Method for purifying aluminum nitride powder

Abstract

The invention discloses an aluminum nitride powder purification method. The method comprises the following steps: S1, screening aluminum nitride powder by using a standard sieve; then putting the treated aluminum nitride powder into deionized water, carrying out ultrasonic cleaning for 10-15 minutes, and pouring out supernate; filtering and collecting powder; s2, cleaning: acid washing or alkali washing is selected according to impurity types; s3, the cleaned aluminum nitride powder is filtered again, and the powder is prepared into slurry with deionized water; s4, 0.5-1% of a complexing agent is added, stirring is conducted for 60-80 min at the room temperature, the pH value is adjusted to be 5-7, and the binding effect of the complexing agent and residual metal ions is enhanced; s5, centrifugally collecting solid powder, and repeatedly washing with deionized water; and S6, drying treatment: if the dried powder is agglomerated, gently crushing by using an agate mortar, and sieving by using a 200-mesh sieve. Solid powder is collected through centrifugation at a high rotating speed, reagent residues can be prevented, and the insulating and heat-conducting properties of the aluminum nitride powder are effectively guaranteed.

Description

Technical Field

[0001] This invention relates to the field of aluminum nitride powder purification technology, and more particularly to a method for purifying aluminum nitride powder. Background Technology

[0002] Aluminum nitride powder is a novel inorganic material with excellent comprehensive properties in optics, heat, electricity, and mechanics. Therefore, it can be widely used in many fields such as metallurgy, electronics, national defense, and machinery. As a result, people are paying more and more attention to the research and development of aluminum nitride and its applications. The properties of aluminum nitride powder directly affect its functions and applications. Large-scale industrial production of aluminum nitride has always received widespread attention and research from the industrial and scientific communities of various countries.

[0003] Existing methods for purifying aluminum nitride powder all have shortcomings. Even with multiple washes during the purification process, trace amounts of acid radicals, alkali ions, or complexing agents may still remain, reducing the powder's insulation and thermal conductivity. Therefore, we propose a new method for purifying aluminum nitride powder. Summary of the Invention

[0004] This invention proposes a method for purifying aluminum nitride powder to solve the problem mentioned in the background art that even after multiple washings during the purification process, trace amounts of acid radicals, alkali ions, or complexing agents may still remain, reducing the insulation and thermal conductivity of the powder.

[0005] This invention proposes a method for purifying aluminum nitride powder, comprising the following steps: S1: Preprocessing, as follows: (1) Select aluminum nitride powder and sieve it with a standard sieve of 200~400 mesh to remove mechanical impurities and large agglomerates; (2) Then place the treated aluminum nitride powder in deionized water and ultrasonically clean it for 10-15 minutes. Pour off the supernatant and remove the adsorbed dust from the surface. (3) Filter and collect the powder, drain the surface moisture and set aside; S2: Cleaning, select acid washing or alkaline washing according to the type of impurities; S3: The cleaned aluminum nitride powder is filtered again, and the powder is mixed with deionized water to form a slurry. S4: Add 0.5~1% complexing agent and stir at room temperature for 60~80 minutes to adjust the pH value to 5~7 to enhance the binding effect of complexing agent and residual metal ions; S5: After S4 is completed, centrifuge to collect the solid powder and wash it repeatedly with deionized water, checking the pH value of each wash until the pH value of the wash is close to 7 and no metal ions are detected. S6: Drying treatment. If the powder clumps after drying, gently crush it with an agate mortar and pestle and pass it through a 200-mesh sieve to obtain purified aluminum nitride powder.

[0006] Preferably, the complexing agent in S4 is disodium EDTA or citric acid.

[0007] Preferably, in S5, the centrifugation is specifically performed at a speed of 3000~5000 r / min for 10~15 minutes.

[0008] Preferably, in S6, the drying process is as follows: First, spread the cleaned aluminum nitride powder evenly on a tray and place it in a vacuum drying oven; Second, dry at 80~120℃ for 1~2 hours to completely remove moisture.

[0009] Preferably, during the drying process, high-temperature baking for extended periods should be avoided to prevent the powder surface from re-oxidizing.

[0010] Preferably, the pickling step in S2 is as follows: Prepare a 5-10% mixture and stir it at 50-80℃ for 100-120 minutes.

[0011] Preferably, the mixture is a mixture of hydrochloric acid and nitric acid, and the volume ratio of hydrochloric acid to nitric acid is 1:1. Preferably, the alkaline washing step in S2 is as follows: Prepare a 5-8% trisodium phosphate solution and stir it at 30-60℃ for 40-90 minutes to avoid decomposition of aluminum nitride due to high temperature.

