Process for producing aluminum nitride and aluminum nitride

• US 20030099590A1
• Filed: 11/07/2002
• Published: 05/29/2003
• Est. Priority Date: 11/13/2001
• Status: Active Grant

• Current Assignee: Ibaragi Laboratory Co., Ltd.
• Original Assignee: Ibaragi Laboratory Co., Ltd.
• Inventors: Tahara, Tsutomu, Miura, Hirohisa, Matunaga, Hirofumi
• Granted Patent: US 6,986,875 B2
• Time in Patent Office: Days
• US Class Current: 423/412
• CPC Class Codes: C01B 21/0722 Preparation by direct nitridation of aluminium
• CPC Class Codes: C01P 2002/60 Compounds characterised by their crystallite size
• CPC Class Codes: C01P 2004/03 obtained by SEM
• CPC Class Codes: C01P 2004/61 Micrometer sized, i.e. from 1-100 micrometer
• CPC Class Codes: C01P 2004/62 Submicrometer sized, i.e. from 0.1-1 micrometer
• CPC Class Codes: C01P 2006/12 Surface area
• CPC Class Codes: C01P 2006/80 Compositional purity

Abstract

A process for producing aluminum nitride includes a step of holding an aluminum powder in a nitrogen atmosphere whose nitrogen gas pressure falls in a range of from 105 to 300 kPa, thereby developing a nitriding reaction at a temperature of from 500 to 1,000° C., wherein a reaction controller gas, controlling the development of the nitriding reaction, is supplied into a reactor chamber in which the aluminum powder is accommodated. In the production process, the reaction controller gas is included in the nitrogen atmosphere in the development of the nitriding reaction. Accordingly, the development of the nitriding reaction is controlled so that it is possible to develop the nitriding reaction at a lower temperature. As a result, it is possible to produce an aluminum nitride powder whose particle diameters are fine.

Claims

1. A process for producing aluminum nitride comprising the step of:

holding an aluminum powder in a nitrogen atmosphere whose nitrogen gas pressure falls in a range of from 105 to 300 kPa, thereby developing a nitriding reaction at a temperature of from 500 to 1,000°

C., wherein a reaction controller gas, controlling the development of the nitriding reaction, is supplied into a reactor chamber in which the aluminum powder is accommodated.

2. The process for producing aluminum nitride set forth in claim 1, wherein the nitriding reaction is developed after subjecting the aluminum powder to a nitrogen occlusion treatment in which the aluminum powder is held in a nitrogen gas atmosphere of 450 to 600°

C. for 30 to 120 minutes to have nitrogen occluded in the aluminum powder.

3. The process for producing aluminum nitride set forth in claim 1, wherein the nitriding reaction is developed while releasing heat, generated by the nitriding reaction, to the outside of the reactor chamber by way of a furnace wall of a reactor furnace, demarcating the reactor chamber, and controlling a temperature difference between a workpiece temperature and an initiation temperature of the nitriding reaction to 100°

C. or less.

4. The process for producing aluminum nitride set forth in claim 1, wherein the nitrogen gas atmosphere is maintained by a nitrogen gas, which is delivered from a nitrogen gas supplying apparatus for continuously supplying a nitrogen gas to the reactor chamber, and a nitrogen gas, which is discharged from a discharging apparatus for discharging a nitrogen gas from the reactor chamber.

5. The process for producing aluminum nitride set forth in claim 1, wherein the reaction controller gas is supplied to the reactor chamber when the nitrogen gas pressure within the reactor chamber drops.

6. The process for producing aluminum nitride set forth in claim 3, wherein the reaction controller gas is supplied into the reactor chamber when the workpiece temperature rises.

7. The process for producing aluminum nitride set forth in claim 1, wherein the reaction controller gas is at least one member selected from the group consisting of an argon gas and an ammonia gas.

8. The process for producing aluminum nitride set forth in claim 1, wherein the reaction controller gas is supplied into the reactor chamber in a proportion of from 1 to 50% by volume when a gas amount within the reactor chamber is taken as 100% by volume.

9. The process for producing aluminum nitride set forth in claim 1, wherein it takes from 2 to 10 hours for the nitriding reaction to complete after the aluminum powder is heated to a predetermined reaction temperature.

10. The process for producing aluminum nitride set forth in claim 9, wherein the supply of the reaction controller gas is started when the aluminum powder is heated to the predetermined temperature, the supply amount of the reaction controller gas is increased gradually to a predetermined partial gas pressure which can control the development of the nitriding reaction, the partial gas pressure of the reaction controller gas is decreased gradually after maintaining the predetermined partial gas pressure for a predetermined period of time, and the supply of the reaction controller gas is stopped.

11. The process for producing aluminum nitride set forth in claim 10, wherein a nitrogen gas is further supplied into the reactor chamber after the supply of the reaction controller gas is stopped.

12. Aluminum nitride subjected to the step of:

holding an aluminum powder in a nitrogen atmosphere whose nitrogen gas pressure falls in a range of from 105 to 300 kPa, thereby developing a nitriding reaction at a temperature of from 500 to 1,000°

C., wherein a reaction controller gas, controlling the development of the nitriding reaction, is supplied into a reactor chamber in which the aluminum powder is accommodated.

13. The aluminum nitride set forth in claim 12 being a powder whose average particle diameter is 1 μ

m or less and specific surface area is 2.5 m²/g or more.

14. The aluminum nitride set forth in claim 12, wherein the nitriding reaction is developed after subjecting the aluminum powder to a nitrogen occlusion treatment in which the aluminum powder is held in a nitrogen gas atmosphere of 450 to 600°

C. for 30 to 120 minutes to have nitrogen occluded in the aluminum powder.

15. The aluminum nitride set forth in claim 12, wherein the nitriding reaction is developed while releasing heat, generated by the nitriding reaction, to the outside of the reactor chamber by way of a furnace wall of a reactor furnace, demarcating the reactor chamber, and controlling a temperature difference between a workpiece temperature and an initiation temperature of the nitriding reaction to 100°

C. or less.

16. The aluminum nitride set forth in claim 12, wherein the nitrogen gas atmosphere is maintained by a nitrogen gas, which is delivered from a nitrogen gas supplying apparatus for continuously supplying a nitrogen gas to the reactor chamber, and a nitrogen gas, which is discharged from a discharging apparatus for discharging a nitrogen gas from the reactor chamber.

17. The aluminum nitride set forth in claim 12, wherein the reaction controller gas is supplied to the reactor chamber when the nitrogen gas pressure within the reactor chamber drops.

18. The aluminum nitride set forth in claim 15, wherein the reaction controller gas is supplied into the reactor chamber when the workpiece temperature rises.

19. The aluminum nitride set forth in claim 12, wherein the reaction controller gas is at least one member selected from the group consisting of an argon gas and an ammonia gas.

20. The aluminum nitride set forth in claim 12, wherein the reaction controller gas is supplied into the reactor chamber in a proportion of from 1 to 50% by volume when a gas amount within the reactor chamber is taken as 100% by volume.