CN117963855A - Aluminum nitride powder purification method - Google Patents
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- C01B21/00—Nitrogen; Compounds thereof
- C01B21/06—Binary compounds of nitrogen with metals, with silicon, or with boron, or with carbon, i.e. nitrides; Compounds of nitrogen with more than one metal, silicon or boron
- C01B21/072—Binary compounds of nitrogen with metals, with silicon, or with boron, or with carbon, i.e. nitrides; Compounds of nitrogen with more than one metal, silicon or boron with aluminium
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Abstract
The invention relates to a purification method of aluminum nitride powder, which belongs to the purification technology of aluminum nitride powder, and comprises the steps of prefabricating raw materials, mixing and heating, cleaning and grinding, detecting primary products and finished products, loading aluminum nitride powder into a crucible, putting the crucible into a PVT (polyvinyl chloride) growth furnace, vacuumizing, carrying out stepped heat treatment on the aluminum nitride powder in a pure nitrogen atmosphere, taking out the aluminum nitride powder, grinding and sieving the aluminum nitride powder, taking the sieved aluminum nitride powder as a basic purification raw material, mixing the sieved aluminum nitride powder with an auxiliary mixture which can be decomposed at a high temperature and volatilizes carried impurities to obtain a powder mixture, loading the powder mixture into the crucible, heating the powder mixture in a high-temperature furnace to obtain primary mixed powder, cleaning, filtering, drying in vacuum, calcining for 2 hours, crushing and grinding under the protection of high-purity inert gas, thus obtaining the final aluminum nitride powder, detecting the carbon content of the primary products and the final products.
Description
Technical Field
The invention relates to the technical field of aluminum nitride powder purification, in particular to an aluminum nitride powder purification method.
Background
The aluminum nitride powder is a novel inorganic material and has very excellent comprehensive properties in the aspects of light, heat, electricity, machinery and the like, so that the aluminum nitride powder can be widely applied to various fields of metallurgy, electronics, national defense, machinery and the like, so that people pay more and more attention to the research and the application development of the aluminum nitride powder, the property characteristics of the aluminum nitride powder directly influence the functions and the application of the aluminum nitride powder, and the large-scale industrial production of the aluminum nitride powder is widely focused and researched in the industry and the scientific community of various countries. Aluminum nitride must be synthesized by reaction at high temperature. The industry mainly comprises a direct aluminum powder nitriding method and an aluminum oxide carbothermic reduction method.
In the Chinese patent of invention with publication number CN110015648B, a high-purity aluminum nitride powder and a purification method of the aluminum nitride powder are proposed, and a reducing gas is utilized to carry out high-temperature gas washing treatment on a synthesis cavity where the mixed powder of Al powder and AlN powder is located, so as to remove oxygen in the synthesis cavity; and removing hydroxide in the mixed powder impurities at a first purification temperature under a vacuum state, removing carbon in the mixed powder impurities at a second purification temperature, and removing alumina in the mixed powder impurities by using the Al steam at a third purification temperature. The purification method is simple, the decomposition of AlN powder in the purification process is effectively inhibited by the reasonable design of the impurity removal sequence and the corresponding purification steps and the addition of Al powder, the loss of raw materials is reduced, and the aluminum nitride powder obtained by testing through a high-frequency combustion infrared absorption method and an inert gas pulse infrared thermal conductivity method has the carbon content of 42PPM, the oxygen content of 220PPM and high purity.
