Ceramic powder preparation method

Abstract

A method for preparing ceramic powder comprises: providing a plasma device; after the second ventilation, performing the third ventilation, continuing to introduce the first gas and the reaction gas into the plasma generating chamber, introducing the second gas into the plasma generating chamber at the same time, and using a radio frequency plasma power supply to dissociate the first gas, the reaction gas and the second gas to form a mixed gas plasma; after the mixed gas plasma is formed, delivering a solid raw material to the plasma generating chamber, the solid raw material is vaporized in the plasma generating chamber to form a gaseous raw material, the gaseous raw material reacts with the dissociated reaction gas in the reaction chamber to generate a process product; and obtaining ceramic powder by condensing the process product, which is beneficial to improving the uniformity and purity of the product, and the process is simple and has no by-products.

Description

Technical Field

[0001] The invention relates to the technical field of materials and manufacturing, and in particular to a method for preparing ceramic powder. Background Art

[0002] Aluminum nitride ceramics have excellent comprehensive properties, with a theoretical thermal conductivity of 320W / (m·K), excellent thermal conductivity, reliable electrical insulation, low dielectric constant and dielectric loss, non-toxicity, and a thermal expansion coefficient that matches silicon. They are very suitable for semiconductor substrates and structural packaging materials, and have great application potential in the electronics industry. Aluminum nitride powder is the raw material for preparing ceramics. Its purity, particle size, oxygen content and impurity content have an important influence on the thermal conductivity of ceramics and the subsequent sintering and forming processes.

[0003] There are many methods for synthesizing aluminum nitride powder, and the most studied ones are the following: aluminum nitride carbon thermal reduction nitridation method, direct nitridation method, self-propagating high temperature synthesis method, plasma synthesis method, chemical vapor deposition method (CVD), aerosol method, etc. Among them, the first three methods have been mainly produced on an industrial scale.

[0004] The carbothermal reduction method is to reduce and nitride the mixed powder of aluminum oxide and carbon in a flowing nitrogen atmosphere at a high temperature of 1400°C to 1800°C. The aluminum oxide powder prepared by the carbothermal reduction method is usually expensive and has poor process stability, which has become the main obstacle to the widespread promotion and application of this method.

[0005] The direct nitridation method is to heat aluminum powder in nitrogen to form aluminum nitride powder. The nitridation reaction needs to be completed at about 1000°C, and the nitridation reaction is a highly exothermic reaction. The melting point of aluminum is 660°C, which makes aluminum easy to melt during the reaction and form large molten "aluminum beads". The nitridation reaction is gas-solid diffusion controlled. The presence of "aluminum beads" makes it difficult for nitrogen to diffuse and react fully with aluminum. As the reaction proceeds, the passivated aluminum layer formed after nitridation on the surface of the aluminum powder particles will also hinder the diffusion of nitrogen to the center of the particles. Secondly, the generated passivated powder is easy to self-sinter and form agglomerates. The generated passivated aluminum powder needs to be ground. The ball milling process is easy to bring in impurities, which affects the purity of the aluminum nitride powder and increases production costs.

[0006] Self-propagating high temperature synthesis is a new type of aluminum nitride powder preparation method developed in recent years. This method uses the high chemical reaction heat generated by direct nitridation of aluminum powder to make the reaction self-sustaining to synthesize aluminum nitride. However, this method has an extremely fast reaction speed, the reaction product is very easy to agglomerate, the reaction is incomplete, and it is difficult to obtain uniform, dispersed loose powder at one time. Generally, ball milling is required to obtain the required aluminum nitride powder of a certain particle size. Generally, the obtained powder particle size is less than 10μm, but the particle size distribution is uneven.

[0007] In conclusion, the existing ceramic powder preparation methods need to be further improved. Summary of the invention

[0008] The technical problem solved by the invention is to provide a method for preparing ceramic powder to improve the performance of the ceramic powder.

