Method for Producing Spherical Aluminum Nitride Powder

Abstract

The present invention provides method for producing a spherical aluminum nitride powder. In an embodiment, the method comprises mixing an Al precursor and a flux in a solvent to produce a mixed solution, spray-drying the mixed solution to form a spray-dried powder, mixing the spray-dried powder and a carbon-based material to form a mixture, heat treating the mixture in a nitrogen atmosphere to form a heat-treated compound, and decarbonizing the heat-treated compound in an air atmosphere, wherein the flux is at least one selected from the group consisting of Cu.sub.2O, TiO.sub.2, Bi.sub.2O.sub.3, and CuO, or a mixture of at least one selected from the group consisting of Cu.sub.2O, TiO.sub.2, Bi.sub.2O.sub.3, and CuO and at least one selected from the group consisting of CaF.sub.2 and Y.sub.2O.sub.3.

Claims

1. A method for producing a spherical aluminum nitride powder, comprising: (i) mixing an aluminum (Al) precursor and a flux in a solvent to produce a mixed solution; (ii) spray-drying the mixed solution produced in step (i) to form a spray-dried powder comprising the Al precursor and the flux; (iii) mixing the spray-dried powder and a carbon-based material to form a mixture; (iv) heat treating the mixture of step (iii) in a nitrogen atmosphere to form a heat-treated compound; and (v) decarbonizing the heat-treated compound of step (iv) in an air atmosphere to produce a spherical aluminum nitride powder, wherein the flux is at least one selected from the group consisting of Cu.sub.2O, TiO.sub.2, Bi.sub.2O.sub.3, and CuO, or a mixture of at least one selected from the group consisting of Cu.sub.2O, TiO.sub.2, Bi.sub.2O.sub.3, and CuO and at least one selected from the group consisting of CaF.sub.2 and Y.sub.2O.sub.3.

2. The method for producing a spherical aluminum nitride powder according to claim 1, wherein the Al precursor is at least one selected from the group consisting of Al(OH).sub.3, boehmite (AlO(OH)), and Al.sub.2O.sub.3.

3. The method for producing a spherical aluminum nitride powder according to claim 1, wherein the solvent is water.

4. The method for producing a spherical aluminum nitride powder according to claim 1, wherein the mixed solution of step (i) further includes at least one selected from the group consisting a binder and a dispersing agent.

5. The method for producing a spherical aluminum nitride powder according to claim 1, wherein the flux is present in the mixed solution of step (i) in an amount of 0.1 to 10% by weight based on the weight of the Al precursor.

6. The method for producing a spherical aluminum nitride powder according to claim 1, wherein the carbon-based material is a carbon black.

7. The method for producing a spherical aluminum nitride powder according to claim 1, wherein the carbon-based material is present in the mixture of step (iii) in an amount of 30 to 70% by weight based on the weight of the Al precursor.

8. The method for producing a spherical aluminum nitride powder according to claim 1, wherein step (iv) further comprises: heat treating the mixture of step (iii) in the nitrogen atmosphere at a temperature ranging from 1200 C. to 1900 C. for 1 to 10 hours.

9. The method for producing a spherical aluminum nitride powder according to claim 1, wherein step (v) further comprises: decarbonizing the heat-treated compound of step (iv) in an air atmosphere at a temperature ranging from 600 C. to 800 C. for 1 to 3 hours.

10. The method for producing a spherical aluminum nitride powder according to claim 1, wherein the spherical aluminum nitride powder has an average particle size of 5 to 200 microns.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0062] FIG. 1 is an XRD graph of aluminum nitride powder (AlN powder) produced according to Example 1.

[0063] FIG. 2A is an SEM photograph at a scale of 10 m of the aluminum nitride powder produced according to Example 1.

[0064] FIG. 2B is an SEM photograph at a scale of 100 m of the aluminum nitride powder produced according to Example 1.

EXAMPLES

[0065] The present invention will now be described with reference to examples, but these examples are provided for better understanding of the invention and the scope of the present invention is not limited thereto.

[0066] In the present invention, the specific surface area was measured according to the BET single point method, and the average particle size was measured by a process in which the sample was dispersed in ethanol to measure the average particle size (D50) by using a laser diffraction particle size distribution meter (Horiba LA-960).

[0067] AlN conversion was calculated by the following Formula 1.

the intensity of the peak of AlN (100)/{the intensity of the peak of AlN (100)+the intensity of the peak of Al.sub.2O.sub.3 (113)}[Formula 1]

[0068] The intensity of the peak is measured in an XRD graph.

[0069] The sphericity according to the present invention was calculated as the ratio of the longest diameter to the shortest diameter of any one particle in a SEM photograph.

[0070] The heat conductivity was measured after by Laser Flash Apparatus (LFA) mixing silicone rubber with AlN in each case, molding the mixture to 12.7 mm diameter and 2 mm in thickness and then performing heat treatment at 150 C. for 1 hour.

Example 1

[0071] 10 g of Al(OH).sub.3 (average particle size: 1 m) and 0.3 g of Cu.sub.2O (average particle size: 1 m) were mixed with water as a solvent using zirconia balls for 24 hours.