In the Chinese patent of invention with publication number CN114105110B, a preparation method of high-purity aluminum nitride is proposed, firstly, the azidodecyl is modified by propiolic acid, an azido group on the azidodecyl and a carbon-carbon double bond on the propiolic acid react to generate a tri-nitrogen dioxy conjugated five-membered ring to prepare modified azidodecyl, the unstable azido group is changed into a stable conjugated five-membered ring structure, nitrogen is not easily generated in the subsequent grinding process of aluminum hydroxide, and simultaneously carboxyl on the modified azidodecyl can react with the aluminum hydroxide to be grafted on the surface of the aluminum hydroxide, so that the aluminum hydroxide is not easily agglomerated in a dispersing way; the aluminum hydroxide is ground and then calcined to prepare a precursor, the modified azidodecane is carbonized in a nitrogen atmosphere and decomposed into nitrogen and hydrogen, so that an internal gap can be generated, the aluminum oxide film formed by dehydration of the aluminum hydroxide in the calcining process is prevented from influencing the calcining efficiency, meanwhile, the generated carbon and hydrogen can reduce the aluminum oxide into aluminum, and the generated nitrogen can directly react with the reduced aluminum to generate aluminum nitride, so that extrusion is avoided, and the calcining effect is improved; and (3) carrying out secondary grinding after calcination and cooling, removing large particles generated by sintering in the calcination process, preparing precursor small particles, carrying out fluidized bed reaction, reacting excessive carbon in the precursor small particles by using carbon dioxide and nitrogen as carrier gas, generating carbon monoxide, further removing trace oxygen elements remained in the precursor small particles by generating carbon monoxide, and reacting aluminum which cannot be completely reacted in the calcination process and aluminum reduced by the carbon monoxide by using the nitrogen to generate aluminum nitride, thereby improving the purity of the prepared aluminum nitride.
The process proposed in the above two references has a lifting space when purifying the powder, and the purity of the final purified aluminum nitride powder is still not high enough, and the present application has been proposed in view of this.
Disclosure of Invention
In order to overcome the technical defects of the prior art, the invention provides the aluminum nitride powder purification method, wherein basic purification raw materials are prepared in a sectional heat treatment mode in a raw material prefabrication stage, impurities in aluminum nitride powder are reduced from the source, and impurities in the aluminum nitride powder can be effectively separated in a secondary heat treatment process by adding an auxiliary mixture which can be decomposed at high temperature and volatilize the impurities in the secondary process, so that the method has a further purification effect.
The technical scheme adopted by the invention is as follows: the method comprises the following steps:
S1, prefabricating raw materials, putting aluminum nitride powder into a crucible, putting the crucible into a PVT (polyvinyl butyral) growth furnace, vacuumizing, carrying out stepped heat treatment on the aluminum nitride powder under a pure nitrogen atmosphere, taking out the aluminum nitride powder, grinding and sieving the aluminum nitride powder, taking the sieved aluminum nitride powder as a basic purification raw material, preparing the basic purification raw material in a sectional heat treatment mode in a raw material prefabricating stage, and reducing impurities in the aluminum nitride powder from the source.
S2, mixing and heating, namely mixing the screened aluminum nitride powder obtained in the step S1 with an auxiliary mixture which can be decomposed at high temperature and volatilized with impurities to obtain a powder mixture, then placing the powder mixture into a crucible, and heating the crucible in a high-temperature furnace to obtain primary mixed powder, wherein impurities in the aluminum nitride powder can be effectively separated in a secondary heat treatment process in a mode of adding the auxiliary mixture which can be decomposed at high temperature and volatilized with the impurities in a secondary processing process, so that a further purification effect is achieved;
s3, cleaning and grinding, namely cleaning, filtering, vacuum drying and calcining the primary mixed powder for 2 hours, and then crushing and grinding under the protection of high-purity inert gas to obtain the final product aluminum nitride powder;
s4, detecting the primary product and the finished product, and detecting the carbon content of the aluminum nitride powder screened after heat treatment and the aluminum nitride powder of the final finished product.
Preferably, the specific method of step S1 is as follows: loading aluminum nitride powder into a crucible, placing the crucible into a PVT growth furnace after loading, vacuumizing the PVT growth furnace to below 10 < -5 > mbar, then filling nitrogen into the PVT growth furnace, performing heat treatment on the aluminum nitride powder in a pure nitrogen atmosphere, taking out the aluminum nitride powder after heat treatment, adding the aluminum nitride powder into a ball mill for grinding, sieving with a 100-300-mesh sieve after grinding, and taking the sieved aluminum nitride powder as a basic purification raw material.