[0009] In order to solve the above technical problems, the technical solution of the present invention provides a method for preparing ceramic powder, comprising: providing a plasma device, the plasma device comprising: a radio frequency plasma power supply, a reaction chamber and a plasma generating chamber located at the top of the reaction chamber, and the plasma generating chamber is connected to the reaction chamber; performing a first ventilation, introducing a first gas into the plasma generating chamber, and using a radio frequency plasma power supply to dissociate the first gas; after the first ventilation, performing a second ventilation, continuing to introduce the first gas into the plasma generating chamber, and introducing a reaction gas into the plasma generating chamber, and using a radio frequency plasma power supply to dissociate the first gas, the first gas and the reaction gas; The reaction gas is dissociated; after the second ventilation, the third ventilation is performed, the first gas and the reaction gas are continuously introduced into the plasma generating chamber, and the second gas is introduced into the plasma generating chamber at the same time, and the first gas, the reaction gas and the second gas are dissociated by using a radio frequency plasma power supply to form a mixed gas plasma; after the mixed gas plasma is formed, a solid raw material is sent to the plasma generating chamber, the solid raw material is vaporized in the plasma generating chamber to form a gaseous raw material, and the gaseous raw material reacts with the dissociated reaction gas in the reaction chamber to generate a process product; and a ceramic powder is obtained by condensing the process product.

[0010] Optionally, the plasma generating chamber has a main air inlet and a side air inlet, and the side air inlet is located at the edge of the plasma generating chamber relative to the main air inlet; the ceramic powder preparation method also includes: in the first ventilation stage, the first gas is introduced from the main air inlet and the side air inlet; in the second ventilation stage, the flow rate of the first gas in the main air inlet remains unchanged, the first gas is introduced from the side air inlet at a set reduced speed, and the reaction gas is introduced from the side air inlet at the same time; in the third ventilation stage, the flow rate of the first gas in the main air inlet remains unchanged, the flow rate of the reaction gas in the side air inlet is maintained, and the second gas is introduced from the side air inlet at the same time.

[0011] Optionally, in the third ventilation stage, the flow rate of the second gas is 1 / 4 to 1 / 3 of the flow rate of the reaction gas.

[0012] Optionally, the process parameters of the first ventilation stage include: a power output range of 30 kW to 60 kW, a gas pressure range of 50 kPa to 80 kPa in the reaction chamber, a flow rate range of 3 m / s to 40 m / s, and a flow rate of 10 m / s to 80 m / s.3 / h to 10m 3 / h; the process parameters of the second ventilation stage include: the power output range of the power supply is 50kW to 200kW, the gas pressure range of the reaction chamber is 80kPa to 110kPa, the first gas flow range is 3m 3 / h to 4m 3 / h, the flow range of the reaction gas is 2m 3 / h to 6m 3 / h; the process parameters of the third ventilation stage include: the power output range of the power supply is 60kW to 200kW, the gas pressure range of the reaction chamber is 80kPa to 110kPa, the first gas flow range is 3m 3 / h to 4m 3 / h, the reaction gas flow range is 2m 3 / h to 6m 3 / h, the second gas flow range is 0.5m 3 / h to 2m 3 / h.

[0013] Optionally, the method for condensing the process product includes: setting a plurality of condensation gas inlets on the side wall of the reaction chamber, the plurality of condensation gas inlets are located below the plasma generating chamber and are evenly arranged around the central axis of the reaction chamber; introducing condensation gas from the plurality of condensation gas inlets, and blowing the condensation gas toward the process product.

[0014] Optionally, there are a plurality of guide pipes extending from outside the reaction chamber through the plurality of condensing gas inlets to inside the reaction chamber, and the condensed gas flows into the reaction chamber from the plurality of guide pipes. The plurality of guide pipes are located in the reaction chamber with their outlets facing downward, and an angle between an extension direction of each guide pipe and a tangent direction of a side wall of the reaction chamber where the guide pipe is located ranges from 30° to 60°.

[0015] Optionally, the condensed gas includes nitrogen.

[0016] Optionally, the flow range of the condensed gas is 3m 3 / h to 8m 3 / h.

[0017] Optionally, the method for condensing the process product also includes: providing a sedimentation collection chamber connected to the reaction chamber, the sedimentation collection chamber having a plurality of fans, the process product enters the sedimentation collection chamber from the reaction chamber, and forms the ceramic powder in the sedimentation collection chamber.