[0012] The aluminum nitride powder purification method proposed in this invention has the following advantages: 1. By using disodium EDTA or citric acid complexing agents, the present invention can enhance the binding effect of complexing agents with residual metal ions, thereby removing residual metal ions.

[0013] 2. The present invention collects solid powder by centrifugation at a speed of 3000~5000 r / min, which can prevent reagent residue and effectively ensure the insulation and thermal conductivity of aluminum nitride powder. Detailed Implementation

[0014] The present invention will be further described below with reference to specific embodiments.

[0015] Example 1 This invention proposes a method for purifying aluminum nitride powder, comprising the following steps: S1: Preprocessing, as follows: (1) Select aluminum nitride powder and sieve it with a standard sieve of 200~400 mesh to remove mechanical impurities and large agglomerates; (2) Then place the treated aluminum nitride powder in deionized water, ultrasonically clean for 10 minutes, pour off the supernatant, and remove the adsorbed dust from the surface. (3) Filter and collect the powder, drain the surface moisture and set aside; S2: Cleaning, select acid washing or alkaline washing according to the type of impurities; The pickling steps are as follows: Prepare a 5-10% mixture, specifically a mixture of hydrochloric acid and nitric acid with a volume ratio of 1:1; and stir at 50°C for 120 minutes. The alkaline washing steps are as follows: Prepare a 5-8% trisodium phosphate solution and stir at 30°C for 90 minutes to avoid decomposition of aluminum nitride due to high temperature. S3: The cleaned aluminum nitride powder is filtered again, and the powder is mixed with deionized water to form a slurry. S4: Add 0.5~1% citric acid and stir at room temperature for 60 minutes to adjust the pH value to 5~7, thereby enhancing the binding effect of the complexing agent with residual metal ions; S5: After S4 is completed, centrifuge at 5000 r / min for 10 minutes to collect the solid powder, and wash it repeatedly with deionized water, checking the pH value each time, until the pH value of the washing is close to 7 and no metal ions are detected. S6: The specific drying process is as follows: First, spread the cleaned aluminum nitride powder evenly on a tray and place it in a vacuum drying oven; Second, dry at 80℃ for 2 hours to completely remove moisture. During the drying process, avoid high-temperature baking for a long time to prevent the powder surface from re-oxidizing. Third, if the powder clumps after drying, gently crush it with an agate mortar and pestle and pass it through a 200-mesh sieve to obtain purified aluminum nitride powder.

[0016] Example 2 This invention proposes a method for purifying aluminum nitride powder, comprising the following steps: S1: Preprocessing, as follows: (1) Select aluminum nitride powder and sieve it with a standard sieve of 200~400 mesh to remove mechanical impurities and large agglomerates; (2) Then place the treated aluminum nitride powder in deionized water and ultrasonically clean it for 10-15 minutes. Pour off the supernatant and remove the adsorbed dust from the surface. (3) Filter and collect the powder, drain the surface moisture and set aside; S2: Cleaning, select acid washing or alkaline washing according to the type of impurities; The pickling steps are as follows: Prepare a 5-10% mixture, specifically a mixture of hydrochloric acid and nitric acid with a volume ratio of 1:1; and stir at 65°C for 110 minutes. The alkaline washing steps are as follows: Prepare a 5-8% trisodium phosphate solution and stir at 45°C for 65 minutes to avoid decomposition of aluminum nitride due to high temperature. S3: The cleaned aluminum nitride powder is filtered again, and the powder is mixed with deionized water to form a slurry. S4: Add 0.5~1% citric acid and stir at room temperature for 70 minutes to adjust the pH value to 5~7, thereby enhancing the binding effect of the complexing agent with residual metal ions; S5: After S4 is completed, centrifuge at 4000 r / min for 13 minutes to collect the solid powder, and wash it repeatedly with deionized water, checking the pH value each time, until the pH value of the washing is close to 7 and no metal ions are detected. S6: The specific drying process is as follows: First, spread the cleaned aluminum nitride powder evenly on a tray and place it in a vacuum drying oven; Second, dry at 100℃ for 1.5 hours to completely remove moisture. During the drying process, avoid high-temperature baking for a long time to prevent the powder surface from re-oxidizing. Third, if the powder clumps after drying, gently crush it with an agate mortar and pestle and pass it through a 200-mesh sieve to obtain purified aluminum nitride powder.