Preferably, the heat treatment is a stepwise heat treatment, in particular:
removing hydroxide in aluminum nitride powder impurities at 800-1000 ℃;
removing carbon in aluminum nitride powder impurities at 1700-1800 ℃;
And (3) at 1900-2200 ℃, high-purity nitrogen is filled, the pressure is 80-120KPa, al powder in the aluminum nitride powder forms Al steam, aluminum oxide in aluminum nitride powder impurities is removed by using the Al steam, then the temperature is reduced, and the aluminum nitride powder is obtained through manual crushing and grinding treatment under the protection of high-purity inert gas.
Preferably, the specific method in step S2 is as follows: mixing the screened aluminum nitride powder obtained in the step S1 with an auxiliary mixture which can be decomposed at high temperature and volatilizes carried impurities according to the weight ratio of 100:0.5-1.0 to obtain a powder mixture, filling the powder mixture into a crucible, and then placing the crucible into a high-temperature furnace again for heat treatment.
Preferably, the auxiliary mixture which can be decomposed at high temperature and carries impurities for volatilization is specifically a mixture of ammonium fluoride, sodium azide and aluminum hydroxide, wherein the NaN3 content of the sodium azide is more than or equal to 99.0wt% and the granularity is less than or equal to 0.15mm.
Preferably, the specific control flow of the heat treatment which is placed in the high-temperature furnace again is as follows: and (3) before heating, pumping out the gas in the furnace to form vacuum, controlling the temperature of the furnace to be raised to 500-600 ℃, preserving heat for 1-2 hours, then charging pure nitrogen, raising the temperature of the furnace to 700-800 ℃, preserving heat for 0.5-1 hour, and naturally cooling to room temperature to obtain primary mixed powder, wherein the temperature raising rate is 5 ℃/min.
Preferably, the specific method in step S3 is as follows: placing the primary mixed powder in a dry beaker, cleaning for 3-5 times by using a cleaning liquid, placing the product in a cleaning liquid with the volume of 20-40 times, stirring for 13 minutes, carrying out suction filtration, placing the product in a vacuum drying chamber for drying, drying at the drying temperature of 50-60 ℃ for 40-60 minutes until moisture is thoroughly separated, placing the dried product in dry air, calcining at the temperature of 660-680 ℃ for 2 hours, and then carrying out crushing and grinding under the protection of high-purity inert gas, thereby obtaining the final product aluminum nitride powder.
Preferably, the cleaning solution is obtained by mixing 100 parts of absolute ethyl alcohol with 10 parts of hydrochloric acid solution with the concentration of 0.08-0.12 mol/L.
The beneficial effects of the invention are as follows: in the preparation stage of the raw materials, basic purification raw materials are prepared in a sectional heat treatment mode, impurities in aluminum nitride powder are reduced from the source, and impurities in the aluminum nitride powder can be effectively separated in the secondary heat treatment process by adding an auxiliary mixture which can be decomposed at high temperature and volatilize the impurities in the secondary process, so that a further purification effect is achieved.
Drawings
Fig. 1 is a basic flow chart of the present invention.
Detailed Description
The invention is further described below with reference to the accompanying drawings:
As shown in fig. 1, the present embodiment provides a method for purifying aluminum nitride powder, comprising the steps of:
S1, prefabricating raw materials, putting aluminum nitride powder into a crucible, putting the crucible into a PVT (polyvinyl butyral) growth furnace, vacuumizing, carrying out stepped heat treatment on the aluminum nitride powder under a pure nitrogen atmosphere, taking out the aluminum nitride powder, grinding and sieving the aluminum nitride powder, taking the sieved aluminum nitride powder as a basic purification raw material, preparing the basic purification raw material in a sectional heat treatment mode in a raw material prefabricating stage, and reducing impurities in the aluminum nitride powder from the source.