[0018] Optionally, the first gas includes argon, the reaction gas includes nitrogen, and the second gas includes hydrogen.

[0019] Optionally, the material of the raw material includes aluminum.

[0020] Optionally, the raw material is in the form of one or more of aluminum powder, aluminum wire, aluminum line, aluminum rod, aluminum tube, aluminum ingot, aluminum bean, aluminum liquid, and aluminum vapor.

[0021] Optionally, the material of the ceramic powder is aluminum nitride; the ceramic powder is a spherical powder; except for aluminum metal, the purity of the ceramic powder is greater than or equal to 99.999%; the particle size distribution of the ceramic powder: D50 ranges from 20 nanometers to 300 nanometers, wherein the ratio of D90 to D50 is less than 3, and the ratio of D10 to D50 is greater than 0.3.

[0022] Optionally, the purity of the raw material is greater than or equal to 99.999%.

[0023] Optionally, the method of feeding the raw material into the plasma generating chamber includes: adding the raw material from the outside of the plasma generating chamber to the inside of the plasma generating chamber through a feeding device or pre-setting the raw material in the plasma generating chamber.

[0024] Optionally, the purity range of the plasma gas source is greater than or equal to 99.999%.

[0025] Compared with the prior art, the technical solution of the embodiment of the present invention has the following beneficial effects:

[0026] In the ceramic powder preparation method provided by the technical solution of the present invention, a solid raw material is sent to the plasma generating chamber, the solid raw material is vaporized in the plasma generating chamber to form a gaseous raw material, the gaseous raw material reacts with the dissociated reaction gas in the reaction chamber to generate a process product, and the ceramic powder is obtained by condensing the process product. On the one hand, a radio frequency plasma power source is used to form a high-temperature plasma, and there is no secondary pollution of the electrode. The radio frequency plasma flame can fully heat the raw material and the atmosphere of the reaction chamber is controllable, which is beneficial to improve the uniformity and purity of the product; on the other hand, a stable thermal plasma is generated in the reaction chamber, which is beneficial to control the uniformity of the product; furthermore, the reaction gas is dissociated as a plasma to provide a reaction heat source, and also as a reaction gas to react with the raw material to form a process product. The process is simple and there are no by-products.

[0027] Furthermore, the reaction gas includes nitrogen, the raw material includes aluminum, and the obtained ceramic powder material is aluminum nitride. Since the temperature of the thermal plasma flame is as high as 10,000°C, the aluminum raw material can be instantly melted and vaporized at such a high temperature, and the aluminum can not only be nitrided instantly, but also the nitridation reaction of the aluminum will not be prevented from further proceeding due to the generation of a solid nitride film, which is conducive to improving the production efficiency and product quality of the product.

[0028] Furthermore, the first gas includes argon, the reaction gas includes nitrogen, and the second gas includes hydrogen. The plasma formed by the mixed gas of argon, nitrogen and hydrogen has the characteristics of high thermal enthalpy and high thermal conductivity, which can instantly vaporize the high-purity aluminum source, and the aluminum and nitrogen in the gaseous state can quickly and fully react to form aluminum nitride, thereby improving the conversion efficiency and production capacity of the reaction process. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is a flow chart of a method for preparing ceramic powder in one embodiment of the present invention;

[0030] Figure 2 and Figure 3 It is a schematic structural diagram of a ceramic powder device in one embodiment of the present invention. DETAILED DESCRIPTION

[0031] As described in the background art, the existing ceramic powder preparation method has the problems of complex process, long process, generation of by-products, difficulty in preparing fine particle size and high purity powder, etc. The existing ceramic powder preparation method needs to be further improved.

[0032] In order to solve the above problems, the technical solution of the present invention provides a method for preparing ceramic powder, wherein a solid raw material is sent to the plasma generating chamber, the solid raw material is vaporized in the plasma generating chamber to form a gaseous raw material, the gaseous raw material reacts with the dissociated reaction gas in the reaction chamber to generate a process product, and the ceramic powder is obtained by condensing the process product. On the one hand, a radio frequency plasma power source is used to form a high-temperature plasma, and there is no secondary pollution of the electrode. The radio frequency plasma flame can fully heat the raw material and the atmosphere of the reaction chamber is controllable, which is beneficial to improve the uniformity and purity of the product; on the other hand, a stable thermal plasma is generated in the reaction chamber, which is beneficial to control the uniformity of the product; furthermore, the reaction gas is dissociated as a plasma to provide a reaction heat source, and also as a reaction gas to react with the raw material to form a process product. The process is simple and there are no by-products.

