METHOD FOR PREPARING ALUMINUM NITRIDE

Abstract

A method for producing aluminum nitride is to disclose, which includes injecting a nitrogen-containing gas and a pure aluminum material into a high-temperature jet mill. In the high-temperature jet mill, the injected pure aluminum material reacts with the nitrogen and forms aluminum nitride on the surface. The aluminum nitride is continuously to pulverize in the high-temperature jet mill to form fine aluminum nitride powder. According to the present disclosure, unnecessary cost and complicated processes in elevated-temperature agglomeration is to avoid.

Claims

1. A method for preparing aluminum nitride, comprising steps of: (a) injecting a nitrogen-containing gas and a pure aluminum material into a high-temperature jet mill; (b) melting the pure aluminum material into a liquid status of the pure aluminum; (c) allowing the liquid status of the pure aluminum material to react with the nitrogen and form aluminum nitride on the surface of the pure aluminum material in the high-temperature jet mill; (d) pulverizing the formed aluminum nitride and removing the formed aluminum nitride from the surface of the pure aluminum material; (e) exposing the remaining liquid status of the pure aluminum material to the nitrogen-containing gas; and (f) repeating steps (c) to (e) until all the liquid status of the pure aluminum material is completely consumed.

2. (canceled)

3. The method for preparing aluminum nitride according to claim 1, wherein the nitrogen-containing gas and the pure aluminum material are injected into the high-temperature jet mill by a high-pressure air, and a high-speed airflow is formed inside the high-temperature jet mill, such that the aluminum nitride formed on the surface of the pure aluminum material by the reaction collides in the high-temperature jet mill because of the high-speed airflow to pulverize into aluminum nitride powder.

4. (canceled)

5. The method for producing aluminum nitride according to claim 1, wherein the nitrogen-containing gas further contains argon or other noble gases.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0029] FIG. 1 is a flow chart of the method for producing aluminum nitride according to one embodiment of the present disclosure.

[0030] FIG. 2 is a schematic diagram of the high-temperature jet mill according to one embodiment of the present disclosure.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] The technical solutions, features and effects of the disclosure is to clearly describe in the description of embodiments referring to the figures below.

[0032] As shown in FIG. 1, the preparing method according to one embodiment of the present disclosure is as the followings:

[0033] (1) Nitrogen-containing gas and a pure aluminum material are to inject into a high-temperature jet mill (step 101).

[0034] (2) In the high-temperature jet mill, the injected pure aluminum material reacts with the nitrogen and forms aluminum nitride on the surface, and the aluminum nitride is continuously pulverized in the high-temperature jet mill so as to form fine aluminum nitride powder (step 102);

[0035] (3) After removing the aluminum nitride on the surface, remained liquid aluminum material without reacting with nitrogen continuously reacts with the nitrogen and forms aluminum nitride on the surface again and, as with step 102, is to pulverize again. Thus, it is continuously to react and to pulverize until all the liquid pure aluminum material is completely to consume (step 103).

[0036] FIG. 2 shows the high-temperature jet mill 1 of the disclosure. The jet mill may include the following five modules. They are at least one pulverizing chamber 11 operating in vacuum, a high-pressure jet module 12 connected with the pulverizing chamber 11, a high-temperature controlling and supplying module 13 connected with the pulverizing chamber 11, a gas supplying module 14 connected with the high-pressure jet module 12, and an aluminum supplying module 15 connected with the high-pressure jet module 12. The gas-supplying module 14 is capable of supplying nitrogen, argon or some other noble gases, and the aluminum-supplying module 15 is to configure for importing powder-shaped or particle-shaped pure aluminum.

[0037] The high-pressure jet module 12 is capable of injecting the nitrogen-containing gas provided by the gas supplying module 14 into the pulverizing chamber 11 by a high-pressure gas, and a high-speed airflow is formed inside the pulverizing chamber 11. The high-temperature controlling and supplying module 13 is capable of controlling the temperature inside the pulverizing chamber 11 to be within the range of 6602200 C., such that the temperature in the pulverizing chamber 11 is higher than the melting point of pure aluminum material and is lower than the melting point of aluminum nitride. When the pure aluminum material enters the pulverizing chamber 11, since the temperature is higher than the melting point of the pure aluminum material, the pure aluminum melts into liquid phase), and pure aluminum material generally begins to react with nitrogen at 500 C., and during 500600 C., the surface oxide films of aluminum particles are removed because of the forming of volatile sub-oxides. The higher temperature in the pulverizing chamber 11 may correspond to faster rate of the forming of the aluminum nitride. Therefore, in one embodiment of the present disclosure, the reaction is performed between 6602200 C.

[0038] In addition, since the standard heat of formation (H.sub.298) of aluminum is 318 kJ/mol, such that the compound (aluminum nitride) is to form only when the ambient of the pulverizing chamber 11 can reach 318 kJ/mol, allowing for the reaction of 2Al.sub.(l)+N.sub.2(g).fwdarw.2AlN.sub.(s). As compared to conventional aluminum powder direct nitriding method, the differences are that the pulverizing chamber 11 of the disclosure can replace the ball-milling treatment in conventional methods. Since the reaction temperature in conventional aluminum powder direct nitriding method is 726.85 C.1226.85 C., and conventional aluminum powder direct nitriding method can be rapidly completed under 1550 C. However, in order to increase the conversion rate and prevent powder agglomeration (fusion), the reaction in the conventional aluminum powder direct nitriding method can be realized under a lower temperature (<1227 C.), which may still result in the problem of fusion. For such problem to be resolved, multiple ball milling could be required.

[0039] In the present disclosure, the pulverizing chamber 11 can replace conventional ball-milling treatments, such that ball milling does not need. In addition, even if the temperature of the pulverizing chamber 11 is controlled to be higher than 1227 C., aluminum nitride can still be pulverized, so that the liquid pure aluminum material can react with the nitrogen and form aluminum nitride on the surface and be pulverized again until all the liquid pure aluminum material is completely consumed. Thus, the present disclosure allows for the application of a higher reaction temperature, which could accelerate the forming of the aluminum nitride, provided that the reaction temperature of the pulverizing chamber 11 cannot be higher than 2200 C., at which point the formed aluminum nitride powder will be melted.

[0040] According to the present disclosure, the high-temperature jet mill 1 is identical to conventional airflow pulverizers, and the only difference is that a module for high-temperature supplying and controlling is to add. The devices that could realize the high-temperature and high-speed airflow inside while the raw material is pulverized for that materials to be colliding with each other falls within the scope which the disclosure seeks to protect.

[0041] According to the method for preparing aluminum nitride of the present disclosure, as compared with other conventional techniques, there are advantages as the followings:

[0042] 1. According to the present disclosure, the aluminum nitride formed under high temperature is to pulverize, such that the aluminum nitride layer is to pulverize during the reaction, which can solve the problem that nitrogen cannot permeate into the powder and aluminum powder cannot be completely nitrided.

[0043] 2. According to the present disclosure, unnecessary cost and complex processes for solving the problem of high temperature melting agglomeration is to avoid. Therefore, the method disclosed according to the present disclosure is a different from its conventional counterparts.

[0044] Note that the specifications relating to the above embodiments should be construed as exemplary rather than as limitative of the present disclosure. The equivalent variations and modifications on the structures or the process by reference to the specification and the drawings of the disclosure, or application to the other relevant technology fields directly or indirectly should be construed similarly as falling within the protection scope of the disclosure.