S2, mixing and heating, namely mixing the screened aluminum nitride powder obtained in the step S1 with an auxiliary mixture which can be decomposed at high temperature and volatilized with impurities to obtain a powder mixture, then placing the powder mixture into a crucible, and heating the crucible in a high-temperature furnace to obtain primary mixed powder, wherein impurities in the aluminum nitride powder can be effectively separated in a secondary heat treatment process in a mode of adding the auxiliary mixture which can be decomposed at high temperature and volatilized with the impurities in a secondary processing process, so that a further purification effect is achieved;
s3, cleaning and grinding, namely cleaning, filtering, vacuum drying and calcining the primary mixed powder for 2 hours, and then crushing and grinding under the protection of high-purity inert gas to obtain the final product aluminum nitride powder;
S4, detecting the primary product and the finished product, detecting the carbon content of the aluminum nitride powder screened after heat treatment and the aluminum nitride powder of the final product, and confirming the reduction amount of the carbon content of the finished product by detecting the carbon content of the aluminum nitride powder screened after heat treatment and the aluminum nitride powder of the final product so as to better quantify the purification degree.
Compared with the existing purification method, on one hand, the method prepares basic purification raw materials in a sectional heat treatment mode in a raw material prefabrication stage, reduces impurities in aluminum nitride powder from the source, and on the other hand, impurities in the aluminum nitride powder can be effectively separated in a secondary heat treatment process by adding an auxiliary mixture which can be decomposed at high temperature and volatilizes the impurities in a secondary processing process, so that further purification effect is achieved, the whole process is simpler, the preparation efficiency is higher, and the purification effect is good.
The specific method of the step S1 is as follows: loading aluminum nitride powder into a crucible, placing the crucible into a PVT growth furnace after loading, vacuumizing the PVT growth furnace to below 10 < -5 > mbar, then filling nitrogen into the PVT growth furnace, performing heat treatment on the aluminum nitride powder in a pure nitrogen atmosphere, taking out the aluminum nitride powder after heat treatment, adding the aluminum nitride powder into a ball mill for grinding, sieving with a 100-300-mesh sieve after grinding, and taking the sieved aluminum nitride powder as a basic purification raw material.
The heat treatment is a stepwise heat treatment, specifically:
removing hydroxide in aluminum nitride powder impurities at 800-1000 ℃;
removing carbon in aluminum nitride powder impurities at 1700-1800 ℃;
And (3) at 1900-2200 ℃, high-purity nitrogen is filled, the pressure is 80-120KPa, al powder in the aluminum nitride powder forms Al steam, aluminum oxide in aluminum nitride powder impurities is removed by using the Al steam, then the temperature is reduced, and the aluminum nitride powder is obtained through manual crushing and grinding treatment under the protection of high-purity inert gas.
The specific method of step S2 is as follows: mixing the screened aluminum nitride powder obtained in the step S1 with an auxiliary mixture which can be decomposed at high temperature and volatilizes carried impurities according to the weight ratio of 100:0.5-1.0 to obtain a powder mixture, filling the powder mixture into a crucible, and then placing the crucible into a high-temperature furnace again for heat treatment.
The auxiliary mixture which can be decomposed at high temperature and volatilizes the carried impurities is specifically a mixture of ammonium fluoride, sodium azide and aluminum hydroxide, wherein the NaN3 content of the sodium azide is more than or equal to 99.0wt% and the granularity is less than or equal to 0.15mm.
The specific control flow of the heat treatment which is placed in the high temperature furnace again is as follows: and (3) before heating, pumping out the gas in the furnace to form vacuum, controlling the temperature of the furnace to be raised to 500-600 ℃, preserving heat for 1-2 hours, then charging pure nitrogen, raising the temperature of the furnace to 700-800 ℃, preserving heat for 0.5-1 hour, and naturally cooling to room temperature to obtain primary mixed powder, wherein the temperature raising rate is 5 ℃/min.
The specific method of the step S3 is as follows: placing the primary mixed powder in a dry beaker, cleaning for 3-5 times by using a cleaning liquid, placing the product in a cleaning liquid with the volume of 20-40 times, stirring for 13 minutes, carrying out suction filtration, placing the product in a vacuum drying chamber for drying, drying at the drying temperature of 50-60 ℃ for 40-60 minutes until moisture is thoroughly separated, placing the dried product in dry air, calcining at the temperature of 660-680 ℃ for 2 hours, and then carrying out crushing and grinding under the protection of high-purity inert gas, thereby obtaining the final product aluminum nitride powder.