[0033] In order to make the above-mentioned objects, features and beneficial effects of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0034] Figure 1 1 is a flow chart of a method for preparing ceramic powder in one embodiment of the present invention.

[0035] Please refer to Figure 1 , the ceramic powder preparation method comprises the following steps:

[0036] Step S101, providing a plasma device, wherein the plasma device comprises: a radio frequency plasma power supply, a reaction chamber, and a plasma generating chamber located at the top of the reaction chamber, and the plasma generating chamber is connected to the reaction chamber;

[0037] Step S102, performing first ventilation, introducing a first gas into the plasma generating chamber, and using a radio frequency plasma power source to dissociate the first gas;

[0038] Step S103, after the first ventilation, performing the second ventilation, continuing to introduce the first gas into the plasma generating chamber, introducing the reaction gas into the plasma generating chamber, and using a radio frequency plasma power supply to dissociate the first gas and the reaction gas;

[0039] Step S104, after the second ventilation, performing the third ventilation, continuing to introduce the first gas and the reaction gas into the plasma generating chamber, introducing the second gas into the plasma generating chamber at the same time, and using a radio frequency plasma power source to dissociate the first gas, the reaction gas and the second gas to form a mixed gas plasma;

[0040] Step S105, after the mixed gas plasma is formed, the solid raw material is sent to the plasma generating chamber, the solid raw material is vaporized in the plasma generating chamber to form a gaseous raw material, and the gaseous raw material reacts with the dissociated reaction gas in the reaction chamber to generate a process product;

[0041] Step S106, obtaining ceramic powder by condensing the process product.

[0042] The following is a detailed description with reference to the accompanying drawings.

[0043] Figure 2 and Figure 3 It is a schematic structural diagram of a ceramic powder device in one embodiment of the present invention.

[0044] Execute step S101, please refer to Figure 2 , a plasma device is provided, which includes: a radio frequency plasma power supply, a reaction chamber 200 and a plasma generating chamber 201 located at the top of the reaction chamber 200, and the plasma generating chamber 201 is connected to the reaction chamber 200.

[0045] The plasma generating chamber 201 has a main air inlet 202 and a side air inlet 203 . The side air inlet 203 is located at the edge of the plasma generating chamber 201 relative to the main air inlet 202 .

[0046] The radio frequency coil and the magnetic field coil 204 of the radio frequency plasma power supply are disposed around the side wall of the plasma generating chamber 201 .

[0047] The radio frequency plasma power supply is used to electrolyze the gas in the plasma generating chamber 201 to convert it into plasma.

[0048] Please continue to refer to Figure 1 and Figure 2 , perform first ventilation, introduce a first gas into the plasma generating chamber, and use a radio frequency plasma power supply to dissociate the first gas.

[0049] In this embodiment, the first gas includes argon.

[0050] Specifically, in the first ventilation stage, the first gas is introduced from the main air inlet 202 and the side air inlet 203 .

[0051] The process parameters of the first ventilation stage include: the power output range of the power supply is 30kW to 60kW, the gas pressure range of the reaction chamber is 50kPa to 80kPa, the flow range of the first gas is 3m 3 / h to 10m 3 / h.

[0052] In this embodiment, the process parameters of the first ventilation stage include: the power output range of the power supply is 50 kW to 60 kW, the gas pressure range of the reaction chamber is 50 kPa to 80 kPa, the flow rate range of the first gas is 7 m / s. 3 / h to 8m 3 / h.

[0053] Please continue to refer to Figure 1 and Figure 2 After the first ventilation, the second ventilation is performed, and the first gas is continuously introduced into the plasma generating chamber 201, and the reaction gas is introduced into the plasma generating chamber 201 at the same time, and a radio frequency plasma power source is used to dissociate the first gas and the reaction gas.