[0072] Thereafter, the balls were separated and the mixture was spray-dried under the conditions of 230 C. at the inlet and 60 C. at the outlet to obtain a dry powder.

[0073] The obtained dry powder and 4 g of carbon black (specific surface area: 70 m.sup.2/g) were mixed in a mortar, and the mixture was heat treated at 1600 C. in a N.sub.2 atmosphere for 3 hours.

[0074] Then, the heat treated aluminum nitride compound was subjected to a decarbonization at 700 C. for 2 hours in an air atmosphere to obtain a spherical aluminum nitride powder.

[0075] The XRD graph of the aluminum nitride powder thus obtained is shown in FIG. 1, and the SEM photographs are shown in FIGS. 2A-B.

[0076] Referring to FIGS. 1 and 2A-B, it can be confirmed that not only was high purity AlN obtained, but also its shape was spherical and the average particle size was about 20 m.

Example 2

[0077] A spherical aluminum nitride powder was obtained in the same manner as in Example 1, except that 0.2 g of TiO.sub.2 (average particle size: 1 m) was further added and mixed with 10 g of Al(OH).sub.3 (average particle size: 1 m) and 0.3 g of Cu.sub.2O (average particle size: 1 m) in Example 1.

Example 3

[0078] A spherical aluminum nitride powder was obtained in the same manner as in Example 1, except that 0.3 g of TiO.sub.2 (average particle size: 1 m) and 0.2 g of Bi.sub.2O.sub.3 (average particle size: 1 m) were used instead of 0.3 g of Cu.sub.2O (average particle size: 1 m) in Example 1.

Example 4

[0079] A spherical aluminum nitride powder was obtained in the same manner as in Example 1, except that 10 g of boehmite (average particle size: 1 m) was used instead of 10 g of Al(OH).sub.3 (average particle size: 1 m) in Example 1.

Example 5

[0080] A spherical aluminum nitride powder was obtained in the same manner as in Example 1, except that 10 g of -Al.sub.2O.sub.3 (average particle size: 1 m) was used instead of 10 g of Al(OH).sub.3 (average particle size: 1 m) in Example 1.

Comparative Example 1

[0081] A spherical aluminum nitride powder was obtained in the same manner as in Example 1, except that 10 g of boehmite (average particle size: 1 m) was used instead of 10 g of Al(OH).sub.3 (average particle size: 1 m), and 0.3 g of Cu.sub.2O (average particle size: 1 m) in Example 1 was not used.

Comparative Example 2

[0082] A spherical aluminum nitride powder was obtained in the same manner as in Example 1, except that 10 g of -Al.sub.2O.sub.3 (average particle size: 1 m) was used instead of 10 g of Al(OH).sub.3 (average particle size: 1 m), and 0.3 g of Cu.sub.2O (average particle size: 1 m) in Example 1 was not used.

Comparative Example 3

[0083] A spherical aluminum nitride powder was obtained in the same manner as in Example 1, except that 0.3 g of Y.sub.2O.sub.3 (average particle size: 1 m) was used instead of 0.3 g of Cu.sub.2O (average particle size: 1 m) in Example 1.

Comparative Example 4

[0084] 10 g of -Al.sub.2O.sub.3 (average particle size: 1 m), 4 g of carbon black (specific surface area: 70 m.sup.2/g), and 0.3 g of Y.sub.2O.sub.3 (average particle size: 1 m) were mixed.

[0085] The mixed powder was heat treated at 1700 C. for 10 hours under a N.sub.2 atmosphere.

[0086] Then, the heat treated aluminum nitride compound was decarbonized at 700 C. for 10 hours in an air atmosphere to obtain an aluminum nitride powder.

Comparative Example 5

[0087] A spherical aluminum nitride powder was obtained in the same manner as in Comparative Example 4, except that 0.3 g of Cu.sub.2O (average particle size: 1 m) was used instead of 0.3 g of Y.sub.2O.sub.3 (average particle size: 1 m) in Comparative Example 4.

Experimental Example

[0088] AlN conversion, sphericity, and heat conductivity of the aluminum nitride powders produced in Examples 1 to 5 and Comparative Examples 1 to 5 were measured, and are shown in Table 1 below.

TABLE-US-00001 TABLE 1 AlN Heat conversion conductivity (%) Sphericity (W/mK) Example 1 100 0.99 2.8 Example 2 100 0.98 2.9 Example 3 100 0.99 2.8 Example 4 100 0.98 2.7 Example 5 100 0.99 2.8 Comparative Example 1 52 0.98 1.4 Comparative Example 2 78 0.97 2.7 Comparative Example 3 86 0.98 1.8 Comparative Example 4 82 0.99 Comparative Example 5 100 0.98

[0089] Referring to Table 1, it can be confirmed that when the aluminum nitride powder was produced according to the present invention as in Examples 1 to 5, AlN conversion is very high while having high sphericity and heat conductivity, whereas in Comparative Examples 1 to 4, the AlN conversion is very low. On the other hand, in Comparative Examples 4 and 5, since the carbon black existing in the AlN was removed in the decarbonization process, the heat conductivity could not be measured.