The cleaning solution is obtained by mixing 100 parts of absolute ethyl alcohol with 10 parts of hydrochloric acid solution with the concentration of 0.08-0.12 mol/L.
Example 1
The aluminum nitride powder purifying process includes the following steps:
S1, prefabricating a raw material, putting aluminum nitride powder into a crucible, putting the crucible into a PVT (polyvinyl butyral) growth furnace, vacuumizing, carrying out stepped heat treatment on the aluminum nitride powder in a pure nitrogen atmosphere, taking out the aluminum nitride powder, grinding and sieving the aluminum nitride powder, and taking the sieved aluminum nitride powder as a basic purification raw material.
S2, mixing and heating, namely mixing the aluminum nitride powder obtained in the step S1 with an auxiliary mixture which can be decomposed at high temperature and volatilizes carried impurities to obtain a powder mixture, and then placing the powder mixture into a crucible and heating the crucible in a high-temperature furnace to obtain primary mixed powder;
s3, cleaning and grinding, namely cleaning, filtering, vacuum drying and calcining the primary mixed powder for 2 hours, and then crushing and grinding under the protection of high-purity inert gas to obtain the final product aluminum nitride powder;
s4, detecting the primary product and the finished product, and detecting the carbon content of the aluminum nitride powder screened after heat treatment and the aluminum nitride powder of the final finished product.
The specific method of step S2 is as follows: mixing the screened aluminum nitride powder prepared in the step S1 with an auxiliary mixture which can be decomposed at high temperature and volatilizes carrying impurities in a weight ratio of 100:0.5-1.0 to obtain a powder mixture, then filling the powder mixture into a crucible, and then placing the crucible into a high-temperature furnace for heat treatment, wherein the auxiliary mixture which can be decomposed at high temperature and volatilizes carrying impurities is specifically a mixture formed by mixing ammonium fluoride, sodium azide and aluminum hydroxide according to a mass ratio of 1:1:1, wherein the NaN3 content of the sodium azide is more than or equal to 99.0wt% and the granularity is less than or equal to 0.15mm, and the specific control flow of the heat treatment which is placed into the high-temperature furnace again is as follows: and (3) before heating, pumping out the gas in the furnace to form vacuum, controlling the temperature of the furnace to be raised to 500-600 ℃, preserving heat for 1-2 hours, then charging pure nitrogen, raising the temperature of the furnace to 700-800 ℃, preserving heat for 0.5-1 hour, and naturally cooling to room temperature to obtain primary mixed powder, wherein the temperature raising rate is 5 ℃/min.
The results of carbon content detection of the primary product and the finished product prepared in this example are shown in the following table.
| Primary product | Finished product | |
| Carbon content% | 0.56 | 0.005 |
Example 2
The aluminum nitride powder purifying process includes the following steps:
S1, prefabricating a raw material, putting aluminum nitride powder into a crucible, putting the crucible into a PVT (polyvinyl butyral) growth furnace, vacuumizing, carrying out stepped heat treatment on the aluminum nitride powder in a pure nitrogen atmosphere, taking out the aluminum nitride powder, grinding and sieving the aluminum nitride powder, and taking the sieved aluminum nitride powder as a basic purification raw material.
S2, mixing and heating, namely mixing the aluminum nitride powder obtained in the step S1 with an auxiliary mixture which can be decomposed at high temperature and volatilizes carried impurities to obtain a powder mixture, and then placing the powder mixture into a crucible and heating the crucible in a high-temperature furnace to obtain primary mixed powder;
s3, cleaning and grinding, namely cleaning, filtering, vacuum drying and calcining the primary mixed powder for 2 hours, and then crushing and grinding under the protection of high-purity inert gas to obtain the final product aluminum nitride powder;
s4, detecting the primary product and the finished product, and detecting the carbon content of the aluminum nitride powder screened after heat treatment and the aluminum nitride powder of the final finished product.