[0054] Specifically, in the second ventilation stage, the flow rate of the first gas in the main air inlet 202 remains unchanged, the first gas is introduced from the side air inlet at a set reduced speed, and the reaction gas is introduced from the side air inlet 203 at the same time.

[0055] Through the second ventilation stage, the first gas introduced from the side gas inlet is slowly replaced by the reaction gas, and through the second ventilation stage, a mixed ion gas of the first gas and the reaction gas is established in the plasma generating chamber 201 .

[0056] In this embodiment, the reaction gas includes nitrogen. In this embodiment, through the second ventilation stage, a mixed ion gas of argon and nitrogen is established in the plasma generating chamber 201.

[0057] The process parameters of the second ventilation stage include: the power output range of the power supply is 50kW to 200kW, the gas pressure range of the reaction chamber is 80kPa to 110kPa, the first gas flow range is 3m 3 / h to 4m 3 / h, the flow range of the reaction gas is 2m 3 / h to 6m 3 / h.

[0058] In this embodiment, the process parameters of the second ventilation stage include: the power output range of the power supply is 80 kW to 100 kW, the gas pressure range of the reaction chamber is 80 kPa to 100 kPa, the first gas flow range is 3 m / s 3 / h to 4m 3 / h, the flow range of the reaction gas is 3m 3 / h to 5m 3 / h.

[0059] Please continue to refer to Figure 1 and Figure 2 After the second ventilation, the third ventilation is performed, and the first gas and the reaction gas are continuously introduced into the plasma generating chamber 201, and the second gas is introduced into the plasma generating chamber at the same time, and a radio frequency plasma power source is used to dissociate the first gas, the reaction gas and the second gas to form a mixed gas plasma.

[0060] Specifically, in the third ventilation stage, the flow rate of the first gas in the main gas inlet 202 remains unchanged, the flow rate of the reaction gas in the side gas inlet 203 is maintained, and the second gas is introduced from the side gas inlet 203 at the same time.

[0061] Through the second ventilation stage, the second gas and the reaction gas are introduced from the side gas inlet 203 to establish a mixed gas ion of the first gas, the reaction gas and the second gas in the plasma generating chamber 201. Through the three-step ventilation, the performance of the obtained mixed gas ion is stable, which is conducive to controlling the subsequent reaction, and then obtaining a ceramic powder product with uniform particle size.

[0062] The process parameters of the third ventilation stage include: the power output range of the power supply is 60kW to 200kW, the gas pressure range of the reaction chamber is 80kPa to 110kPa, the first gas flow range is 3m 3 / h to 4m 3 / h, the reaction gas flow range is 2m 3 / h to 6m 3 / h, the second gas flow range is 0.5m 3 / h to 2m 3 / h.

[0063] In this embodiment, the process parameters of the third ventilation stage include: the power output range of the power supply is 80kW to 100kW, the gas pressure range of the reaction chamber is 80kPa to 100kPa, the first gas flow range is 3m 3 / h to 4m 3 / h, the reaction gas flow range is 3m 3 / h to 5m 3 / h, the second gas flow range is 1m 3 / h to 1.5m 3 / h.

[0064] In the third ventilation stage, the flow rate of the second gas is 1 / 4 to 1 / 3 of the flow rate of the reaction gas.

[0065] The second gas includes hydrogen. In this embodiment, the argon, nitrogen and hydrogen mixed gas ions formed have the characteristics of high thermal enthalpy and high thermal conductivity, which can instantly vaporize the high-purity aluminum source, and the aluminum and nitrogen in the gaseous state can quickly and fully react to form aluminum nitride, thereby improving the conversion efficiency and production capacity of the reaction process.

[0066] The gas source purity of the plasma is greater than or equal to 99.999%. The gas source of the plasma includes the first gas, the reaction gas and the second gas. Improving the gas source purity of the plasma is conducive to improving the purity of the ceramic powder product finally obtained.

[0067] Please continue to refer to Figure 1 and Figure 2 After the mixed gas plasma is formed, the solid raw material is sent to the plasma generating chamber, the solid raw material 205 is vaporized in the plasma generating chamber to form a gaseous raw material, and the gaseous raw material reacts with the dissociated reaction gas in the reaction chamber to generate a process product 208.