[0017] Example 3 This invention proposes a method for purifying aluminum nitride powder, comprising the following steps: S1: Preprocessing, as follows: (1) Select aluminum nitride powder and sieve it with a standard sieve of 200~400 mesh to remove mechanical impurities and large agglomerates; (2) Then place the treated aluminum nitride powder in deionized water and ultrasonically clean it for 10-15 minutes. Pour off the supernatant and remove the adsorbed dust from the surface. (3) Filter and collect the powder, drain the surface moisture and set aside; S2: Cleaning, select acid washing or alkaline washing according to the type of impurities; The pickling steps are as follows: Prepare a 5-10% mixture, specifically a mixture of hydrochloric acid and nitric acid, with a volume ratio of hydrochloric acid to nitric acid of 1:1; and stir at 80°C for 100 min. The alkaline washing steps are as follows: Prepare a 5-8% trisodium phosphate solution and stir at 60°C for 40 minutes to avoid decomposition of aluminum nitride due to high temperature. S3: The cleaned aluminum nitride powder is filtered again, and the powder is mixed with deionized water to form a slurry. S4: Add 0.5~1% disodium EDTA and stir for 80 minutes at room temperature to adjust the pH to 5~7, thereby enhancing the binding effect of the complexing agent with residual metal ions; S5: After S4 is completed, centrifuge at 5000 r / min for 10 minutes to collect the solid powder, and wash it repeatedly with deionized water, checking the pH value each time, until the pH value of the washing is close to 7 and no metal ions are detected. S6: The specific drying process is as follows: First, spread the cleaned aluminum nitride powder evenly on a tray and place it in a vacuum drying oven; Second, dry at 120℃ for 1 hour to completely remove moisture. During the drying process, avoid high-temperature baking for a long time to prevent the powder surface from re-oxidizing. Third, if the powder clumps after drying, gently crush it with an agate mortar and pestle and pass it through a 200-mesh sieve to obtain purified aluminum nitride powder.

[0018] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for purifying an aluminum nitride powder, characterized by, The method comprises the following steps: S1: pretreatment, specifically as follows: (1) selecting aluminum nitride powder, screening the aluminum nitride powder with a standard sieve of 200-400 meshes to remove mechanical impurities and large agglomerated particles; (2) then placing the treated aluminum nitride powder in deionized water, ultrasonic cleaning for 10-15 minutes, discarding the supernatant to remove surface adsorbed dust; (3) filtering and collecting the powder, and draining the surface moisture for standby use; S2: cleaning, acid washing or alkali washing according to the type of impurities; S3: filtering the aluminum nitride powder after cleaning, and adjusting the powder into slurry with deionized water; S4: adding 0.5-1% complexing agent, stirring for 60-80 minutes at room temperature to adjust the pH value to 5-7, and enhancing the binding effect of the complexing agent and residual metal ions; S5: after S4 is completed, centrifugally collecting the solid powder, and repeatedly washing with deionized water, detecting the pH value of each washing until the pH value of the washing approaches 7 and no metal ion is detected; S6: drying treatment, to obtain the purified aluminum nitride powder.

2. The method of purifying aluminum nitride powder according to claim 1, characterized by: The complexing agent in S4 is specifically disodium EDTA or citric acid.

3. The method of purifying aluminum nitride powder according to claim 1, wherein: In S5, the centrifugation is specifically centrifugation at a speed of 3000-5000 r / min for 10-15 minutes.

4. The method of purifying aluminum nitride powder according to claim 1, wherein: In S6, the drying treatment is specifically as follows: First, the washed aluminum nitride powder is laid flat on a tray and placed in a vacuum drying oven; Second, drying at 80-120°C for 1-2 hours to completely remove the moisture.

5. The method of purifying aluminum nitride powder according to claim 4, wherein: During the drying process, high-temperature long-time baking should be avoided to prevent the surface of the powder from being re-oxidized.

6. The method of purifying aluminum nitride powder according to claim 1, wherein: The acid washing step in S2 is as follows: Prepare a mixed solution of 5-10%, and stir at 50-80°C for 100-120 minutes.

7. The method of purifying aluminum nitride powder according to claim 6, wherein: The mixed solution is specifically a mixed solution of hydrochloric acid and nitric acid, and the volume ratio of hydrochloric acid to nitric acid is 1:

1.

8. The method of purifying aluminum nitride powder according to claim 1, wherein: The alkali washing step in S2 is as follows: Prepare a 5-8% trisodium phosphate solution, and stir at 30-60°C for 40-90 minutes to avoid high temperature leading to decomposition of aluminum nitride.

9. The method of purifying aluminum nitride powder according to claim 1, wherein: In S6, if the powder after drying is agglomerated, it is lightly crushed with a marquis mortar and passed through a 200-mesh sieve.