The specific method of step S2 is as follows: mixing the screened aluminum nitride powder prepared in the step S1 with an auxiliary mixture which can be decomposed at high temperature and volatilizes carrying impurities in a weight ratio of 100:0.5-1.0 to obtain a powder mixture, then filling the powder mixture into a crucible, and then placing the crucible into a high-temperature furnace for heat treatment, wherein the auxiliary mixture which can be decomposed at high temperature and volatilizes carrying impurities is specifically a mixture formed by mixing ammonium fluoride, sodium azide and aluminum hydroxide according to a mass ratio of 1:0.5:0.5, wherein NaN3 content of the sodium azide is more than or equal to 99.0wt% and granularity is less than or equal to 0.15mm, and the specific control flow of the heat treatment which is placed into the high-temperature furnace again is as follows: and (3) before heating, pumping out the gas in the furnace to form vacuum, controlling the temperature of the furnace to be raised to 500-600 ℃, preserving heat for 1-2 hours, then charging pure nitrogen, raising the temperature of the furnace to 700-800 ℃, preserving heat for 0.5-1 hour, and naturally cooling to room temperature to obtain primary mixed powder, wherein the temperature raising rate is 5 ℃/min.
The results of carbon content detection of the primary product and the finished product prepared in this example are shown in the following table.
| Primary product | Finished product | |
| Carbon content% | 0.64 | 0.0036 |
Example 3
The aluminum nitride powder purifying process includes the following steps:
S1, prefabricating a raw material, putting aluminum nitride powder into a crucible, putting the crucible into a PVT (polyvinyl butyral) growth furnace, vacuumizing, carrying out stepped heat treatment on the aluminum nitride powder in a pure nitrogen atmosphere, taking out the aluminum nitride powder, grinding and sieving the aluminum nitride powder, and taking the sieved aluminum nitride powder as a basic purification raw material.
S2, mixing and heating, namely mixing the aluminum nitride powder obtained in the step S1 with an auxiliary mixture which can be decomposed at high temperature and volatilizes carried impurities to obtain a powder mixture, and then placing the powder mixture into a crucible and heating the crucible in a high-temperature furnace to obtain primary mixed powder;
s3, cleaning and grinding, namely cleaning, filtering, vacuum drying and calcining the primary mixed powder for 2 hours, and then crushing and grinding under the protection of high-purity inert gas to obtain the final product aluminum nitride powder;
s4, detecting the primary product and the finished product, and detecting the carbon content of the aluminum nitride powder screened after heat treatment and the aluminum nitride powder of the final finished product.
The specific method of step S2 is as follows: mixing the screened aluminum nitride powder prepared in the step S1 with an auxiliary mixture which can be decomposed at high temperature and volatilizes carrying impurities in a weight ratio of 100:0.5-1.0 to obtain a powder mixture, then filling the powder mixture into a crucible, and then placing the crucible in a high-temperature furnace for heat treatment, wherein the auxiliary mixture which can be decomposed at high temperature and volatilizes carrying impurities is specifically a mixture formed by mixing ammonium fluoride, sodium azide and aluminum hydroxide according to a mass ratio of 1:0.5:1, wherein the NaN3 content of the sodium azide is more than or equal to 99.0wt% and the granularity is less than or equal to 0.15mm, and the heat treatment in the high-temperature furnace comprises the following specific control flow: and (3) before heating, pumping out the gas in the furnace to form vacuum, controlling the temperature of the furnace to be raised to 500-600 ℃, preserving heat for 1-2 hours, then charging pure nitrogen, raising the temperature of the furnace to 700-800 ℃, preserving heat for 0.5-1 hour, and naturally cooling to room temperature to obtain primary mixed powder, wherein the temperature raising rate is 5 ℃/min.