[0068] A radio frequency plasma power source is used to generate high-temperature plasma, and there is no secondary pollution of the electrode. The radio frequency plasma flame can fully heat the raw materials and the atmosphere in the reaction chamber is controllable, which is beneficial to improving the uniformity and purity of the product. The reaction gas is dissociated as plasma to provide a reaction heat source, and also as a product of the reaction gas and the raw material reaction to form the process. The process is simple and there are no by-products.

[0069] The material of the raw material includes aluminum.

[0070] Specifically, since the temperature of the thermal plasma flame is as high as 10,000°C, the aluminum raw material can be instantly melted and vaporized at such a high temperature. Not only can the aluminum be nitrided instantly, but the production of a solid nitride film will not prevent the aluminum nitridation reaction from further proceeding, which is beneficial to improving product production efficiency and product quality.

[0071] The raw material may be in the form of one or more of aluminum powder, aluminum wire, aluminum rod, aluminum tube, aluminum ingot, aluminum bean, aluminum liquid, and aluminum vapor. In this embodiment, the raw material is in the form of aluminum wire.

[0072] The purity of the raw material is greater than or equal to 99.999%. Improving the purity of the raw material is conducive to improving the purity of the ceramic powder product finally obtained.

[0073] The method of feeding the raw material into the plasma generating chamber includes: adding the raw material from the outside of the plasma generating chamber 201 to the inside of the plasma generating chamber 201 through a feeding device or pre-setting the raw material in the plasma generating chamber 201 .

[0074] In this embodiment, the top wall of the plasma generating chamber 201 has a feed port 206 , and the aluminum wire raw material is added into the interior of the plasma generating chamber 201 through the feed port 206 .

[0075] Please continue to refer to Figure 1 and Figure 2 , by condensing the process product 208, ceramic powder 213 is obtained.

[0076] In this embodiment, the method for condensing the process product includes: setting a plurality of condensation gas inlets 209 on the side wall of the reaction chamber 200, wherein the plurality of condensation gas inlets 209 are located below the plasma generating chamber 201 and are evenly arranged around the central axis of the reaction chamber 200; introducing condensation gas from the plurality of condensation gas inlets 209, and blowing the condensation gas toward the process product.

[0077] In this embodiment, the arrangement of the plurality of condensing gas inlets 209 on the side wall of the reaction chamber 200 is described in detail in detail. Figure 3 , Figure 3 yes Figure 2 Schematic diagram of the top view of area A in the middle.

[0078] Please refer to Figure 3There are also a plurality of guide pipes 210 from the outside of the reaction chamber 200 through the plurality of condensed gas inlet ports 209 to the inside of the reaction chamber 200, and the condensed gas is passed into the reaction chamber 200 from the plurality of guide pipes 210. The outlets of the plurality of guide pipes 210 located in the reaction chamber 200 are arranged downward, and an angle a between an extension direction of each guide pipe 210 and a tangent direction of a side wall of the reaction chamber 210 where each guide pipe 210 is located ranges from 30° to 60°.

[0079] The direction in which the guide tube 210 is arranged enables the airflow of the condensed gas to move in a direction surrounding the central axis of the reaction chamber 200. In addition, the plurality of guide tubes 210 are evenly arranged around the central axis of the reaction chamber 200, so that the process product is fully condensed and the uniformity of the particle size of the formed spherical ceramic powder is improved.

[0080] In this embodiment, the condensed gas includes nitrogen.

[0081] In this embodiment, the flow rate range of the condensed gas is 3m 3 / h to 8m 3 / h.

[0082] In this embodiment, the method for condensing the process product also includes: providing a sedimentation collection chamber 211 connected to the reaction chamber 200, and the sedimentation collection chamber 211 has a plurality of fan blades 212; the process product enters the sedimentation collection chamber 211 from the reaction chamber 200, and forms the ceramic powder 213 in the sedimentation collection chamber 211.

