator respectively.
7. The method for preparing high-purity ultrafine aluminum nitride powder by using plasma according to claim 6, wherein when argon and nitrogen are used as discharge gases, the volume flow ratio of the argon to the nitrogen is 1:2-10, and the flow of the discharge gases is 5-20m 3 /hr; the output power of the plasma generator is 30-200 kW; aluminum powder particle size of 10-100 microns, carrier gas flow rate of 0.5-5m 3 And/h, carrying the aluminum powder by 200-3000g/h.
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| CN100434573C (en) * | 2006-04-03 | 2008-11-19 | 深圳大学 | Method for developing aluminum nitride crystal in large size through flow of plasma flame |
| CN103769594A (en) * | 2013-11-25 | 2014-05-07 | 王利民 | Technological method and device for preparing high-purity spherical superfine/nanoscale powdered materials in plasma atomization mode |
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| CN108059134A (en) * | 2017-12-07 | 2018-05-22 | 四川义结科技有限责任公司 | A kind of method that hydrogen hot plasma method prepares high-purity nm aluminium nitride |
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