The results of carbon content detection of the primary product and the finished product prepared in this example are shown in the following table.
| Primary product | Finished product | |
| Carbon content% | 0.53 | 0.0048 |
Example 4
The aluminum nitride powder purifying process includes the following steps:
S1, prefabricating a raw material, putting aluminum nitride powder into a crucible, putting the crucible into a PVT (polyvinyl butyral) growth furnace, vacuumizing, carrying out stepped heat treatment on the aluminum nitride powder in a pure nitrogen atmosphere, taking out the aluminum nitride powder, grinding and sieving the aluminum nitride powder, and taking the sieved aluminum nitride powder as a basic purification raw material.
S2, mixing and heating, namely mixing the aluminum nitride powder obtained in the step S1 with an auxiliary mixture which can be decomposed at high temperature and volatilizes carried impurities to obtain a powder mixture, and then placing the powder mixture into a crucible and heating the crucible in a high-temperature furnace to obtain primary mixed powder;
s3, cleaning and grinding, namely cleaning, filtering, vacuum drying and calcining the primary mixed powder for 2 hours, and then crushing and grinding under the protection of high-purity inert gas to obtain the final product aluminum nitride powder;
s4, detecting the primary product and the finished product, and detecting the carbon content of the aluminum nitride powder screened after heat treatment and the aluminum nitride powder of the final finished product.
The specific method of step S2 is as follows: mixing the screened aluminum nitride powder prepared in the step S1 with an auxiliary mixture which can be decomposed at high temperature and volatilizes carrying impurities in a weight ratio of 100:0.5-1.0 to obtain a powder mixture, then filling the powder mixture into a crucible, and then placing the crucible in a high-temperature furnace for heat treatment, wherein the auxiliary mixture which can be decomposed at high temperature and volatilizes carrying impurities is specifically a mixture formed by mixing ammonium fluoride, sodium azide and aluminum hydroxide according to a mass ratio of 0.5:1:1, wherein the NaN3 content of the sodium azide is more than or equal to 99.0wt% and the granularity is less than or equal to 0.15mm, and the heat treatment specific control flow of the heat treatment which is placed in the high-temperature furnace again is as follows: and (3) before heating, pumping out the gas in the furnace to form vacuum, controlling the temperature of the furnace to be raised to 500-600 ℃, preserving heat for 1-2 hours, then charging pure nitrogen, raising the temperature of the furnace to 700-800 ℃, preserving heat for 0.5-1 hour, and naturally cooling to room temperature to obtain primary mixed powder, wherein the temperature raising rate is 5 ℃/min.
The results of carbon content detection of the primary product and the finished product prepared in this example are shown in the following table.
| Primary product | Finished product | |
| Carbon content% | 0.46 | 0.0035 |
The results of the four examples are shown in the following table.
| Carbon content of the primary product% | The carbon content of the finished product is% | |
| Example 1 | 0.56 | 0.005 |
| Example 2 | 0.64 | 0.0036 |
| Example 3 | 0.53 | 0.0048 |
| Example 4 | 0.46 | 0.0035 |
From the data, the purity of the aluminum nitride powder purified by the process method can be effectively improved.
While the basic principles and main features of the invention and advantages of the invention have been shown and described, it will be understood by those skilled in the art that the present invention is not limited by the foregoing embodiments, which are described in the foregoing description merely illustrate the principles of the invention, and various changes and modifications may be made therein without departing from the spirit and scope of the invention as defined in the appended claims and their equivalents.
Claims (8)
1. The aluminum nitride powder purification method is characterized by comprising the following steps of:
S1, prefabricating a raw material, namely filling aluminum nitride powder into a crucible, putting the crucible into a PVT (polyvinyl butyral) growth furnace, vacuumizing, carrying out stepped heat treatment on the aluminum nitride powder in a pure nitrogen atmosphere, taking out the aluminum nitride powder, grinding and sieving the aluminum nitride powder, and taking the sieved aluminum nitride powder as a basic purification raw material;
s2, mixing and heating, namely mixing the aluminum nitride powder obtained in the step S1 with an auxiliary mixture which can be decomposed at high temperature and volatilizes carried impurities to obtain a powder mixture, and then placing the powder mixture into a crucible and heating the crucible in a high-temperature furnace to obtain primary mixed powder;
s3, cleaning and grinding, namely cleaning, filtering, vacuum drying and calcining the primary mixed powder for 2 hours, and then crushing and grinding under the protection of high-purity inert gas to obtain the final product aluminum nitride powder;
s4, detecting the primary product and the finished product, and detecting the carbon content of the aluminum nitride powder screened after heat treatment and the aluminum nitride powder of the final finished product.