[0083] In this embodiment, the sedimentation collection chamber 211 is arranged in parallel with the reaction chamber 200, and the side wall of the reaction chamber 200 has an outlet 214, and the outlet 214 is located below the plurality of guide tubes 210; the sedimentation collection chamber 211 is connected to the reaction chamber 200 through the outlet 214. A small amount of ceramic powder 213 product is also provided at the bottom of the reaction chamber 200. The process product 208 is allowed to enter the sedimentation collection chamber 211 to obtain the ceramic powder 213 product. The sedimentation collection chamber 211 is separately arranged relative to the reaction chamber 200, which can reduce the adhesion of the product in the reaction chamber 200 and reduce the difficulty of cleaning the reaction chamber 200. In other embodiments, the sedimentation collection chamber 211 can also be arranged at the bottom of the reaction chamber 200.

[0084] In this embodiment, the side wall of the sedimentation collection chamber 211 also has an exhaust gas outlet 215 .

[0085] The material of the ceramic powder is aluminum nitride.

[0086] The ceramic powder is spherical powder.

[0087] The purity of the ceramic powder is greater than or equal to 99.999%, except for aluminum. This means that the obtained ceramic powder product may contain aluminum, and after removing the aluminum, the content of aluminum nitride in the ceramic powder is greater than or equal to 99.999%.

[0088] The particle size distribution of the ceramic powder: D50 ranges from 20 nanometers to 300 nanometers, wherein the ratio of D90 to D50 is less than 3, and the ratio of D10 to D50 is greater than 0.3. D represents the diameter of the powder particles, D50 represents the diameter at the cumulative 50% point, D10 represents the diameter at the cumulative 10% point, and D90 represents the diameter at the cumulative 90% point. In this embodiment, the obtained ceramic powder particle size: D50 is 100 nanometers, D90 is less than 300 nanometers, and D10 is greater than 30 nanometers.

[0089] The aluminum nitride ceramic powder has the characteristics of high purity and small particle size, and can reduce the sintering temperature of aluminum nitride ceramic powder to prepare aluminum nitride ceramics, thereby preparing aluminum nitride ceramics with high thermal conductivity, meeting the semiconductor industry's demand for high thermal conductivity aluminum nitride ceramic materials.

[0090] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined by the claims.

Claims

1. A method for preparing ceramic powder, characterized in that: include: A plasma device is provided, the plasma device comprising: a radio frequency plasma power supply, a reaction chamber and a plasma generating chamber located at the top of the reaction chamber, and the plasma generating chamber is connected to the reaction chamber; Performing a first ventilation, introducing a first gas into the plasma generating chamber, and using a radio frequency plasma power source to dissociate the first gas; After the first ventilation, the second ventilation is performed, the first gas is continuously introduced into the plasma generating chamber, and the reaction gas is introduced into the plasma generating chamber at the same time, and the first gas and the reaction gas are dissociated by using a radio frequency plasma power supply; After the second ventilation, the third ventilation is performed, the first gas and the reaction gas are continuously introduced into the plasma generating chamber, and the second gas is introduced into the plasma generating chamber at the same time, and the first gas, the reaction gas and the second gas are dissociated by using a radio frequency plasma power supply to form a mixed gas plasma; After the mixed gas plasma is formed, the solid raw material is sent to the plasma generating chamber, the solid raw material is vaporized in the plasma generating chamber to form a gaseous raw material, and the gaseous raw material reacts with the dissociated reaction gas in the reaction chamber to generate a process product; By condensing the process product, ceramic powder is obtained.

2. The method for preparing ceramic powder according to claim 1, characterized in that: The plasma generating chamber has a main air inlet and a side air inlet, and the side air inlet is located at the edge of the plasma generating chamber relative to the main air inlet; the ceramic powder preparation method also includes: in the first ventilation stage, the first gas is introduced from the main air inlet and the side air inlet; in the second ventilation stage, the flow rate of the first gas in the main air inlet remains unchanged, the first gas is introduced from the side air inlet at a set speed reduction, and the reaction gas is introduced from the side air inlet at the same time; in the third ventilation stage, the flow rate of the first gas in the main air inlet remains unchanged, the flow rate of the reaction gas in the side air inlet is maintained, and the second gas is introduced from the side air inlet at the same time.

