Method for Manufacturing Alpha Alumina Powders and Applications Thereof

Abstract

A method for fabricating an α-Al2O3 powder with a size distribution substantially ranging from 30 nm to 100 nm, wherein the method comprises the following steps: First, at least one transition phase Al2O3 crystallite is provided, and then a coating process is conducted on the Al2O3 crystallite coating an aluminum compound on the Al2O3 crystallite to form a plurality of agglomerates having a size distribution substantially ranging from 50 nm to 200 nm. Subsequently, the agglomerates are thermally treated to form α-Al2O3 powder.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing aspects and many of the attendant advantages of this invention will become more readily appreciated as the same becomes better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein:

FIG. 1 illustrates the particles size distribution curve of the core (θ-Al₂O₃ crystallites)-shell (boehmite) agglomerates in accordance with the embodiment 1.

FIG. 2 illustrates the differential thermal analysis (DTA) profile conducted on the core-shell agglomerates during the thermal treatment of the Embodiment 1.

FIG. 3 illustrates the X-ray diffraction (XRD) pattern of the α-Al₂O₃ powders provided by the Embodiment 1.

FIG. 4 illustrates the transmission electron microscopy (TEM) micrograph of the α-Al₂O₃ powders provided by the Embodiment 1.

FIG. 5 illustrates the X-ray diffraction (XRD) pattern of the α-Al₂O₃ powders provided by the Embodiment 2.

FIG. 6 illustrates the transmission electron. microscopy (TEM) micrograph of the α-Al₂O₃ powders provided by the Embodiment 2.

FIG. 7 illustrates the X-ray diffraction (XRD) pattern of the α-Al₂O₃ powders provided by the Embodiment 3.

FIG. 8 illustrates the transmission electron. microscopy (TEM) micrograph of the α-Al₂O₃ powders provided by the Embodiment 3.

Claims

1. A method for fabricating an α-Al2O3 powder with a size substantially ranging from 30 nm to 100 nm, comprising: providing at least one transition phase Al2O3 crystallite;conducting a coating process, coating an aluminum compound on the transition phase Al2O3 crystallite to form a plurality of agglomerates having a size substantially ranging from 30 nm to 200 nm; andthermally treating the agglomerates.

2. The method according to claim 1, wherein the transition phase Al2O3 crystallite is selected from the group consisting of a θ-Al2O3 crystallite, a δ-Al2O3 crystallite, a κ-Al2O3 crystallite, an χ-Al2O3 crystallite, a γ-Al2O3 crystallite and the arbitrary combination thereof.

3. The method according to claim 1, wherein the aluminum compound is selected form the group consisting of boehmite, gibbsite and the combination thereof.

4. The method according to claim 1, wherein the coating process comprises: neutralizing an aqueous solution containing inorganic aluminum salt to form boehmite; andprecipitating boehmite over the transition phase Al2O3 crystallite.

5. The method according to claim 4, wherein the inorganic aluminum salt is selected form the group consisting of (Al(NO3)3.9H2O), Al(SO4)3 and the combination thereof.

6. The method according to claim 1, wherein the coating process comprises: hydrolyzing an aluminum alcoholate to form boehmite; andprecipitating boehmite over the transition phase Al2O3 crystallite.

7. The method according to claim 6, wherein the aluminum alcoholate is selected form the group consisting of aluminum isopropoxide, aluminum isobutoxide and the combination thereof.

8. The method according to claim 1, wherein each of the agglomerates substantially comprises 10% to 50% the transition phase Al2O3 crystallite by weight.

9. The method according to claim 1, wherein the thermal treatment is conducted under an operation temperature substantially ranging from 1,000° C. to 1,200° C.

10. The method according to claim 1, wherein the agglomerates provided by the coating process comprises a core-shell structure.

11. An Al2O3 agglomerate with a particle size substantially ranging from 50 nm to 200 nm, comprising: a transition phase Al2O3 crystallite; andan aluminum compound coating over the Al2O3 crystallite.

12. The Al2O3 agglomerate according to claim 1, wherein the aluminum compound is selected form the group consisting of boehmite, gibbsite and the combination thereof.

13. The Al2O3 agglomerate according to claim 1, wherein the Al2O3 crystallite is selected from the group consisting of a θ-Al2O3 crystallite, a δ-Al2O3 crystallite, a κ-Al2O3 crystallite, an χ-Al2O3 crystallite, a γ-Al2O3 crystallite and the arbitrary combination thereof.

14. The Al2O3 agglomerate according to claim 1, wherein the agglomerate substantially comprises 10% to 50% the transition phase Al2O3 crystallite by weight.

15. The Al2O3 agglomerate according to claim 1, wherein the agglomerate is constructed by a core-shell structure particle.

16. The Al2O3 agglomerate according to claim 1, wherein the agglomerate is constructed by a plurality of core-shell structure particles.