2. The method for purifying aluminum nitride powder according to claim 1, wherein the specific method of step S1 is as follows: loading aluminum nitride powder into a crucible, placing the crucible into a PVT growth furnace after loading, vacuumizing the PVT growth furnace to below 10 < -5 > mbar, then filling nitrogen into the PVT growth furnace, performing heat treatment on the aluminum nitride powder in a pure nitrogen atmosphere, taking out the aluminum nitride powder after heat treatment, adding the aluminum nitride powder into a ball mill for grinding, sieving with a 100-300-mesh sieve after grinding, and taking the sieved aluminum nitride powder as a basic purification raw material.
3. The aluminum nitride powder purification method according to claim 2, wherein the heat treatment is a stepwise heat treatment, specifically:
removing hydroxide in aluminum nitride powder impurities at 800-1000 ℃;
removing carbon in aluminum nitride powder impurities at 1700-1800 ℃;
And (3) at 1900-2200 ℃, high-purity nitrogen is filled, the pressure is 80-120KPa, al powder in the aluminum nitride powder forms Al steam, aluminum oxide in aluminum nitride powder impurities is removed by using the Al steam, then the temperature is reduced, and the aluminum nitride powder is obtained through manual crushing and grinding treatment under the protection of high-purity inert gas.
4. The method for purifying aluminum nitride powder according to claim 1, wherein the specific method in step S2 is as follows: mixing the screened aluminum nitride powder obtained in the step S1 with an auxiliary mixture which can be decomposed at high temperature and volatilizes carried impurities according to the weight ratio of 100:0.5-1.0 to obtain a powder mixture, filling the powder mixture into a crucible, and then placing the crucible into a high-temperature furnace again for heat treatment.
5. The method for purifying aluminum nitride powder according to claim 4, wherein the auxiliary mixture which is decomposable at high temperature and carries impurities for volatilization is a mixture of ammonium fluoride, sodium azide and aluminum hydroxide, wherein the NaN3 content of sodium azide is not less than 99.0wt% and the particle size is not more than 0.15mm.
6. The method for purifying aluminum nitride powder according to claim 5, wherein the specific control flow of the heat treatment performed in the high temperature furnace again is: and (3) before heating, pumping out the gas in the furnace to form vacuum, controlling the temperature of the furnace to be raised to 500-600 ℃, preserving heat for 1-2 hours, then charging pure nitrogen, raising the temperature of the furnace to 700-800 ℃, preserving heat for 0.5-1 hour, and naturally cooling to room temperature to obtain primary mixed powder, wherein the temperature raising rate is 5 ℃/min.
7. The method for purifying aluminum nitride powder according to claim 1, wherein the specific method in step S3 is as follows: placing the primary mixed powder in a dry beaker, cleaning for 3-5 times by using a cleaning liquid, placing the product in a cleaning liquid with the volume of 20-40 times, stirring for 13 minutes, carrying out suction filtration, placing the product in a vacuum drying chamber for drying, drying at the drying temperature of 50-60 ℃ for 40-60 minutes until moisture is thoroughly separated, placing the dried product in dry air, calcining at the temperature of 660-680 ℃ for 2 hours, and then carrying out crushing and grinding under the protection of high-purity inert gas, thereby obtaining the final product aluminum nitride powder.
8. The method for purifying aluminum nitride powder according to claim 7, wherein the cleaning liquid is obtained by mixing 100 parts of absolute ethanol with 10 parts of hydrochloric acid solution having a concentration of 0.08 to 0.12 mol/L.
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| CN202311582500.6A CN117963855A (en) | 2023-11-24 | 2023-11-24 | Aluminum nitride powder purification method |
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