3. The method for preparing ceramic powder according to claim 2, characterized in that: In the third ventilation stage, the flow rate of the second gas is 1 / 4 to 1 / 3 of the flow rate of the reaction gas.

4. The method for preparing ceramic powder according to claim 1, characterized in that: The process parameters of the first ventilation stage include: the power output range of the power supply is 30kW to 60kW, the gas pressure range of the reaction chamber is 50kPa to 80kPa, the flow rate range of the first gas is 3m 3 / h to 10m 3 / h; the process parameters of the second ventilation stage include: the power output range of the power supply is 50kW to 200kW, the gas pressure range of the reaction chamber is 80kPa to 110kPa, the first gas flow range is 3m 3 / h to 4m 3 / h, the flow range of the reaction gas is 2m 3 / h to 6m 3 / h; the process parameters of the third ventilation stage include: the power output range of the power supply is 60kW to 200kW, the gas pressure range of the reaction chamber is 80kPa to 110kPa, the first gas flow range is 3m 3 / h to 4m 3 / h, the reaction gas flow range is 2m 3 / h to 6m 3 / h, the second gas flow range is 0.5m 3 / h to 2m 3 / h.

5. The method for preparing ceramic powder according to claim 1, characterized in that: The method for condensing the process product comprises: setting a plurality of condensation gas inlets on the side wall of the reaction chamber, the plurality of condensation gas inlets are located below the plasma generating chamber and are evenly arranged around the central axis of the reaction chamber; introducing condensation gas from the plurality of condensation gas inlets, and blowing the condensation gas toward the process product.

6. The method for preparing ceramic powder according to claim 5, characterized in that: There are also a number of guide pipes from the outside of the reaction chamber through the number of condensed gas inlets to the reaction chamber. The condensed gas passes into the reaction chamber from the number of guide pipes. The outlets of the number of guide pipes located in the reaction chamber are arranged downward, and the angle between the extension direction of each guide pipe and the tangent direction of the side wall of the reaction chamber where the guide pipe is located ranges from 30° to 60°.

7. The method for preparing ceramic powder according to claim 5, characterized in that: The condensed gas includes nitrogen.

8. The method for preparing ceramic powder according to claim 5, characterized in that: The flow range of the condensed gas is 3m 3 / h to 8m 3 / h.

9. The method for preparing ceramic powder according to claim 5, characterized in that: The method for condensing the process product also includes: providing a sedimentation collection chamber connected to the reaction chamber, the sedimentation collection chamber having a plurality of fans, the process product enters the sedimentation collection chamber from the reaction chamber, and forms the ceramic powder in the sedimentation collection chamber.

10. The method for preparing ceramic powder according to claim 1, characterized in that: The first gas includes argon, the reaction gas includes nitrogen, and the second gas includes hydrogen.

11. The method for preparing ceramic powder according to claim 10, characterized in that: The material of the raw material includes aluminum.

12. The method for preparing ceramic powder according to claim 11, characterized in that: The form of the raw material includes one or more of aluminum powder, aluminum wire, aluminum line, aluminum rod, aluminum tube, aluminum ingot, aluminum bean, aluminum liquid, and aluminum vapor.

13. The method for preparing ceramic powder according to claim 11, characterized in that: The material of the ceramic powder is aluminum nitride; the ceramic powder is spherical powder; except for aluminum metal, the purity of the ceramic powder is greater than or equal to 99.999%; the particle size distribution of the ceramic powder: D50 ranges from 20 nanometers to 300 nanometers, wherein the ratio of D90 to D50 is less than 3, and the ratio of D10 to D50 is greater than 0.

3.

14. The method for preparing ceramic powder according to claim 11, characterized in that: The purity of the raw material is greater than or equal to 99.999%.

15. The method for preparing ceramic powder according to claim 1, characterized in that: The method of feeding the raw material into the plasma generating chamber includes: adding the raw material from the outside of the plasma generating chamber to the inside of the plasma generating chamber through a feeding device or pre-setting the raw material in the plasma generating chamber.

16. The method for preparing ceramic powder according to claim 1, characterized in that: The purity range of the plasma gas source is greater than or equal to 99.999%.

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